  Individual movements of a rod-like self-propelled particle on a flat
substrate are quantified. Biological systems that fit into this description may
be the Gram-negative delta-proteobacterium Myxococcus xanthus, Gram-negative
bacterium Escherichia coli, and Mitochondria. There are also non-living
analogues such as vibrated polar granulates and self-driven anisotropic
colloidal particles. For that we study the Brownian motion of an asymmetric
rod-like rigid particle self-propelled at a fixed speed along its long axis in
two dimensions. The motion of such a particle in a uniform external potential
field is also considered. The theoretical model presented here is anticipated
to better describe individual cell motion as well as intracellular transport in
2D than previous models.
