‘Sur de nouvelles series pour le probleme de masses critiques de routh dans le probleme restreint plan des trois corps’ by J. Roels

The conclusions of the paper mentioned in the title are not in agreement with a previous paper of Meyer and Schmidt (1971). A mistake in Roels' paper is corrected which makes the two papers agree.     

Influence of the residual circulation on the physico-chemical characteristics of water masses and the dynamics of ecosystems in the Belgian coastal zone

Classical models of the residual circulation in the North Sea predict a north-bound residual flow in the Southern Bight. A more refined model, taking into account the mesoscale Reynolds stress exerted in the mean on the residual flow by the non-linear interactions of mesoscale processes (tides, storm surges, etc.), shows on the contrary off the Belgian coast a south-bound coastal current in relation with a residual coastal gyre. Observations of the physico-chemical characteristics of coastal waters confirm the existence of the gyre. The dynamics of coastal ecosystems here are found to be determined by the gyre; successive stages of the pelagic food chain displaying a typical spatial distribution along the deflected plume of the Scheldt estuary around the gyre ‘outerlagoon’.     

Proof of a conjecture of E. Strömgren

The conjecture of Strömgren according to which, in the restricted problem, a class of doubly asymptotic orbits are limit members of families of periodic orbits is examined in the more general framework of analytic Hamiltonian system with two degrees of freedom. Sufficient conditions for the conjecture to become a theorem are established. Theses conditions amount to a transversality condition for the doubly asymptotic orbits and are likely to be verified in the cases considered in the literature of numerical explorations of the restricted problem.     

Joint Electrical and Time Domain Electromagnetism (TDEM) Data Inversion Applied to the Super Sauze Earthflow (France)

In order to evaluate the risk of an earthflow to evolve abruptly into torrential surge, knowledge of its internal structure is necessary. This study deals with the internal structure of the Super Sauze earthflow developed in black marls in the southern French Alps. Difficulties in this study area are a rough topography, surface heterogeneities and a large thickness variability of the earthflow mass. These conditions hamper the application of geotechnical methods as a preferred investigation mean. Moreover, they pose problems to geophysical investigations and their interpretation.This paper shows the advantage offered by the joint inversion of Time Domain ElectroMagne-tism data (TDEM) and data obtained from Direct Current soundings (DC). The results of the joint inversions are checked using geotechnical data. The internal structure of the earthflow interpreted on the basis of joint inversion data is comparable to that obtained from geotechnical results. Moreover, contrary to separate electrical and TDEM inversions, a satisfactory joint inversion model can be derived without supplying additional a priori information.