Abstract: A depth control device (1) for a subsmersible body comprises a depth monitor (5) and depth controller (6). A variable volume buoyant body operates under the control of the depth controller and comprises three chambers, the first (10) containing air and the second and third chambers (7, 8) containing hydraulic fluid. The second and third chambers (7, 8) communicate reversibly with one another by means of a tube (13) and bypass valve (12) in a pump (3), so that a piston (9) at the entrance to the first chamber (10) is displaced in response to movement of fluid between the second and third chambers. Thus, the volume of the buoyant body is varied and hence the buoyancy of the subsmersible body which it controls. To keep the submersible body at a particular depth, a depth trigger value is set in the depth controller (6), so that a reversible change in the volume of the buoyant body is initiated in response to a change in depth sensed by the depth monitor (5) by pumping fluid between the two chambers (7, 8).

Abstract: A method of manufacture of solid-walled hollow polymeric fibres comprises the steps of dissolving polymeric material in a suitable solvent liquid to form a dope solution (44), extruding the dope solution through an aperture in a spinneret (41) to form a narrow jet of liquid injecting a coagulant (46) through an aperture (53) in the centre of the liquid dope jet as it leaves the spinneret, directing the jet through an air gap into a coagulant bath containing a further coagulant; and directing the fibre through a drawing bath to reduce the diameter, each coagulant solution being a mixture of a coagulant liquid capable of causing gelation and solidification of the liquid dope jet and between 20% and 80% of the solvent liquid.

Abstract: A sensor system (10) incorporating an interferometer operates as an optical strain gauge. The system (10) is arranged to generate interferograms characterised by an optical path difference between light traversing a sensor arm (12) of the interferometer and light traversing a reference arm (58). Each arm incorporates a highly birefringent optical fibre (38, 58) capable of supporting light propagation at two velocities in two different polarisation modes. A first interferogram is generated between light coupled into the fast eigenmodes of each fibre and a second is generated between light coupled into the slow eigenmodes. Mean optical group delay (.tau..sub.MGD) and differential optical group delay (.tau..sub.DGD) of these interferograms are affected differently by temperature and strain and thus provide a means of discriminating between these attributes of the sensor environment. Thus simultaneous measurement of strain and temperature is achieved.

Abstract: Proteins are provided having luciferase activity with greater heat stability than wildtype luciferases by replacing the glutamate equivalent to that at position 354 of Photinus pyralis luciferase or 356 of Luciola luciferases with an alternative amino acid, particularly lysine. DNA, vectors and cells that encode for and express the proteins are also provided as are test kits and reagents for carrying out luminescence assays using the proteins of the invention. Preferred proteins have a second replaced amino acid at a position equivalent to position 215 of Photinus pyralis luciferase or 217 of Luciola luciferases.

Abstract: A semiconductor device wherein the layer of highly doped p-type material typically found in devices of the prior art is replaced with a layer of doped n-type material, having a doping concentration of between 1.times.10.sup.18 cm.sup.-3 and less than 1.times.10.sup.19 cm.sup.-3, and a thin layer of doped p type material thus facilitating low resistance contact, transparency to radiation produced by the device and confinement with low loss of radiation produced by laser devices.

Abstract: A thermal sensing system (10) including an array of photon detectors (14) produces a detector-dependent response to irradiation. Variations in individual detector characteristics produce a fixed pattern noise which degrades an image or other response. A switchable mirror (M1) may at one position (P.sub.cal) direct infrared radiation from a light emitting diode (20) onto the detector array (14). The diode (20) is both a negative and positive luminescent emitter, the flux emitted is current controlled to be equivalent to black body radiation at a range of temperatures both colder and hotter than ambient. Calibration relationships comprising transfer functions relating incident intensity to signal response are derived for each detector. Alternatively the mirror (M1) may be at an observation position (P.sub.obs) and infrared radiation from a remote scene reaches the detector array (14).

Abstract: A ferroelectric liquid crystal display comprises a layer of ferroelectric liquid crystal material contained between two cell walls, surface treated to align the material in a tilted layer. The walls carry eg row and column electrodes forming an x,y matrix of addressable elements or pixels. Multiplex addressing voltages are provided by driver circuits. An improved addressing is obtained by varying the addressing voltage applied during switching of a pixel to maximize torque applied on liquid crystal molecules. Addressing voltages are from two data waveforms and one strobe waveform; the data waveforms have more than two voltage levels, dc balance, and equivalent rms. values; the strobe waveform has two or more voltage levels (which may include a zero level). The strobe and data waveforms combine to provide a resultant voltage that form an addressing voltage at each pixel.

Abstract: A liquid crystal device is provided with a pair of substrates (12, 16) containing a liquid crystal material (22). A wall structure comprising, for example, a plurality of walls (14) is provided between the two substrates. The wall structure provides mechanical strength to the device and resistance to flow of liquid crystal material which can cause deterioration in the device performance. The walls may extend in two mutually different directions (FIG. 8, 40) to provide mechanical strength and resistance to flow in two directions while the device can still be readily filled. The device is particularly applicable to a ferroelectric liquid crystal device.

Abstract: A semiconductor substrate, suitable for epitaxial growth thereon, comprising a plurality of layers of material. The interfaces between layers act as reflectors of electromagnetic radiation. The reflectors may be used in, for example, resonant cavities in which may be located, for example, multi-quantum well detectors, the efficiency of said detectors being increased by virtue of the enhanced electric field associated with resonance in the cavity.

Abstract: A protective material and a method for the protection of the human head or body from soft tissue damage caused by an impacting object comprises at least two layers of viscoelastic polymeric material to be interposed between head or body and impactor, including at least one first layer of material substantially matched in acoustic impedance to the impacting object and at least one second layer of material selected to produce a large mismatch in acoustic impedance between the first layer and the human head or body. A particular aspect applies the invention to head protection, especially in boxing and like sports, in the form of boxing head guards and boxing gloves.

Abstract: Liquid crystalline compounds useful in super twisted nematic liquid crystal displays are described and have the formula: ##STR1## wherein n is 1-5;m is 0-5;p is 0, 1 or 2;q is 0, 1 or 2p+q is less than or equal to 3;A.sub.1, A.sub.2, A.sub.3 are independently chosen from 1,4-disubstituted benzene 2,5-disubstituted pyrimidine, 1,5-disubstituted pyridine, 2,6-disubstituted naphthalene which may be laterally substituted with F, Cl, Br or CN, trans-1,4-disubstituted cyclohexane 2,5-disubstituted dioxane, 2,5-disubstituted thiophene, 2,5-disubstituted furan, 2,5-disubstituted thiodiazoleZ.sub.1 may be COO, OOC, OCH.sub.2, O;Z.sub.2, Z.sub.3 are independently chosen from a direct bond, COO, OOC, C.sub.2 H.sub.4, CH.sub.2 O, OCH.sub.2, C.sub.4 H.sub.8, C.sub.3 H.sub.6 O, (E)--CH.dbd.CHC.sub.2 H.sub.4, (E)--CH.dbd.CHCH.sub.2 O, --C.tbd.C--;R.sub.1 is alkyl, and may contain up to 20 carbon atoms and may be branched or a straight chain; provided that at least one of, A.sub.1, A.sub.2, A.sub.

Abstract: A display makes use of circularly polarised activation light; to this end it comprises a liquid crystal cell (7) acting as a half-wave plate so as to reverse the handedness of incident light in one setting and not to affect the handedness in another, and a filter (9) such as a cholesteric mirror for passing only that part of the light from the liquid crystal that has a predetermined handedness. When the light is passed by the filter (9), it strikes a photoluminescent screen (12), causing it to emit visible light for the display. The nematic cell is easy to produce and to switch, and the display does not need polarisers.

Abstract: A ferroelectric liquid crystal display comprises an addressable matrix of pixels 7 and addressing circuitry comprising a data signal generator 14 for applying data signals to column electrode tracks 4.sub.1, 4.sub.2. . . . . 4.sub.n and a strobe signal generator 15 for applying strobe signals to row electrode tracks 5.sub.1, 5.sub.2. . . . . 5.sub.m in order to selectively switch the pixels 7. In order to provide a large number of well defined grey levels, the addressing circuitry includes spatial and/or temporal dither control circuits for addressing separately addressable subpixels of each pixel 7 with different combinations of spatial dither signals and/or for addressing at least part of each pixel with different combinations of temporal dither signals applied to separately addressable temporal bits corresponding to subframes of different periods to produce a plurality of different transmission levels.

Abstract: Susceptible tumors are treated by first sensitizing them to incident electromagnetic radiation by of a compound of the formula: ##STR1## where M is a diamagnetic metal ion or a diamagnetic metal compound or silicon or a compound of silicon or is 2H; one H being bonded to each of the two nitrogen atoms depicted as being bonded to M at positions 29 and 31;R.sub.1 to R.sub.25 are the same or different and are independently selected from C.sub.1 -C.sub.20, alkyl, C.sub.2 -C.sub.20 alkenyl, X--O--Y, ##STR2## X.sup.2 COOX.sup.1, x.sup.2 COONR.sup.1 R.sup.11 and H; wherein X and X.sub.2 are independently selected from a chemical bond, --(CH.sub.2).sub.n -- where n is an integer from 1 to 20 and --(CH.sub.2).sub.a CH.dbd.CH(CH.sub.2).sub.b where a and b are independently selected from integers 0-20 and a+b totals from 0 to 20;X.sup.1 is independently selected from C.sub.1-20 alkyl, C.sub.2-20 alkenyl and H;R.sup.1 and R.sup.11 are independently selected from H, C.sub.1-20 alkyl, C.sub.

Abstract: A parallel processing system computer which utilizes the logic programming language Prolog comprising a plurality of processing nodes, each node comprising three central processing units (CPUs), a memory architecture adapted for Prolog execution and interfacing hardware, each processing node being connected to a communication bus and a real-time broadcast bus whereby the real-time data from an input can be broadcast via the real-time broadcast bus to each processing node. One of the CPUs is used to control the communications and scheduling of the node, the other two CPUs are used as sequential Prolog Processors (SPPS). Each node can be arranged such that the collection of unused memory is carried out by one SPP while another SPP continues to run Prolog program enabling continuous real-time operation. The memory architecture is hybrid and comprises local static RAM and global dynamic RAM. The dynamic RAM comprises a Prolog database of known signal for comparison with the real-time input signals.

Abstract: A ferroelectric liquid crystal display element is structured so that ferroelectric liquid crystal is provided between a plurality of signal line electrodes and a plurality of scanning line electrodes running perpendicular to one another, and includes a signal line electrode driving circuit made up of a gray-scale signal amplifying circuit and a gray-scale signal producing circuit, and a scanning line electrode driving circuit made up of a scanning signal amplifying circuit and a scanning signal producing circuit. The signal line electrode driving circuit applies to the signal line electrodes gray-scale signals including pulses which are phase modulated in accordance with a gray-scale level, and the scanning line electrode driving circuit selectively applies to the scanning line electrodes scanning signals including, in each scanning period, an erasure voltage, a selection voltage, and a non-selection voltage.

Abstract: An infrared optical system incorporates a lens for imaging a remote scene onto a detector within a cold shield. Stray radiation incident on the detector is reduced by an optical stop in the form of a light emitting diode producing negative luminescence. The LED emits less radiation than background, and contributes less to the detector photon noise than an optical stop not exhibiting negative luminescence.

Abstract: A multi-layer Auger suppressed diode having at least two exclusion interfaces and at least two extraction interfaces. A specific embodiment has two composite contacts, each consisting of a heavily doped layer (3, 4) and a buffer layer (8, 9) of lower doped, high bandgap material sandwiched between the heavily doped layer and the active region (2) of the device.

Abstract: This invention relates to metal oxides based films and a method for their production via a sol-gel route using metal bis(.beta.-diketonate) salts as precursors. They can be conveniently doped by Group (III), (IV) or (V) impurities and may be used to provide coductive coating on optically transparent substrates such as glass, ceramics or polymers.

Abstract: In order to the effects of impact on liquid crystal devices a polymer network is introduced into ferroelectric liquid crystal cells. A liquid crystal device comprises two spaced cell walls each bearing electrode structures and treated on at least one facing surface with an alignment layer, a layer of a smectic liquid crystal material enclosed between the cell walls, characterised in that the liquid crystal material contains a small amount of monomer. The liquid crystal material may also contain a photoinitiator. The monomer material may be cured to produce the polymer network; the curing may be carried out in the presence of an electric or magnetic field. Further, the monomer may be cured in an isotropic or liquid crystal phase.