The optical navigational control strategy used to intercept moving targets was explored using a real-world object that travels along complex, evasive pathways. Fielders ran across a gymnasium attempting to catch a moving robot that varied in speed and direction, while ongoing position was measured using an infrared motion-capture system. Fielder running paths were compared with the predictions ...

An optical trap was used to measure the relationship between restoring force and displacement of a 1.26 μm polystyrene microsphere attached to a 3.5 kilobase-pair DNA strand. Fitting to a wormlike chain model, the persistence length of the DNA molecule was measured as 53.0± 11.6 nm, and the contour length was measured as 713 ± 36 nm. The Hookean spring constant of DNA, at small displacements, w...