Abstract: A grating, suitable for filtering optical radiation, comprises a plurality of concatenated grating sections each having different physical characteristics as compared with adjacent grating sections. At least one of the sections comprises a waveguide structure formed by a thin strip (100) of a material having a relatively high free charge carrier density surrounded by material having a relatively low free charge carrier density. The strip has finite width (W) and thickness (t) with dimensions such that optical radiation having a wavelength in a predetermined range couples to the strip and propagates along the length of the strip as a plasmon-polariton wave. Various grating architectures may be implemented, e.g. chirped, interleaved, uniform, etc. A method of producing such gratings derives normalized phase constants and attenuation constants and then uses, for example, TMM or Coupled Mode Theory to derive therefrom the optical response of the grating.

Abstract: The purely bound electromagnetic modes of propagation supported by waveguide structures comprised of a thin lossy metal film of finite width embedded in an infinite homogeneous dielectric have been characterized at optical wavelengths. One of the fundamental modes supported by the structure exhibits very interesting characteristics and is potentially quite useful. It evolves with decreasing film thickness and width towards the TEM wave supported by the background (an evolution similar to that exhibited by the sb mode in symmetric metal film slab waveguides), its losses and phase constant tending asymptotically towards those of the TEM wave. Attenuation values can be well below those of the sb mode supported by the corresponding metal film slab waveguide. Low mode power attenuation in the neighbourhood of 10 to 0.1 dB/cm is achievable at optical communications wavelengths, with even lower values being possible.

Abstract: A low loss, low drive voltage plasmon-polariton electro-optic modulator based on mode cutoff comprises a waveguide structure formed by a thin metallic strip surrounded by material having a relatively low free charge carrier density. The metallic strip has finite width and thickness with dimensions such that optical radiation having a wavelength in a predetermined range couples to the metallic strip and propagates along the length of the metallic strip as a plasmon-polariton wave. The surrounding material comprises two distinct portions with the metallic strip extending between them. The modulator comprises means for varying an electric field applied to at least one portion so as to vary the value of the electromagnetic property and thereby the propagation characteristics of the plasmon-polariton wave.

Abstract: Waveguide structures comprising a thin lossy metal film of finite width embedded in an infinite homogeneous dielectric support purely bound electromagnetic modes of propagation low mode power attenuation in the neighbourhood of 10 to 0.1 dB/cm is achievable at optical communications wavelengths, with even lower values being possible. Carefully selecting the film's thickness and width can make this mode the only long-ranging one supported. In addition, the mode can have a field distribution that renders it excitable using an end-fire approach. The finite-width metal film waveguide may be used for applications requiring short propagation distances and 2-D field confinement in the transverse plane, enabling various devices to be constructed, such as couplers, splitters, modulators, interferometers, switches and periodic structures. Under certain conditions, an asymmetric structure can support a long-ranging mode having a field distribution that is suitable to excitation using an end-fire technique.

Abstract: An optical device comprises a waveguide structure formed by a strip (100) of a material having a relatively high free charge carrier density surrounded by a material having a relatively low free charge carrier density. The strip has finite width (W) and thickness (t) of the same order with dimensions such that optical radiation having a wavelength in a predetermined range couples to the strip and propagates along the length of the strip as a plasmon-polariton wave. Preferably the width and thickness are substantially equal and less than about 300 nm.

Abstract: A television receiver includes a microphone and an A/D converter for converting a spoken message into a digital signal, and a memory for storing the digital signal. When desired, the stored signal is then converted to a text message and is then displayed on the screen of the television receiver. Alternatively, or in addition, the stored digital message may be reconverted into an electrical audio signal and played by via the loudspeaker of the television receiver.

Abstract: Waveguide structures comprising a thin lossy metal film of finite width embedded in an infinite homogeneous dielectric support purely bound electromagnetic modes of propagation low mode power attenuation in the neighbourhood of 10 to 0.1 dB/cm is achievable at optical communications wavelengths, with even lower values being possible. Carefully selecting the film's thickness and width can make this mode the only long-ranging one supported. In addition, the mode can have a field distribution that renders it excitable using an end-fire approach. The finite-width metal film waveguide may be used for applications requiring short propagation distances and 2-D field confinement in the transverse plane, enabling various devices to be constructed, such as couplers, splitters, modulators, interferometers, switches and periodic structures. Under certain conditions, an asymmetric structure can support a long-ranging mode having a field distribution that is suitable to excitation using an end-fire technique.

Abstract: The purely bound electromagnetic modes of propagation supported by symmetric waveguide structures comprised of a thin lossy metal film of finite width embedded in an infinite homogeneous dielectric have been characterized at optical wavelengths. The modes supported are divided into four families depending on the symmetry of their fields. In addition to the four fundamental modes that exist, numerous higher order ones are supported as well. A nomenclature suitable for identifying all modes is discussed. The dispersion of the modes with film thickness and width has been assessed and the effects of varying the background permittivity on the characteristics of the modes determined. The frequency dependency of one of the modes has been investigated. The higher order modes have a cut-off width, below which they are no longer propagated and some of the modes have a cut-off thickness.

Abstract: The invention relates to a radial bearing assembly for a drive shaft of vehicles which connects a transmission (2) with a driven front wheel (5), with a laterally sealed radial bearing (11a) received in a holder (15) which is securely fixed in place on the side of an internal combustion engine for supporting the drive halfshaft (7). In accordance with the invention, a drive shaft (7) in the form of a hollow shaft is provided, with an inner ring (12a) of the radial bearing (11a) being formed from a sheet metal band in a non-cutting fashion. The radial bearing (11a) is received via a spherically shaped outer surface area (14) of an outer ring (13a) in an oriented position in the holder (15) which is assembled from flanges (16, 17).

Abstract: Device for the accelerated cooling of a continuous substrate moving rapidly in a vertical plane, formed by a closed chamber, which includes, in succession in the direction of travel of the substrate, at least one so-called main cooling zone provided with coolant injectors, a so-called secondary cooling zone promoting contact between the coolant and the substrate, a coolant extraction zone and coolant retainers both at the inlet and outlet of the cooling device. The main cooling zone includes, spray injectors for forming one or more water/air fog curtains arranged in space so that they come into direct contact with the substrate to be cooled.

Abstract: Cover to place on a door (5) with unlocking by means of rotation as to slightly open it and making it possible to appropriately sterilize the entire inside of the receptacle it closes, whilst enabling bactericide vapors to easily reach the surfaces adjacent to the door. In order to do this, the cover includes a fixed dome portion (20) flanged on the receptacle around the door, and a handling device (40 to 42) created through the dome and able to grip the door so as to slightly lift it up without breaking its imperviousness.

Abstract: This invention relates to an offset printing apparatus, which comprises a frame and a removable cassette comprising a plate cylinder and a blanket cylinder, with parallel transverse axes, tangential to each other and adapted to be engaged in the frame of the apparatus so that the plate cylinder is in contact, under pressure, with each inking roller with a predetermined touch, i.e. a predetermined crushing of the peripheral layer, of supple material, of the inking roller. This touch is determined by a first bearing element or touch way, associated with each bearing of an inking roller and, on each removable cassette, a second bearing element or touch way. In order automatically to obtain the correct touch when a cassette is changed, the second touch way of the cassette is constituted by a fixed disc bearing a covering, forming a coating of thickness equal to that of the covering associated with the plate.

Abstract: The present invention relates to a device for detecting, in a machine, the position of contact of two rollers of parallel axes of which at least one is mounted mobile. This device is characterized in that it comprises an elastic member mounted so as to undergo, during contacting of the two rollers, a deformation, limited by a bearing, further to the relative displacement of two elements mobile with respect to each other, and means for measuring this deformation.

Abstract: A centrifuge for performing biological and medical analyses for samples in test packs mounted in holders peripherally disposed on the centrifuge rotor. The test pack holders are also rotated relative to the rotor by means of a mechanical spinning portion fitted below the rotor. Analyses are made with a spectrophotometric measuring device, whose optical path is perpendicular to the plane of the rotor.

Abstract: A device for analyzing a liquid sample such as blood includes a cartridge portion and a casing portion. The cartridge includes an inlet for directly receiving a sample. The cartridge is then irreversibly clipped to the casing so that an inlet of the casing is in communication with an outlet of the cartridge. The sample is then mixed in the casing with a diluent and/or reagent by using a centrifuge, and measurements are taken. The device allows a sample to be taken directly into the cartridge, and restricts employment of the device to a single use.

Abstract: At the exit from the hot rolling mill the rail temperature is reduced to a value not less than that at which the pearlite transformation begins in the rail head. From this temperature the continuously advancing rail is subjected to rapid cooling in a rapid cooling line. Subsequently the rail is cooled to ambient temperature. For a given rail head temperature at the extreme to the rapid cooling line, the length of the line, the speed of advance of the rail, and the average thermal flux density applied to the head, flange, and web of the rail are controlled so that the final mechanical properties of the rail head are obtained, although less then 60% of the cross-section of the head has undergone the austenite-pearlite transformation upon leaving the rapid cooling line, and differences in elongation between the head and the web and between the head and the flange are minimized.

Abstract: Steel concrete-reinforcing rod is manufactured on a high speed rod rolling ill including a finisher followed by a cooling device for superficial quenching. The traction applied to the product leaving the finisher and approaching the cooling device is arranged to be appropriate to the correct advancement of the rod, by increasing the drive force of the rod and/or reducing the braking forces produced in the cooling device. Braking force in the cooling device can be reduced by introducing air into the cooling water.

Abstract: At the outlet of a hot rolling mill the temperature of a hot rolled rail is reduced to a value not lower than that at which the pearlitic transformation begins in the rail head. The continuously moving rail is then rapidly cooled to below 650.degree. C. so that at least 80% of the austenite-pearlite transformation has occurred at the end of rapid cooling. The rail is then cooled to ambient temperature.

Abstract: Halogen derivatives of 8-hydroxycarboxylic acids, which correspond to the formula ##STR1## (open form, in a basic medium) or to the formula ##STR2## (cyclized form, in an acid medium) in which formulae: X.sub.1 and X.sub.2 are halogen atoms, n.sub.1 and n.sub.2 are integers between 0 and 5, but, if n.sub.1 =0, n.sub.2 is different from 0, and vice versa, R is a hydrogen atom or an alkyl or aryl group, and Cation represents an ion originating from a base, or a metal ion, which is pharmaceutically compatible are suitable as antidepressants having a psychostimulant action.

Abstract: Tetrahydro-.alpha.-pyrones and their intermediate salts of 5-hydroxy-2,3-diphenyl hexanoic acid have psychostimulant activity. A process for the preparation of these compounds comprises preparing the alkyl ester of a 5-oxo alkanoic acid from a 4-oxo alkane carbonitrile, obtained in a first stage by the action of benzyl cyanide on the corresponding alkenone, and then saponifying the obtained ester, followed by hydrogenation to form the 5-hydroxy-2,3-diphenyl hexanoic acid salt, followed if desired by cyclization to form the tetrahydro-.alpha.-pyrone.