Abstract: A filter system is provided to remove electrical supply line noise at a first frequency from an input signal to a medical monitor. An arithmetic unit produces an intermediate signal having a frequency component that corresponds to a difference between the first frequency and a reference frequency. A calculator determines the period of the intermediate signal and a signal converter produces a sinusoidal signal which has the period determined by the calculator. An adder produces a filter control signal having a value that represents the sum of the reference frequency and the frequency of the intermediate signal. A notch filter is employed to remove the electrical supply line noise from the input signal. The filter control signal tunes the notch filter to the first frequency of the electrical supply line noise.

Abstract: A power supply has a transformer for isolating circuitry to which power is furnished from the electrical supply lines. The transformer includes a core of ferro-magnetic material with primary and secondary windings wound side-by-side on the core. The primary winding has two layers of turns with a center tap formed at a connection of the turns of each layer that are closest to the secondary winding. Similarly, the secondary winding has two layers of turns with a center tap formed at a connection of the turns of each layer which are closest to the primary winding. A driver applies excitation voltage across the center tap, which also is coupled to earth ground, and a turn of the innermost primary winding layer. The center tap of the secondary winding is used as an isolated ground and a supply voltage is produced between two turns from different layers of the secondary winding.

Abstract: A medical monitor determines the period of a physiological function, such as blood circulation pulses, by operating a probe that produces an electrical signal which corresponds to the physiological function. The electrical signal is digitized at a given sampling rate to acquire a plurality of signal samples which are stored in a memory. A time scaling factor is adjusted dynamically so that the amount of signal samples being processed does not exceed a maximum limit. The magnitude of the signal samples also may be scaled dynamically. Serial autocorrelation is applied to the signal samples to produce a sequence of summation values. The quantity of summation values from the initial one in the sequence to a peak summation value is determined. The physiological function period is derived from the quantity of summation values, the given sampling rate, and any time scaling factor that was used.

Abstract: A pulse oximetry sensor comprises a photoemitter; a photodetector; and, a generally tubular housing having an inner wall, an outer wall and a lumen for receiving a body part of a patient. The housing has a pair of opposed pockets for removably receiving the photoemitter and the photodetector, respectively. Each of the pockets has a bottom window through which light can pass and an open top. The housing also has side passages between the inner wall and the outer wall of the housing through which the photoemitter and the photodetector can be introduced into and removed from their respective pockets.

Abstract: An apparatus periodically measures the carbon dioxide content of the breath of a medical patient. The need to recalibrate the apparatus is determined by comparing the carbon dioxide measurements taken at different times during the respiratory cycle to corresponding reference levels. These levels often occur when the apparatus no longer is measuring accurately. When recalibration is indicated the apparatus waits until the patient begins inhaling so that the recalibration does not interfere with measuring the carbon dioxide during exhalation. The apparatus then measures the carbon dioxide content of the ambient air to define an offset value used in patient monitoring.

Abstract: Linear and cyclic peptides of the E1 and C protein of the rubella virus are disclosed. These peptides and analogues, mixtures and combinations of them are useful in detecting and quantifying antibodies raised against the rubella virus. They are also useful in raising antibodies to the rubella virus for use in the diagnosis of and protection against rubella viral infections.

Abstract: Methods and compositions for preventing or treating human immunodeficiency virus (HIV) infections characterized by 2-substituted-5-substituted-1,3-oxathiolanes.

Abstract: There are provided novel 2-substituted-4-substituted-1,3-dioxolanes which are particularly useful as antiviral agents.

Abstract: A protection system for a gas analyzer is described which monitors gas pressure adjacent a sample cell included in the analyzer. The sample cell is connected via a gas/liquid separator to an input sample conduit. The measured pressure indicates when the separator is clogged with excessive liquid. A control circuit is provided which responds to selected pressure conditions by automatically controlling the valve to interrupt the flow of gas from the separator to the sample chamber. In this way, the sample chamber is protected against contamination by liquid. In the preferred embodiment, the sample chamber and the separator are automatically backflushed to remove any water contamination.

Abstract: A gas/liquid separator for a gas analyzer is described. The separator includes a separator chamber made up of two component chambers. The first of these component chambers is relatively shallow in depth and serves to connect an input port with a lower output port. The second of these two component chambers is less shallow in depth and serves to interconnect the lower output port with the upper output port. This second component chamber is bounded by two diverging surfaces which diverge in the direction of the upper output port. A barrier extends into the separator chamber to separate the input port from the upper output port and to prevent the flow of liquid directly from the input port to the output port.

Abstract: A method of assembling a sensor head and permeable membrane with encapsulated electrolyte. A disposable fixation ring is part of a similarly disposable fixation ring assembly, the latter of which serves as a fixture for automatically mounting the membrane on the sensor head body with the electrolyte encapsulated. The ring is then employed to fasten the head to a patient's skin while the remainder of the assembly is discarded, the ring also being disposable after use on a patient.

Abstract: A polarized sensor assembly for a polarographic oxygen sensor. The assembly comprises a sensor head and a shielded cable, with a power unit in the cable. The head electrodes remain polarized at all times, permitting transfer of the sensor assembly from one patient monitoring system amplifier to another without losing its polarization.