Abstract: A bladed heat exchanger fin, tube assemblies in which the fin is installed, and methods of using the fin. The bladed fin includes a collar and a radial portion extending radially from an axis of the collar. The radial portion has a base region adjacent the collar and first and second sets of blades that radially extend therefrom. Each blade has a span-wise axis that is transverse to the axis of the collar. Each of the first set of blades is revolved about the span-wise axis thereof so as to have radial edges that are axially spaced from each other, and each of the second set of blades is not revolved about the span-wise axis thereof. At least some of the blades of the first set are between at least some of the blades of the second set.

Abstract: A learning device for people with damage to the cortical areas of the brain and minimal brain disfunction related to learning. It comprises an elongated housing one end of which is provided with a writing instrument and the other end of which is provided with an electromagnetic transducer which, when connected to a sound recording source, such as a cassette player, causes the elongated housing to vibrate mechanically in accordance with the frequency of sound signals. The device, when held against the skull while vibrating, transmits sound to both hemispheres of the brain so as to accomplish auditory perceptual training.

Abstract: An apparatus for intercranial transmission of a plurality of audio signals in which a pair of transducers are independently mounted on a headband for transmitting audio signals from a source to the cranium. The apparatus is comprised of two parallel wires having earmuffs attached to each end which fit over the ears to eliminate external stimuli. The transducer assemblies are adjustably mounted on the wire headband for sliding adjustment to different positions. The transducer assemblies each include separately oscillatable transducers which are insulated from external stimuli and from each other. A stereophonic plug is provided for connecting the independent transducer assembly to a stereophonic audio signal source.