Abstract: Signals produced by brain activity are measured by each sensor of an array of magnetic and/or electrical sensors external to but proximate to the head (or other portion of the body) of a subject. The measurements obtained simultaneously from all of the sensors are combined in a manner to permit selective measurement of the electrical activity from a specified location within the body, or alternatively, to permit the location in the body producing a particular type of response to be identified. The instantaneous measurement of each sensor is scaled by a weighting coefficient for that sensor, and the products added over all of the sensors. The weighting coefficients are calculated from a mathematical model of the brain that includes information on the shape of the potential source, the extent or type of source activity, the electrical and magnetic properties of the media, and the locations and orientations of the sources and the sensors.

Abstract: A vacuum-tight, nonmetallic hollow article is fabricated from composite material of fibers in a resin matrix. The article has a closed end, and is laid up from sheets of the composite material and end pieces to form the closed end. The layers are mechanically worked and debulked repeatedly during layup between the addition of successive layers, to remove irregularities that can cause vacuum leaks. The joints between the sheets applied to the sidewalls and the end pieces are mechanically worked to effect a vacuum-tight seal, and the joints are staggered as between succeeding layers for strength and integrity. The laid up and debulked piece is finally cured.

Abstract: A self contained cryogenic cooler, requiring only electricity to operate, maintains apparatus therein at cryogenic temperatures without introducing liquefied gas, and with a minimum of mechanical vibration. The cooler includes an elongated cylindrical insulated container with an end plate, the container having a vacuum conduction barrier and a heat shield radiative barrier so that the heat flow through the walls is small. The interior of the container and the apparatus are cooled by a mechanical cooler that achieves intermediately low temperatures, and a helium gas expansion cooler providing the final stage of cooling to below about 5K. The mechanical cooler is supported from the end plate on a first support, and the expansion cooler and apparatus are supported from the end plate on a second support independent of the first support, so that minimal vibration from the mechanical cooler is introduced into the apparatus.

Abstract: Apparatus for performing sensitive magnetic measurements using cryogenically cooled instrumentation, wherein the instrumentation is separated from the bubbles present in a cryogenic cooling fluid. In one embodiment, the magnetic measurement instrumentation is placed in a tail piece joined by heat conducting bolts to a dewar containing a cryogenic fluid, and heat from the instrumentation is conducted to the cryogenic fluid heat sink by metallic strips reaching to the bolts. The cryogenic fluid does not contact the instrumentation directly, resulting in a significantly reduced level of noise in the instrumentation. The tail piece may also be evacuated to avoid pressure and temperature variations that may cause noise and affect the magnetic instrumentation.

Abstract: Apparatus for making biomagnetic measurements includes a biomagnetometer for measuring magnetic fields produced by the body and an electromagnetic location measurement and recording system for automatically determining the location of the portion of the body from which the magnetic signals are being gathered. The electromagnetic location recording system permits establishing a real time body frame of reference with respect to the biomagnetometer, so that biomagnetic signals can be correlated directly with body location and structure. The electromagnetic location recording system may be operated continuously at radiation wavelengths which do not interfere with the taking of data, or intermittently with the taking of biomagnetic data, to avoid interference with the measured values of the biomagnetic data.

Abstract: A vacuum-tight nonmetallic Dewar component is fabricated from composite material of nonmagnetic fibers in a resin matrix. The component is cylindrical with a closed end, and is laid up from sheets of the composite material and circles cut from the sheets to form the closed end. The layers are mechanically worked and debulked repeatedly during layup between the addition of successive layers, to remove irregularities that can cause vacuum leaks. The joints between the sheets applied to the cylindrical surface and the circular end pieces are mechanically worked to effect a vacuum-tight seal, and the joints are staggered as between succeeding layers for strength and integrity. The laid up and debulked piece is finally cured.