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IPSL-Perm-LandN: improving the IPSL Earth System Model to represent permafrost carbon-nitrogen interactions
No full textInternational audienceAbstract. Permafrost soils have the potential to release large amounts of soil carbon to the atmosphere under climate change. However, in the Sixth Coupled Model Intercomparison Project (CMIP6), only two Earth System Models (ESM) represented permafrost carbon, both sharing the same land surface model. This makes future permafrost carbon dynamics highly uncertain and underscores the urgent need to include permafrost carbon in ESMs to enable more reliable future projections of climate change and remaining carbon budget estimates. Here, we present IPSL-Perm-LandN, an improved version of the Institut Pierre-Simon Laplace (IPSL) ESM (used for CMIP6) aiming at better representing high-latitude land ecosystems. The main developments are the inclusion of an explicit nitrogen cycle and of key permafrost physical and biogeochemical processes. The latent heat associated with soil water freeze/thaw is taken into account in the energy budget, as well as soil thermal insulation by soil organic matter and a surface organic layer (e.g. litter or moss). Soil organic carbon and nitrogen are vertically resolved with depth-dependent decomposition dynamics, a key feature for representing the effect of gradual permafrost thaw on soil biogeochemistry. Cryoturbation is represented as a diffusion process that buries organic matter in the deeper soil layers. Compared to the previous version of the model used for CMIP6, we show that the extent of the permafrost region has improved significantly and that the simulated active layer thickness in the Arctic is in better agreement with observations. Permafrost soil carbon stocks have increased 20-fold to reach 1006 PgC in the top 3 m of soil, which is consistent with observation-based estimates. We simulate that the permafrost region has been a net carbon sink over the past 150 years (+0.32 ± 0.04 PgC yr−1 on average between 2005 and 2014), primarily due to carbon uptake from boreal forests. This is comparable with recent pan-Arctic carbon balance estimates, when accounting for unrepresented processes in our model (fire and riverine carbon losses). Overall, the inclusion of permafrost processes has improved the response of the model to anthropogenic perturbations in high latitudes over the past century, marking a step forward in the representation of Arctic ecosystems
Cross-sectional study characterizing the porcine faecal microbiome in commercial farms
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Assessing the artificial radionuclide Cesium-137 spatial distribution in the Southern Hemisphere from lake sediment records
No full textInternational audienceWhen supported by a reliable geochronology, lake sediments provide important archives for environmental and climatic changes. Artificial radionuclides in general, and cesium-137 (137Cs) in particular, are frequently used to validate sediment chronologies over the past century. This review and meta-analysis assessed the spatial distribution and variability of 137Cs in lake records from the Southern Hemisphere, while also identifying geographical data gaps. The 137Cs profile shapes and inventories were compared and categorized, and their relationships with environmental variables were tested. The spatial distribution of available data reveals an imbalance in studies available across the Southern Hemisphere, with South America showing the greatest research coverage. While the sedimentation rate was identified as a key factor of 137Cs variability, two groups identified from the database presented high peak activities regardless of sedimentation rate, particularly in lakes located between 40°S and 50°S in Chile and Argentina. Lake geographic location (and their distance from nuclear test sites) appears to be the most influential factor explaining disparities in 137Cs deposition. Surprisingly, neither precipitation nor lake elevation showed a significant correlation with 137Cs peak activity
Cascaded Transfer: Learning Many Tasks under Budget Constraints
No full textMany-Task Learning refers to the setting where a large number of related tasks need to be learned, the exact relationships between tasks are not known. We introduce the Cascaded Transfer Learning, a novel many-task transfer learning paradigm where information (e.g. model parameters) cascades hierarchically through tasks that are learned by individual models of the same class, while respecting given budget constraints. The cascade is organized as a rooted tree that specifies the order in which tasks are learned and refined. We design a cascaded transfer mechanism deployed over a minimum spanning tree structure that connects the tasks according to a suitable distance measure, and allocates the available training budget along its branches. Experiments on synthetic and real many-task settings show that the resulting method enables more accurate and cost effective adaptation across large task collections compared to alternative approaches
CHEX-MATE: Relationship between X-ray and millimetre inferences of galaxy cluster temperature profiles
No full textInternational audienceThermodynamic profiles from X-ray and millimetre observations of galaxy clusters are often compared under the simplifying assumptions of smooth, spherically symmetric intracluster medium. These approximations lead to expected discrepancies in the inferred profiles, which can provide insights about the cluster structure or cosmology. Motivated by this, we present a joint XMM-\textit{Newton} and \textit{Planck} analysis of 116 CHEX-MATE clusters to measure , the ratio between spectroscopic X-ray temperatures and a temperature proxy derived from Sunyaev-Zel'dovich (SZ) pressures and X-ray densities. We considered relativistic corrections to the thermal SZ signal and implemented X-ray absorption by Galactic molecular hydrogen. The distribution has a mean of , with average changes of and when relativistic corrections and molecular hydrogen absorption are not included, respectively. The distribution is positively skewed, with the scatter mostly affected by cluster morphology: relaxed clusters are closer to unity and less scattered than mixed and disturbed systems. We find little or no correlation with redshift, mass, or temperature
Euclid preparation. 3D reconstruction of the cosmic web with simulated Euclid Deep spectroscopic samples
No full textInternational audienceThe ongoing Euclid mission aims to measure spectroscopic redshifts for approximately two million galaxies using the H line emission detected in near-infrared slitless spectroscopic data from the Euclid Deep Fields (EDFs). These measurements will reach a flux limit of in the redshift range , opening the door to numerous investigations involving galaxy evolution, extending well beyond the mission's core objectives. The achieved H luminosity depth will lead to a sufficiently high sampling, enabling the reconstruction of the large-scale galaxy environment. We assess the quality of the reconstruction of the galaxy cosmic web environment with the expected spectroscopic dataset in EDFs. The analysis is carried out on the Flagship and GAEA galaxy mock catalogues. The quality of the reconstruction is first evaluated using geometrical and topological statistics measured on the cosmic web, namely the length of filaments, the area of walls, the volume of voids, and its connectivity and multiplicity. We then quantify how accurately gradients in galaxy properties with distance from filaments can be recovered. As expected, the small-scale redshift-space distortions, have a strong impact on filament lengths and connectivity, but can be mitigated by compressing galaxy groups before skeleton extraction. The cosmic web reconstruction is biased when relying solely on H emitters. This limitation can be mitigated by applying stellar mass weighting during the reconstruction. However, this approach introduces non-trivial biases that need to be accounted for when comparing to theoretical predictions. Redshift uncertainties pose the greatest challenge in recovering the expected dependence of galaxy properties, though the well-established stellar mass transverse gradients towards filaments can still be observed
Genetic variation in molting time and its effects on growth and color traits in the Pacific blue shrimp Litopenaeus stylirostris
No full textInternational audienceTo grow and develop, shrimps must shed their exoskeletons. In shrimp an inter-individual variability in molting time is spread over about a week. The genetic basis of this variability and its implications for selective breeding programs to improve growth or quality traits remains largely unexplored.We estimated the effect of molting stage on genetic parameters of growth and color traits in the Pacific blue shrimp Litopenaeus stylirostris. As the variability of molting time may also be partly genetically determined, we estimated the heritabilities of molt stages and molting time under the hypothesis that some families may have the additive genetic potential to molt earlier (or later) than others.To address these questions, 1200 shrimp progenies (mean body weight 14.5 g) from 49 full- and half-sib families, bred according to a partly factorial design with double-sire insemination, were phenotyped over 3 successive days, 3 to 5 days before the full moon. Body weight, body length, head length and molt stage were recorded on uncooked shrimp and external color traits on uncooked or both uncooked and cooked shrimp.Molt stage had a significant phenotypic effect on all traits except for body length and head-to-length ratio. The heritability estimates for both growth and color traits were, however, similar in models with or without molting, and the estimated breeding values were highly correlated between these models.The heritability of molt stage with a four-class threshold model was low (0.07 [0.02–0.28]). When the stage classes were combined into just two to simplify the description of the molting process, the heritability of early or late molting was intermediate (from 0.16 [0.10–0.28] to 0.22 [0.13–0.40]), indicating that this trait is partly under additive genetic determinism rather than solely under environmental control. The genetic correlations of molting traits with body weight were not different from zero.These results are discussed for selective breeding practices and shrimp molting biology to consider in future study molting as a factor to improve selection practices for disease resistance, feed efficiency and robustness
PM2.5, Black Carbon and NO2 associations with rhinitis and asthma multimorbidity in adults: The Constances Cohort
No full textInternational audienceBackground: Rhinitis and asthma often co-occur; however, studies on their associations with air pollution have always considered them separately.Objective: We investigated the association between long-term air pollution exposure and rhinitis and asthma multimorbidity in adults.Methods: Data at inclusion from Constances, a large French population-based adult cohort were used. Current Rhinitis (CR) and Current Asthma (CA) were defined by questionnaire. Annual exposure to nitrogen dioxide (NO2), particulate matter ≤2.5 μm (PM2.5) and black carbon (BC) were estimated by linking participants' residential address to land-use regression models. Cross-sectional multinomial logistic regressions were performed between each air pollutant and CR alone, CA alone, and CR+CA (no-CR/no-CA being the reference) adjusted for age, sex, smoking, education level and French deprivation index.Results: Among the 177,968 participants included in the analyses (mean age: 47 yrs., 54% females), 111,108 (62%) were classified as no-CR/no-CA, 49,971 (28%) CR alone, 6,435 (4%) CA alone, and 10,454 (6%) CR+CA. One interquartile range (IQR) increase of BC and NO2 was significantly associated with the three phenotypes, with adjusted ORs from 1.04 to 1.13 for BC (IQR: 0.55 10-5.m-1), and from 1.06 to 1.14 for NO2 (IQR: 13.7 μg.m-3). For PM2.5, one IQR increase (4.09 μg.m-3) was significantly associated with CR alone and CR+CA. In all our analysis, the highest associations were observed for CR alone.Conclusion: Our results show that long-term air pollution is more associated with rhinitis alone or with asthma multimorbidity than with asthma alone
Hair stress hormones in individuals with a recent suicide attempt experiencing a depressive episode
No full textInternational audienceBackground: Stressful events and dysregulation of the hypothalamic-pituitary-adrenal (HPA)-axis contribute to the risk of suicide attempt (SA) in persons in depressive episodes. Hair cortisol, cortisone and dehydroepiandrosterone (DHEA) concentrations may serve as reliable indicators of HPA axis dysregulation prior to SA. Methods: Participants (n = 75; mean age [standard deviation] = 30.0 [10.2] years; n = 49 [65 %] women; Jena site) comprised three groups: individuals with a history of SA approximately one month (SA; n = 22); individuals with a current depressive episode without SA history (CC; n = 31) and healthy individuals (HC; n = 22). SA was defined as self-initiated, potentially injurious behavior accompanied by some intent to die. Stress hormones were measured using LC-MS/MS protocol (days from sampling to analysis = 342 [171]) and logarithmic transformed. Group differences in hair stress hormones with hair segments representing time were tested using linear mixed models on a p < .05 threshold. Exploratory models further examined the effects of childhood abuse, frequency of SAs, suicide intent level and impulsiveness of the last SA of mean hormone levels, on a corrected p corr < .012 threshold.Results: There was a main effect of group for the DHEA-log (p = .02) and post-hoc tests indicated that SA group had higher DHEA compared to CC (p corr = .01) and HC (p corr = .08) in the peri-suicidal period. There were no significant (p < .05) interaction or group effects on cortisol-log and cortisone-log. Preliminary exploratory analyses showed that SA with multiple attempts had higher mean DHEA-log compared to SA with a single suicide attempt (p uncorr = .05). Furthermore, there were positive associations between level of suicide intent and both mean cortisol-log (p uncorr = .02) and mean cortisone-log (p uncorr = .02). Childhood abuse and impulsiveness of the last SA were not related to hair stress hormones. Conclusions: Individuals with a recent history of SA showed alterations in the DHEA hair levels. These results partially support dysregulation of the HPA axis as a biopsychosocial feature of SA. Future longitudinal and experimental studies should investigate whether hair HPA axis hormones can serve as markers of suicidal crisis and vulnerability.</div
Low-redshift 3D Lyman-α Forest Correlations with China Space Station Telescope
No full textInternational audienceWhile the Lyman- (Ly) forest traces the large-scale matter distribution over a wide range of redshift, its three-dimensional (3D) clustering at has not yet been measured. We investigate the prospects for measuring low-redshift Ly correlations with the UV slitless spectroscopic instrument of the China Space Station Telescope (CSST). We construct mock CSST quasar spectra that reproduce the expected survey depth, spectral resolution and noise properties, and derive Ly auto-correlation functions and cross-correlations with quasars (QSO) and emission-line galaxies (ELG) in the range . We then interpret these three-dimensional correlation functions with a standard anisotropic redshift-space clustering model and obtain forecast constraints on the Ly and tracer parameters. At an effective redshift (1.58 for ELGs), the Ly bias parameters will be measured with a 10-30% precision, depending on priors on other tracer's biases. We also forecast a marginal () detection of the BAO feature, corresponding to a 10% (7%) constraint on the isotropic BAO scale, from the combination of Ly auto- and Ly-QSO (ELG) cross-correlations. These results show that CSST can provide the first three-dimensional characterization of the low-redshift Ly forest and a complementary Ly-based BAO measurement at , helping to link galaxy clustering surveys with high-redshift Ly forest studies