Abstract: Magnetic direct current to direct current converter with the input isolated from the output. A pulse generator from the feedback is incorporated in the feedback circuitry to regulate the output relative to the input.

Abstract: A new drill-type cranial perforator is disclosed of the type which comprises a front drill head assembly made up of a leading inner drill and a trailing outer drill, and a rear support and drive assembly adapted to enable both drills so long as the leading inner drill is encountering a resistive surface and to disable both drills when the leading inner drill stops encountering the resistive surface.The leading inner drill has at least one drilling flute with a forward cutting edge including a reentrant cutting segment axially rearward from the outer end of the forward cutting edge and extending inwardly towards the longitudinal axis of the perforator.

Abstract: Apparatus for defoaming a fluid material. The apparatus comprises a non-wetting material in closely adjacent relationship to a material having a lesser degree of non-wetting characteristics with respect to the fluid being defoamed. In one embodiment, fibers with different non-wetting characteristics are woven together with one type of fibers being woven at a 90.degree. angle with respect to the other type of fibers. In another embodiment, fabrics consisting of one type of fibers are in alternate adjacent contact with fabric of the other type of fibers. The characteristics of the fibers are preferably inherent in the material.

Abstract: A method for oxygenating blood by combining blood and oxygen in a receptacle to form a foam, the foam flowing upwardly through a bead bed having a multitude of tortuous paths and contact surfaces. The oxygenated blood is then defoamed and collected for recirculation to the patient.