Critical velocities have been observed in an ultracold superfluid Fermi gas throughout the BEC-BCS crossover. A pronounced peak of the critical velocity at unitarity demonstrates that superfluidity is most robust for resonant atomic interactions. Critical velocities were determined from the abrupt onset of dissipation when the velocity of a moving one-dimensional optical lattice was varied. The...

Beef cattle feedlots contain unconsolidated surface material that accumulates within feedlot pens during a feeding cycle. Runoff from feedlot surfaces is diverted into settling basins. The storage capacity of the settling basins will be substantially reduced if large quantities of solid material are transported in runoff from the feedlot surfaces. The objective of this study was to identify the...

A case of combined planar Couette-Poiseuille flow corresponding to vanishing horizontal flux has been generalized by the introduction of a model for the surface velocity gradient. A relation corresponding to the Orr-Sommerfeld equation has been derived for this model. The critical value of the surface velocity gradient has been obtained. At the critical point, the corresponding critical Reynold...

We investigate the statistical properties of single phase slip events observed in vortex nucleation experiments in He by the groups in Berkeley and Paris. From the cumulative distribution function of the events we calculate the slip rate as a function of flow velocity. The critical velocity is defined as the mean velocity and its statistical width as the standard deviation. From the slip rate a...

Individuals in streams are constantly subject to predominantly unidirectional flow. The question of how these populations can persist in upper stream reaches is known as the “drift paradox.” We employ a general mechanistic movement-model framework and derive dispersal kernels for this situation. We derive thinas well as fat-tailed kernels. We then introduce population dynamics and analyze the r...

In the present work, the effect of fluid’s elasticity was investigated on the hydrodynamic instability of Blasius flow. To determine the critical Reynolds number as a function of the elasticity number, a two-dimensional linear temporal stability analysis was invoked. The viscoelastic fluid is assumed to obey the Walters’ B fluid model for which base flow velocity profiles were fortunately avail...

introduction : cerebral autoregulation (ca) and mean cerebral blood flow velocity in males and females are still under controversy. the present study was scheduled to address the effect of sex on these parameters. materials and methods : the present study was interventional and performed on 30 healthy volunteers (15 males aging from 20-30 yrs and mean age of 23.9±3 years old and 15 females agin...

purpose: to compare ophthalmic artery velocity in eyes with nonarteritic anterior ischemic optic neuropathy (naion) with that of normal fellow eyes. methods: in this case-control study, 20 patients with unilateral naion and disease onset less than 8 weeks, were enrolled. using color doppler imaging, mean, maximum systolic and end diastolic ophthalmic artery velocities were evaluated. the result...