Abstract: The cushion has a contoured base with a layer of resilient cushion foam thereover. The cushion foam is of uniform thickness over a substantial part of the base and is suitably covered. The shape is such that the buttocks of the seated person are clasped positioned rather than supported. A recess is provided under the ischia, under the trochanters, and beneath the sciatic nerves to limit the local pressure. In one configuration, these recesses may contain air bladders which are inflated by body motion against a back bladder in the cushion. In another embodiment, the various bladders may be sequentially pressurized to shift the bearing areas under the buttocks of the seated user in order to periodically lift the user for stimulating blood circulation.

Abstract: Measurements having physiological significance can be obtained by analyzing radiation which is reflected by an artery of the body. Such measurements are preferably made by immobilizing a part of the body such as the human wrist where an artery extends substantially linearly and is adjacent to and generally parallel with the surface of the skin, by then directing radiation from a radiation source or sending apparatus toward any of several specific locations along the artery at an angle such that some of the radiation will be reflected, and by next measuring the amount of reflected radiation in accordance with time through the use of a receiving or detection apparatus. These locations are specific regions or areas generally along and generally extending transverse to the artery which have been established on the basis of experience as normally being capable of reflecting back at least some radiation in an amount having physiological significance.