Abstract: A personal monitor (10, 100, 200) for work and heat stress has a heart beat sensor (12) producing output electrical signals indicating a user's heart beats. A memory (127) stores heart beat information corresponding to the heart beat signals produced over predetermined time intervals. A microprocess (126) is connected to receive the heart beat information from the memory (127). The microprocessor (126) analyzes the heart beat information incrementally over the predetermined time intervals under program control to obtain a physiological demand during the predetermined time intervals and compares the obtained physiological demand against a stored physiological demand limit. Light emitting diodes (208) and a sound producing diaphragm (186) provide indications to the user when the stored physiological demand limit has been exceeded. The microprocessor (126) controls operation of the LEDs (208) and the diaphragm (186).

Abstract: An evoked potential autorefractometry system includes a computer driving an alternating checkerboard mirror stimulus to project a stimulus pattern directly to a patient through a continuously variable focus lens controlled by the computer and which maintains a constant image size on the patient's retina. The evoked potentials produced by the patient are amplified, asychronously filtered both in an analog and digital fashion to allow peak to peak detection of the evoked potentials to determine amplitude. The digital filter includes a 255 point running sum. The peak to peak amplitudes are asychronously digitally filtered using a 16 point running sum to produce an amplitude measure of the evoked potentials. The lens is swept rapidly from one extreme of focus to the other extreme in relatively large steps to determine the area in which the peak amplitude occurs.

Abstract: A self-contained, closed circuit breathing apparatus having a balanced breathing resistance system is provided by an apparatus comprising an inhalation conduit and an exhalation conduit, a mouth connection communicating with said conduits for making connection with the mouth of the operator, an inhalation check valve and an exhalation check valve on either side of said mouth connection providing uni-directional flow through said inhalation and exhalation conduits, respectively, a chemical canister connected across said inhalation and exhalation conduits, a pre-canister storage container communicating with said exhalation conduit, said pre-canister storage container being provided with a uni-directional impedance component comprised of a resistance means for allowing one part of the exhaled air during exhalation to pass into the pre-canister storage container and the remainder to pass through said chemical canister into a post-canister storage container and a uni-directional check valve permitting essentially