Nehemiah and Nehama Cohen Rm. The distance between fingers is determined by the availability of oxygen. The width of the fingers is determined by the height of the system and by mechanisms of heat transport. This demonstrates that flames belong to a class of pattern forming systems determined by diffusion limited growth. The transition from flutter to tumble occurs at a well defined value of the Froude number, which serves as a control parameter.
Vortices shed at every zig and zag are found to be central to the phenomenon.
We investigated the phenomenology of transformations in lipid bilayers that are excited using laser tweezers. A wide variety of dynamic instabilities and shape transformations are observed, including the pearling instability, expulsion of vesicles, unbinding of lamellae and exotic transitions such as the formation of passages. Pearling in Cells In collaboration with A. Bershadsky and S.A. Safran, we have shown that the pearling instability, characteristic of tension in membranes, appears in cell whose actin cytoskeleton has been chemically disrupted. Characterization of the instability yields insight on what holds a cell together, and on how its shape is determined.