Abstract: A new family of fluorescent antibodies (FAB) and a method for their synthesis is disclosed for use in an apparatus and method wherein the effects of background fluorescence are virtually eliminated from fluorescence measurements. The novel fluorescent antibodies consist of antibodies conjugated with rare-earth chelates which have unique fluorescent properties. These fluorescent antibodies are useful because when excited with short pulses of light, they exhibit fluorescent decay times which are much longer than typical background fluorescence at room temperature and with a spectral width far narrower than typical background fluorescence.

Abstract: A tapped delay line (38) terminated with its characteristic impedance at both ends is connected to receive a differential input signal in intermediate taps (27, 29) of a delay line. Delay line taps (25, 27, 29, 31), as well as ends (21, 23) are connected symmetrically to two pair of summing networks (59, 61 and 83, 85) where voltage signal components having different delays from the input signal are linearly combined. One pair of summing networks (59, 61) produces a balanced differential output signal which is an amplitude equalized and differentiated version of the input signal, while the other pair of summing networks (83, 85) produces another balanced differential output signal which is a different amplitude equalized version of the input signal. Each version is needed in one of the channels of a dual channel signal detector for detecting the peaks of the variable amplitude input signal.

Abstract: A power driver control circuit (38) provides control signals (44, 46, 48, 50, 52, 54) for switching transistors in a power driver (56) for an electromagnetic actuator (11) of the type used for controlling a servo head (12) in a closed loop servo system. The control circuit includes variable time delay circuits (70, 71) connected to threshold detectors (74, 84) so that dead zones can be created when the servo error signal changes polarity thereby isolating the switches and preventing switch burn-out.

Abstract: As an aid in counting servo tracks in a position servo system, a position window detector (30) which normally provides coarse and fine pulses to counting logic (53) also provides fine pulses to a reset switch (45) of a tachometer signal integrator means (33), resetting the integrator once for each track. In the event of position signal drop-out wherein coarse pulses are not properly generated, a threshold detection means (43) senses when the output of the integrator reaches a threshold level and produces a threshold reached signal which is transmitted to counting logic means (53) for incrementing a track counter (61).

Abstract: A tapped delay line (39) terminated with its characteristic impedance at both ends is connected to receive a differential input signal across ends (35, 37) of the delay line. Delay line taps 41, 43), as well as ends, are connected symmetrically to a pair of summing networks (71, 73) where voltage signal components having different delays from the input signal are linearly combined. The output waveforms from both summing networks are combined to provide a balanced differential signal that has been both amplitude equalized and differentiated from the input signal with variable amplitude for use in a signal detector (87, 89) that requires such a shaped signal waveform.

Abstract: A sense amplifier and sensing scheme for sensing the normal or blown condition of fuses in a programmable read only memory (PROM) or similar device. A sensing circuit is provided with a threshold level separating high and low input levels indicative of the fuse condition. The sensing circuit has one circuit branch with a first current mirror with a temperature characteristic which provides a threshold level which is slightly divergent with reference to a low level input. Another circuit branch clamps the high input level to the slightly divergent threshold level and uses a second current mirror with a temperature characteristic which provides a high level slightly more divergent than the threshold level. By selecting mirror currents proportionally, high level and threshold level temperature characteristic divergence can be proportionally controlled in selected amounts with respect to the low level.

Abstract: A phase comparator for a digital phase locked loop which provides first and second order error signals for phase and frequency correction of a voltage controlled oscillator in the loop with respect to data being read for self synchronization of the data. A first order error signal is generated in a first phase detector which operates only during a VCO "unsafe" condition, i.e., when a data pulse is beyond a present limit. A finer, second order error signal is generated in a second phase detector which operates only during a VCO "safe" condition, i.e., when a data pulse is within a preset limit.

Abstract: A hub for a disk storage medium which is a unitary article of two dissimilar metals having a single plated coating. An example is an aluminum support member and a joined steel armature plate wherein the two metals have been joined, cleaned and plated on exposed surfaces, but without plating on joining surfaces.

Abstract: A longitudinally excited gas laser having a laser tube in contact with a readily fabricated mass of material which conducts and dissipates heat generated in the tube, serves as part of a low inductance electrical transmission line for the laser tube discharge and aligns sections of the tube for ease of assembly and operation.

Abstract: A servo system for accurately positioning a transducer relative to data paths on a recording medium by detecting sync and servo signals from two parallel abutting servo tracks sharing a common longitudinal boundary within circumferentially spaced sectors of the medium. Within each sector of the recording medium, two servo waveforms of different frequencies in two abutting servo tracks are preceded by a sync reference waveform of the same frequency in both servo tracks which is used as a reference for a phase locked oscillator, connected to the transducer, generating a pair of modulation signals that are to be mixed with transducer signals from both servo waveforms. A pair of servo channels are provided for receiving the pair of modulation signals and the servo signals for deriving an imbalance error signal representing deviation of the transducer from the center line of a data path, which is the projection from the sectors of the common longitudinal boundary between servo tracks.

Abstract: A water heating and forced air heating system that provides potable hot water and that also provides heated air for heating enclosed spaces within buildings, including: a water heater including a water tank filled with water, a burner for heating the water in the tank, and an exhaust flue for removing hot gases generated by the burner; a gas-to-liquid heat exchange unit disposed within the flue; a forced air heater having a casing that defines a chamber, a liquid-to-gas heat exchange unit disposed within the chamber, a gas-to-gas heat exchange unit also disposed within the chamber, and a blower for pulling fresh air into the chamber and blowing it past the heat exchange units to absorb heat; a pump for pumping water through the gas-to-liquid heat exchange unit so that the water becomes heated by the hot gases within the flue; another pump for pumping heated water through the liquid-to-gas heat exchange unit to heat the air flowing within the chamber; and a conduit for connecting the terminal end of the flue t

Abstract: A loader system for agricultural trailer boxes wherein a self-propelled carriage is provided with wheels to be driven on beams placed atop trailer boxes. The carriage supports conveyors extending over lateral sides of the trailer and the conveyors feed a chute emptying into the trailer interior. The beams of each trailer box can be linearly connected so that the carriage may be driven for one trailer to a queued trailer over a bridge formed by joining beams.

Abstract: Apparatus for measuring distance between a gauge head orifice, and the front planar surface of an object by sensing acoustic pressure near the gauge head orifice. The acoustic pressure is initially generated by an audio oscillator activating a speaker which emits acoustic waves through a first orifice. Acoustic pressure is sensed through a second orifice, proximate to the first, and the pressure is converted to an electrical signal which is processed to yield a distance signal for a display. Two similar distance gauges spaced apart on opposite sides of a planar member at a known distance are used to compute the thickness of the planar member.

Abstract: A collar construction for a disk hub in which the interior of the collar is adapted with a plurality of cylinders truncated in a shape mating with portions of a spindle to which the hub is fit. The cylinders have longitudinal slots extending partially therethrough allowing compression of the cylinders when in contact with a spindle. The collar is used for centering a disk on a spindle.

Abstract: A method and apparatus for background correction in photoluminescent analysis of a selected photoluminescent target substance with a relatively narrow emission spectrum in the presence of ambient substances with a combined photoluminescent spectrum which is relatively broad. The photoluminescence of the target substance is sampled and measured in a narrow wavelength band corresponding to the principal emission spectrum of the target. A second sample of photoluminescence is measured in one or more wavelength bands adjacent to the first wavelength band, but excluding substantially all of the photoluminescence of the target substance, and transmitting only ambient photoluminescence. The second measurement is converted into an amount which would occur if ambient photoluminescence had been sampled in the first wavelength band and then the converted amount is subtracted from the first measured amount, thereby correcting the first measured amount for photoluminescence derived from ambient substances.

Abstract: An array of spiral antennas formed conformally about a cylindrical surface. The antennas share a common cavity or resonance chamber of annular cross section inside the cylinder.

Abstract: A needle for leading dental floss or other fibrous material through narrow apertures. A curved substantially rigid needle is provided with an eye having resilient, deformable sides for temporary expansion of the eye for ease of threading and for temporary compression in passing through narrow apertures.

Abstract: A timer in which a lesser cylinder having funnel-shaped top and bottom portions is disposed within a greater cylinder. Granular material is disposed in the greater cylinder, with a passage or gap provided between the outside diameter of the lesser cylinder and the inside diameter of the greater cylinder so that granular material funneled through the lesser cylinder downwardly to the base of the greater cylinder may be quickly returned at any time by inverting the greater cylinder, thereby allowing another pass of the granular material through the lesser cylinder.

Abstract: A legless chair possessing an arcuate exterior permitting rocking and reclining. The arcuate surface contacts a floor for stability and reclining to a selected position. Weight in the nose of the chair brings the chair to an upright position when not in use. A lightweight filler material may be provided for buoyancy, easy portability and for use in water.