"Negative" backaction noise in interferometric detection of a microlever.

Interferometric detection of mirror displacements is intrinsically limited by laser shot noise. In practice, however, it is often limited by thermal noise. Here we report on an experiment performed at the liquid helium temperature to overcome the thermal noise limitation and investigate the effect of classical laser noise on a microlever that forms a Fabry-Perot cavity with an optical fiber. The spectral noise densities show a region of "negative" contribution of the backaction noise close to the resonance frequency. We interpret this noise reduction as a coherent coupling of the microlever to the laser intensity noise. This optomechanical effect could be used to improve the detection sensitivity as discussed in proposals going beyond the standard quantum limit.

[Dealing with overweight children: an example of a multifaceted approach for accompanying the families]. / Prise en charge du surpoids chez l'enfant: un exemple de suivi multidisciplinaire en faveur des families.

"éq-kilo" is a multifaceted project for families with an overweight or obese child. The accompaniment includes the following: physical activity and sports, diet and eating behaviour, psychological and educational support for the families. Excess weight is not only a result of the number of calories consumed and burnt. Overweight children and their families are also affected by emotional, behavioural and cognitive elements. Parents worry about their children's excess weight; they may even feel guilty. So the educational part of the project consists in helping parents to detach from "the enemy to fight", which quickly becomes "the issues". Moreover they need full support in their search for sense between their overweight children and their family reality.

Image Upconversion from the Visible to the UV Domain: Application to Dynamic UV Microstereolithography.

We present what to our knowledge is a new application of optical frequency upconversion of images in quadratic materials to dynamic UV microstereolithography. A 150 x 150 point visible image transmitted by a liquid-crystal display was upconverted in a lithium triborate crystal, and the UV image was successfully used to polymerize a commercial stereolithographic resin.