Recently Ciufolini has suggested to use the perigee of the proposed LARES/WEBER-SAT satellite in order to measure the secular precession which would be induced on such Keplerian orbital element by a weak-field modification of gravity occurring in some Brane-World scenarios put forth by Dvali. This precession would amount to 0.04 milliarcseconds per year for LARES. In this paper we show that, ac...

Résumé – Les méthodes classiques d’estimation dense de la vitesse (de type flot optique) s’appuient sur l’estimation des dérivées spatio-temporelles de l’image. Celles-ci sont difficiles à estimer dans le cas d’occlusion d’une partie des acquisitions. Les approches issues de l’assimilation de données s’appuient sur un modèle d’évolution temporelle, qui permet de répondre à ce problème des donné...

[1] Enhancements in F-region electron density and temperature and bottomside Pedersen conductivity caused by soft electron precipitation are shown to enhance the Joule heating per unit mass and the mass density of the thermosphere at F-region altitudes. The results are derived from the coupled magnetosphere-ionosphere-thermosphere model (CMIT) including two types of causally specified soft elec...

Here we give two examples of low-latitude plasma blobs accompanied by linearly polarized perpendicular magnetic deflections which imply that associated field-aligned currents (FACs) have a 2-D sheet structure located at the blob walls. The estimated FAC density is of the order of 0.1 μA/m2. The direction of magnetic deflections points westward of the magnetic meridian and there is a linear corr...

[1] The diamagnetic effect generally reduces the magnetic field inside a plasma. Its importance is appreciated in regions like the magnetosphere and the solar wind. In the ionosphere, depletions of the geomagnetic field have up to now been considered negligible. The CHAMP satellite provides for the first time the combination of highresolution magnetic field measurements and plasma density obser...