Abstract: A non-mechanical modulating device for use in infrared detection. The device is of particular use in the 8-14 &mgr;m range and has application in thermal imaging cameras and gas sensing systems. The modulator comprises a germanium element and a means of varying the carrier concentration. In particular, the variation of the hole concentration gives rise to the absorption of infrared radiation due to interband transitions between the light and heavy hole bands in the split valence band in germanium. The variation in hole concentration may be initiated in any convenient way, for example, by the irradiation of the germanium with visible or near infrared light, by the electrical injection of free carriers across a germanium diode structure or by electron impact on the germanium surface following acceleration under vacuum. In the case where the variation in carrier concentration is initiated by optical means, the surface of the germanium is treated so as to produce a low surface recombination velocity.

Abstract: A thermal imaging system (10) which is accoupled and by scanning recreates a thermal image by superimposing measured variations in infrared emission from a scene (22) onto a reference level supplied by a light emitting diode (28). The diode (28) is both a positive and negative luminescent emitter. Emitted flux is current controlled to be equivalent to black body radiation at a range of temperatures which may be colder or hotter than ambient. A signal generated with the system (10) switches between scene and diode observation is a measure of the difference between the mean scene temperature and the diode effective temperature. In response to this digital, control means adjust the bias current through the diode (28) in order to reduce the temperature difference. The reference temperature converges towards the mean scene temperature as this process is repeated. Absolute temperature is thus restored and some image defects removed.

Abstract: Proteins are provided having luciferase activity with lower Km than wild-type luciferases by altering the amino acid residue at position 270 of the wild-type to an amino acid other than glutamate. Greater heat stability than wild-type luciferases while retaining the lower Km is provided by also 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 and/or the amino acid residue at 215 of Photinus pyralis and 217 of the Luciola species with a hydrophobic amino acid. 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.

Abstract: A mixture of a ferroelectric or anti-ferroelectric liquid crystal material and a monomer having a single photopolymeric functional group is injected in the space between two electrode substrates while heat is applied. After cooling of the mixture it is irradiated with ultraviolet light at a temperature at which the liquid crystal material remains in the smectic phase so as to polymerise the monomer. Areas of liquid crystal material requiring different threshold voltages for switching are thereby produced. Alternatively such areas can be produced by changing the conditions applied to a mixture of liquid crystal material with a suitable dopant so as to cause separation of the dopant out of the liquid crystal material in order to provide a polarity of nucleation points for controlling domain formation within the liquid crystal material. Such control of domain formation can be used to provide greyscale in a liquid crystal device.

Abstract: A light modulating device, such as a ferroelectric liquid crystal display (FLCD) comprises an addressable matrix and modulating elements or pixels and associated circuitry for selectively addressing each element in a series of addressing frames in order to vary the transmission level of each element relative to the transmissions levels of the other elements. Such addressing utilises a temporal dither addressing scheme for addressing at least part of each element within each frame with different combinations of temporal dither signals applied to separately addressable temporal bits within the frame to produce different transmission levels. In order to enable a large number of grey levels to be produced whilst limiting the perceived errors at transitions between different grey levels, the temporal bits are addressed in a first order in a first frame (or in a first spatial location) and in a second order, which is different to the first order, in a second frame (or in a second spatial location).

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.