We introduce order-based diffusion processes as the solutions to multidimensional stochastic differential equations, with drift coefficient depending only on the ordering of the coordinates of the process and diffusion matrix proportional to the identity. These processes describe the evolution of a system of Brownian particles moving on the real line with piecewise constant drifts, and are the ...

Solving transport equations in heterogeneous flows might give rise to scale dependent transport behavior with effective large scale transport parameters differing from those found on smaller scales. For incompressible velocity fields, homogenization methods have proven to be powerful in describing the effective transport parameters. In this paper, we aim at studying the effective drift of trans...

We present numerical simulations of the kinematic induction equation in order to examine the dynamo efficiency of an axisymmetric von Kármán-like flow subject to time-dependent nonaxisymmetric velocity perturbations. The numerical model is based on the setup of the French von Kármán-sodium dynamo (VKS) and on the flow measurements from a water experiment conducted at the University of Navarra i...

We report experimental measurements of the axial plasma flow and the parallel ion temperature in a magnetized linear plasma device. We used laser induced fluorescence to measure Doppler resolved ion velocity distribution functions in argon plasma to obtain spatially resolved axial velocities and parallel ion temperatures. We also show changes in the parallel velocity profiles during the transit...

The effect of a magnetic-field-aligned plasma flow with a transverse velocity gradient on the excitation of current-driven ion-acoustic-like waves in a plasma having equal electron and ion temperatures (T(e) = T(i)) was investigated experimentally. In agreement with theoretical predictions, the presence of sheared plasma flow substantially reduces the critical electron drift velocity needed to ...

In tokamaks, Ware pinch is a well known neoclassical effect for trapped particles in response to a toroidal electric field. It is generally believed that there exists no similar neoclassical effect for circulating particles without collisions. However, this belief is erroneous, and misses an important effect. We show both analytically and numerically that under the influence of a toroidal elect...

A novel experimental technique was used to quantify the motion of E. coli to varying serine concentrations and gradients so as to capture the spatial and temporal variation of the chemotactic response. The average run speed and the cell diffusivity are found to be dependent on the serine concentration. The measured diffusivities were in the range of 1.2-2.5 x 10 (-10) m(2) s(-1). The study reve...

We have investigated the role of turbulence for two problems, the effect of the polarization current on the NTM and the effect of diamagnetic drifts on mode penetration. For the NTM problem, we find that the fluctuations exert a drag force on the island that results in a stabilizing slowdown in the propagation velocity. For the mode penetration problem, we have investigated the influence of pol...

As MOS devices scale to submicron lengths, short-channel effects become more pronounced, and an improved transistor model becomes a necessary tool for the VLSI designer [10]. We present a simple, physically based charge-controlled model. The current in the MOS transistor is described in terms of the mobile charge in the channel, and incorporates the physical processes of drift and diffusion. Th...

We investigate the relationship between the effective diffusivity and effective drift of a particle moving in a random medium. The velocity of the particle combines a white noise diffusion process with a local drift term that depends linearly on the gradient of a gaussian random field with homogeneous statistics. The theoretical analysis is confirmed by numerical simulation. For the purely isot...