We found that the ultrasonic irradiation induced significant but reversible changes in the excitation level of neurones in the central ganglia of a marine molluse, Aplysia. The experiments indicate the potential applicability of ultrasonics as a means of non-invasive stimulation for a selected area of the central nervous system.

A Dynamic Depth Extraction Method (DDEM) is proposed, which measures the time required for an edge to move through a known distance on the image plane and hence is able to calculate depth. Experimental results for three vertical bars in different depths show that the mean depths obtained by DDEM were almost the same as those obtained from direct measurement. The fluctuation of obtained depth was about 3.6%, which corresponds to one half frame difference in matching time of the near bar. Three kins of thresholds (λ1, λ2 and λ3) were introduced to reduce the noise affection. There was a wide range of thresholds for which the depth can be extracted stably. The DDEM was also successfully applied to recovering 3D structure of a complicated room.