Search results for "MBL"
showing 10 items of 1636 documents
Seasonal reproducibility and predictability of the West African Monsoon in coupled GCMs
2009
In the framework of the ENSEMBLES FP6 project, an ensemble prediction system based on five different state-of-the-art European coupled models has been developed. This study evaluates the performance of these models for forecasting the West African monsoon (WAM) at the monthly time scale. From simulations started the 1 May of each year and covering the period 1991–2001, the reproducibility and potential predictability (PP) of key parameters of the WAM—rainfall, zonal and meridional wind at four levels from the surface to 200 hPa, and specific humidity, from July to September—are assessed. The Sahelian rainfall mode of variability is not accurately reproduced contrary to the Guinean rainfall …
Structural characterization of 2,2-di-n-butyl-4-methyl-1,3,2-dioxastannolane isolated from supercritical CO2 conditions
2009
The title compound has been isolated as single crystals from the synthesis of propylene carbonate from racemic 1,2-propanediol and carbon dioxide using n-Bu2SnO as a catalyst precursor. The X-ray crystallographic structure analysis revealed the self-assembly of di-n-butyltin(IV) 1,2-propanediolate units, linked together through long-distance Sn-O interactions leading to a one-dimensional polymeric architecture organized in a syndiotactic arrangement. The coordination geometry around the tin atoms can be described as an unusual faced-capped trigonal bipyramidal environment.
Functionalised Imidazoporphyrins and their application in catalysis
2017
A broad series of functionalized imidazo[4,5-b]porphyrins was synthesized by the acid-catalyzed condensation of 2,3-dioxo-5,10,15,20-tetraarylchlorins with aromatic aldehydes. Both steric and electronic features of meso-aryl substituents influence on the product yield ranging from 18% to 90%.Single-crystal X-ray diffraction analysis of the structure of zinc(II) 5,10,15,20-tetramesityl-2-(4-pyridyl)-1H-imidazo[4,5-b]porphyrinate showed that this compound forms 1D coordination chains in the solid state.The post-synthetic modifications of imidazo[4,5-b]porphyrins were investigated by performing the Suzuki-Miyaura coupling reaction, preparing water-soluble imidazoporphyrins and linear/angular b…
Arbres couvrants presque disjoints
2015
International audience; Dans un réseau, la recherche de plusieurs arbres couvrants avec des propriétés intéressantes a amené à l'introduc-tion de plusieurs notions : les arbres couvrants arête-disjoints, les arbres indépendants enracinés en un sommet et les arbres complètement indépendants. Afin de généraliser ces notions, nous introduisons la notion d'arbres couvrants (i, j)-disjoints, où i et j sont respectivement le nombre maximum de noeuds internes et d'arêtes communs aux arbres couvrants. Nous montrons que déterminer s'il existe deux arbres couvrants (i, j)-disjoints dans un graphe G est un problème NP-complet pour i et j quelconques, et nous déterminons les valeurs minimales de i et j…
Magnetic Control over the Fractal Dimension of Supramolecular Rod Networks
2021
<p>Controlling supramolecular polymerization is of fundamental importance to create advanced materials and devices. Here we show that the thermodynamic equilibrium of Gd<sup>3+</sup>-bearing supramolecular rod networks is shifted reversibly at room temperature in a static magnetic field of up to 2 T. Our approach opens opportunities to control the structure formation of other supramolecular or coordination polymers that contain paramagnetic ions.</p>
Stratégie de sortie du glyphosate : audition du PDG de l'INRA et des experts. Communication orale à l’Assemblée Nationale le 13 février 2020
2020
International audience; Statégie de sortie du glyphosate : audition du PDG de l'INRA
Consequences of sown grass margin strip on weed flora
2010
The intensification of the management of weed populations, led by a potential decrease in the yield and quality of crop harvest, has largely induced their decline in arable zones across the last decades. This floristic decline in arable landscape, has induced a loss of a larger biodiversity because the presence of others organisms (birds, insects, mammals) are strongly linked with the abundance of trophic resources as weed are. To counter with this loss of biodiversity and to limit the negative impacts of farming practices on environment, numerous agri environmental schemes were launched through Europe. In France, sown grass strips were established by farmers along streams and rivers to lim…
Dynamique et assemblage des communautés adventices : Approche par modélisation statistique
2011
To develop solutions for a productive and sustainable agriculture, principles, theories, andmethods of ecology may contribute to understand the biological processes governing the agroecosystem.The present case study was based on data collected by a network of observatories of weeds covering the whole of France (‘Biovigilance Flore’) and aimed at establishing forrules governing the assemblage and dynamics of weed communities in fields grown with annual crops. We particularly studied the possible relationships between species within acommunity, as well as the relationships between communities and their environment. Analyses were based on species abundances to take account of their effect on c…
Deciphering biotic interactions and their role in soil microbial community assembly
2021
National audience; Soil microbial communities play key roles in ecosystem functioning. Yet, little is known aboutthe importance of microbe-microbe interactions in soil microbial community assembly andfunctions. To address this knowledge gap, the objective of my thesis is to assess the role ofinteractions between micro-organisms in soil microbial communities. For this purpose, we willmanipulate the interactions between microorganisms within complex soil microbialcommunities by (i) removing different members of the soil community, (ii) adding microbialtaxa to the soil community and (iii) increasing the physical distance between members of thesoil community. How shifts in microbial interaction…
Weed communities in conservation agriculture: what really changes?
2022
Conservation agriculture (CA) has been identified as one of the farming systems likely to deliver sustainable agriculture but its effects over time on the diversity and composition of weed communities are still discussed. For ten years, different studies were carried out in in East of France in cropping system with short rotations essentially composed with winter crops. The objective of these different studies was to identify, focusing on the transition period, the changes in the composition of communities and the consequences in terms of agronomic risk in CA systems. Using networks of 100 winter wheat fields selected to encompass a gradient of years in CA (1 to 20 years), the changes that …