Abstract: A braking device for use in an in-line roller skate includes at least one braking member. Braking members are positioned relative to the skate wheels allowing the braking members to engage the circumference of at least one skate wheel. The degree of contact between the braking members and the skate wheels is variable to allow a skater to gain proficiency with reduced risk of sustaining injury. The braking device is easily removable from the skate.

Abstract: An electromagnetic shutter for a photographic lens is disclosed. The shutter comprises an optical stop mounted between focusing elements with a flap mounted for rotating substantially along one side of said stop. The flap has a first position in which it blocks the passage of light through the stop and a second position in which it is removed therefrom. An electromagnetic means for rotating the flap from its first position to its second position comprises a permanent magnet mounted on said rotatable shaft and an electromagnet having a horseshoe-shaped core with two poles which surround the permanent magnet. When the electromagnet is energized, the magnetic field produced causes said permanent magnet and attached shaft to rotate, thereby rotating the flap from its first position to its second position and thereby opening the shutter. A spring returns the flap to its first position when the electromagnet is not energized, thereby closing the shutter.

Abstract: A signal processor for use in a system including a gamma camera and a cathode ray tube type display device for displaying the distribution of a radioactive pharmaceutical on X-ray film. The system incorporates a sample-and-hold circuit for extending the duration of each output pulse produced by the camera upon impingement of a radioactive particle. The extended pulses cause the X-ray film to be exposed for a longer period of time by the display apparatus, thereby allowing beam current in the tube to be reduced for smaller spot size and improved resolution in the image.

Abstract: Camera for photographing an oscilloscope screen or a cathode-ray tube including a housing having a lens mounted therein with a first opening on one side of the lens for aligning with the oscilloscope screen and a second opening at the other side of the lens for receiving a film cassette. Magnetic means is provided for mounting the film cassette on the camera housing at the second opening including a strip of flexible or resilient magnet material about the opening and a strip of magnetic material on the film cassette.