Optical fiber systems are convectively unstable

We theoretically and experimentally evidence that fiber systems are convective systems since their nonlocal inherent properties, such as the dispersion and Raman effects, break the reflection symmetry. Theoretical analysis and numerical simulations carried out for a fiber ring cavity demonstrate that the third-order dispersion term leads to the appearance of convective and absolute instabilities. Their signature is an asymmetry in the output power spectrum. Using this criterion, experimental evidence of convective instabilities is given in a fiber cavity pumped by a pulsed laser

Suction measurements on a natural unsaturated soil: A reappraisal of the filter paper method

International audienceSoil suction measurements on an unsaturated soil were performed using the filter paper method and a high capacity tensiometer so as to analyse the reliability of the filter paper technique. The results show that an alternative approach of the filter paper method based on using a previously wetted filter paper can fruitfully be used to measure suction provided an appropriated calibration curve is used. This method was compared to the standard filter paper method in which the paper is initially dry and a good agreement was found between the two approaches, being the “wet” method somewhat faster in terms of suction equilibration. Suction data also agree well with results obtained independently using a home made high capacity tensiometer. The two methods finally provide a first outlook of the water retention properties of an unsaturated loess from Northern France, observing some evidences of hydraulic hysteresis on it

Infection inapparente spontanée du Singe cynocéphale (Papio papio L.) au virus de Rubarth

Martin L.- A., Delage B. Infection inapparente spontanée du Singe cynocéphale (Papio papio L.) au virus de Rubarth. In: Bulletin de l'Académie Vétérinaire de France tome 108 n°6, 1955. pp. 225-228

Testing surfactants as additives for clay improvement: compaction and suction effects

Environmental Geotechnics (Joint TC106-TC215 Session)This paper presents an exploratory study on surfactants as additives to improve soil properties. It is hypothesized that surfactant molecules populate the air-water interfaces reducing surface tension and suction thus allowing a control of the mechanical response of the soil. Suction measurements by means of a high suction tensiometer, compaction tests and Atterberg limits were conducted in mixtures of sand and kaolin, with and without a surfactant solution. The results revealed a prominent effect on suction, but to a lesser extent on the Atterberg limits and compaction behavior (the maximum dry density). This targeted effect of the surfactants suggests its molecules populate, not only the air-water interfaces decreasing surface tension, but may be adsorbing to the clay particles and forming micelles in the pore water as well. Therefore the interplay between the three may influence the soil behavior.published_or_final_versio