Le Ginkgo biloba L. (de la préhistoire au Domaine de Saint Jean d'Illac)

Le Ginkgo biloba L. est un arbre qui possède une longue histoire. Celle-ci commence à l'ère primaire avec l'apparition des Ginkgoales. Après un apogée pendant le Secondaire, cet ordre connaît un déclin important qui débute dès la fin de cette ère, avec la diparition progressive de ses représentants. Sous l'effet de la sélection naturelle, il ne reste bientôt qu'une seule espèce rescapée qui se replie en Chine, berceau de ses premiers contacts avec l'humanité. Rapidement, le Ginkgo biloba est employé dans la médecine traditionnelle chinoise et pour certaines applications de la vie courante. Grâce aux moines dont il entoure les temples, il se propage en Asie où il devient riche en symboles. Sa découverte par l'occident au début du XVIIIème siècle, permet à l'arbre de reconquérit le Monde puis d'intégrer l'arsenal thérapeutique occidental grâce à sa composition particulière qui ne cesse d'alimenter le milieu de la recherche. De grandes plantations sont ainsi réalisées dans les années 1980 en Gironde, destinées à approvisionner l'industrie pharmaceutique en feuilles.BORDEAUX2-BU Santé (330632101) / SudocSudocFranceF

Zones rurales isolées (le généraliste de garde est-il nécessaire ?)

POITIERS-BU Médecine pharmacie (861942103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Cryogenic thermoacoustics in the SPIRAL2 LINAC

International audience•Investigation of thermo-acoustic oscillation in heavy ions superconducting linear accelerator.•Statistical study of amplitudes and frequencies of TAO.•Comparison of different TAO damping solutions.•Investigation of damping solutions side effects on cryogenic operation. SPIRAL2 is a superconducting LINAC subject to cryogenic thermoacoustic oscillations occurring in its valves boxes. 4 years of monitoring and experimental investigations with thousands of datasets turned these unwanted effects into an opportunity to study and understand thermoacoustics in a complex environment such as a real life accelerator. Without digging deep into Rott’s thermoacoustics theory, thoroughly shown in other works, this paper describes the instrumentation and the methods that prepare more advanced modeling of these phenomena either to damp or to harness the energy of cryogenic thermoacoustics

A SOLAR DRIVEN THERMOACOUSTIC REFRIGERATOR TACSOL

International audienceAmong the alternatives to electrically driven vapour compression cycle for refrigeration, heat driven thermoacoustic refrigerators seem a promising technology. These machines have already proved their capability in laboratory or in space refrigeration. Some previous studies have also demonstrated the possibility of using concentrated solar energy as thermal energy sources for low power heat driven thermoacoustic refrigerators. New investigations are nowadays carried out to improve the efficiency and increase the refrigerating power in order to develop this technology in the industrial refrigeration domain. The aim of the work presented here is to investigate the global performances of a solar driven thermoacoustic refrigerator plant by mean of computer aided modelling. The interest of such refrigerators are introduced in a first part. The modelling, at the system level, of the main elements of the prototype is developed in a second section. Then the first simulation results are presented and analysed

A SOLAR DRIVEN THERMOACOUSTIC REFRIGERATOR TACSOL

International audienceAmong the alternatives to electrically driven vapour compression cycle for refrigeration, heat driven thermoacoustic refrigerators seem a promising technology. These machines have already proved their capability in laboratory or in space refrigeration. Some previous studies have also demonstrated the possibility of using concentrated solar energy as thermal energy sources for low power heat driven thermoacoustic refrigerators. New investigations are nowadays carried out to improve the efficiency and increase the refrigerating power in order to develop this technology in the industrial refrigeration domain. The aim of the work presented here is to investigate the global performances of a solar driven thermoacoustic refrigerator plant by mean of computer aided modelling. The interest of such refrigerators are introduced in a first part. The modelling, at the system level, of the main elements of the prototype is developed in a second section. Then the first simulation results are presented and analysed

In-vivo dosimetry for conformal arc therapy using several MOSFET in stereotactic radiosurgery computed by an inverse model

In-vivo dosimetry is still a challenge in stereotactic radiosurgery since most of treatments are delivered using rotational technique with small fields. A realistic and practical solution for these treatments delivered in conformal radiotherapy is proposed to control the absorbed dose at isocentre, using multiple surface MOSFET measurements over an arc. On the one hand, a forward method was developed to optimize the location of the detectors at the patient surface, taking into account arc length, prescribed isocentre dose, collimator and field size. On the other hand, an inverse method was used to compute the dose at isocentre for conformal arc therapy in stereotactic radiosurgery, using MOSFET measurements. Finally, the reconstructed dose at isocentre was compared to real measurement, obtained for several detectors positioned at a phantom surface. Results show that the inverse method gives good results with five MOSFET equi-spaced positioned within the arc beam course: deviation between prescribed and computed average total dose at isocentre was below 2% both for 30×30 mm2 and 18×18 mm2 field siz