Abstract: A liquid crystal device comprises a liquid crystal cell including a layer of ferroelectric smectic liquid crystal material contained between two walls bearing electrodes and surface treated to give both an alignment and a surface tilt to liquid crystal molecules. The material adopts a C2 rather than a C1 arrangement by arranging the surface pretilt &xgr; and the ratio of azimuthal to zenithal anchoring energies &bgr;/&agr; to give a positive energy difference &Dgr;Ws for the liquid crystal director at the surface in the C1 and C2 states. Additionally the provision of a C2 state may be enhanced by allowing the cell to cool from the isotropic phase to a temperature just below a smectic A to chiral smectic phase, then applying 50 Hz ac voltage in the range typically 0.1 to 5 volts rms. across the liquid crystal layer for about 90 seconds, then allowing the cell to cool to ambient temperature.

Abstract: An optical fiber for transmitting radiation comprising two or more core regions, two or more core regions, each core region comprising a substantially transparent core material and having a core refractive index, a core length, and a core diameter, wherein said core regions are arranged within a cladding region, said cladding region comprising a length of first substantially transparent cladding material, having a first refractive index, wherein said first substantially transparent cladding material has an array of lengths of a second cladding material embedded along its length, wherein the second cladding material has a second refractive index which is less than said first refractive index, such that radiation input to said fiber propagates along at least one of said core regions. The cladding region and the core regions may be arranged such that radiation input to said optical fiber propagates along one or more said lengths of said core regions in a single mode of propagation.

Abstract: Liquid crystal compounds of formula (I) are described, where formula (I) is given as R1—A—(X)m—(B)n—R2 where A is selected from naphthyl, fluorinated naphthyl, brominated naphthyl, B is selected from phenyl, methylated phenyl, brominated phenyl, fluorinated phenyl, thiophene, pyrimidine and pyridine. R1 and R2 are independently selected from alkyl, alkoxy, akynyl, thioalkyl, Br, CN, SCN, NCS, perfluoroalkyl, perfluoroalkoxy and hydrogen, X is selected from C≡C, COO and C≡C, m is 0 or 1, n is 0 or 1 where m is 1 and n is 0 where m is 0; provided that where A is naphthyl, n is 1 and m is 0 then B is selected from methylated phenyl, brominated phenyl, thiophene, pyrimidine and pyridine; and further provided that where A is naphthyl, X is C≡C, m is 1 and n is 1, then B is selected from thiophene, pyrimidine and pyridine.

Abstract: A speech processing system (10) incorporates an analogue to digital converter (16) to digitize input speech signals for Fourier transformation to produce short-term spectral cross-sections. These cross-sections are compared with one hundred and fifty reference patterns in a store (34), the patterns having respective stored sets of formant frequencies assigned thereto by a human expert. Six stored patterns most closely matching each input cross-section are selected for further processing by dynamic programming, which indicates the pattern which is a best match to the input cross-section by using frequency-scale warping to achieve alignment. The stores formant frequencies of the best matching pattern are modified by the frequency warping, and the results are used as formant frequency estimates for the input cross-section. The frequencies are further refined on the basis of the shape of the input cross-section near to the chosen formants.

Abstract: A liquid crystal display of the UV-phosphor type comprises a light source 1 for producing activation light at a predetermined narrow range of UV wavelengths, a collimator 3 for directing the activation light in parallel in a predetermined direction, a LC cell 5 formed from an array of pixels, a photoluminescent screen (7) on the cell arranged to emit a visible output when struck by the narrow-band excitation light passing through the cell, and a drive circuit for addressing the LC cell in a multiplexed manner. The direction of the light and the thickness of the cell are chosen to give the best contrast ratio for the liquid crystal. Such an effect is only possible when monochromatic, collimated light is used, which for a normal display is not practical.

Abstract: Materials of formula (I): [G]g(SiO1/2)x are described where G is R3SiR1R2(O)k; R1, R2, R3 are independently a C1-16 alkyl which may be partly or fully halogenated, H and formula (IA), wherein Y is selected from COO, OCO, O, S, CHOH, CHF, CH2; Q=(CH2)n where one or more non-adjacent methylenes may be replaced by O and n=1=20; Z is O, S, a single covalent bond, COO, OCO; when Y is CH2, then n may also be 0; (a) represents any mesogenic group; provided that at least one of R1, R2, R3, is selected from formula (IA): k=0 or 1; g=4 or 6 or 8 or 10 or 12; 1=3 or 8 provided that: if k=1, 1=3 and x is selected form 6, 8, 10, 12 then g=x; if k=0, 1=8 and g=4 then x=1; and further provided that G may have up to g different structures for any single compound.

Abstract: An enzymically active cell free extract or membrane fraction capable of catalysing the removal of nitrite from hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is provided. The cell free extract is produced by culturing a strain of Rhodococcus rhodochrous bacterium from nature. The strain designated 11Y has been deposited as NCIMB 40820. Methods of bioremediation using the enzymically active cell free extract so produced are also provided. Additionally there is provided a method for detecting the presence of RDX in a sample together with a biosensor for use in such a method. The nitrite produced in the enzyme catalysed reaction with RDX is detected, for example, colorimetrically, or alternatively a product of RDX degradation, such as formal behyde, is detected.

Abstract: A collision warning system (10) discriminates between objects which pose a threat of collision from those which do not by measuring the relative sightline rate of the object, this being a measure of the rate of change of angular position of the object if the sightline rate is above a threshold value, there is little risk of collision. To measure the sightline rate, a radar source (20) emits microwave frequency radiation which is received by two detectors (22 and 24) after reflection from a target. Signals from the detectors are processed by processing means (26). The processing means determines if the sightline rate of an object is below a certain threshold. If it is, and the relative velocities of the object and the system are such that a collision is likely, a warning buzzer (28) sounds.

Abstract: A method and an apparatus for distinguishing systematic artifacts from noise involves localizing functional noise in the vicinity of predicted functional peaks. The method is particularly relevant to detection and tracking of time-varying signals. An apparatus implementing such an application of the method comprises a detection system (50) which monitors each component of a multi-component periodic signal via its basis repeat unit: a cyclet, of periodicity &tgr;. The signal is digitized and clocked through the system (50) in segments. A cyclet remover (62) subtracts predicted values of previously detected cyclets from the incoming signal segment to produce a residual signal. A cyclet detector (60) uses a sliding window procedure to detect further cyclets in this residual and to measure their amplitude profiles {overscore (b)}(&tgr;) and periodicities (&tgr;).

Abstract: A panel-form loudspeaker has a resonant multi-mode radiator panel which is excited at frequencies above the fundamental frequency and the coincidence frequency of the panel to provide high radiation efficiency through multi-modal motions within the panel, in contrast to the pistonic motions required of conventional loudspeakers. The radiator panel is skinned composite with a honeycomb or similar core and must be such that it has a ratio of bending stiffness to the third power of panel mass per unit area (in mks units) of at least 10 and preferably at least 100. An aluminum skinned, aluminum honeycomb cored composite can meet this more severe criterion easily.

Abstract: An electrolyte comprises a composite of a polymer and a molten salt electrolyte immobilized within the polymer. The electrolyte is stable and ionically conducting at a temperature substantially equal to the melting point of the molten salt electrolyte. In this form, the electrolyte is suitable for use in electrochemical cells, supercapacitors or electrochromic windows and displays.

Abstract: An electoclinic device having 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, where the liquid crystal material contains one or more of the compounds described by formula I as defined in the specification.

Abstract: The present invention relates to protection agents, in particular to topical compositions such as barrier creams which can prevent the passage of toxic chemicals and chemical warfare agents through the skin. Formulations contain hexamethylene tetramine derivatives or analogues thereof and perfluorinated polymeric compounds.

Abstract: In order to reduce 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 networks the curing many 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.

Abstract: An optical filtering device incorporates first and second prisms, the latter prism counteracting the angular dispersion of the former prism. A spatial light modulator provides a positionally variable optical stop located to block radiation within a wavelength interval and received from a location within a scene. Unobscured radiation from that and other scene locations passes to a camera, which produces an image on a display. Opaque pixels in the stop are positioned to block unwanted light sources. The invention attenuates potentially dazzling monochromatic radiation while retaining radiation at other wavelengths for imaging purposes.

Abstract: This invention describes a method by which microparticles, typically in the size range from 0.3 &mgr;m to 100 &mgr;m, which are carried in a fluid suspension, may be rapidly detected and characterized. The method primarily relates to the measurement of atmospheric particles such as those in clouds or environmental aerosols, but it may be used to measure other forms of particulate suspension wherever the flow of suspension through a defined measurement space can be achieved. The method is based upon a rapid analysis of the spatial laser scattering profile (i.e., the complex manner in which individual particles scatter laser light) recorded from individual particles as they are carried in suspension through a measurement space. Using this method it is possible to differentiate various types of particles based on particle shape and structure, as manifest in characteristics of their individual spatial light scattering patterns.

Abstract: Compounds of formula (I) are provided which are particularly useful in super twisted nematic devices, where n may be 0-5; m may be 0-5; p may be 1-9; q may be 1, 1, or 2; A1, A2 are independently chosen from 1-4, -disubstituted benzene, 2,5-disubstituted pyrimidine, or 2,5-disubstituted pyridine, trans- 1,4-disubstituted cyclohexane, trans- 2,5-disubstitued dioxane. The aromatic rings may be laterally substituted with F, Cl, Br or CN; Z1 may be O, COO, OOC; Z2, Z3 are independent chosen from a direct bond, COO, OOC, C2H4, CH2O, OCH2, or -c≡c-, provided that when Z1 is O and m is 1, 3 or 5 the carbon—carbon double bond configuration is E; provided that when Z1 is O and m is 2 or 4 the carbon—carbon double bond configuration is Z; provided that when Z1 is COO or OOC and m is 0, 2 or 4 the carbon—carbon double bond configuration is E; and provided that when Z1 is COO or OOC and m is 1, 3 or 5 the carbon—carbon double bond configuration is Z.

Abstract: A group fo liquid crystalline compounds defined by formulas (1) and (2) including polymers, monomers, oligomers and intermediates for their preparation. Also included are symmetric and non-symmetric poly(dimethylsiloxy) compounds having end groups derived from Formulas (1) and (2).

Abstract: Methods, based on the Wittig-Horner reaction, are provided for the synthesis of compounds of formula (I) where m is from 5-150, X and Y are independently selected from: CN, H, OH, COCH3, CO2H, CO2H, CO2R1, where R1 is C1-12 alkyl, NCS, SCN, CF3, CH2X where X is F, Cl, Br, OH, CHF2 and formula (IB), where J for each X and Y group is independently selected from: CH2, single covalent bond, OOC, CO2, O, CH2O, OCH2, CH2CO2, CH2OOC; p=1-20; L for each X and Y group is independently selected from: O, CH2OCO, CO2, S, NH; (a) is defined by formula (IC), where rings A, B and C are independently selected from phenyl, cyclohexyl, pyridine and pyrimidine and may be independently of each other substituted with at least one of Cl or F; linking groups A and B may be selected from single bond, CO2, OOC, CH2O, OCH2, CH2CH2, C≡C; Z is selected from CN, F, Cl, NO2, R, OR, CO2R, CF3, OOCR, NCS, SCN, where R=straight chain or branched chain alkyl and may include from 1-16 carbon atoms and incl

Abstract: A segmented electrode drive circuit of a passive-matrix type liquid crystal display apparatus includes one analog switch in each of segmented electrodes, supplies “0” as a control signal in the first slot of a three-slot selecting period so as to make the electrical potential of a segmented electrode zero. “1” is supplied as a control signal in the second slot so as to bring the output terminal of an analog switch selected by the data signal into a high-impedance state. As a result, the electric potential of the segmented electrode in the high-impedance state becomes an average electric potential of scanning electrodes capacitive-coupled with the segmented electrode.