A Cryogenic High-Reynolds Turbulence Experiment at CERN

The potential of cryogenic helium flows for studying high-Reynolds number turbulence in the laboratory has been recognised for a long time and implemented in several small-scale hydrodynamic experiments. With its large superconducting particle accelerators and detector magnets, CERN, the European Laboratory for Particle Physics, has become a major world center in helium cryogenics, with several large helium refrigerators having capacities up to 18 kW @ 4.5 K. Combining a small fraction of these resources with the expertise of three laboratories at the forefront of turbulence research, has led to the design, swift implementation, and successful operation of GReC (Grands Reynolds Cryogéniques) a large axisymmetric turbulent-jet experiment. With flow-rates up to 260 g/s of gaseous helium at ~ 5 K and atmospheric pressure, Reynolds numbers up to 107 have been achieved in a 4.6 m high, 1.4 m diameter cryostat. This paper presents the results of the first runs and describes the experimental set-up comprehensively equipped with "hot" wire micro-anemometers, acoustic scattering vorticity measurements and a large-bandwidth data acquisition system

Filaire hyperévoluée, parasite de la paroi intestinale d’un Coendou

Description d’une Filaire parasite de la paroi intestinale de Coendu prehensilis à Belem (Para, Brésil).L’espèce est remarquable par son extrême gracilité (longueur de la femelle : 62,8 mm, largeur : 50 µ) et par un cône transparent très développé à la pointe caudale du mâle. Elle est interprétée comme étant une forme hyperspécialisée du groupe des Dipetalonema, mais nécessite la création d’un genre nouveau, et est nommée Filarissima lainsoni n. g., n. sp