Contains several programs. TWEEZ13E.PAS is a Brownian dynamics simulation for the mechanical unzipping of a DNA hairpin molecule attached to a bead in an optical-trap. See README.PDF for instructions. HEATFLOW.PAS simulates the temperature rise caused by a heating-laser beam passing through a glass micro-chamber. See README2.PDF for instructions. SEQ5C.PAS is useful for examining known basepair sequences.