Figure 1.

Typical trajectory. The position of a CD48-coated bead driven along a CD2-derivatized surface by a wall shear rate of 22 s⁻¹ is shown. Periods of regular motion with constant velocity (of order of 20 μm/s) are interspersed by arrests of variable duration ranging from a few tens of milliseconds (double arrows) to several hundreds of milliseconds (simple arrow) or more (not shown).