Distribution spatio-temporelle des précipitations de type PMP utilisant un modèle de champ de pluie : application en Suisse

Les précipitations maximales probables (PMP) représentent les pluies extrêmes les plus élevées raisonnablement possibles (période de retour d'environ 10'000 ans) qui sont notamment utilisées pour dimensionner des barrages contre des crues extrêmes. En Suisse, ces précipitations sont représentées sous forme des cartes avec une résolution horizontale de 2 km. Cet article présente la méthode nécessaire pour utiliser les cartes de type PMP dans le but final d'estimer la crue maximale probable (PMF) pour les barrages. Cette méthode a été développée suite aux problèmes rencontrés avec une application inadéquate des PMP. Ces problèmes peuvent être résolus par la distribution spatio-temporelle des PMP avec une résolution affinée conservant les données physiques. La conception de la méthode de distribution spatio-temporelle des précipitations se base sur la création de champ de pluie. Cette méthode a été validée en s'appuyant sur des évènements extrêmes de type supercellulaire et confirme la possibilité de reproduire des structures réelles de pluie en utilisant un algorithme de champ de pluie

Effets de l'eutypiose sur des feuilles de Vitis vinifera cv. Cabernet Sauvignon. Etude cytologique

Effects of Eutypa dieback on the leaves of Vitis vinifera cv. Cabernet Sauvignon. Cytological studiesThe fungus Eutypa lata only grows in lignified wood (trunk and arms) and causes at a distance typical symptoms on the leaves of Vitis vinifera cv. Cabernet Sauvignon, a very sensitive variety. For the first time, lesions induced in vivo in leaf cells were examined by transmission electron microscopy. The main alterations of ultrastructure are depending on the level of disease. In the cells of slightly affected leaves, the enlarged chloroplasts show dilated thylakoids with a lowered electron density and sometimes contain very large starch grains. In the severely affected leaves, the cells are completely disorganized, with plasmalemma retraction, chloroplast degradation, cytoplasm lysis and endomembrane breakdown. These results suggest that structural decline of the photosynthetic system can be responsible, at least partly, for the death of Cabernet Sauvignon grapevines

Structural and magnetic dynamics of a laser induced phase transition in FeRh

We use time-resolved x-ray diffraction and magnetic optical Kerr effect to study the laser induced antiferromagnetic to ferromagnetic phase transition in FeRh. The structural response is given by the nucleation of independent ferromagnetic domains (\tau_1 ~ 30ps). This is significantly faster than the magnetic response (\tau_2 ~ 60ps) given by the subsequent domain realignment. X-ray diffraction shows that the two phases co-exist on short time-scales and that the phase transition is limited by the speed of sound. A nucleation model describing both the structural and magnetic dynamics is presented.Comment: 5 pages, 3 figures - changed to reflect version accepted for PR

Ultrastructural changes produced in plantlet leaves and protoplasts of Vitis vinifera cv. Cabernet Sauvignon by eutypine, a toxin from Eutypa lata

Eutypine is a toxin produced by Eutypa lata (Pers.: Pr.) Tul., the causal agent of dying-arm disease of the grapevine. Ultrastructural alterations induced by eutypine in leaf cells and protoplasts isolated from plantlets of Vitis vinifera cv. Cabernet Sauvignon, a very sensitive variety cultured in vitro, were observed for the first time by transmission electron microscopy. Eutypine caused early cytoplasm lysis and vesiculation followed by chloroplast swelling with thylakoid dilation. The eutypine-induced alterations of the cellular ultrastructure are similar to those previously described in vivo in the leaves of diseased grapevines. These results confirm that eutypine, synthesized by E. lata mycelium present in the trunk or arms, is involved in symptom expression of eutypiosis in the herbaceous parts of grapevine

Substrate Induced Strain Field in FeRh Epilayers Grown on Single Crystal MgO (001) Substrates

Equi-atomic FeRh is highly unusual in that it undergoes a first order meta-magnetic phase transition from an antiferromagnet to a ferromagnet above room temperature (Tr ≈ 370 K). This behavior opens new possibilities for creating multifunctional magnetic and spintronic devices which can utilise both thermal and applied field energy to change state and functionalise composites. A key requirement in realising multifunctional devices is the need to understand and control the properties of FeRh in the extreme thin film limit (tFeRh < 10 nm) where interfaces are crucial. Here we determine the properties of FeRh films in the thickness range 2.5–10 nm grown directly on MgO substrates. Our magnetometry and structural measurements show that a perpendicular strain field exists in these thin films which results in an increase in the phase transition temperature as thickness is reduced. Modelling using a spin dynamics approach supports the experimental observations demonstrating the critical role of the atomic layers close to the MgO interface

Microscopic description of Coulomb and nuclear excitation of multiphonon states in 40^{40}Ca + 40^{40}Ca collisions

We calculate the inelastic scattering cross sections to populate one- and two-phonon states in heavy ion collisions with both Coulomb and nuclear excitations. Starting from a microscopic approach based on RPA, we go beyond it in order to treat anharmonicities and non-linear terms in the exciting field. These anharmonicities and non-linearities are shown to have important effects on the cross sections both in the low energy part of the spectrum and in the energy region of the Double Giant Quadrupole Resonance. By properly introducing an optical potential the inelastic cross section is calculated semiclassically by integrating the excitation probability over all impact parameters. A satisfactory agreement with the experimental results is obtained.Comment: 20 pages, 2 figures, revtex, to be published in Phys. Rev.

Spectroscopy of 18^{18}Na: Bridging the two-proton radioactivity of 19^{19}Mg

The unbound nucleus $^{18}$Na, the intermediate nucleus in the two-proton radioactivity of $^{19}$Mg, was studied by the measurement of the resonant elastic scattering reaction $^{17}$Ne(p,$^{17}$Ne)p performed at 4 A.MeV. Spectroscopic properties of the low-lying states were obtained in a R-matrix analysis of the excitation function. Using these new results, we show that the lifetime of the $^{19}$Mg radioactivity can be understood assuming a sequential emission of two protons via low energy tails of $^{18}$Na resonances

Total Absorption Spectroscopy Study of 92^{92}Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape

The antineutrino spectra measured in recent experiments at reactors are inconsistent with calculations based on the conversion of integral beta spectra recorded at the ILL reactor. $^{92}$Rb makes the dominant contribution to the reactor spectrum in the 5-8 MeV range but its decay properties are in question. We have studied $^{92}$Rb decay with total absorption spectroscopy. Previously unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding was found to be 87.5(25)%. The impact on the reactor antineutrino spectra calculated with the summation method is shown and discussed.Comment: 6 pages, 3 figure

Online Monitoring of the Osiris Reactor with the Nucifer Neutrino Detector

Originally designed as a new nuclear reactor monitoring device, the Nucifer detector has successfully detected its first neutrinos. We provide the second shortest baseline measurement of the reactor neutrino flux. The detection of electron antineutrinos emitted in the decay chains of the fission products, combined with reactor core simulations, provides an new tool to assess both the thermal power and the fissile content of the whole nuclear core and could be used by the Inter- national Agency for Atomic Energy (IAEA) to enhance the Safeguards of civil nuclear reactors. Deployed at only 7.2m away from the compact Osiris research reactor core (70MW) operating at the Saclay research centre of the French Alternative Energies and Atomic Energy Commission (CEA), the experiment also exhibits a well-suited configuration to search for a new short baseline oscillation. We report the first results of the Nucifer experiment, describing the performances of the 0.85m3 detector remotely operating at a shallow depth equivalent to 12m of water and under intense background radiation conditions. Based on 145 (106) days of data with reactor ON (OFF), leading to the detection of an estimated 40760 electron antineutrinos, the mean number of detected antineutrinos is 281 +- 7(stat) +- 18(syst) electron antineutrinos/day, in agreement with the prediction 277(23) electron antineutrinos/day. Due the the large background no conclusive results on the existence of light sterile neutrinos could be derived, however. As a first societal application we quantify how antineutrinos could be used for the Plutonium Management and Disposition Agreement.Comment: 22 pages, 16 figures - Version