Boundary Condition in Liquid Thin Films Revealed through the Thermal Fluctuations of Their Free Surfaces.

We investigate the properties of nanometric liquid films with a new noninvasive technique. We measure the spontaneous thermal fluctuations of the free surfaces of liquids to probe their hydrodynamic boundary condition at a solid wall. The surface fluctuations of a silicon oil film could be described with a no-slip boundary condition for film thicknesses down to 20 nm. Oppositely, a 4 nm negative slip length had to be introduced to describe the behavior of n-hexadecane, consistently with previous surface force apparatus data on the same system. Our results demonstrate that at vanishing flow a nanometric solidlike layer close to the wall may exist according to the nature of the liquid.

[Electroencephalographic problems in a department of infant resuscitation]. / Problèmes électroencéphalographiques dans un service de réanimation infantile

The authors analyse the technical problems encountered in using E.E.G. in children's reanimation. They show some examples which illustrate the importance of E.E.G. in diagnosis and therapy of such cases. Emphasis is laid upon the need for close collaboration between the EEGers and the reanimation staff.