Abstract: A surgical instrument for use in forming a tracheostomy comprises a needle with a sharply pointed angled tip joined at its rear end to plastics hub. The length of the needle from the hub is greater than the thickness of neck tissue but less than the distance between the skin surface and the anterior wall of the trachea. The hub has a laterally extending face which has an area at least fifty times the cross sectional area of the needle. Two parallel walls have stepped edges which provide a gripping region for the hub, enabling it to be gripped between finger and thumb. A tapered recess in the hub receives the nose of a syringe which provides a loss of resistance device so that the plunger can be displaced along the barrel when the tip of the needle enters the trachea.

Abstract: A pyrometer has a lock nut that engages a threaded sighting tube. The lock nut has a flange with a circle of thirteen apertures. A second similar flange is mounted on the body of the pyrometer which is restrained from rotation by splines which engage splines in the sighting tube. The second flange has a circle of only twelve apertures which is concentric with the circle of apertures on the first flange. The two flanges are locked together and the pyrometer is thereby locked in the sighting tube by means of a split pin pushed through aligned apertures. The different number of apertures in the flanges gives a number of locking positions that exceeds the number of apertures.

Abstract: A pyrometer or other optical system has a silicon microstructure with a beam that is vibrated by optical radiation from an alternating source. The beam alternately blocks and passes radiation supplied to a photodiode from an optically emissive region. A sample and hold circuit receives the output of the photodiode and provides two simultaneous signals representative of the output of the photodiode when radiation is passed to the photodiode and blocked from the photodiode respectively. A processor measures the difference between the two signals and provides an output representative of the temperature of the optically emissive region.

Abstract: An image processing system has sixteen processing assemblies provided by transputers which each have a memory and a processor. An infra-red television camera supplies signals representing different areas of the field of view to respective different ones of the processing assemblies. The assemblies also receive external signals from other sources and are interconnected with one another by a line which enables synchronization between the assemblies. Each processor processes only that information in its memory and provides output signals representative of the respective area of the field of view.

Abstract: A helmet for aircrew in a highly manueverable aircraft has six air bags which are inflated or deflated by a control system so as to counteract acceleration forces on the wearer's head and helmet. Two pairs of air bags engage the wearer's body, and two bags engage the seat headrest so that restoring forces in yaw, pitch and lateral directions can be applied. A position sensor determines the actual position of the helmet which is compared with the predicted position, as derived from an inertial sensor or inputs from the aircraft flight control system, the difference between these two positions being used to control operation of the air bags. A memory module programmed with information about the behavior of the wearer's head and helmet characterizes the control system to the particular wearer and is removable for use in other systems.

Abstract: A heat and moisture exchanger for use in medico-surgical applications has an element formed by a strip of bacterial filter material that is folded laterally into pleats and bent into a loop so that the folds extend radially. The element is sealed around its outer edge into a circular casing having axial, tapered ports at its opposite ends. A conical gas diverter is sealed into a central opening of the element on each side. Exhaled gas warms and moistens the element; inhaled gas is filtered and takes up some of the heat and moisture from the element. The exchanger is symmetrical so that it can be used either way around.

Abstract: Apparatus for processing the image seen by a television camera viewing the surroundings of an aircraft has a store of topographical mapping information and object data stores which contain information about the appearance, location and size of objects in the area to be viewed. The apparatus derives information as to the location of an object in the field of view and determines where the line of sight of the object from the camera intercepts the stored topographical mapping. The range of the object is determined trigonometrically from its location relative to a corresponding part of the stored topographical mapping and the position of the aircraft. New objects are indicated when they are not present in the object data stores. The angle subtended by an identified object is compared with the known size of the object to provide another indication of range. An indication of the size of the object can be provided from knowledge of its range and the angle subtended.

Abstract: A seal for a linear displacement optical transducer has a tubular flexible bellows which is joined at one end to a movable carriage supporting an optically encoded track and which is movable along a cylinder supporting an optical read head. The bellows extends within the cylinder and has its other end sealed to an open end of the cylinder. A compensation chamber is sealed to the outside of the cylinder to enclose a major part of the length of the bellows and forms a sliding seal with a push-rod extending from a carriage. The bellows encloses a first volume of the dry inert gas within the cylinder to one side of the bellows and a second, similar volume of gas on the other side of the bellows and in the compensation chamber. Displacement of the carriage causes only a small change in pressure across the bellows which is accommodated by flexure.

Abstract: An adjustable flange for a tracheostomy tube has a circular aperture and two semi-circular arms hinged with one another by an integral flexible web. One arm has a smooth surface that is slidable along the tube; and the other arm has circumferential ribs that bite into the surface of the tube. A bolt passes through one arm and into a threaded recess of the other enabling the flange to be locked in position.

Abstract: An adhesive ring assembly for an ostomy bag comprises a circular ring of adhesive around the opening of the bag and protected by two release paper sheets. The release sheets are of siliconized paper and are of an annular shape. Each sheet is folded in half along its diameter so that one half releasably adheres to the adhesive and the second half overlays the first half. The folded edge of one sheet overlaps the folded edge of the other sheet. The release sheets are removed by pulling the edge of each second half parallel to the ring so that each sheet peels away from the adhesive from its folded edge.

Abstract: A wc disposable ostomy bag has a wall formed from an inner layer of polyethylene and an outer layer of polyvinyl alcohol. Two flexible layers of aluminum are located between the inner and outer layers to reduce odor transmission through the wall. The material of the walls may be formed by vapor depositing the aluminum layers on respective faces of the inner and outer layers and then laminating the inner and outer layers together with the aluminum layers facing one another. Alternatively, both aluminum layers may be deposited on the same one of the inner or outer layers with a thin non-metallic layer between them to prevent the aluminum layers having common grain boundaries.

Abstract: An aircraft collision avoidance instrument system has a display located in the aircraft glareshield in the peripheral field of view of the pilot when the pilot is looking forwardly through the aircraft window. The display has a matrix array of LCD elements which is controlled to provide a continually changing image that is visible in the peripheral field of view of the pilot when a possible collision with another aircraft is likely. The changing image may be arrows moving up or down the display to indicate climb or decend, or a flashing horizontal line to indicate that present height must be maintained. An alphanumeric legend indicative of the collision avoidance action to be taken is also provided by the display. When no collision is likely, the display is used to present other information to the pilot.

Abstract: Electrosurgery apparatus includes an r.f. power amplifier with an output to a patient electrode. The amplifier is controlled by the voltage of input signals from a control unit which receives a sample of the voltage and current of the output signal. The voltage and current signals are supplied to A/D converters to provide two digital signals that are used to address a look-up table in an EPROM and provide a digital output representative of impedance. A switch is set by the user to the desired mode/power curve and this provides a digital signal which together with the impedance signal is used to address a second look-up table in an EPROM which contains digital representations of the required output voltage of the amplifier to produce the desired power level. An adder compares the required voltage with a feedback of the actual voltage to produce an error signal that is supplied to the amplifier to control its output.

Abstract: Electrical sockets are positioned for insertion in holes in a circuit board by means of a sheet of a bendable plastics having an array of apertures in some of which the sockets are inserted. Each socket has a knurled region around its upper end just below a flange. The flange is undercut to give it a sloping lower surface and a peripheral edge that bites into the upper surface of the sheet. Ultrasonic energy is used to cause the sheet material around the sockets to flow into close contact with the terminals. The assembly of the sheet and sockets is used to insert the sockets in the circuit board following which they are soldered in place and the sheet is removed by pulling back from one edge over the sockets.

Abstract: A female external urine collection device has a moulded plastics tray that supports an insert or a planar top with an upper surface that contacts the wearer. The upper surface is shaped with an annular wall that engages around the vulva and an opening with a urine-resistant surface within the wall. The opening communicates with an outlet orifice in the tray so that discharge of urine is contained within the wall and flows to the outlet. A longitudinal ridge extends posteriorly of the wall and is located between the buttocks of the user.

Abstract: An electrical igniter has an outer shell with a tungsten forward end which forms an annular outer electrode. A central rod extends axially within the shell and has a tungsten forward end forming an inner electrode which is separated from the outer electrode by a semiconductive surface discharge path. The inner and outer electrodes both have chromium diffused into the tungsten to form surface layers that are oxidation resistant at high temperatures. The electrodes are made by placing the tungsten forward ends in a furnace in a chromium rich atmosphere between 1000 and 1200 degrees Centrigrade for between 10 to 24 hours and allowing them to cool in the furnace. Chromium is removed from the rear ends of the tungsten parts before joining them to the rear parts of the electrodes which are of different metals.

Abstract: An electrical igniter has an outer metal shell within which extends a semiconductive tubular pellet that provides a cylindrical cavity which opens through an orifice formed by an inturned lip of the shell which forms a first electrode of the igniter. The diameter of the cavity and the diameter of the orifice are in the ratio of about 5 to 6. A second electrode extends axially within the shell into the rear end of the pellet with which it makes electrical contact. Discharge between the first and second electrodes causes a plasma of discharge products produced in the cavity to be ejected through the orifice.

Abstract: In a multi-conductor electrical assembly, each conductor is connected to a first common electrical plane via first unidirectional current devices and each conductor is further connected to a second common electrical plane via second unidirectional current devices having an opposite sense to the first unidirectional current devices. The assembly includes first and second energy-dissipating devices connected between ground and respective ones of the electrical planes such that an excessive positive or negative voltage excursion on any one of the conductors is conducted via a respective one of the first or second unidirectional current devices to the first or second plane and to ground via the energy-dissipating devices.

Abstract: A two-part ostomy bag assembly comprises a bag and a fitment secured around the stoma. The bag has a coupling in the form of a neck with an annular lip which is insertable in a deformable collar in the fitment. A resilient ring embraces the collar and has projecting tabs by which the ring can be tightened to deform the collar about the neck of the bag coupling. The lip prevents full tightening of the ring before the neck is fully inserted in the collar and the lip engages in an annular recess in the collar. The ring is retained in a tightened state by means of a releaseable ratchet arrangement.