Abstract: A switching type power supply is provided which includes a first and a second SCR with a diode connected in reverse across each of them. The first SCR-diode pair in response to a clock pulse charges a capacitor which when fully charged causes the first SCR current to return to zero, forward biases the first diode and commutates the first SCR off for at least the required minimum turn-off time of the SCR. After the capacitor reaches the peak charge value, the second SCR is selectively triggered to couple the desired portion of the stored energy to the power supply load via a transformer. After the currents in the secondary windings of the transformer reverse, and the capacitor achieves a peak charge of the opposite polarity, the current through the second SCR becomes zero, the second diode is forward biased, and the second SCR is commutated off.

Abstract: A method for cooling gas chromatograph ovens with ambient room temperature air utilizing two separate air passages through an oven door. The door remains closed during the heating and cooling cycles which take place inside the oven housing. A rotating stirring fan internal to the oven creates regions of relatively higher and lower air pressures. The two air passages are disposed adjacent to these pressure regions to draw room temperature air into the oven, and to exhaust hot air from the oven. Within the oven door there is a movable, spring mounted, oven closure hatch in which the first air passage is located. This air passage is opened and closed by a movable cover. The hatch also establishes the second air passage when it is spaced-apart from the oven housing. Both air passages are opened and closed in response to movement of the hatch. An actuation device that can interface with a programmable actuation controller opens and closes the hatch as necessary for cooling the inside of the oven housing.

Abstract: The present invention relates to an apparatus for measuring, by cross-correlation, the period and frequency of a substantially periodic signal having random components, such as fetal heart beat signals and other biological signals.

Abstract: Dental floss is tensioned between a pair of spaced-apart, L-shaped arms attached to a handle. The configuration of the arms permits effective flossing of target areas within the mouth with minimal visual obstruction and facial distortion. The handle may be attached to the arms for right- or left-handed use. An electrical actuator attached to the handle reciprocates the dental floss in the target area.

Abstract: This is an ion-producing source having a distinct chemical ionization configuration and a distinct electron impact configuration. In this source, a hollow chamber including an ion source and a source of sample molecules receives a hollow, slidable cylindrical member having a chemical ionization chamber within it. Orifices in the chamber and the cylindrical member connect the chemical ionization source chamber to the electron source and to the sample molecule source when the cylindrical member is pulled to one position. When the cylindrical member is pulled to another position, the slidable cylindrical member and the inside walls of the chamber define the ionization region to which the electron source and the sample molecule source are directly connected. By moving the cylindrical member, the ionization source can be changed from a chemical ionization source to an electron impact source.

Abstract: This invention relates to a system for measuring in real time, by auto-correlation, the period and frequency of a periodic biomedical source signal with random components such as an ultrasound doppler fetal heart beat signal.Before and during delivery of a fetus, the invention enables an obstetrician to continuously monitor and record the heart rate of the fetus in real time.

Abstract: An optically excited diode current limiter, when placed in series with a lead having an electrode attached to a patient such as an EKG or EEG lead, conducts physiological signals picked up by the electrode and protects the patient from electrical shock by limiting the amount of current flowing through the lead.

Abstract: A gas chromatograph system includes a central processor (CPU) and a printer-plotter. The printer-plotter prints characters and plots data using a single 1 by 7 array of thermal resistors to perform both the printing and plotting operations in real time. The system provides continuous and uniform traces despite changes in the plotting rate.Data from the chromatograph is temporarily stored by the CPU, then forwarded upon programmed command through a print-plot controller to the printer-plotter. Data is plotted as it is received from the CPU. As peaks in the data are detected, plotting is suspended temporarily without loss of data, and characters are printed adjacent to the peaks, thus annotating the peaks with digital data.

Abstract: A respiration monitor for measuring the variations of the thorax impedance of a patient due to respiration activity includes circuitry for suppressing the indication of unwanted signals caused by the activity of the heart. This circuitry is connected to receive separate signals corresponding to the heart beat rate and compare the periods of these signals to those of the signals measured at the thorax of the monitored person. If the periods of both signals are substantially equal, i.e. the signals measured at the thorax are actually due to heart activity rather than to respiration, the trigger threshold value of the monitor is automatically and stepwise raised so that the monitor does no longer respond to heart beat related signals but indicates that no respiration signals are measured.

Abstract: In a keyboard entry word processing system, text is stored in a recirculating refresh memory along with a carriage return code at the end of each line. The text is displayed on a CRT screen. A cursor symbol, also displayed on the screen, may be moved by keyboard control to designate a particular character position on the screen where editing is to occur. When the cursor is within the field of displayed text, characters may be edited at the location in memory corresponding to the location of the cursor on the screen. When the cursor is outside the field of displayed text, the cursor is first "found" by altering the refresh memory to provide a new memory location corresponding to the cursor location, and then editing is performed at the new memory location.

Abstract: A method and apparatus for obtaining an accurate measure of the gas volume expired by a patient by deriving a signal that provides a positive indication of when the patient is exhaling. This signal is used to limit the gas flow monitoring to the expired flow of the patient, thus eliminating the monitoring of a gas volume that leaks through a partially closed ventilator expiration valve during patient inspiration. The gas flow through the expiration valve and the mouth pressure of the patient are used to obtain an indication of the resistance of the expiration valve. This resistance indication is then compared with a preselected threshold valve resistance to accurately determine the time of expiration.

Abstract: A dental implant includes a porous ceramic cup or ring filled with silicone rubber which supports an artificial tooth or other prosthetic device such as a denture. The jawbone grows into the porous ceramic to hold the implant firmly in place. The silicone rubber cushions the jawbone from shock caused by multidirectional masticatory forces. A fibrous matting is partially embedded into the upper periphery of the silicone rubber that extends from the ceramic cup or ring. Gingival tissue becomes attached to the matting to form a seal that precludes bacteria from invading and infecting the implant area. In another embodiment, the implant includes a metal sleeve completely filled with and surrounded by silicone rubber. Fibrous matting is partially embedded into the surface of the silicone rubber. Both the jawbone and the gingival tissue adhere to the matting to hold the implant firmly in place and to prevent bacterial invasion.