Velocity fields for Poiseuille flow through tubes having general cross section are calculated using a path integral method involving the first-passage times of random walks in the interior of the cross sectional domain B of the pipe. This method is applied to a number of examples where exact results are available and to more complicated geometries of practical interest. These examples include a...

We show that the speed of microtubules gliding over a kinesin-coated surface can be controlled over a wide range of values by the application of an electric field. The speed can be increased by up to a factor of 5 compared to the speed at zero field when assisting forces are applied and slowed down to zero velocity for opposing fields. Sideways applied fields also induce significant motion. The...

A reconstruction method for recovering the initial conditions of the Universe starting from the present galaxy distribution is presented which guarantees uniqueness of solutions. We show how our method can be used to obtain the peculiar velocities of a large number of galaxies, hence trace galaxies orbits back in time and obtain the entire past dynamical history of the Universe above scales whe...

We describe a new method of overcoming problems inherent in peculiar velocity surveys by using data compression as a filter with which to separate large–scale, linear flows from small– scale noise that biases the results systematically. We demonstrate the effectiveness of our method using realistic catalogs of galaxy velocities drawn from N–body simulations. Our tests show that a likelihood ana...

We studied the temporal evolution of the electromagnetic and velocity fields in an incompressible conducting fluid by means of computer simulations from the Navier Stokes and Maxwell’s equations. We then derived the set of coupled partial differential equations for the stream function vector field and the electromagnetic field. These equations are first order difference equations in time and fe...

Global motion of magnetohydrodynamic fluid in a domain bounded by a free surface and under the external electrodynamic field is proved. The motion is such that velocity and magnetic field are small in H3-space.

Rotation effects on MHD flow past an impulsively started vertical plate with variable mass diffusion is studied here. The governing equations involved in the present analysis are solved by the Laplace-transform technique. The velocity, concentration and skin friction are studied for different parameters like mass Grashof number, Schmidt number, magnetic field parameter, rotation parameter and t...

We consider the pulsar velocity problem and relate it to some unconven-tional neutrino oscillation mechanisms based on a violation of the equivalence principle by neutrinos. We show that the observed pulsar velocities may be explained by violations at the level from 10 −9 to 10 −10 in the case of a non-universal tensor neutrino-gravity coupling, whereas there is no solution in the case of a non...