Abstract: An autocapture system within an implantable pulse generator automatically maintains the energy of a stimulation pulse at a level just above that which is needed to effectuate capture. The electrical post-stimulus signal of the heart following delivery of a stimulation pulse is compared to a polarization template, determined during a capture verification test. A prescribed difference between the polarization template and the post-stimulus signal indicates capture has occurred. Otherwise, loss of capture is presumed, and a loss-of-capture routine is invoked that increases the energy a prescribed amount to obtain capture. Periodically, and/or at programmed intervals or events, the capture verification test is performed. During the capture verification test, the pulse generator determines a polarization template for a particular stimulation energy and for each of a plurality of sensitivity or threshold settings. A determination is also made as to which sensitivity settings yield capture.

Abstract: Vapor phase catalytic hydrogenation of maleic anhydride to gamma-butyrolactone is achieved in a conversion of 95% or more and a selectivity of 80% or more during a prolonged period of production. The process uses an activated catalyst prepared by reducing a catalyst composition comprising 30-65% by weight of CuO, 18-50% by weight of ZnO and 8-22% by weight of Al.sub.2 O.sub.3, and activating the reduced catalyst composition in hydrogen at an activation temperature of at least 400.degree. C., preferably 400.degree. to 525.degree. C., and optimally about 425.degree. C. The process suitably is carried out under predetermined and advantageous process conditions, including a defined molar ratio of hydrogen to maleic anhydride in the vapor reactant stream, a selected pressure during hydrogenation, a defined feed rate space velocity, a predetermined contact time, and a suitable reaction temperature.

Abstract: An atrial tracking dual-chamber pacemaker and method of use thereof for terminating a pacemaker-mediated tachycardia (PMT). The pacemaker includes means for determining whether the present heart rate exceeds a tachycardia reference rate, and if so, whether a PMT-indicating sequence of a tracked P-wave, including a retrograde P-wave followed by a V-pulse, occurs repetitiously for at least a predetermined number of cardiac cycles. The pacemaker includes means for measuring the interval between a P-wave and a V-pulse (PVI) and sets the PVI to 250 milliseconds when the measured value is less than 250 milliseconds. The pacemaker issues a PMT-terminating timed atrial pulse which is timed from a retrograde P-wave by a time equal to the PVI, plus a delay of about 25-100 milliseconds. In the event the atrial pulse fails to terminate the PMT, the process is repeated after a fixed number of cardiac cycles has occurred.

Abstract: Vapor phase catalytic hydrogenation of maleic anhydride to gamma-butyrolactone is achieved in a conversion of 95% or more and a selectivity of 80% or more during a prolonged period of production. The process uses an activated catalyst prepared by reducing a catalyst composition comprising 30-65% by weight of CuO, 18-50% by weight of ZnO and 8-22% by weight of Al.sub.2 O.sub.3, and activating the reduced catalyst composition in hydrogen at an activation temperature of at least 400.degree. C., preferably 400.degree. to 525.degree. C., and optimally about 425.degree. C. The process suitably is carried out under predetermined and advantageous process conditions, including a defined molar ratio of hydrogen to maleic anhydride in the vapor reactant stream, a selected pressure during hydrogenation, a defined feed rate space velocity, a predetermined contact time, and a suitable reaction temperature.

Abstract: An implantable pacemaker having means for detecting and responding to a premature ventricular contraction (PVC), also includes circuit means for minimizing the likelihood of sensing a PVC when in fact a PVC has not occurred. The circuit means latches the occurrence of any atrial events sensed during the relative atrial refractory period of the pacemaker, whether such atrial events are noise or an early P-wave; and, in response to such latching, disables the PVC detection circuit until certain prescribed events occur, whereupon the PVC detection circuit is re-enabled. The prescribed events that re-enable the PVC detection circuit after it has been disabled include, e.g., the occurrence of a ventricular pulse or sensed R-wave. Further, in the event a PVC is detected and a desired PVC response is invoked, an additional circuit means automatically terminates the PVC response in the event the PVC response becomes stuck.

Abstract: A pacemaker mediated tachycardia (PMT) is detected by circuitry within an implantable pacemaker. The PMT is detected by first detecting a tachycardia condition that includes a prescribed number of consecutive cardiac cycles having a rate faster than a prescribed rate. Each cardiac cycle of the tachycardia condition includes a natural atrial event, i.e., a P-wave, and a paced ventricular event, i.e., a V-pulse generated by a pacemaker. After the prescribed number of such cardiac cycles, e.g., two to ten, a P-V delay in a single cardiac cycle is modified by a first prescribed amount, e.g., 50 milliseconds. The time interval of a V-P interval associated with at least one cardiac cycle preceding the modified P-V delay is then compared to a V-P interval immediately following the modified P-V delay. Only if the difference between the V-P intervals thus measured is less than a second prescribed amount, e.g., 25 milliseconds, is a PMT indicated. If a PMT is indicated, a PMT termination regimen, e.g.

Abstract: What is provided herein is a vapor phase process for the production of butyrolactone in which the vapor mixture of the feed compound and hydrogen is provided at high flow rates from finely divided droplets of the feed compound which are vaporized rapidly with hot hydrogen gas.

Abstract: In accordance with the principles of the present invention, a connector for coupling a coaxial transmission line to a strip transmission line comprises a length of transmission line having an inner conductor having a longitudinal axis, an annular ring of dielectric material disposed around the inner conductor and an outer conductor. The length of transmission line at one end, is coupled to a coaxial transmission line connector. The other end of the transmission line is mounted to a printed wiring board which supports a controlled impedance strip transmission line and the inner conductor, which projects beyond the dielectric material immediately adjacent the strip transmission line, is electrically coupled to the strip transmission line. The ground plane, located either on the same side or the obverse side of the printed wiring board is coupled to the outer conducting member of the length of transmission line either directly or via a conductive trace.

Abstract: A method of constructing written educational tests at the local school district level from validated test questions linked to statements of specific learning objectives in a data base recorded on compact laser discs. A laser disc player operated by the educator who is formulating the test displays and edits the available questions in selected topics on a visual monitor. The questions which are displayed may be selected at the local level to reflect the actual content of the course which is being examined. After all questions have been selected, they can be downloaded (including graphics) to a laser printer which prints professional quality test booklets at the local site. Alternatively, reference to the selected questions (numbers) can be downloaded onto a floppy disc which is transported to a service bureau for printing of the test booklets there. The test results can be scored locally and test reports can be printed locally.

Abstract: Programmable timing and logic circuitry is provided to detect crosstalk between paced chambers of the heart and to provide compensation in the event crosstalk is detected. Signals sensed during a prescribed time window early in the cardiac cycle following an atrial pulse are presumed to be crosstalk. If crosstalk occurs, a shortened AV delay is triggered. If crosstalk does not occur, a programmed AV delay is maintained. Absent the occurrence of a ventricular event after the prescribed time window up to the end of the AV delay, a ventricular stimulation pulse is provided. If a ventricular event is sensed during this time, the ventricular stimulation pulse is inhibited.

Abstract: A re-usable examination booklet for the administration of written tests includes overlaid question sheets bound together with the unbound edge of each sheet overlapping the underlying sheet. An answer sheet may be inserted in the booklet beneath the question sheets. Answer areas on the answer sheet are arranged in columns extending along the unbound edges of the question sheets to locate the answer areas in close proximity to the corresponding questions on the question sheets. A modified booklet includes question sheets having openings arranged in columns extending along their unbound edges so that the selected answers can be marked through the openings onto the answer areas of the answer sheet.

Abstract: An atrial tracking dual-chamber pacemaker and method of use for reducing the risk of initiating a pacer mediated tachycardia (PMT), and breaking such a PMT if once started. The pacemaker includes means for sensing a premature ventricular contraction (PVC). The pacemaker operates in a conventional manner unless a PVC is sensed. If a PVC is sensed, in accordance with one embodiment, an extended atrial refractory period is triggered in an attempt to block any retrograde atrial events resulting from the PVC. This is followed by an atrial alert time window. After a prescribed A-V delay subsequent to the timing out or other termination of the atrial alert time window, a ventricular stimulation pulse is generated, unless prior ventricular activity is sensed that inhibits such ventricular stimulation pulse.

Abstract: The present invention provides a novel holder for knives or other utensils which tilts forward to present the handles to a prospective user, making it easier, safer, and more convenient to withdraw the utensils from their place of storage.

Abstract: A do-it-yourself picture frame includes a plurality of edge members, each having a circular or slot-like aperture proximate each end thereof, joined by a plurality of corner members. Each corner member includes first and second perpendicular channels for receiving the ends of adjacent edge members. Each channel is provided with a stop plate against which an end of an edge member may abut and an internally threaded projection which extends into an aperture in an edge member. A screw threadably engages the projection to secure the edge member in its channel.

Abstract: A hair curling and waving device is provided having a plurality of elongated waving members disposed in two groups with the groups being secured at one end to a handle and relatively rotatable as groups into and out of intermeshing engagement, with several of the members being provided with heating and/or steaming means for permanently setting hair wrapped about the members. A plurality of comb-like wave guides are also secured to the handle and extend parallel to the waving members and adjacent thereto for engaging the hair as it is wrapped around adjacent waving members. Some of the wave guides are preferably movable longitudinally so as to move portions of the hair which are engaged with the comb-like teeth of the wave guides in order to produce a further wavy appearance in the hair.

Abstract: A dynamoelectric machine having a thermal protector held in intimate thermal contact with the machine's electrical winding by a spring inserted between the machine's enclosing frame and protector. The spring is generally a V-shaped member whose one leg mates with the protector and whose other leg is divided in two with each of those divided legs being engageable with the frame. The closed end of the V-shaped spring member is progressively inserted between the protector and frame with the open end following. The frame engageable legs are sharp and thus gouge into the relatively softer frame so as to resist relative movement between the spring member and frame in the direction opposite its insertion.