Abstract: A bipolar transistor with vertical geometry comprises a base region (1) provided with a base contact (21), emitter and collector regions (2,3) arranged to extract minority carriers from the base region, and an excluding structure for counteracting entry of minority carriers into the base region via the base contact, wherein the base region has a bandgap of greater than 0.5 eV and a doping level greater than 1017 cm?3. As shown the base includes an excluding heterojunction (4) preventing entry of carriers from the base contact (21), but alternatively the base region could comprise a “high-low” doping homojunction. The construction shows improved resistance to thermal runaway even in multi-finger transistors. It is particularly useful for high power, high frequency transistors, e.g. base on gallium indium arsenide. The collector region preferably has a heterostructure.

Abstract: A control device (1) for controlling the position of a marine streamer comprising; an annular aerofoil (2), a mount (3) for mounting the annular aerofoil onto and around the streamer; and control means (4a, 4b) for controlling the tilt and/or rotation of the annular aerofoil (2) whereby to adjust the lateral position and/or depth of the streamer.

Abstract: A frequency synthesiser for generating wideband signals for zero Hz up to frequencies in the millimetre wave band provides the ability for arbitrarily fine increments in output frequency. The synthesiser has an optical comb generator that provides a set of reference signals at predetermined intervals. These reference signals are fed to two or more laser devices, at least one of which is a frequency selection and translation device capable of selecting a particular output line from the comb generator and shifting it by some desired frequency. The outputs from the laser devices are then combined and detected using a photodetector. The output from this is the system output. Various methods of producing the frequency selection and translation device are disclosed, as are various methods of producing the optical comb reference signal. Some possible applications of the invention are also disclosed.

Abstract: An optical interference filter (2) is provided by a substrate (1) in which is formed a plurality of parallel slots so as to define layers (slots and substrate laminae) of alternating refractive index. As shown, the filter comprises a central Fabry-Perot resonator slot cavity (3) between two mirror groups (4, 5) of alternating slots and substrate laminae, and is coupled to optical fibers (7) accommodated in V-grooves (6) on either side. For tuning, one mirror group (5) may be movable in the direction of arrow (A), or, where the central resonator is provided by substrate material, by altering its temperature. One or more further Fabry-Perot filters may be formed in the substrate and coupled to the filter (2). The invention encompasses non-resonating filters.

Abstract: In a digital acoustic transmission device in which a digital sequence (31) is electrically modulated (22) on a carrier cos ?t, the modulated carrier (23) is prefaced with at least two pulse signals (24) of known timing relative to each other and to the modulated digital sequence to provide an output signal (13) for acoustic transmission. The pulse signals indicate to receiver the start of a transmission, and contain Doppler information for resampling the modulated signal prior to demodulation. Where the information sequence is in encoded blocks of equal length, the relationship between successive blocks can be used to update the Doppler information for use with the following block. Channel information can also be derived from the pulse signals and/or blocks for raking the next part of the incoming signal. Preferably the pulse signals have good correlation characteristics. In the embodiments the pulse signals are an immediately successive identical pair of linearly rising chirps.

Abstract: A horizontal access semiconductor photo detector (2) comprises a horizontal light absorbing layer (8) for converting light into photo-current which layer is configured to confine light within it in whispering gallery modes of propagation. The detector is configured to have a first waveguide portion (18) and a second light confining portion (20, 21) arranged such that the waveguide portion couples light into the detector and transfers light into the light confining portion so as to excite whispering gallery modes of propagation around the light confining portion. The light absorbing layer may be part of the light confining portion or alternatively light can be coupled into the light confining portion or alternatively light can be coupled into the light absorbing layer from the light confining portion by evanescent coupling. The excitation of whispering gallery modes within the light absorbing layer significantly increases the effective absorption coefficient of the light absorbing layer.

Abstract: A method of measuring oestrogen or progesterone receptor (ER or PR) comprises identifying in histopathological specimen image data pixel groups indicating cell nuclei, and deriving image hue and saturation. The image is thresholded using hue and saturation and preferentially stained cells identified. ER or PR status is determined from normalised average saturation and proportion of preferentially stained cells. A method of measuring C-erb-2 comprises correlating window functions with pixel sub-groups to identify cell boundaries, computing measures of cell boundary brightness and sharpness and brightness extent around cell boundaries, and comparing the measures with comparison images associated with different values of C-erb-2. A C-erb-2 value associated with a comparison image having similar brightness-related measures is assigned. A method of measuring vascularity comprises deriving image hue and saturation, producing a segmented image by hue and saturation thresholding and identifying contiguous pixels.

Abstract: A three-dimensional imaging system is described which exploits the defocusing of non-zero diffraction order images caused by the quadratic distortion of a diffraction grating (4). An optical system (1) is used such that objects (5, 6 and 7), located at different distances from grating (4), are imaged simultaneously and spatially separated on a single plane B.

Abstract: An optical filter comprises a multimode waveguide, and first and second coupling waveguides which communicate with the multimode waveguide at respective ends thereof. Filtering is achieved by the effect of self-imaging in the multimode waveguide. The filter further comprises one or more series of aperture within the multimode waveguide, the or each series being located at a longitudinal position within the multimode waveguide at which 1-to-N way intensity division of an input optical field occurs, the optical field being the lowest order transverse mode of the coupling waveguides. The (one or more) series of apertures reduces the transmission of the filter at wavelength other than those corresponding to transmission peaks of filter's transmission function, thus providing improved filtering performance compared to prior art optical filters based on self-imaging.

Abstract: The invention relates to novel photochromic liquid crystal materials which may be used in various electro-optic devices including liquid crystal devices. The materials can be converted into another form on irradiation by light which may make it feasible for them to be addressed by light in electro-optic devices. The materials are based on 5-membered heterocycles.

Abstract: Measuring apparatus for providing information on the relative location of a target site which is radiating a target signal that includes a predetermined pulse signal, comprises receiver means for providing a pair of temporally spaced output pulses in response to a single received said predetermined pulse signal and cross-correlation means coupled to said receiver means for cross-correlating said pair of output pulses or signals derived therefrom.

Abstract: A micro power unit comprises a Rankine cycle circuit powered by combustion of hydrocarbon fuel from tank (2). Combustion takes place on a combustion catalyst (6) in a chamber (5). The fluid circuit includes a boiler (10), turbine (11), a condenser (12) and feed pump (13). The feed pump impeller (13A) is driven by magnetic coupling with the turbine rotor (11A) and further magnetic couplings may be used to drive e.g. a propeller (15) for a micro air vehicle and/or electrical generator (16).

Abstract: A method and apparatus for annealing an integrated ferroelectric device (10) is disclosed in which the device (10) comprises a first layer of material capable of existing in a ferroelectric state and a second layer of material defining an integrated circuit below the first layer such as a microbridge thermal detector. The method comprises producing a pulse of energy, extending the pulse temporally using a pulse extender (200) and illuminating the first layer with the extended pulse. The duration and wavelength and fluence of the extended pulse are selected so that the material of the first layer is annealed into a ferroelectric state without exceeding the temperature budget of the integrated circuit. Application of the method in heating other articles which comprise a layer to be heated and a temperature sensitive layer is also disclosed.

Abstract: A signal processing technique for generating separated signal components incorporates the steps of correlating basis vectors with input data to produce output vectors, applying a non-linear function to the output vectors to produce non-linearized vectors, and convolving the non-linearized vectors with the basis vectors to produce separated signal components. Each vector may comprise a set of one-dimensional channel vectors. Separated signal components are combined to form an input signal reconstruction and an anomaly signal indicating deviation of the reconstruction from the associated input signal. Basis vectors are determined by training which involves use of weighting factors referred to as basis scales. When used to scale separated signal components in the production of reconstruction vectors, basis scales have the effect of reducing a mean squared error between such vectors and associated input data used to derive them.

Abstract: An electric drive configuration for a tracked vehicle comprises a pair of propulsion motors (1a, 1b) each in operable communication with one of a first pair of track drive sprockets (3a, 3b) for driving a pair of tracks (4a, 4b) of the tracked vehicles; a steer motor (5) in driveable communication with a controlled differential steer gear unit (6) positioned centrally of a pair of steering cross-shafts (7a, 7b) and in driveable communication with each shaft, the opposing ends of the steering cross-shafts (7a, 7b) being each in operable communication with one of a second pair of track drive sprockets (9a, 9b) for controlling the relative speeds of the two track to steer the tracked vehicle; the first pair of track drive sprockets (3a, 3b) being engageable with the tracks (4a, 4b) at a first end of a tracked vehicle and the second pair of track drive sprockets (9a, 9b) being engageable with the tracks at a second end of the tracked vehicle.

Abstract: A method of preparing an elastomeric polymer comprising the step of reacting a bisoxazolone with a primary or secondary di-amine terminated oligomer.

Abstract: The use of a compound of formula (A), which comprises a group of sub-formula (I) where R1, R2, R3, R4, R5, R6, X1 and Y1 are various specified organic groups wherein at least one of said groups has sufficient electron whitdrawing properties to activate the multiple bonds to polymerisation, in a stereolithographic composition. Stereolithographic applications of these compounds are also described and claimed.

Abstract: An apparatus for detection and analysis of optical systems. Prior art systems exploit the phenomenon of photon scattering in order to range the distance of objects from the ranging apparatus. However, no information other than the distance of the target object is obtained from such systems. There is therefore provided an apparatus that exploits the technique of single photon counting and the phenomenon of retro reflection to provide information about a target optical system. Such information can be analysed and compared against known optical systems to provide a means of identification. Alternatively such information can be used as a method of quality control when constructing precision optical instruments such as telescopes or microscopes.

Abstract: An electrode assembly is formed by respectively overlaying a sheet cathode 1, a sheet separator 3 and a double-sided sheet anode 8 to form a stacked structure 10, and subjecting the stacked structure to multiple folds, wherein the initial fold comprises folding the cathode in half around the double-sided anode so as to surround the respective upper and lower active anode surfaces thereof. The multiple folds may comprise one or more subsequent parallel folds made with the fold line D-D extending perpendicular to the original length of the stacked structure such that its overall length is halved at each fold. A pouch battery comprising said electrode assembly has improved safety and performance characteristics. The pouch battery construction has especial application to lithium primary batteries.

Abstract: Organic light emitting diode devices having a substrate bearing an organic layer sandwiched between electrode structures. The organic layer includes, in a single layer a hole transporter, an electron transporter and a light emitter where the electron transporter or the light emitter or the electron transporter and the light emitter include a material of general formula 1.