Abstract: A blood pumping device is described for internal use in humans or animals and which is particularly suitable for use as a left ventricular assist device. The device is comprised of a unitary pancake-shaped deformable sac of flexible resilient, blood compatible material. A pair of oppositely acting plates on each side of the pancake-shaped sac are moved toward and away from each other by the action of driving means to deform the sac and provide the pumping action. Inlets and outlets are arranged in the annular side wall of the sac.

Abstract: A method and apparatus are described for detecting a selected gas in an unknown gas sample. The power output of a radiant energy source is modulated at a first frequency and passed through the sample, the density of the sample being varied at a second frequency. The radiant energy passing through the sample is detected by and converted to an electrical signal which is then processed in order to produce an output signal representative of the selected gas. Density of the sample is preferably modulated or varied periodically by means of a pulsating pump which also supplies the unknown gas.