Abstract: A ballast for driving a gas discharge tube light with overvoltage protection and dimming. A clamp winding coupled to the internal DC power source prevents overvoltage of the secondary terminals by permitting induced current flow in the clamp winding if the clamp winding voltage exceeds that of the internal DC power source. The transformer core includes a shunt leg which supports a dimmer control winding. When the dimmer control winding is open-circuited, magnetic flux is shunted away from the secondary winding, reducing the light intensity; when the dimmer control winding is short-circuited, currents induce in the dimmer control winding prevent substantial of magnetic flux density and increase the light intensity.

Abstract: Apparatus and methods for noninvasively measuring cardiovascular system parameters. According to a first preferred embodiment, the apparatus generates a time varying electrical voltage waveform having voltages corresponding to systolic and diastolic arterial pressures of the subject, the parameters being modelled by a lumped element electric circuit model analogous to the living subject's cardiovascular system, said circuit model including a systolic capacitor analogous to arterial compliance during systole, said apparatus comprising means for computing the value of said systolic capacitor from a measurement of an elapsed time between two voltage levels within a portion of said voltage waveform corresponding to systole, according to a predetermined criteria; and means for computing at least one said cardiovascular system parameter from said capacitor value. According to a second embodiment, a time-varying systolic arterial compliance is measured by measuring an arterial pulse pressure waveform.

Abstract: The invention relates to a device for use in methods of assay, for example those involving fluorescent moieties. The device possesses a cavity or cavities into which the sample liquid may be drawn by capillary action. Each cavity is formed from two transparent solid plates (35,36): one (36) is adapted to act as a waveguide and carries a suitable immobilized reagent on its surface within the cavity; the other (35) carries on its external surface and optionally also on part only of its internal surface a layer of light-absorbing material (37). The invention also relates to a method of manufacturing devices according to the invention, and to a method of assaying for a ligand in a sample using a device according to the invention.

Abstract: A specifically-reactive sample-collecting and testing device possessing a cavity or cavities each having a dimension small enough to enable sample liquid to be drawn into the cavity by capillary action, wherein said cavity includes an electrode structure for making measurements of one or more electrically measurable characteristics of the sample, and wherein a surface of a wall of the cavity optionally also carries a coating of a material appropriate to the test to be carried out in the device.

Abstract: An assay technique for qualitative and quantitative detection of a chemical, biochemical or biological detection of a chemical, biochemical or biological species in sample. The technique comprises: (a) coating at least a predetermined part of a pre-formed surface on a substrate with a thin film of a material capable of binding the species to be assayed, the pre-formed surface being optically active with respect to radiation at least over a predetermined band of wavelengths; (b) contacting the coated surface with sample; and (c) observing the optical properties of said pre-formed surface in order to determine a qualitative and quantitative change in optical properties as a result of the binding of the species onto said thin film of material. The optical properties as a result of the pre-formed surface may be observed before and after step (b) in order to determine any change in optical properties, or they may be monitored during step (b). The pre-formed surface is preferably a grating.

Abstract: A specifically-reactive sample-collecting and testing device possessing a cavity or cavities each having a dimension small enough to enable sample liquid to be drawn into the cavity by capillary action, wherein a surface of the cavity carries an immobilized reagent appropriate to the test to be carried out in the device, and wherein said surface is a surface of a transparent solid plate to act as a light-transmissive waveguide and forming a wall of the cavity, said plate having an edge which is substantially optically smooth and transverse to the plane of the plate.

Abstract: An assay technique for qualitative and quantitative detection of a chemcial, biochemical or biological detection of a chemical, biochemical or biological species in sample. The technique comprises (a) coating at least a predetermined part of a pre-formed surface on a substrate with a thin film of a material capable of binding the species to be assayed, the pre-formed surface being optically active with respect to radiation at least over a predetermined band of wavelengths; (b) contacting the coated surface with sample; and (c) observing the optical properties of said pre-formed surface in order to determine a qualitative and quantitative change in optical properties as a result of the binding of the species onto said thin film of material. The optical properties of the pre-formed surface may be observed before and after step (b) in order to determine any change in optical properties, or they may be monitored during step (b). The pre-formed surface is preferably a grating.

Abstract: A resonant inverter is current mode-controlled with a transistor supplying current through a primary winding of a transformer. The cycle of operation includes conducting, resonating, and clamping portions of the cycle, with the transistor being turned on for the conducting portion. The resonating portion includes a storage capacitor connected to the primary winding and commences when current-responsive means of the transistor or first semiconductor turns on a second semiconductor, which in turn turns off the first semiconductor. During this resonating stage, the current in the primary winding reverses and stores energy in a storage capacitor. A clamping portion of the cycle includes a unidirectional conducting means or diode which conducts for a time for the excess energy stored in the tank circuit to return to the input and be stored in a filter capacitor.

Abstract: A method of optical analysis of a test sample which comprises a sample material with light-absorbing, scattering, fluorescent, phosphorescent or luminescent properties, which sample is partly in a liquid phase and partly bound to an adjacent solid surface, to discriminate the respective parts of said sample material which are located in the liquid and bound to said solid surface: comprising the steps of providing as said solid surface a surface of a transparent solid optical waveguide, and measuring light from the sample material bound to said solid surface that has passed into and through said transparent solid optical waveguide with total internal reflections and emerged from said waveguide at an angle that deviates from the optical axis of said waveguide by an angle appreciably less than .alpha., where.alpha.=arcsin.sqroot.(n.sub.2.sup.2 -n.sub.1.sup.2)where n.sub.2 is the refractive index of the material of the waveguide and n.sub.

Abstract: A vandalism-resistant antenna for the UHF band comprises a ring-shaped radiator printed on a dielectric board or disc mounted within a shallow enclosure of insulating material having high impact strength. The radiator is approximately 1/4 wavelength long at the operating frequency and is located at a constant spacing above a ground plane. A coaxial RF connector fastens the radiator-board assembly to a mounting surface serving as the ground plane, and couples the antenna to a transmitter or receiver.

Abstract: A phase control ballast in which a reactor and a triac are connected in series with an hid discharge lamp across an ac voltage source. A supra-linear converter connected to a rectifier-filter provides a reference voltage which is a supra-linear function of the source voltage. A ramp generator provides a ramp voltage climbing at a constant rate. At the instant when the ramp voltage exceeds the level of the reference voltage, a comparator circuit provides a signal to the gate of the triac which turns it on. A triac state detector responds to the turning on of the triac in either polarity by dropping the ramp voltage to zero and holding it at zero until the triac turns itself off.

Abstract: In a simple optical fibre duplex coupler of high light-coupling efficiency, two elongate optical guides are so arranged that, over a part of their lengths extending from one end of the coupler, one optical guide surrounds and is coaxial with the other optical guide with their neighboring end faces lying in a substantially common plane. At a position intermediate the ends of the coupler, the optical guides separate into distinct optical channels. The optical guides are surrounded by and enclosed in a body 1 of a transparent plastics material having a refractive index less than that of the outer optical guide. Preferably, the inner optical guide is a composite optical fibre and the outer optical guide is an elongate body of moulded transparent plastics material having a refractive index greater than that of the material of the cladding of the composite optical fibre.

Abstract: An apparatus for recording information in the form of a two dimensional array of miniature images on a recording material such as electrophotographic, photographic or photochromic material. Means are included for forming those images (by such of the processes of sensitizing, charging, exposing, developing or fixing as are appropriate to the particular material used) from originals or copies of legible size. A facility is provided to form one or more miniature images occupying only part of a storage member on one occasion, and to record a further such image or images on later occasions. Guide means and propulsion means in two dimensions are included for adjusting the relative positions of the storage member and the image forming or image viewing device so that any image space may be presented to the image forming device and any image may be presented to an image viewing device.

Abstract: This invention relates to a circuit for shifting a control signal from governance by one variable function to governance by another. It is more particularly concerned with a phase-controlled ballast wherein such a circuit shifts the control from a function of lamp current to a function of line voltage for better overall performance and economy.

Abstract: A bifluxer type transformer for use in a static inverter utilizes an E-E or shell-type core. Such configuration is particularly suitable for ballasting hid lamps because it minimizes stray flux which causes eddy current losses in the luminaire metal enclosure. A pair of apertures are provided in the yoke area, one above and the other below the central leg, around which the main winding is wound. Control windings are looped through the apertures and provide feedback from the output to the input of a power transistor as a result of linkage by transverse flux.

Abstract: Static inverter comprises a transformer and transistor for intermittent asymmetric energization of the transformer. The transformer includes three feedback windings which in response to saturation of a branch of the transformer core but before full core saturation discontinue regenerative feedback and then apply degenerative feedback. A fourth feedback winding in the transformer assures commutation and re-triggering of the transistor.