Archive Ouverte d'INRAE
Not a member yet
513551 research outputs found
Sort by
Beyond species means – the intraspecific contribution to global wood density variation
No full textInternational audienceWood density is central for estimating vegetation carbon storage and a plant functional trait of great ecological and evolutionary importance. However, the global extent of wood density variation is unclear, especially at the intraspecific level. We assembled the most comprehensive wood density collection to date, including 109 626 records from 16 829 plant species across woody life forms and biomes (GWDD v.2, available here: doi: 10.5281/zenodo.16919509 ). Using the GWDD v.2, we explored the sources of wood density variation within individuals, within species and across environmental gradients. Intraspecific variation accounted for c . 15% of overall wood density variation (SD = 0.068 g cm −3 ). Variance was 50% smaller in sapwood than heartwood, and 30% smaller in branchwood than trunkwood. Individuals in extreme environments (dry, hot and acidic soils) had higher wood density than conspecifics elsewhere (+0.02 g cm −3 , c . 4% of the mean). Intraspecific environmental effects strongly tracked interspecific patterns ( r = 0.83) but were 70–80% smaller and varied considerably among taxa. Individual plant wood density was difficult to predict (root mean square error > 0.08 g cm −3 ; single‐measurement R 2 = 0.59). We recommend (1) systematic sampling of multiple individuals and tissues for local applications, and (2) expanded taxonomic coverage combined with integrative models for robust estimates across ecological scales.La densidad de la madera es fundamental para estimar el almacenamiento de carbono vegetal y constituye un rasgo funcional de gran importancia ecológica y evolutiva. Sin embargo, el alcance global de la variación de la densidad de madera no está claramente descrito, especialmente a nivel intraespecífico. Recopilamos la colección más completa de densidad de madera hasta la fecha, que incluye 109 626 registros de 16 829 especies de plantas leñosas de diversas formas de vida y biomas (GWDD v.2, disponible aquí: doi: 10.5281/zenodo.16919509 ). Utilizando la GWDD v.2, exploramos las fuentes de variación en la densidad de la madera entre individuos y especies, así como a través de gradientes ambientales. La variación intraespecífica representó aproximadamente el 15% de la variación total de la densidad de la madera (SD = 0.068 g cm −3 ). La varianza fue un 50% menor en la albura que en el duramen, y un 30% menor en la madera de ramas que en la del tronco. Los individuos en ambientes extremos (secos, cálidos, suelos ácidos) presentaron una densidad de madera mayor que sus congéneres en otros lugares (+0.02 g cm −3 , ~4% de la media). Los efectos ambientales intraespecíficos siguieron estrechamente los patrones interespecíficos ( r = 0.83), sin embargo, resultaron entre un 70% y un 80% menores y variaron considerablemente entre los taxones. La densidad de madera por individuo fue difícil de predecir (RMSE >0.08 g cm −3 ; R 2 de medición única = 0.59). Recomendamos (1) el muestreo sistemático intraespecífico de múltiples individuos para aplicaciones locales y (2) una cobertura taxonómica ampliada combinada con modelos integradores para obtener estimaciones robustas a través de las escalas ecológicas.La densité du bois est essentielle pour estimer le stockage de carbone de la végétation et constitue un trait fonctionnel d’une grande importance écologique et évolutive. Cependant, l’ampleur de la variation globale de la densité du bois reste mal caractérisée, en particulier au niveau intraspécifique. Nous avons rassemblé la base de données la plus complète à ce jour sur la densité du bois, comprenant 109 626 mesures provenant de 16 829 espèces de plantes ligneuses appartenant à diverses formes de vie et biomes (GWDD v.2, disponible ici: doi: 10.5281/zenodo.16919509 ). À l’aide de la GWDD v.2, nous avons exploré les sources de variation de la densité du bois au sein des individus, au sein des espèces et le long de gradients environnementaux. La variation intraspécifique représentait environ 15% de la variation totale de la densité du bois (SD = 0,068 g cm −3 ). La variance était 50% plus faible dans l’aubier que dans le duramen, et 30% plus faible dans le bois des branches que dans celui du tronc. Les individus vivant dans des environnements extrêmes (secs, chauds, sols acides) présentaient une densité du bois plus élevée que leurs congénères ailleurs (+0,02 g cm −3 , soit ~4% de la moyenne). Les effets environnementaux intraspécifiques reflétaient les tendances interspécifiques ( r = 0,83), mais étaient 70 à 80% plus faibles et variaient considérablement entre taxons. La densité du bois à l’échelle individuelle était difficile à prédire (RMSE >0,08 g cm −3 ; R 2 = 0,59). Nous recommandons (1) un échantillonnage systématique de plusieurs individus et tissus pour les applications locales et (2) un élargissement de la couverture taxonomique combiné à des modèles intégratifs afin d’obtenir des estimations robustes à travers les échelles écologiques
Attributable mortality of ICU-acquired bloodstream infections: Impact of the source, causative micro-organism, resistance profile and antimicrobial therapy
No full textInternational audienc
Unraveling how mycorrhizal inoculation shapes the wheat foliar transcriptome and enhances resistance to septoria tritici blotch
No full textInternational audienceArbuscular mycorrhizal fungi (AMF), known to form mutualistic associations with most terrestrial plant species, could represent promising ecological alternatives to agrochemicals, which are harmful to both human health and environment. Although most studies investigate the effectiveness of mycorrhizal symbiosis in controlling root diseases, its influence on foliar diseases is still poorly explored, particularly in wheat. A prior investigation conducted under controlled conditions revealed that inoculation with the AMF species Funneliformis mosseae (Fm) protects wheat leaves from both pathogenic fungi, the biotrophic Blumeria graminis f. sp. tritici, responsible for powdery mildew (Mustafa et al, 2016, 2017), and the hemibiotrophic Zymoseptoria tritici (Zt), causing septoria tritici blotch (STB). This protection seems to be linked to the activation of "Mycorrhiza-Induced Resistance" (MIR), facilitating the systemic induction of plant defenses mediated by AMF (Allario et al., 2025). Nonetheless, the metabolic alterations that contribute to this resistance are poorly understood. In this study, we performed transcriptomic analyses to investigate how mycorrhizal symbiosis impacts gene expression in wheat leaves, resulting in plant protection against STB. Leaves from 6-week-old seedlings, inoculated or not with Fm and/or Zt, were sampled to study gene expression, 48 hours after Zt spores inoculation. Transcriptomic data showed a systemic induction of numerous genes in leaves of mycorrhizal plants under non-infectious conditions, many of which were common to those induced by Zt inoculation in non-mycorrhizal plants. These genes were involved in proteolysis, antioxidant mechanisms and plant immune response, particularly linked to jasmonic acid and ethylene signalling pathways. This induction of specific defense mechanisms by Fm before Zt inoculation (cell wall thickening, stomatal closure, defense proteins, maintenance of homeostasis and cellular function) was later completed by a downregulation of genes participating in photosynthesis and chloroplastic functions in mycorrhizal plants under infectious conditions. Together, these findings highlight AMF potential to induce MIR in wheat through systemic and coordinated metabolic reprogramming, leading to STB symptom reduction.Keywords : Wheat, septoria tritici blotch, arbuscular mycorrhizal fungi, Mycorrhiza-Induced Resistance, transcriptomic analysis
Water losses: A productivity analysis of the water supply in Portugal
No full textInternational audienceEnvironmental concerns have increasingly influenced production processes, particularly in recent years, as natural resources become progressively scarce. Among these, water remains the most critical resource, further exacerbated by climate change and its associated challenges, such as frequent droughts, especially in warm and mild-climate regions like Southern Europe. This study analyzes the performance of the Portuguese water supply sector, focusing on a sample of 116 water utilities between 2013 and 2021, representing diverse geographic and management structures. The production process is conceptualized as a non-linear joint-production process, incorporating water losses as an undesirable output within performance evaluations. By applying exponential Hicks-Moorsteen and Malmquist indices within a non-parametric Data Envelopment Analysis framework, this study provides an assessment of the efficiency and productivity trends in the sector. The findings offer insights into how Portuguese water utilities manage resources under environmental and infrastructural constraints, with a focus on reducing water losses and enhancing sustainable practices
Climate shocks and banking sector stability: Evidence from El Niño southern oscillation
No full textInternational audienceThis study introduces a novel ex ante approach to assess the short-term impact of climate shocks on banking sector stability by examining the effect of El Niño Southern Oscillation (ENSO) on banking sector distance-to-default. Using dynamic panel data econometric modeling, we investigate the macroeconomic implications of ENSO-induced climate shocks, such as El Niño and La Niña events, on banking sector stability in 51 countries across three regions particularly exposed to the consequences of ENSO oscillations (East Asia and Pacific, Latin America and the Caribbean, and Sub-Saharan Africa) during the period 2000–2020. Our findings show that the adverse effects of these climate shocks on banking sector stability are unevenly distributed among countries, with more pronounced and robust adverse effects of El Niño events in the short-term, particularly in Latin America and the Caribbean and, to a lesser extent, Sub-Saharan Africa. We also document the short-term adverse effects of La Niña events for Latin American and the Caribbean countries. Further estimates suggest that the increase in non-performing loans is a key transmission channel linking El Niño events to banking sector stability. As global warming should intensify the frequency and magnitude of ENSO's cyclical pattern, these findings can help estimate the potential adverse effects of climate change-related natural disasters on banking sector stability and inform future mitigation and adaptation policies
Evidence for the absence of a relationship between inflammation and cognition in a cohort of 1565 individuals with bipolar spectrum disorders: a Bayesian analysis of network
No full textInternational audiencePrevious studies have reported variable associations between peripheral inflammatory markers and cognitive functioning in individuals with bipolar spectrum disorders (BSD), with some identifying significant links and others finding no relationship. Such inconsistencies raise important questions about the role of inflammation in cognitive impairment among individuals with BSD. This study aims to investigate the relationship between peripheral inflammatory markers and cognitive function in a clinical sample of individuals with BSD using a Bayesian network analysis framework. We analyzed data from a large cohort (n = 1565) focusing on hsCRP and a subsample (n = 249) that included concurrent assessments of additional cytokines including Interleukin-6 and Tumor Necrosis Factor-alpha. A Bayesian approach was utilized to quantify uncertainty regarding the presence or absence of associations between inflammation and cognitive function. Our findings revealed no significant associations between inflammatory markers and cognitive performance in both samples. Strong evidence was found supporting the absence of association, with network analysis indicating distinct clusters for cognitive and inflammatory variables, suggesting they function as independent constructs with limited interactions. In our clinical sample of individuals with BSD, our findings do not support a direct association between some inflammatory markers and cognition, aligning with studies that found minimal or no associations. Our study emphasizes the importance of utilizing Bayesian methods to assess these relationships rigorously and suggests further exploration of individual differences and subgroup effects in future research
Measuring shade use of dairy cattle at pasture with an on-cow light sensor: a case study
No full textInternational audienceGrazing cows preferentially access shade to shield against the sun. However, the conditions that provide cows with optimal shade access and use (e.g. no competition for access to shade) are still unknown. Continuous monitoring of shade use by grazing cattle could help to understand how and when cows use shade resources. The aim of this study was to validate a method based on a light sensor (HOBO Pendant MX2202) attached to the back (on the transverse processes of the lumbar vertebrae) of 7 dairy cows at pasture to continuously record their use of natural shade for research purposes. Live behavioral observations of shade use and cow posture were recorded in summer (June to September, between 9 am and 6 pm). Based on the behavioral observation data, we determined thresholds in lux to discriminate between cows in shade and cows in sun on a randomly-generated training dataset representing 15 % of the initial dataset. This process was repeated 100 times, generating 100 thresholds and threshold performances. Data loss due to sensor loss or battery discharge was 9 %, which is acceptable. The thresholds ranged from 15,688 to 40556 lx: sensitivity ranged from 92.0 % to 99.8 % and specificity ranged from 88.7 % to 99.9 %, showing that the performances were robust to threshold variation within this range. This study demonstrates that an efficient threshold to discriminate cows in shade from cows in the sun can be determined via a relatively short (about 12 h) series of live observations. As performances seem to be slightly lower for lying cows than for standing cows (mean false-positive rate is 7.4 % for lying cows versus 1.8 % for standing cows), future studies should consider the posture (which can also be monitored continuously with other sensors such as accelerometer installed on the legs or on the neck collar of the cows)
Simulation of shockless spalling fragmentation using the Discrete Element Method (DEM)
No full textInternational audienceIn the present study a Discrete Element Method (DEM) is considered to model the dynamic behaviour and fragmentation mechanisms of alumina ceramic under high strain-rate shockless loading. GEPI (high-pulsed power) spalling experiments are simulated. The DEM allows to take into account the accurate propagation and interaction of stress waves within the samples upon calibration of microscopic bond parameters. The results indicate that a standard failure criterion can effectively represent the spalling phenomenon, though discrepancies with experimental data increase at higher strain rates. To address this, the study combines the DEM approach with a damage law, specifically the first and second order Kachanov damage law, tomodel crack initiation and propagation. Comparative analysis with experimental rear face velocity profiles validates the approach. The strain-rate sensitivity of the present DEM model is explored using loading pulses of increasing intensity that induce different strain-rate levels. This research demonstrates that the DEM approach can effectively model dynamic behaviour in brittle solids leading to a multiple fragmentation sensitive to the strain rate
