860 research outputs found
A New Family of Planets ? "Ocean Planets"
A new family of planets is considered which is between rochy terrestrial
planets and gaseous giant ones: "Ocean-Planets". We present the possible
formation, composition and internal models of these putative planets, including
that of their ocean, as well as their possible Exobiology interest. These
planets should be detectable by planet detection missions such as Eddington and
Kepler, and possibly COROT (lauch scheduled in 2006). They would be ideal
targets for spectroscopic missions such as Darwin/TPF.Comment: 15 pages, 3 figures submitted to Icarus notes (10 july 2003
Scanning electron microscope study of two African populations of Radopholus similis (Nematoda : Pratylenchidae) and proposal of R. citrophilus as a junior synonym of R. similis
Les structures cuticulaires de #Radopholus similis provenant de CÎte d'Ivoire et de Guinée Bissau ont été étudiées en microscopie électronique à balayage. Les résultats montrent que les structures cuticulaires sont identiques dans les deux populations et exhibent une variabilité supérieure à celle observée dans les populations américaines de #R. similis et de #R. citrophilus qui est proposé comme un synonyme mineur de #R. similis. Des données additionnelles sont apportées sur la forme de la queue et les champs latéraux chez la femelle, et sur la forme de la région céphalique et de la bursa chez le mùle. (Résumé d'auteur
Mesures de facteurs spectroscopiques de 61Ni par réaction (d, p) en régime sous-coulombien
Nous avons utilisé la réaction (d, p) en régime sous-coulombien pour mesurer les facteurs spectroscopiques de deux états excités par transferts l = 0 et l = 2 dans 61Ni au voisinage de 4,8 MeV. Nos résultats confirment que la rÚgle de somme pour le remplissage des couches 3s1/2 et 2d n'est satisfaite qu'à 50 % dans 61Ni
Phase field modeling of electrochemistry I: Equilibrium
A diffuse interface (phase field) model for an electrochemical system is
developed. We describe the minimal set of components needed to model an
electrochemical interface and present a variational derivation of the governing
equations. With a simple set of assumptions: mass and volume constraints,
Poisson's equation, ideal solution thermodynamics in the bulk, and a simple
description of the competing energies in the interface, the model captures the
charge separation associated with the equilibrium double layer at the
electrochemical interface. The decay of the electrostatic potential in the
electrolyte agrees with the classical Gouy-Chapman and Debye-H\"uckel theories.
We calculate the surface energy, surface charge, and differential capacitance
as functions of potential and find qualitative agreement between the model and
existing theories and experiments. In particular, the differential capacitance
curves exhibit complex shapes with multiple extrema, as exhibited in many
electrochemical systems.Comment: v3: To be published in Phys. Rev. E v2: Added link to
cond-mat/0308179 in References 13 pages, 6 figures in 15 files, REVTeX 4,
SIUnits.sty. Precedes cond-mat/030817
DĂ©pouillement et analyse de spectres Ă l'aide d'un ordinateur IBM 1800
On décrit briÚvement un systÚme d'analyse de résultats d'expériences à basse énergie. Un dialogue utilisateur-ordinateur améliore fortement la rapidité et la facilité des analyses
Impact du Petit Age Glaciaire sur les plaines alluviales méditerranéenne françaises : apport de la géoarchéologie à l'évolution du bassin du Roussillon
International audienceDans la zone méditerranéenne, le Petit Age Glaciaire est enregistrée par le systÚme fluvial sous le nom bien connu de "Younger Infill". Selon des résultats récents obtenus dans le bassin du Roussillon, nous proposons une premiÚre esquisse pour le moment, a savoir les causes et les conséquences de cet épisode climatique, basé à la fois sur des données géoarchéologiques et d'archives
Un nouveau vaccin injectable contre la maladie de Newcastle préparé en cultures de cellules bovines
Provost A., Valette L. R., Papageorgiou C. Un nouveau vaccin injectable contre la maladie de Newcastle préparé en cultures de cellules bovines. In: Bulletin de l'Académie Vétérinaire de France tome 115 n°9, 1962. pp. 399-402
Modeling diffusion of intracellular metabolites in the mouse brain up to very high diffusion-weighting: Diffusion in long fibers (almost) accounts for non-monoexponential attenuation
Purpose: To investigate how intracellular metabolites diffusion measured in vivo up to very high q/b in the mouse brain can be explained in terms of simple geometries. / Methods: 10 mice were scanned using our new STEâLASER sequence, at 11.7 Tesla (T), up to qmaxâ=â1âÎŒmâ1 at diffusion time tdâ=â63.2 ms, corresponding to bmaxâ=â60 ms/”mÂČ. We model cell fibers as randomly oriented cylinders, with radius a and intracellular diffusivity urn:x-wiley:07403194:media:mrm26548:mrm26548-math-0004, and fit experimental data as a function of q to estimate urn:x-wiley:07403194:media:mrm26548:mrm26548-math-0005 and a. / Results: Randomly oriented cylinders account well for measured attenuation, giving fiber radii and urn:x-wiley:07403194:media:mrm26548:mrm26548-math-0006 in the expected ranges (0.5â1.5â”m and 0.30â0.45â”m2/ms, respectively). The only exception is Nâacetylâaspartate (NAA) (extracted aâŒ0), which we show to be compatible with a small fraction of the NAA pool being confined in highly restricted compartments (with short T2). / Conclusion: The nonâmonoexponential signal attenuation of intracellular metabolites in the mouse brain can be described by diffusion in long and thin cylinders, yielding realistic Dintra and fiber diameters. However, this simple model may require small âcorrectionsâ for NAA, in the form of a small fraction of the NAA signal originating from a highly restricted compartment
Advanced concepts and methods for very high intensity accelerators
AbstractFor very high intensity accelerators, not only beam power but also space charge is a concern. Both aspects should be taken into consideration for any analysis of accelerators aiming at comparing their performances and pointing out the challenging sections. As high beam power is an issue from the lowest energy, careful and exhaustive beam loss predictions have to be done. High space charge implies lattice compactness making the implementation of beam diagnostics very problematic, so a clear strategy for beam diagnostic has to be defined. Beam halo is no longer negligible. Its dynamics is different from that of the core and plays a significant role in the particle loss process. Therefore, beam optimization must take the halo into account and beam characterization must be able to describe the halo part in addition to the core one. This paper presents the advanced concepts and methods for beam analysis, beam loss prediction, beam optimization, beam diagnostic, and beam characterization especially dedicated to very high intensity accelerators. Examples of application of these concepts are given in the case of the IFMIF accelerators
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