Centre d'études et d'expertise sur les risques, l'environnement, la mobilité et l'aménagement

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We present velocity spectra measured in three cryogenic liquid 4He steady flows: grid and wake flows in a pressurized wind tunnel capable of achieving mean velocities up to 5 m/s at temperatures above and below the superfluid transition, down to 1.7 K, and a "chunk" turbulence flow at 1.55 K, capable of sustaining mean superfluid velocities up to 1.3 m/s. Depending on the flows, the stagnation pressure probes used for anemometry are resolving from one to two decades of the inertial regime of the turbulent cascade. We do not find any evidence that the second order statistics of turbulence below the superfluid transition differ from the ones of classical turbulence, above the transition.Comment: 13 pages, 9 figure

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The Superfluid High REynolds von Kármán experiment facility exploits the capacities of a high cooling power refrigerator (400 W at 1.8 K) for a large dimension von Kármán flow (inner diameter 0.78 m), which can work with gaseous or subcooled liquid (He-I or He-II) from room temperature down to 1.6 K. The flow is produced between two counter-rotating or co-rotating disks. The large size of the experiment allows exploration of ultra high Reynolds numbers based on Taylor microscale and rms velocity [S. B. Pope, Turbulent Flows (Cambridge University Press, 2000)] (Rλ > 10000) or resolution of the dissipative scale for lower Re. This article presents the design and first performance of this apparatus. Measurements carried out in the first runs of the facility address the global flow behavior: calorimetric measurement of the dissipation, torque and velocity measurements on the two turbines. Moreover first local measurements (micro-Pitot, hot wire,…) have been installed and are presented.

It is well established that most signals supporting intercellular communication are produced either at distance or in the local environment of the target cells. From the pioneering work of Kanno and Loewenstein (1), it has become clear that, in most tissues, adjacent cells can communicate in a more direct way, without dilution of the signalling molecules in extracellular compartments. This mode of communication is taking place through specialized structures, named gap junctions, that allow the cell-414-27 Munari-Silem Y. Audebet C. Rousset B. Hormonal control of cell to cell communication: regulation by thyrotropin of the gapjunction-mediated dye transfer between thyroid cells. Endocri¬ nology 1991:128:3299-309 Green LM. Lazarus JP, Labue M. Shah MM. Reduced cell-cell communication in a spontaneous murine model of autoimmune thyroid disease. Endocrinology 1995;136:3611-8

This study was carried out to build statistical models for defining FGR (Fetal Growth Restriction) in weight and/or length after taking growth potential of an infant into account. From a cohort of pregnant women having given birth to 47,733 infants in 141 French maternity units, two statistical models gave individualized limits of birth weight and birth length (based on the 5th centile) below which, after adjustment for its individual growth potential, a newborn must be considered as FGR in weight and/or in length. A sample of 906 infants had measures taken of cord blood growth factors (IGF1, IGFBP3). The FGR(W) definition (weight<5th centile for growth potential) permitted the identification of infants who presented rates of maternal hypertension (13.6%) and of Apgar score at 5 min<6 (2.9%) higher than in the classical group SGA(W) (weight<5th centile for sex and gestational age) (9.6% and 2.2% respectively). By combining FGR(W) and SGA(W), a subgroup of infants, not currently recognized as SGA, presented very high rates of maternal hypertension (19.9%) and of low Apgar score (3.9%). Conversely a subgroup of infants, currently recognized as SGA(W), had rates as low as in the normal infants group, and had to be considered as "constitutionally small" (that is to say 24% of the SGA(W)). Combining FGR(W) and FGR(L) (length<5th centile of growth potential), 7.6% of infants appeared growth-restricted, and 1.8% appeared constitutionally small in weight and/or in length. The FGR(W)-FGR(L) infants showed the lowest mean values of IGF1 (126.2+/-3.2) and IGFBP3 (0.86+/-0.03). These new definitions of FGR(W) and FGR(L) could help to better identify infants at birth requiring neonatal care, and monitoring of growth catch-up and neurodevelopmental outcome.