Abstract: A device for monitoring a patient or pacing a patient is disclosed which can safely operate in a MRI system. The device uses unique RF filtering and shielding to attenuate voltages on the leads resulting from the high frequency RF signals produced in the MRI. The device is uniquely shielded to prevent induced currents from disrupting the amplifying and processing electronics. The device uses an optional secondary low pass or band reject filter to eliminate interference from the MRI's gradient magnetic field. The device uses optional inductors placed close to electrodes to limit RF currents through the electrodes. Several embodiments of the RF filter are taught which depend on the number of sensing leads, whether the leads are shielded, whether the RF filter is contained in the electronic shielded housing or whether single or multistage filtering is employed. The device may operate as an extended ECG monitor or may be an implantable MRI safe pacemaker.

Abstract: A head mounted display is disclosed for providing a monocular or binocular wide field of view. The head mounted display contains a unique configuration and unique folding optics so that it can be worn like a pair of spectacles or goggles. The optics and frame of the goggles are uniquely designed to accommodate different head dimensions.

Abstract: An efficient hardware cache manager controls the top-of-stack data underflow/overflow. A processor chip includes a processor, a stack buffer and the invented cache management hardware. The processor chip communicates with a remove overflow stack through an address/data bus. The cache management hardware efficiently manages overflow and underflow to and from the processor chip in such a manner less than 1% of the processor's time is spent managing the stack cache.

Abstract: A "pulse to zero" modulation scheme is taught to transmit binary information by modulating a bit mark onto a carrier at the start of each "0" in the bit stream. The "pulse to zero" decoder produces an output that switches to "0" at the occurrence of the detected bit mark and resets to "1" if a second bit mark has not occurred within a preset time lapse from the previously detected bit mark.

Abstract: The present invention is a universal interface allowing a main implant to supply power and receive data from remotely implanted sensor modules through a minimum number of interconnecting lines. The main module can supply a single DC voltage, two sequentially applied DC voltages or an AC voltage to the sensor module. A capacitor means in the sensor module supplies power while the sensor module is transmitting data.

Abstract: A highly automated device to measure the impedance to fluid flow of a vessel by means of direct injection at normal physiologic pressures. The device produces objective impedance data including dynamic impedance, capacitance, and Direct Current resistance, without operator induced error. The device can be used for intraoperative impedance measurements by directly cannulating the vessel under study. Non-operative impedance measurement is performed by means of percutaneous catheters. The device can also inject imaging materials or a lytic solution into the vessel while also measuring vessel impedance.

Abstract: An apparatus and method is disclosed for generating a bit reversed sequence. The apparatus includes a reverse addition means for adding binary words in most significant to least significant bit order with the overflow or carry bit propagated to the left. The invention is used to generate a bit reversed address and/or an address sequence that is mapped into a "closed" space.

Abstract: A capacitive chemical sensor is disclosed that uses an ion exchange layer to detect analyte ions in a liquid medium. An exchange mechanism occurs on the surface of the ion exchange layer, wherein a portion of the counter-ions are removed from the surface in favor of analyte ions. The resulting movement of counter-ions from the surface of the ion exchange layer alters the dielectric constant of the liquid medium along the surface of the ion exchange layer. This change in dielectric constant produces a change in capacitance of the capacitive chemical sensor.

Abstract: A method for performing computations with an asynchronous linear array of multiple processing stages is disclsoed. The linear array comprises multiple processing stages interspersed with flow control flag mechanisms and with dual port linking memories. The method utilizes the flow control flag mechanisms between processing stages to control the flow of computations through the array.

Abstract: An apparatus and method for the passive, non-invasive magnetoencephalographic (MEG) localization and tracking of sources of magnetic signals in the brain is disclosed. The apparatus and method uses a multi-axis magnetic gradiometer to detect the magnetic field, field gradient, and polarization emanating from neuronal sources in the brain under either normal or pathological conditions.

Abstract: A differential polarimeter is disclosed for detecting changes in optical rotation between a test cell and reference cell. The test cell contains a fluid sample exposed to an analyte specific enzyme; the reference cell contains a fluid sample not exposed to the enzyme. To enhance the sensitivity of the system a phase sensitive differential polarimetric technique is taught. In this technique, the phase difference between two resulting sinewave voltages is a measure of analyte concentration.

Abstract: An apparatus for generating pseudo-random codes is disclosed. The apparatus uniquely stores a set of codes in a memory and uniquely retrieves a particular code sequence. The apparatus has particular application to Global Position Satellite (GPS) earth receivers.

Abstract: An apparatus and method of intercomputer communications based on message broadcast with receiver selection is taught. A distributed computer system is described in which each computing element includes a hardware message filter which provides content tag recognition and selection. The overall system architecture allows software modularity and both hardware and software extensibility. The message filter can be preset or dynamically programmed, and can be operated in conjunction with a serial or parallel broadcast bus.

Abstract: An RF circuit to generate a stable carrier signal using a Voltage Controlled Saw Oscillator (VCSO) is disclosed. The invention teaches the use of a phase lock loop circuit employing a temperature compensated crystal oscillator (TCXO), or similar stable oscillator, to stabilize the output of the VCSO.

Abstract: An apparatus and method for non-invasive sensing of bone healing is disclosed. The apparatus and method uses an electromagnetic field to measure impedance changes at and about the bone fracture site during the healing process. The impedance change at the fracture site is a direct indication of the mechanical strength of the fracture site. A multi-coil sensor array is taught, which may be sutured to the patient's skin or mounted onto a plug that is inserted through a window in the cast.

Abstract: A method for noninvasively sensing bone mass loss associated with osteoporosis is disclosed. The method uses an electromagnetic field to measure impedance (or conductivity) changes in the bone. A decrease in conductivity is indicative of osteoporosis.

Abstract: A temperature responsive transmitter is disclosed. The transmitter utilizes a unique circuit design that allows encapsulation in an ingestible size capsule. The inventive circuit design uses a one transistor inverting amplifier with a tank circuit forming the link between the transistor's collector and the battery. The tank circuit is tuned to provide a lagging capacitive load which causes the inverting amplifier to oscillate. The tank circuit contains a coil inductor that emits a near field magnetic communications field containing temperature information. The ingestible size temperature pill can be configured in a rechargeable embodiment. In this embodiment the pill uses the inductive coil in the tank circuit as the magnetic pickup to charge a rechargeable nickel cadmium battery.

Abstract: An improved apparatus and method for detecting singlet oxygen emission produced during photoradiation is disclosed. The invention utilizes a two-band optical comparator to detect optical emissions. The optical comparator comprises an in-band filter that passes light in the 1270 nm singlet oxygen emission band and an out-of-band filter that passes light outside of the 1270 nm singlet oxygen emission band. The signal detected when the out-of-band filter is used is composed essentially of a fluorescence emission. This detected signal is used to synchronize an electronic reference signal. The electronic reference signal is used by a signal processing means to isolate a phase delayed singlet oxygen emission component which appears with a fluorescence emission component in the 1270 nm singlet oxygen emission band.

Abstract: An apparatus for detecting the presence and/or measuring the concentration of an analyte in the fluid medium is disclosed. The apparatus relies on biospecific binding between a biochemical binding system and the analyte to change the dielectric properties of a capacitive affinity sensor. The biological affinity sensor is optimized by: (1) adjusting the thickness and dielectric properties of a passivation layer to generally match the impedance of the biological binding system; and (2) minimize the double layer capacitance so that bulk capacitance changes associated with the biological binding system are maximized.

Abstract: An apparatus and method for non-invasively sensing physiological changes in the brain is disclosed. The apparatus and method uses an electromagnetic field to measure localized impedance changes in brain matter and fluid. The apparatus and method has particular application in providing time-trend measurements of the process of brain edema associated with head trauma.