Abstract: An apparatus and method for communicating data between at least two data devices, suitable for use as a wireless local-area network, that provides robust data communication via a radio communications channel corrupted by multipath interference, particularly at high data rates. A preferred embodiment of the invention represents data as a sequence of Walsh-function waveforms encoded by pseudo-noise direct-sequence spread-spectrum modulation. Walsh-function-encoding of the data provides a long symbol duration, thereby allowing the spread-spectrum modulation to provide processing gain sufficient to substantially overcome multipath interference, while providing a high data rate. In another preferred embodiment, Walsh-function modulation is supplemented with various forms of phase modulation, such as coherent PSK for bi-orthogonal signalling, and DPSK between orthogonal symbols for noncoherent bi-orthogonal signalling, thereby further increasing data rate without reducing processing gain.

Abstract: The disclosed pressure transducer assembly includes an external enclosure, a thermal shell disposed within the external enclosure, and a pressure sensor disposed within the thermal shell. The pressure sensor senses the gas or vapor pressure present in a tube coupling the sensor to a source of pressurized gas or vapor. The assembly includes a device for heating the thermal shell, and thermal insulation is disposed between the thermal shell and the external enclosure. The thermal insulation includes a plurality of metalized high temperature films stacked one on top of another and a plurality of spacer layers, each of the spacer layers being disposed between adjacent ones of the metalized high temperature films.

Abstract: A multi-channel mass flow transducer has a single laminar flow element in a primary fluid flow path and multiple secondary flow paths in parallel with and in fluid communication with the primary flow path. Flow restriction elements are disposed in one or more of the secondary flow paths to establish different flow rate measurement "channels" having particular flow rate ranges. The multi-channel transducer of the present invention is capable of measuring fluid flow rates over an extended range and eliminates the need for multiple transducers to measure varying fluid flows.

Abstract: A differential pressure transducer includes a pair of interior chambers separated by a peripherally supported, nominally planar electrically conductive diaphragm. A magnetic assembly is positioned on at least one chamber wall opposite to a central portion of the diaphragm. The magnetic assembly includes an electrical conductor and preferably a magnetic field permeable electric field shield between the electrical conductor and the chamber so that as the central portion of diaphragm is displaced from its nominal plane in response to an applied pressure differential, the inductance of the magnetic assembly changes. The transducer may be a portion of a tank circuit of an oscillator having a frequency of oscillation that varies with the pressure differential applied across the diaphragm.

Abstract: Apparatus and methods for the measurement of total organic carbon, total inorganic carbon, total carbon and total heteroorganic carbon of deionized water are described. In a preferred embodiment, the sample is split into a first stream and a second stream. Inorganic carbon in the first stream is measured using a temperature and conductivity cell, and then the organic carbon in the first stream is oxidized in a U.V. oxidation module. The resulting carbon dioxide is transferred through a carbon dioxide permeable membrane into the second stream. The second stream then passes into a second temperature and conductivity cell for the measurement of total carbon.

Abstract: A multiple angle tomographic system includes a rotating gantry with a source, e.g., an x-ray source, and detector array combination mounted thereon so as to acquire a plurality of projections of objects passing through the gantry. A pre-screen subsystem utilizes a subset of the projections from those that can be acquired during a full scan so as to define a first plurality of projections--e.g., eight projections--that are sufficient analyze whether there is a likelihood that a targeted object, e.g., a firearm and/or plastic explosives is present. If there is a likelihood that a targeted object is present, a full-image CT reconstruction is commanded, automatically or manually, so as to verify and more fully assess the detected object. This combination of pre-screen and selective full-image CT reconstruction provides thorough inspection of closed containers, e.g., passenger luggage, by providing multiple angle and perspective viewing of targeted objects.

Abstract: High pressure liquid chromatographic apparatus in which a fluid mixture containing at least one solute that is reactive with chromatographically reactive surfaces in the column is loaded into the column, and a number of plugs of different eluant fluids are injected into that column. The injections are made in a manner that minimizes the amount of eluant required. In one embodiment, the injections are made to insure that flow of at least the eluant fluids through the column will occur, preferably with a substantially flat wave front, at speeds corresponding to reduced velocities greater than about 5,000, i.e. at flow rates sufficient to induce turbulent flow in those fluids, thereby minimizing the time required for the entire succession of mixture and eluant fluids to traverse the column.

Abstract: The disclosed BTSC encoder includes a left high pass filter means for receiving a digital left channel audio signal and for digitally high pass filtering the digital left channel audio signal and thereby generating a digital left filtered signal; a right high pass filter means for receiving a digital right channel audio signal and for digitally high pass filtering the digital right channel audio signal and thereby generating a digital right filtered signal; a matrix means for receiving the digital left and digital right filtered signals, and including means for summing the digital left and digital right filtered signals and thereby generating a digital sum signal, and including means for subtracting one of the digital left and digital right filtered signals from the other of the digital left and digital right filtered signals and thereby generating a digital difference signal; a difference channel processing means for digitally processing the digital difference signal; and a sum channel processing means for d

Abstract: Disclosed is a method of reducing or inhibiting the tumorigenicity of a tumor cell in which a vector including a nucleotide sequence encoding a differentiation factor receptor, or a polypeptide portion thereof, is transferred to the tumor cell such that the nucleotide sequence is expressed. Tumorigenicity is monitored by cell growth and colony formation in a semi-soft medium, a reduction in proliferation being indicative of the reduction or inhibition of tumorigenicity of the treated tumor cell.

Abstract: The invention provides an apparatus for measuring the flying height and orientation of a magnetic head (54) relative to a transparent disk (20) based on frustrated total internal reflection. The apparatus comprises a housing (10) that mounts an electric motor (12) which rotationally supports the aforementioned disk. The disk (20) has a tapered lateral surface (20c) with light emitting means (22) such as a laser(24) installed on one side of the disk lateral surface and a light detecting means (30) on a side of the disk diametrically opposite to the laser. The light is emitted from the laser (24) and is directed to the disk (20) perpendicular to the tapered lateral surface (20c) of the disk (20). The latter has a tapering angle of 45.degree. so that the light is propagated through the body of the disk (20) in the channel region (49) with total internal reflection from two parallel surfaces (20a and 20b) of the disk into the body of the disk.

Abstract: The invention relates to the efficient coding of packetized binary (NRZ) data, for example Ethernet packets, over a binary channel. Since Ethernet packetized data has three states (0, 1, and Idle), the theoretical bandwidth required for transmission, assuming completely random packets of arbitrary length and arbitrary interpacket idle periods, i.e. gaps, is 1.585 the data rate. The invention uses the information that both packets and gaps have predetermined minimum lengths constructs more efficient codes. In particular, a coding scheme is shown that provides in two states signal requiring a bandwidth of only 1.25 the three state signal data rate.

Abstract: The invention provides an article of manufacture comprising a substantially non-immunogenic articular cartilage heterograft for implantation into humans. The invention further provides a method for preparing an articular cartilage heterograft by removing at least a portion of an articular cartilage from a non-human animal to provide a heterograft; washing the heterograft in saline and alcohol; subjecting the heterograft to at least one treatment selected from the group consisting of exposure to ultraviolet radiation, immersion in alcohol, ozonation, freeze/thaw cycling, and optionally to chemical crosslinking. In accordance with the invention the heterograft has substantially the same mechanical properties as the native xenogeneic articular cartilage.

Abstract: An instrument holder configured so as to fit around the neck of the user and engage a portion of the chest, allowing the user to support the instrument without clenching the instrument between the chin and shoulder as is now customary. The invention further includes an attaching mechanism that allows the user to easily attach and detach the violin from the supporting brace assembly. The device is of low profile and can be designed to easily fit in a case alongside the instrument. It is of simple construction and is an improvement over the prior art.

Abstract: In an x-ray scanning system having an x-ray source and an x-ray detector assembly, including a plurality of x-ray detector crystals grouped in substantially linear arrays and cooperative with the x-ray source, a substantially continuous radiation detection zone is established by positioning the detector arrays so that substantially all radiation from the source passing through the detector assembly passes through at least a portion of at least one detector crystal. The detector arrays are tilted at a preselected angle .alpha. with respect to a nominally perpendicular orientation relative to radial lines extending from the focal spot, so that the spaces between adjacent detector crystals in an array are not aligned with x-rays emanating from the x-ray source. The angle .alpha. is a function of the geometry of the detector crystals and the spaces between adjacent crystals in an array.

Abstract: Disclosed is a method of selecting for a compound which modulates the behavior of an insect. In this method, electrical characteristics of an insect chemoreceptor neuron in the presence of control stimulation, then a known chemical modulator of insect activity, and then a test compound are measured after the neuron is contacted therewith. These measurements are compared and the test compound classified based on this comparison.

Abstract: An interactive learning system is disclosed that includes a note-making facility, a mentor facility, and an editor facility as its major subsystems. The note-making facility allows the user to create notes while scanning through an electronic text file that is accessible from a suitable memory space. The mentor facility provides content-specific information in response to the selection of certain passages or quotations from the text file by the user. The editor facility provides generalized learning strategies and recommendations useful in the analysis of text and the preparation of a written report. The information provided by the editor facility is generalized, and hence is not specific to the current text file; in contrast, the mentor facility is content-specific, and furnishes the user with information that is specifically related to the text under review.

Abstract: Layered carbon-carbon composites having improved interlaminar tensile strength are disclosed together with a process for making such composites. A metal catalyst is first deposited on a panel comprising a plurality of layers of carbon fiber cloth. The panel is then exposed to a gaseous hydrocarbon in an inert atmosphere at elevated temperature in order to promote the growth of graphite whiskers between the carbon cloth layers.

Abstract: An instrument and kit for harvesting a bone-patella tendon-bone (BTB) graft having substantially cylindrical bone plugs, and a method for harvesting a BTB graft. The instrument comprises two cylindrical shell portions extending along an axis from a drive end to a cutting end. One of the shell portions, which is positionable around a portion of the tendon, includes an axial slot which permits the graft portion of the tendon to extend therethrough. The shell portions interlock together in a hinged and mutually biased engagement to form a cylindrical tube around the graft portion, with a cutting edge that extends a full 360 degrees about the axis of rotation. Bone plugs obtained using the instrument are fully circular in cross-section for substantially their entire length.

Abstract: In an improved CT scanner calibration method and apparatus, a radiation beam, for example an x-ray beam, is directed at a plurality of radiation detectors. The beam is attenuated by a phantom of known attenuation characteristics. The detectors generate measured attenuation data from the attenuated beam. The measured attenuation data is back-projected to generate a measured phantom image. The measured phantom image is converted to an ideal phantom image. The ideal phantom image is forward projected to generate ideal attenuation data. Calibration values for each detector channel in the scanner are generated by cross-referencing the ideal and measured attenuation data. In a preferred embodiment, this cross-referenced data is compressed and stored in a look-up table for referencing during later interrogation of subjects.

Abstract: Solid state optically coupled power switch with light induced or modified voltage applied or removed at one or more MOSFET gate and source electrode pairs to shift each MOSFET between its high and low impedance states and in various circuit arrays for ac or dc switching and/or cross points switching or mechanical Form C relay substitution or other purposes