Optical determination and identification of organic shells around nanoparticles: application to silver nanoparticles

We present a simple method to prove the presence of an organic shell around silver nanoparticles. This method is based on the comparison between optical extinction measurements of isolated nanoparticles and Mie calculations predicting the expected wavelength of the Localized Surface Plasmon Resonance of the nanoparticles with and without the presence of an organic layer. This method was applied to silver nanoparticles which seemed to be well protected from oxidation. Further experimental characterization via Surface Enhanced Raman Spectroscopy (SERS) measurements allowed to identify this protective shell as ethylene glycol. Combining LSPR and SERS measurements could thus give proof of both presence and identification for other plasmonic nanoparticles surrounded by organic shells

Ionization states of metallic elements in a quiescent prominence

Inthe frame of the Joint Observing Program 133, which was run during the 6th MEDOC Campaign, a quiet prominence was observed on the 1st of November 2000, between17:30-20:00 UT. From the data we obtained, we want to characterize the emission line profiles and to study the different ionization states of many chemical elements present in the cool plasma of the observed prominence. We also intend to analyze the macroscopic velocities of the material and compare the results with theoretical calculations

Spatial multi-criteria decision analysis to predict suitability for African swine fever endemicity in Africa

Background African swine fever (ASF) is endemic in several countries of Africa and may pose a risk to all pig producing areas on the continent. Official ASF reporting is often rare and there remains limited awareness of the continent-wide distribution of the disease. In the absence of accurate ASF outbreak data and few quantitative studies on the epidemiology of the disease in Africa, we used spatial multi-criteria decision analysis (MCDA) to derive predictions of the continental distribution of suitability for ASF persistence in domestic pig populations as part of sylvatic or domestic transmission cycles. In order to incorporate the uncertainty in the relative importance of different criteria in defining suitability, we modelled decisions within the MCDA framework using a stochastic approach. The predictive performance of suitability estimates was assessed via a partial ROC analysis using ASF outbreak data reported to the OIE since 2005. Results Outputs from the spatial MCDA indicate that large areas of sub-Saharan Africa may be suitable for ASF persistence as part of either domestic or sylvatic transmission cycles. Areas with high suitability for pig to pig transmission (‘domestic cycles’) were estimated to occur throughout sub-Saharan Africa, whilst areas with high suitability for introduction from wildlife reservoirs (‘sylvatic cycles’) were found predominantly in East, Central and Southern Africa. Based on average AUC ratios from the partial ROC analysis, the predictive ability of suitability estimates for domestic cycles alone was considerably higher than suitability estimates for sylvatic cycles alone, or domestic and sylvatic cycles in combination. Conclusions This study provides the first standardised estimates of the distribution of suitability for ASF transmission associated with domestic and sylvatic cycles in Africa. We provide further evidence for the utility of knowledge-driven risk mapping in animal health, particularly in data-sparse environments.</p

Une plantation de noyers à bois en plaine de Vaucluse

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Un verger à bois précieux en terres agricoles de l'Hérault

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Un reboisement communal pour valoriser des terres agricoles

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Gestion des forêts soumises à des contraintes environnementales particulières. Des expériences de gestion

Compte rendu de la tournée réalisée dans le cadre de Foresterranée'87 sur le thème "Gestion des forêts soumises à des contraintes environnementales particulières" chez un propriétaire forestier de Pourrières (Var)

Un cas de gestion difficile pour un domaine agricole de la vallée de la Cèze

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