Les expéditions scientifiques au piton de la Fournaise

Evocation, à travers la toponymie, le long de la route du Volcan, des naturalistes et autres contributeurs à l'histoire de la découverte et à la connaissance géologique du massif du Piton de la Fournaise : M. de Villers, Maurice et Katia Krafft, Bory de Saint-Vincent, Philibert Commerson, Alfred Lacroix, René Just Haüy, Chisny, Joseph Hubert, Bellecombe, Patu de Rosemont, Dolomieu, Bert, et Fouqué et des personnages qui ont gravité autour d'eux. Certains d'entre eux sont venus sur place

Au-delà de la photographie, Le nouvel âge, Fred Ritchin

Au-delà de la photographie, Le Nouvel âge s’inscrit dans le prolongement des recherches engagées par Fred Ritchin depuis une vingtaine d’années et concrétisées par la publication d’un ouvrage publié chez Aperture en 1990, In Our Own Image : The Coming Revolution in Photography. Ce nouvel essai théorique paru aux éditions Victoires rejoint les perspectives qui situent l’avènement d’un « Nouvel âge » en 1982, alors que la couverture d’un numéro spécial du National Geographic fait paraître une v..

Emma de Lafforest (dir.), Constant Puyo

Entourée de grands spécialistes, l’auteur nous invite à un voyage dans le temps, permettant le dialogue entre la narration et les fragments épistolaires qui rythment le récit d’anecdotes ou de précisions techniques. L’entreprise de recontextualisation de Michel Poivert permet d’étayer le développement chronologique, au service d’une grande clarté de l’ensemble. Ainsi Emma de Lafforest applique-t-elle les préceptes de Constant Puyo, en renouant avec le mode d’expression du cousin germain de ce..

A strategic approach to [6,6]-bicyclic lactones:application towards the CD fragment of DHβE

We report an effective synthetic protocol to access [6,6]-bicyclic lactone moieties through a regio- and stereoselective intramolecular Mizoroki–Heck cross-coupling reaction followed by a 6π-electrocyclization. This method enabled the first synthesis of the elusive CD fragment of the Erythrina alkaloid DHβE. Preliminary pharmacological evaluations support the notion that the key pharmacophores of DHβE are located in the A and B rings

Potential of Sentinel-2 satellite images to monitor vine fields grown at a territorial scale

Aim: The aim of this short note is to provide first insights into the ability of Sentinel-2 images to monitor vine growth across a whole season. It focuses on verifying the practical temporal resolution that can be reached with Sentinel-2 images, the main stages of Mediterranean vineyard development as well as potential relevant agronomic information that can be seen on the temporal vegetation curves arising from Sentinel-2 images. Methods and results: The study was carried out in 2017 in a production vineyard located in southern France, 2 km from the Mediterranean seashore. Sentinel-2 images acquired during the whole vine growing cycle were considered, i.e. between the 3rd of March 2017 and the 10th of October 2017. The images were used to compute the classical normalized difference vegetation index (NDVI). Time series of NDVI values were analyzed on four blocks chosen for exhibiting different features, e.g. age, missing plants, weeding practices. The practical time lag between two usable images was closer to 16 days than to the 10 theoretical days (with only one satellite available at the date of the experiment), i.e. near 60% of the theoretical one. Results show that it might be possible to identify i) the main steps of vine development (e.g. budburst, growth, trimming, growth stop and senescence), ii) weed management and inter-row management practices, and iii) possible reasons for significant inter-block differences in vegetative expression (e.g. young vines that have recently been planted, low-productive blocks affected by many missing vines). Conclusions: Although this experiment was conducted at a time when Sentinel-2b was not fully operational, results showed that a sufficient number of usable images was available to monitor vine development. The availability of two Sentinel satellites (2a and 2b) in upcoming seasons should increase the number of usable images and the temporal resolution of the time series. This study also showed the limitations of the Sentinel-2 images’ resolution to provide within-block information in the case of small blocks or blocks with complex borders or both. Significance and impact of the study: This technical note demonstrated the potential of Sentinel-2 images to characterize vineyard blocks’ vigor and to monitor winegrowers’ practices at a territorial (regional) scale. The impact of management operations such as weeding and trimming, along with their incidence on canopy size, were observed on the NDVI time series. Some relevant parameters (slope, maximum values) may be derived from the NDVI time series, providing new insights into the monitoring of vineyards at a large scale. These results provided areas for further investigation, especially regarding the development of new indicators to characterize block-climate relationships

Regioselective zincation of indazoles using TMP2Zn and Negishi cross-coupling with aryl and heteroaryl iodides.

The metalation of various SEM-protected functionalized indazoles with TMP2Zn provides 3-zincated indazoles which undergo palladium-catalyzed Negishi cross-couplings in good yields