Abstract: A method and apparatus for creating a leukocyte rich sample from a mixed population of blood cells. The method comprises the steps of: separating an amount of blood into layers that include a buffy coat layer having a mixed population of blood cells including plasma and red blood cells; providing a chamber having an opening for receiving a fluid; causing the buffy coat layer to enter the chamber; centrifuging the chamber to separate the buffy coat layer into at least a plasma containing layer, a leukocyte containing layer, and a red blood cell containing layer; and separating the leukocyte containing layer from the other layers in the chamber.

Abstract: A closed loop idle speed controller for a fuel injection system operates to control an air valve which controls an air passage bypassing the main air flow. The air valve is positioned by an actuator whose output position is controlled by fuel pressure operating against a spring. The fuel pressure is controlled by a pair of solenoid-operated on-off valves, one of which responds to electrical signals representing engine speeds below a speed reference to direct fuel to the actuator and the other of which responds to signals representing speeds above the reference to permit fuel to be withdrawn from the actuator and returned to its source. Each of the solenoid on-off valves is supplied from a pulse width modulator. The engine-driven distributor provides pulses responsive to engine speed which are connected to a sample and hold circuit. The sample and hold circuit provides d.c.