The bacterium Escherichia coli (E. coli) moves in its natural environment in a series of straight runs, interrupted by tumbles which cause change of direction. It performs chemotaxis towards chemo-attractants by extending the duration of runs in the direction of the source. When there is a spatial gradient in the attractant concentration, this bias produces a drift velocity directed towards its...

We study the dynamics of r-modes in the ocean of a magnetic neutron star. We modeled the star’s ocean with a spherical rotating thin shell and assumed that the magnetic field symmetry axis is not aligned to the shell’s spin axis. In the magnetohydrodynamic approximation, we calculate the frequency of ` = m rmodes in the shell of an incompressible fluid. Different r-modes with ` and `±2 are coup...

The effect of a long length scale static inhomogeneity on spiral wave dynamics is studied in the two-dimensional complex Ginzburg-Landau equation. We find that the inhomogeneity leads to the formation of a dominant spiral domain that suppresses other spiral domains, and that the spiral vortices slowly drift in the presence of an inhomogeneity with a velocity that is proportional to the local pa...

Nonlinear coherent structures governed by the coupled drift wav&on-acoustic mode equations in nonuniform plasmas with sheared magnetic fields are studied analytically and numerically. A solitary vortex equation that includes the effects of density and temperature gradients and magnetic shear is derived and analyzed, The analytic and numerical studies show that for a plasma in a sheared magnetic...

the majority of iran’s area is covered by arid and semiarid climates. in these areas, wind causes more erosion compared to water. therefore, determination of wind characteristics especially its velocity is very important. one of the simplest methods that can supply researchers with the origin of wind erosion in the shortest time is synthesizing sand rose model and interpretation of aerial photo...

Theory of drift of spiral waves has been developed for isotropic and anisotropic plane and isotropic sphere. Here, we proceed to parts of the isotropic torus surface with no-flux boundary conditions and show how velocity components and drift coefficients depend on core position, grid size and local surface curvature.

2014 It has been observed that in cholesterics shear flow induces a transverse drift of small particles suspended in the liquid crystal. Quantitative measurements of the drift velocity are presented. The effect is interpreted using the analogy of the thermomechanical coupling, predicted for cholesterics. J. Physique LETTRES 42 ( 1981 ) L-41 L-43 Classification Physics Abstracts 61.30 15 JANVIER...

The majority of Iran’s area is covered by arid and semiarid climates. In these areas, wind causes more erosion compared to water. Therefore, determination of wind characteristics especially its velocity is very important. One of the simplest methods that can supply researchers with the origin of wind erosion in the shortest time is synthesizing sand rose model and interpretation of aerial photo...

Some years ago Donovan and Wilson concluded that carrier motion on a single chain of the quasi-one-dimensional polymer crystal PDA-TS exhibits highly unusual features. From the electric field dependence of the peak photocurrent and carrier generation rate they concluded that carriers had an ultra-high mobility and a low-field saturated drift velocity. We report new measurements in the time-depe...

The electrostatic and electromagnetic low frequency waves propagating in azimuthal direction in a Hall thruster channel are found to be unstable due to the resistive coupling to the electrons’ closed drift in the presence of collisions. The thermal motion of the electrons and their collisions significantly affect the growth of these waves. With respect to the collision frequency, wave number, e...