We show that plane parabolic flow in a microfluidic channel causes nonmotile, helically shaped bacteria to drift perpendicular to the shear plane. Net drift results from the preferential alignment of helices with streamlines, with a direction that depends on the chirality of the helix and the sign of the shear rate. The drift is in good agreement with a model based on resistive force theory, an...

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...

It is now becoming widely accepted that photon recoil forces from the asymmetric reflection and thermal re-radiation of absorbed sunlight are, together with collisions and gravitational forces, primary mechanisms governing the dynamical and physical evolution of asteroids. The Yarkovsky effect causes orbital semi-major axis drift and the YORP effect causes changes in the rotation rate and pole ...

Rotating spiral waves are a form of self-organization observed in spatially extended systems of physical, chemical, and biological nature. In the presence of a small perturbation, the spiral wave's center of rotation and fiducial phase may change over time, i.e., the spiral wave drifts. In linear approximation, the velocity of the drift is proportional to the convolution of the perturbation wit...

Aims. We investigate the reconstruction of pulsar magnetospheres close to the light cylinder surface to study the curvature drift instability (CDI) responsible for the twisting of magnetic field lines in the mentioned zone. The influence of plasma dynamics on the saturation process of the CDI is studied. Methods. On the basis of the Euler, continuity, and induction equations, we derive the incr...

the rotational friction dampers can be improved the seismic behavior of the steel structures, and they can be reduced the internal forces in the bracing members, columns and the other structural members. in this research, a simple method for modeling and analysis of braced frames equipped by these dampers is proposed. the proposed model describes seismic behavior of dampers very well and it is ...