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Analyzing the precision of discrete kernel regression by Bayesian modeling
No full textInternational audienceBayesian modeling is investigated in the nonparametric regression estimator using discrete kernels to provide information on the uncertainty of point estimates. The approach studied was applied to study the precision of posterior estimates of discrete simulated data and real data from experiments on fed fish and stock-recruitment salmon series. The discrete kernels considered were distinguished in the results according to goodness of fit and the extent to which the uncertainty of the parameters was taken into account. The approach studied benefited both from the robustness of nonparametric kernel method for estimating distributions of discrete data with small sample sizes and the ability of Bayesian modeling to conduct uncertainty analysis
Mon paysage quotidien est devenu une icône médiatique du changement climatique
No full textInternational audienceIt does not yet have the evocative force of the polar bear on the ice floe, but its media trajectory is gradually establishing it as an iconic image of climate change. This photograph is that of a bridge over the Loire, a fairly ordinary landscape after all, whose dissemination and especially interpretation require work of critical deconstruction.Elle n’a pas encore la force évocatrice de l’ours blanc sur la banquise mais sa trajectoire médiatique l’érige peu à peu comme une image iconique du changement climatique. Cette photographie est celle d’un pont sur la Loire, un paysage assez ordinaire somme toute, dont la diffusion et surtout l’interprétation nécessitent un travail de déconstruction critique
Tendances conjointes des évolutions thermiques et hydrologiques des rivières : implications pour une gestion durable des écosystèmes et de la ressource en eau dans les bassins versants
No full textInternational audienceClimate change has dramatically increased river temperatures and altered the spatiotemporal dynamics of flows, posing challenges for ecosystem functioning and water resources for anthropogenic uses. This communication proposes an overview of the results from several coupled hydrology-thermal-fish community modeling projects, analyses of observations in the Loire basin and outline future directions. Firstly, sensitivity of streams and rivers to atmospheric warming will be discussed according to thermal and hydrological regimes, their size, the cumulative impacts of reservoirs and shading. In a second step, the evolutions of the co-occurrences of high temperature and low flow will be presented over 57 years (1963-2019) and during the 21st century based on climate scenarios. These associations evolved heterogeneously across the basin, becoming more frequent in the southern basin in both winter and summer. Results on three emblematic migratory fish species will be presented in connection with the counts at fish monitoring stations located on the Loire River, Allier, Vienne and Creuse streams, and highlighting the differentiated role of hydro-climatic conditions. Thirdly, the communication will provide the main scientific obstacles, in particular on the prediction of spatio-temporal heterogeneities in the river temperature and the role of groundwater exchanges. The analysis of thermal infrared images on the Arroux and the Bourbince streams during a heatwave event (41°C) and severe low water in July 2019, will introduce the notions of thermal refuge of cooler water and the need to better locate and characterize them. The increase in the frequency of low flow and high temperature episodes could compromise water availability for human activities, such as drinking water production, irrigation and cooling of nuclear power plants. These results highlight the urgency of adopting more holistic local adaptation strategies (water uses, biogeochemistry, connectivities) to be able to meet the ecological and water resource availability challenges related to climate change.Le changement climatique a fortement augmenté la température des rivières et a modifié la dynamique spatio-temporelle des débits, ce qui pose des défis pour le fonctionnement des écosystèmes et les ressources en eau pour des usages anthropiques. Cette communication se propose de faire le point sur les enseignements tirés de plusieurs travaux de modélisations couplées hydrologie-thermie-communautés piscicoles et d’analyses des observations dans le bassin de la Loire. Dans un premier temps la sensibilité différente des cours d’eau au réchauffement atmosphérique, sera discutée en fonction des régimes thermiques et hydrologiques, de la taille des cours d’eau, des impacts cumulés des retenues, de la végétalisation des berges. Dans un second temps, les évolutions des co-occurrences de température élevée et de faible débit, seront présentées sur les 57 années de suivis (1963-2019) et de scénarios pour la fin du XXIème siècle. Ces associations ont évolué de manière hétérogène à travers le bassin, devenant plus fréquentes dans le sud du bassin en hiver et en été. Des résultats sur 3 espèces de poissons migrateurs emblématiques seront présentés en lien avec les comptages réalisés sur la Loire, l’Allier, la Vienne et la Creuse, et soulignant le rôle différencié des évolutions hydro-climatiques. Dans un troisième temps, la communication donnera les principaux verrous scientifiques, notamment sur la prédiction des hétérogénéités spatio-temporelles de la température des cours d’eau et le rôle des apports d’eau souterraines. L’analyse des images infrarouge thermique sur l’Arroux et la Bourbince lors d’un évènement caniculaire (41°C) et d’étiage sévère de juillet 2019, permettra d’introduire les notions de refuge thermique d’eau plus fraiche et la nécessité de mieux les localiser et les caractériser. L’augmentation de la fréquence de ces épisodes de bas débit et de températures élevés pourrait compromettre la disponibilité en eau pour les activités humaines, telles que la production d’eau potable, l’irrigation et le refroidissement des centrales nucléaires. Ces résultats soulignent l'urgence d'adopter des stratégies d’adaptation locales, plus holistiques (usages, biogéochimie, connectivités) pour pouvoir relever les défis écologiques et de disponibilité des ressources en eau liés au climat
Decomposition rates of Tea Bags in two agricultural systems under the climatic conditions of the Algerian Sahara
No full textInternational audienceAimsThis study is one of several preliminary attempts to measure decomposition rates in two different agricultural systems in the Algerian Sahara. The aim is to assess the degradation of soil organic matter dynamics in two agricultural systems (palm groves—PG and potato fields—PF).MethodsEmploying (Keuskamp et al. Methods Ecol Evol 4 (1070):1075 2013) protocol, two types of commercial teas (green tea and rooibos tea) were used to determine the rate of organic matter decomposition (K) and the stabilization factor (S). The chosen soils are two distinct agrosystems located in two regions: El-Oued (E) and Oued Righ (O), where forty-eight pairs of tea bags were buried. The findings show that green tea decomposed faster than rooibos tea in both PG and PF.ResultsThe remaining mass in PG ranged from 43.2% (O) to 45.5% (E) for green tea, while the values for rooibos tea were 85.2% (Site O) and 89.7% (Site E). In the PF, the remaining mass for green tea was 38.6% (Site E) and 38.6% (Site O), while for rooibos tea, it was 63.5% (Site E) and 64.2%. Importantly, PF had significantly higher decomposition rates (K = 0.026 g.g−1.day−1) than PG (K = 0.005 g.g−1.day−1).ConclusionSoil variables in arid regions, such as electric conductivity (EC), pH, CaCO3, and sandy texture, all play an important role in carbon decomposition. This process is more rapid in PF soils than in PG soils. These findings emphasize the importance of developing land use management strategies to improve soil properties in Saharan agrosystem
AVATAR-SOL, une méthode en développement pour évaluer l'impact des pratiques de gestion sur l'activité biologique des sols
No full textInternational audienceAVATAR-SOL est une méthode d’évaluation de l’activité biologique actuellement en développement grâce au soutien de l’ADEME (projet BIOSOL-EVAL - 2025-2028). Elle se distinguera des solutions actuelles par son faible coût, sa facilité d’usage, son adossement à un référentiel d’interprétation et à une solution digitale d’analyse in-situ. La solution de diagnostic AVATAR-SOL est basée sur un film biodégradable inséré dans un squelette rigide. L'activité biologique du sol est estimée en mesurant la dégradation du film après incubation dans le sol durant quatre à six semaines. AVATAR-SOL comprend un module permettant de corriger des conditions météorologiques durant l’incubation in situ ainsi qu’un référentiel d’interprétation pour qualifier le niveau d’activité biologique.Pour construire le référentiel, des incubations seront menées dans une grande diversité́ de contextes agro-pédo-climatiques, dans une démarche de science ouverte. 182 dispositifs de recherche expérimentaux hautement instrumentés et plus de 200 parcelles testant des pratiques de gestion contrastées chez des partenaires non académiques seront ainsi mobilisés. Nous développerons également une application web/mobile de captation et analyse des données sur le terrain fournissant directement à l’utilisateur le niveau de qualité biologique de son sol
Empowering Bioinformatics Communities with nf-core: The success of an open-source bioinformatics ecosystem
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Urban tree architectural modifications over the growing season and water restriction significantly contribute to variations in climate services
No full textInternational audienceStreet trees have gained attention for improving thermal comfort in cities, yet seasonal changes in tree services in relation to the evolution of tree architecture are not well understood. This study hypothesizes that over a growing season and for sunny days, changes in climate services primarily rely on tree architecture influence on castshadow, especially during summer droughts. Two alignments of ornamental apple trees were grown in a reduced-scale street canyon, with a non-vegetated control zone. All trees were well watered until July 5th, 2022, after which one alignment experienced moderate water restriction while the other remained well-watered. The street microclimate was characterized, the universal thermal climate index (UTCI) calculated, and tree architecture at the organ and crown scales was measured. On sunny days, well-watered trees improved thermal comfort from 5.8 • C UTCI in mid-May to 7.9 • C in late August, while water restriction reduced this benefit by up to 2.7 • C UTCI after 8 weeks. The changes in thermal comfort were primarily linked to tree architectural development and cast-shadow, although these effects were moderate due to leaf area index high enough in May to ensure 87.5 % of interception of radiation. Increases in crown projected area and volume enhanced tree services, with larger effects on the side than just below the tree canopy. Water restriction diminished thermal comfort by inhibiting stem growth and accelerating leaf fall, thus reducing light interception. This study highlights the significant role of architectural plasticity in tree climate services under water restriction, warranting further research in other species
Flavonoid compounds as a way to identify sources of carrot resistance to Alternaria leaf blight
No full textInternational audienceBreeding varieties that are highly resistant to Alternaria leaf blight is crucial to enable carrot growers to drastically reduce their use of synthetic fungicides. Some sources of resistance have been identified in recent years, but in limited number and the genetic control as well as the screening for resistance remain complex and tedious. Flavonoid compounds have been reported to be involved in plant resistance to biotic or abiotic stresses. Their level of variation could therefore be a way of assisting screening activities for resistance. The aim of the study is to validate this link throughout the carrot growth cycle, in various environments and across a wide genetic diversity. A kinetic study showed that three flavonoid compounds are differentially accumulated between resistant and susceptible accessions as early as the 2-leaf stage and all along the plant development. Moreover, this differential is maintained throughout the potential infectious process in different environments. The analysis of a large range of accessions representing a very wide diversity of geographical origins, genetic structures, breeders and varietal types validates the link between resistance and the content in flavonoid compounds. These results open up extremely interesting prospects for the development of a marker-assisted early selection tool that would facilitate the screening and introgression of resistances into elite material, a complex task due to the polygenic control of resistance and biennial nature of the crop
Le pôle pour la gestion des migrateurs amphihalins dans leur environnement (MIAME) Bilan d'activité 2019-2024
No full textInternational audienceLes amphihalins, espèces qui effectuent leurs cycles biologiques entre les milieux marins et dulçaquicoles, font l’objet de préoccupations et de mesures de protection grandissantes. Le pôle pour la gestion des MIgrateurs AMphihalins dans leur Environnement (MIAME) rassemble des compétences scientifiques et techniques uniques en France. Ses travaux ont une vocation opérationnelle pour la préservation de cette biodiversité remarquable et de ses habitats. Ce numéro spécial de la revue Science Eaux & Territoires présente une sélection des résultatsacquis sur la période 2019-202
Effect of transglutaminase on Maillard browning of lactose-free milk powder
No full textInternational audienceLactose intolerance is a clinical condition of the alimentary tract characterized by an individual's inability to digest and absorb lactose. This condition affects a non negligeable proportion of worldwide population. Thus, many dairy products have been developed by hydrolysing lactose. Hydrolysed milk in powder is not only challenging to produce due to problems related to caking, adherence to the chamber during spray drying and but also shows browning during storage. The application of enzymes such as transglutaminase (TGase) may have the potential to delay browning by rendering lysine unavailable, as it would be involved in the cross-linking process (Salunke & Metzger, 2023; Chen et al., 2021; Francisquini et al., 2024). Thus, this study aims to evaluate the impact of TGase addition on the browning of lactose-hydrolysed powders. Different skimmed milk powders (control, with lactase, with TGase, with lactase and TGase) were produced at pilot scale and stored in controlled conditions (40 °C). They were sampled at different times during storage (0, 0.5, 1, 2 months) and analysed. The degree of polymerization (DP) of milk proteins was evaluated by size-exclusion chromatography. Targeted Maillard reaction markers (lactose, glucose, glucose as precursors and furfural, 5-methylfurfural, 2-furylmethylketone, furfuryl alcohol, 5-hydroxymethylfurfural as intermediate compounds) were quantified by chromatography. The degree of browning was determined by colorimetry. This approach makes it possible to explain the individual and synergistic role of precursors and enzymes together on reaction pathways. The extent of cross-linking of proteins by Tgase was confirmed and the hydrolysis of lactose into glucose and galactose was observed as expected. The results also show the apparent difference in the rates of precursors consumption and furanic compounds generation in different powders. These kinetic data enable not only a clearer understanding of the Maillard reaction in lactose-hydrolysed milk powders but could also be used for further kinetic modelling