Abstract: Apparatus is disclosed for deriving weighted values SHD i, DHD i and MHD i to respectively represent the systolic, diastolic and mean blood pressures for each heartbeat of a patient from the values S.sub.i, D.sub.i and M.sub.i that are the maximum, minimum and means blood pressures of the current heartbead; S.sub.i-1, D.sub.i-1 and M.sub.i-1 that were the maximum, minimum and mean blood pressures for the previous heartbeat; SHD i-1, DHD i-1 and MHD i-1 that respectively represented the systolic, diastolic and means blood pressures of the previous heartbeat; and a constant K.sub.i that is a function, F, of the difference between M.sub.i and the mean pressure M.sub.i-1 of the previous heartbeat. The expressions for S.sub.i, D.sub.i, M.sub.i and K.sub.

Abstract: A noise reduction circuit for a DC power supply in which the input of a high pass filter is coupled to the output circuit of the supply so as to receive a noise signal, the output of the high pass filter is coupled to the primary winding of a transformer via an amplifier, and the secondary winding of the transformer is coupled to the output circuit of the supply so as to reduce the noise therein.

Abstract: A pace pulse identification apparatus in which low frequency signals are rejected by a filter and the pace pulses and high frequency noise are applied to one input of a comparator. A threshold wave having an amplitude that is not significantly affected by pace pulses or spikes of noise is provided that has a minimum value when steady high frequency noise is absent and a value equal to the sum of the minimum value and a value that varies with the amplitude of high frequency noise when high frequency noise is present and which is applied to the other input of the comparator. The state of the comparator is changed when a pace pulse is present at the output of the filter because its amplitude exceeds that of the threshold wave.

Abstract: A regulated power supply that provides two desired direct current voltages at respective outputs thereof, the supply maintaining the difference between voltages appearing at the outputs the same as the difference between the desired values, series regulators respectively coupled to each output that are in a saturation mode when a voltage that is a fraction of the voltage between the outputs lies within a given range, where one of the series regulators is placed in a linear mode when the voltage is at or beyond one edge of the range, and the other series regulators is placed in a linear mode when the voltage is at or beyond the other end of the range.

Abstract: The radio frequency powered gas discharge tube of an atomic emission detector is cooled with a flow of liquid, and means are provided for grounding points in the flow that are on opposite sides of the radio frequency field so as to reduce the amount of radio frequency energy escaping from the discharge tube in the liquid.

Abstract: The sampling volume of a pulsed Doppler system is increased to a length greater than that corresponding to one pulse by sampling the reflections of each launched pulse a plurality of successive times and accumulating the samples.

Abstract: A circuit for combining independently controlled AC and DC voltages in which AC and DC voltages are respectively applied to different inputs of a first amplifier, its output is connected to a first output terminal, the DC voltage is applied to the input of a second amplifier, its output is connected to a second output terminal that is grounded for AC, a voltage divider is connected between said output terminals and the gains of the amplifiers for DC are the same.

Abstract: A precise volume of sample liquid is injected by inserting a syringe into the vaporizing chamber of the injection assembly for a gas chromatograph by performing the entire injection including withdrawal of the syringe in such a short time that essentially none of the liquid is vaporized while in the needle.

Abstract: A stand-off device for use with acoustic transducers is described in which a chamber having a diaphragm portion contains liquid, the ratio of the acoustic impedance of said diaphragm to the acoustic impedance of soft body tissue and the ratio of the acoustic impedance of said liquid to the acoustic impedance of said diaphragm being whole numbers or fractions, and said diaphragm being of such thickness that reflections from its diaphragm/body interface, when it is held against the body of a patient, and its liquid/diaphragm interface tends to cancel each other.

Abstract: A power supply for producing DC voltage with a minimum voltage drop from a source voltage that is either AC or DC in which the emitter-base junction of a transistor is coupled to the source so as to provide base current required to turn the transistor on, an output capacitor is connected in series with the emitter-collector path, and a capacitor and resistor are connected in parallel in the base circuit of the transistor.

Abstract: Flue-cleaning apparatus having longitudinal springs mounted transversely on a flexible shaft at one end, the other end of the shaft being adapted to be clamped by the chuck of a hand-held drill.

Abstract: The temperature coefficient of the combination of a transducer and any one of a plurality of disposable plastic domes manufactured to given specifications is reduced by making the temperature coefficient of the transducer have a slope that is equal and opposite to the slope of the temperature coefficient of the average dome.

Abstract: A method of providing a temperature compensating resistor having a desired ohmic change with temperature comprising the steps of connecting a resistor R.sub.T that is made of material having a high temperature coefficient in parallel with a resistor R.sub.S that is made of material having a lower temperature coefficient, connecting the parallel combination in a circuit and increasing the value of R.sub.S by cutting it with a laser until the circuit indicates that the desired result is obtained.

Abstract: A stand-off device for use with an acoustic transducer in the form of a volume having a flexible cup section and a stiff cup section with the lips of the cups joined together and almost filled with liquid. The bottom of the stiff cup section has an opening across which a membrane is mounted and a clip for holding the active section of a transducer in contact with the membrane.

Abstract: An EKG signal processing apparatus comprising an input to which the EKG signal may be applied, an output at which the processed EKG signal is to appear, a resistor and a normally conductive signal switch connected in series between one terminal of said input and one terminal of said output, a capacitor connected across the output, a differentiator, and a bipolar comparator for providing a signal indicating the presence of a pace pulse at said input, and a signal switch control responsive to said signal for making said signal switch nonconductive for at least a portion of a pace pulse and until any voltage following the pace pulse has reached a low value.

Abstract: A pressure dome that is attached to a transducer housing by springs is provided with means for limiting the amount by which the springs can be flexed so as to prevent them from being damaged. The springs are of the beam type and projections extending from them engage stops on the body of the dome so as to limit their movement.

Abstract: A pressure dome in which the wall forming the cavity containing fluid under a pressure that is to be measured has such a low compliance as to prevent expansion or contraction of the base of the dome resulting from changes in its temperature from causing the diaphragm of a transducer coupled thereto from buckling.

Abstract: An automatic gain control circuit in which a current source is provided for charging a capacitor and a current source is provided for discharging it, there being means for controlling the ratio of the currents supplied by each source in response to the amplitude of the alternating wave being controlled.

Abstract: A circuit for coupling a transducer having a reactive sensing element to equipment providing either AC or DC drive voltage and equipped with strain gauge amplifiers in which the sensing impedance varies the gain of the feedback loop of an oscillator, an AGC circuit is coupled to the loop so as to derive a control signal related to the amplitude of oscillations therein and a gain control means is included in the loop that responds to the control signal in such manner as to restore the loop gain to unity after it has been changed therefrom by changes in the value of the sensing impedance. If the gain control means is a voltage divider having a variable resistor as the operative element, a matched variable resistor is used as the unbalancing element of a resistive bridge, and the values of the circuit are chosen such that the output signal from the bridge which may be applied to strain gauge amplifiers is linearly or desirably nonlinearly related to changes in the value of the reactive sensing impedance.

Abstract: Method and apparatus for forming an electrical contact between mounting pins extending from an electrical component and insulated wires from the component that are wrapped around the pins in which the tips of the pins are held in a flowing pool of molten solder until the heat travelling up the pins loosens the insulation up to a desired level, and the pins are then quickly immersed up to that level and then quickly removed so as to cause the solder to melt and carry away the loosened insulation but to leave substantially intact the insulation that is not loosened.