An aspect of the present invention facilitates analysis of software code written in a programming language. An occlusion valve is disclosed having a threshold pressure that is less than a rupture tolerance of the infusion system components. The forward end overlap is set greater than a pitch of the cell subject to cell to cell comparison inspection. Etching is used to provide contacts for the gates, source, and drain of the device. 5% by mass of sodium dodecyl sulfate, followed by stirring for 90 min and by irradiating with ultrasonic waves of 20 kHz and 80 W for 5 min, and a liquid containing the toner dispersed therein is centrifugated at 3,000 rpm for 5 min. In other forms, the velocity is ascertained by transmitting an ultrasonic beam through the shedding vortices to determine vortex frequency which is proportional to velocity.