BACKGROUND Keratocytes are specialised, rapidly moving cells that generate substantial contractile force perpendicular to their direction of locomotion. Potential roles for contractile force in cell motility include cell-body transport, regulation of adhesion, and retraction of the cell's trailing edge. RESULTS To investigate contact dynamics, we used simultaneous confocal fluorescence and in...

Sea ice contains flaws including frictional contacts. We aim to describe quantitatively the mechanics of those contacts, providing local physics for geophysical models. With a focus on the internal friction of ice, we review standard micro-mechanical models of friction. The solid’s deformation under normal load may be ductile or elastic. The shear failure of the contact may be by ductile flow, ...

A design of a class of linkages is presented which are less complex than those suggested by Kapovich and Millson in the con…guration of conventional planar linkages. Conventional linkage constraints are relaxed allowing sliding joints and telescoping links. The precise number of …xed links, telescoping links, and sliding contacts is determined for this modern linkage to trace a Bézier curve of ...