The Bénard-von Karman vortex shedding instability in the wake of a cylinder is perhaps the best known example of a supercritical Hopf bifurcation in fluid dynamics. However, a simplified physical description that accurately accounts for the saturation amplitude of the instability is still missing. Here we present a simple self-consistent model that provides a clear description of the saturation...

We explore experimentally the fluidization of vertically agitated polymethylmethacrylate spheres wetted by liquid 4He . By controlling the temperature around the lambda point, we change the properties of the wetting liquid from a normal fluid (helium I) to a superfluid (helium II). For wetting by helium I, the critical acceleration for fluidization (Gamma_{c}) shows a steep increase close to th...

The Bénard-von Kármán vortex shedding instability in the wake of a cylinder is perhaps the best known example of a supercritical Hopf bifurcation in fluid dynamics. However, a simplified physical description that accurately accounts for the saturation amplitude of the instability is still missing. Here, we present a simple self-consistent model that provides a clear description of the saturatio...

The procedures for culturing the experimental organism, P. jhorescens, and for preparing the crude cell-free extract have been described previously (1). Partial Purification of Crude Enzyme Preparation-Powdered ammonium sulfate was added to a given volume of the crude cell-free extract to obtain 20 per cent saturation. The resulting precipitate was collected by centrifugation for 30 minutes at ...

The effect on the right atrial pressure and oxygen saturation of expansion of the plasma volume by rapid infusion of 500 ml. 5 per cent glucose has been studied in I4 patients with recent uncomplicated cardiac infarction, and in 5 patients with cardiogenic shock. The findings are contrasted with the effect of intravenousfrusemide (40 mg.) in 8 patients with recent cardiac infarction complicated...

In this work a functional relationship between capillary pressure and wetting phase saturation has been developed. Both the imbibition and drainage of a wetting phase liquid into a porous medium consisting of clean unconsolidated silica particles have been considered. In all, two bead packings, with average particle diameters of 120 #m and 360 #In, and three liquids--water, ethanol, and refrige...

PURPOSE To determine the relative contrast of normal cranial tissues at magnetization transfer (MT) spin-echo magnetic resonance (MR) imaging. MATERIALS AND METHODS MR imaging at 1.5 T was performed with conventional spin-echo techniques without and with off-resonance MT saturation pulses. The signal intensities of normal cranial tissues were measured in 10 healthy volunteers on spin-density-...

Landslides are one of the main natural threats for both people and infrastructure in mountainousregions. In most cases, landslides are triggered by the loss of cohesion in a soil due to the increasingliquid saturation level after long or intense rainfalls. Only little is known on the triggering of failuresat the microscopic scale due to the limited experimental accessibility and the...