Abstract: An adaptive bias method and circuits for amplifiers that provide a substantial current boost based at least partly upon a sensed input power of an amplifier circuit. Methods and circuits of the invention provide an additional bias current based upon the sensed input power. Circuits of the invention may be simple, area-efficient, low-power, stable and digitally-programmable. In addition, methods and circuits of the invention may be used with a number of amplifier circuit configurations, including amplifiers having either inductor and/or resistive degeneration.

Abstract: A locking fastener apparatus for coupling objects together. The locking fastener apparatus includes a bolt having a head portion and a shaft portion with a plurality of shaft slots along the shaft. A nut has a threaded hole for threadably receiving the shaft portion of the bolt. A nut slot is centrally positioned across a width of a first side portion of the nut. The nut has a nut lock bore extending inwardly through the nut slot from the first side portion towards a central hole of the nut. The nut includes a nut lock member for movably positioning in the nut lock bore of the nut. The inner end of the nut lock member has a catch portion that is engagable with the shaft slots. A lever member pivotally coupled to the nut is positioned in the nut slot, with a first end attached to the nut lock member and a second end abutting a biasing member which biases the catch portion into one of the shaft slots to facilitate locking the two together until.

Abstract: A hyperthermia apparatus, suitable for transurethral application, has an energy radiating element comprising a leaky-wave antenna. The leaky wave antenna radiation pattern is characterized by a surface wave which propagates along an aperture formed by openings (small in comparison to a wavelength) in the outer conductor of a transmission line. Appropriate design of the leaky wave antenna produces a uniform, broadside pattern of temperature elevation that uniformly heats all or part of the periurethral tissues.

Abstract: A single ended audio amplifier having at least two primary windings, not necessarily matched, in the primary of an output matching transformer: one for the amplifier final stage; and another winding to produce in the same core a magnetizing force equal and opposite for out-of-band currents. Primary among these is quiescent current, but subsonic anode current variations due to signal or drift of operational conditions may be cancelled as well. A sensor tracks the quiescent and subsonic currents of the output amplifier device. The sensor output is low-pass filtered to control a three terminal current regulator that drives the second coil to oppose the out-of-band anode currents in the first (signal) coil of output transformer primary.

Abstract: A method and apparatus for nondestructive evaluation of a composite material specimen is characterized by exposing the specimen to pulsed radio frequency energy to produce an elastic wave that propagates on the surface of the specimen. The wave is detected by a piezoelectric or electro-optic displacement mode transducer which produces a signal corresponding to the wave. The signal is analyzed by a processor to classify the specimen into one of a plurality of predetermined reference groups defined in accordance with a minimum number of defective and nondefective samples.

Abstract: A method and apparatus for millimeter wave flow cytometry of a cell stream hydrodynamically focused in a zone of interaction with a millimeter wave source and complex ratiometric receiver. The cell stream is characterized by complex power wave scattering parameters as a function of frequency, scattering angle and polarization. These parameters train a signal processor to sort specimen cells into one of a plurality of predetermined reference groups in accordance with a minimum number of normal cell types and functional states.

Abstract: An ultra-low friction bearing including an inner race, an outer race, bearing elements engaged between the inner and outer races and a seal between the inner and outer races is disclosed. The seal includes first and second sealing washers. The first washer has an outer diameter greater than an inner diameter of the outer race and an inner diameter greater than the outer diameter of the inner race. The second washer has an inner diameter less than the outer diameter of the inner race and an outer diameter less than the inner diameter of the outer race. The first washer slidably engages the outer race, the second washer slidably engages the inner race and the washers overlap and slidably engage one another. One of the washers snap fits into its respective inner or outer race while the other washer engages a stepped surface of the other of the inner and outer races.

Abstract: A method and apparatus for therapeutic deep heating of musculoskeletal tissues are characterized by an improved transducer that serves simultaneously to couple the power from the generator into the patient and to sense the therapeutic response for treatment control including a method of manufacture and testing of contact applicators for dielectric heating of musculoskeletal tissue. The applicator is comprised of a rectangular wave guide in which the location of the dielectric material is adjusted to reduce the measured value of the guide wave length to the free-space value at the frequency of operation. In addition, the invention comprises a method and apparatus for the noninvasive detection of therapeutic response in tissue to dielectric heating. This response is then used to control the treatment. Both heating and sensing are accomplished by one transducer and one apparatus if dielectric heating is employed.

Abstract: A method and apparatus for body joint rotation and measurement to isolate the joint under test is characterized by imposing movement on one member of the joint in a series of discrete increments, whereupon strain is measured at rest over a predetermined range of motion. Measurement of static force v. displacement at each of a plurality of steps in the angular range provides a quantitative test and evaluation of the elastic component of joint stiffness that resists the applied angular displacement. In this way, a static stress-strain loop is produced for each plane of movement. The static modulus of elasticity is derived by the slope of the stress-strain loop at the extremes of the range of motion.

Abstract: A method and apparatus for therapeutic deep heating of musculoskeletal tissues are characterized by an improved transducer that serves simultaneously to couple the power from the generator into the patient and to sense the therapeutic response for treatment control including a method of manufacture and testing of contact applicators for dielectric heating of musculoskeletal tissue. The applicator is comprised of a rectangular wave guide in which the location of the dielectric material is adjusted to reduce the measured value of the guide wave length to the free-space value at the frequency of operation. In addition, the invention comprises a method and apparatus for the noninvasive detection of therapeutic response in tissue to dielectric heating. This response is then used to control the treatment. Both heating and sensing are accomplished by one transducer and one apparatus if dielectric heating is employed.

Abstract: Therapeutic deep heating of musculoskeletal tissues is accomplished with an improved transducer that serves simultaneously to couple the power from the generator into the patient and to sense the therapeutic response for treatment control including a method of manufacture and testing of contact applicators for dielectric heating of musculoskeletal tissue. The applicator has a rectangular waveguide in which dielectric material is placed to reduce the guide wave length to the free space value at the frequency of operation. The noninvasive detection of therapeutic response in muscle tissue to dielectric heating is then used to control the treatment. Both heating and sensing are accomplished by one transducer and one apparatus if dielectric heating is employed. If other forms of heating are used, such as ultrasound, the sensor still occurs but the apparatus must be modified, the modifications including replacement of the high power electromagnetic source with a low power source version.

Abstract: A method and apparatus for cardiac hemodynamic monitoring is described. It is based on the complex field amplitudes of microwaves propagated through and scattered by thoracic cardiovascular structures, particularly the heart chambers, as a function of time during the cardiac cycle. Movement artifact and signal leakage are controlled by the use of closely coupled, flexible, light weight, passivated, conformal microstrip antennas that operate in the UHF band. The basic measurement technique is vector network analysis of the power wave scattering parameter in forward scatter configurations of various projections such as posterioanterior (PA), left anterior oblique (LAO), and right anterior oblique (RAO). Non-invasive evaluation of hemodynamic aspects of cardiovascular function is provided. Calibration is possible in human subject without invasive methods.

Abstract: A method for therapeutic deep heating of musculoskeletal tissues with an improved transducer that serves simultaneously to couple the power from the generator into the patient and to sense the therapeutic response for treatment control including a method of manufacture and testing of contact applicators for dielectric heating of musculoskeletal tissue. The applicator is comprised of rectangular wave guide in which dielectric material is placed to reduce the guide wave length to the free-space value at the frequency of operation. In addition, the invention comprises a method and apparatus for the noninvasive detection of therapeutic response in muscle tissue to dielectric heating. Ths response is then used to control the treatment. Both heating and sensing are accomplished by one transducer and one apparatus if dielectric heating is employed.

Abstract: A physiologic facsimile image of a biological target without multipath comination is obtained by first producing, for each one of a plurality of sample locations which are spaced so as to define a two-dimensional array, a time delay spectrum wherein the frequency of each spectral ordinate represents the instantaneous differential propagation delay between a first microwave signal which has been propagated through the target and a second microwave signal which initially corresponds to the first microwave signal, and which has been propagated through means having a predetermined propagation delay, and measuring the amplitude of the spectral ordinate corresponding to the direct ray path of propagation through the target, so as to obtain a set of data. The set of data is then digitized and converted from time domain to frequency domain.

Abstract: A physiologic facsimile image of a biological target is obtained by: scang the target by transmitting a microwave signal through the target and measuring at least one of the amplitude and phase components of the complex microwave power transmission coefficient at each one of a plurality of sample locations which are spaced so as to define a two-dimensional array and such that a set of digital data for each of the measured components is obtained, and for at least one of the sets of data; sorting the set of data into column order; magnifying data derived from the sorting step so as to enhance the resolution of the image; mapping data derived from the magnifying step into further data using a predetermined mapping function so as to enhance the contrast between selected portions of the image; and obtaining the set of control signals by filtering data derived from the mapping step using a band pass function which rejects spatial frequencies below a predetermined first frequency and/or rejects spatial frequencies a

Abstract: A rapid and accurate method for calibrating an instrument for measuring the reflection coefficient and complex permittivity of unknown dielectric materials in a lumped capacitance method for an automatic network analyzer is described. The method includes the discovery that the capacitance of the instrument filled with air can be calculated by measuring only the reflection coefficients of the instrument filled with air and filled with a standard liquid of known permittivity, without the necessity of calculating the capacitance value from the dimensions of the instrument. The complex permittivity of the unknown can then be calculated by measuring the reflection coefficient of the instrument filled with the unknown dielectric. Complex permittivity measurements are useful in, for example, evaluating the time course of dielectric dispersions in biological samples.

Abstract: A method for electromagnetic analysis of cellular or cell ghost physiology and pharmacology without disrupting the physcial integrity of the cell membrane is described. The method utilizes the technique of multifrequency automatic network analysis and signal processing to derive complex permittivities from the error corrected complex reflection coefficient of cell containing samples at each measured frequency. Complex permittivity at each frequency is then related to the dispersion in dielectric conductivity (a term which includes ohmic and non-ohmic losses) thereby measuring the ion permeability barrier and transport functions of the cell membrane and ion distribution inside of and outside of the cell membrane. The method measures the complex reflection coefficient of a capacitive termination containing a cellular sample as high frequencies are applied.

Abstract: A system for remote microwave interrogation and imaging of biological tars comprises at least one microwave, double ridged waveguide antenna probe which operates at S-band frequencies, and a high dielectric liquid medium, preferably water, in which both the probe and the target are completely immersed. For imaging applications, the probe is positioned with respect to the target such that the target is in the near field of the antenna.

Abstract: A thermometric transducer device is provided for use in measuring the temperature of a dielectric, such as human tissue, during exposure of the dielectric to microwave radiation. The system includes a transducer electrode sub-assembly which is partially inserted into the dielectric and comprises a thermistor mounted on one end of an elongate substrate and thick film conductors which extend along the length of the substrate and which are tapered so as to provide electrothermal matching of the heat produced in an equivalent volume of the dielectric so that the transducer electrode serves neither as a heat source or a heat sink. The transducer sub-assembly is connected to measurement instrumentation by a transmission line formed by ultra-thin thin film conductors whose thickness relative to the skin depth of the microwave field in the conductors is such that the conductors are a poor medium for microwave conduction and are thus microwave decoupled.

Abstract: Remote interrogation of biological targets is accomplished in accordance h the present invention by method and apparatus wherein a microwave signal is generated which varies in frequency from a first frequency to a second frequency in a predetermined time period. The signal is divided into two signals, one of which is propagated through a test channel comprising a transmitting antenna for transmitting the signal through the target, and a receiving antenna for receiving the signal transmitted through the target, and the other of which is propagated through a reference channel providing a fixed time delay of propagation. The propagated signals are detected and mixed to produce a time delay spectrum wherein the frequency of each spectral line represents the instantaneous difference in the frequencies of the detected signals.