Abstract: Provided are a nitride semiconductor device and a manufacturing method thereof. The nitride semiconductor device includes an insulating layer and a metal layer formed on a nitride semiconductor layer. The insulating layer makes contact with the nitride semiconductor layer. A separation preventing layer is formed between the insulating layer and the metal layer so as to make contact with each of these layers. The separation preventing layer has, as a main component, at least one kind of oxide of a metal selected from the group consisting of tungsten, molybdenum, chromium, titanium, nickel, hafnium, zinc, indium and yttrium.

Abstract: The nitride semiconductor device includes an insulating layer and a metal layer formed on a nitride semiconductor layer. The insulating layer makes contact with the nitride semiconductor layer. A separation preventing layer is formed between the insulating layer and the metal layer so as to make contact with each of these layers. The separation preventing layer includes, as a main component, at least one oxide of a metal selected from a group of metals consisting of tungsten, molybdenum, chromium, titanium, nickel, hafnium, zinc, indium and yttrium.

Abstract: A variance correction method includes generating a reference current depending on a resistance within a lowpass filter and outputting the reference current to a voltage controlled oscillator, and correcting characteristics of the lowpass filter and a gain of the voltage controlled oscillator based on an output clock of the voltage controlled oscillator.

Abstract: A variance correction method includes generating a reference current depending on a resistance within a lowpass filter and outputting the reference current to a voltage controlled oscillator, and correcting characteristics of the lowpass filter and a gain of the voltage controlled oscillator based on an output clock of the voltage controlled oscillator.

Abstract: Provided are a nitride semiconductor device and a manufacturing method thereof The nitride semiconductor device includes an insulating layer and a metal layer formed on a nitride semiconductor layer. The insulating layer makes contact with the nitride semiconductor layer. A separation preventing layer is formed between the insulating layer and the metal layer so as to make contact with each of these layers. The separation preventing layer has, as a main component, at least one kind of oxide of a metal selected from the group consisting of tungsten, molybdenum, chromium, titanium, nickel, hafnium, zinc, indium and yttrium.

Abstract: A semiconductor light emitting element, includes: a substrate; a first conductive semiconductor layer formed on the substrate; a strained emission layer formed on the first conductive semiconductor layer; and a second conductive semiconductor layer formed on the strained emission layer, wherein the strained emission layer includes: an element other than a constituent element of the substrate; and a rare earth element.

Abstract: A semiconductor light emitting element, includes: a substrate; a first conductive semiconductor layer formed on the substrate; a strained emission layer formed on the first conductive semiconductor layer; and a second conductive semiconductor layer formed on the strained emission layer, wherein the strained emission layer includes: an element other than a constituent element of the substrate; and a rare earth element.

Abstract: A navigation communication system in which a plurality of clients access information stored in a server via a network, having a personal information control section provided in the server and controls the personal information of the users of the clients which access the same information and a personal information display section provided in the client and displays the personal information controlled by the personal information control section, a selector for selecting one of the personal information displayed, and a communication application section for communicating with a client corresponding to the selected personal information.

Abstract: Information inputted from an information terminal and destination information of a third person added to specific information which should be transferred to the third person and which is included in the information inputted are transferred to an information processing unit through a communication unit and are accumulated in a data base of the information processing unit, the specific information is extracted from the information accumulated in the data base on the basis of the destination information, thereby preparing a file and the specific information accumulated in the file is transmitted to the third person.

Abstract: The multicast communication scheme which can enable a user to easily comprehend the multicast groups existing on the network, easily carry out an operation to join a desired multicast group, and easily specify a desired communication quality. At each user terminal, a virtual space with a plurality of regions defined therein in correspondence to a plurality of multicast groups is displayed on a screen, while an information indicating a range of each region in the virtual space is stored in correspondence to an address information for a corresponding multicast group. A desired position in the virtual space on the screen is specified by an input device, and joining/leaving to/from multicast groups is controlled by using the address information stored in correspondence to a region in the virtual space which contains the desired position.

Abstract: A nuclear magnetic resonance imaging apparatus using asymmetric torque-free active shield gradient coils for realizing a sufficient imaging field of view, a sufficient eddy current magnetic field suppression effect, and a substantially complete torque cancellation. The gradient coil is formed by: a primary coil having an asymmetric current distribution in which all current returns are asymmetrically arranged toward one side of the primary coil, a shield coil having a current distribution for cancelling out a leakage magnetic field generated by the asymmetric current distribution of the primary coil, and a torque cancellation coil, provided adjacent to the primary coil and the shield coil, having a current distribution for cancelling out a torque acting on the primary coil and the shield coil in a static magnetic field. The primary coil generates the gradient magnetic field which cancels out a gradient field contribution from the torque cancellation coil to produce a desired gradient magnetic field.

Abstract: An MRI system is provided for improving the magnetic coupling and positional relationship between gradient coils and shim coils, thus simplifying positioning of the coils (retention of orthogonality), designing an MRI system compactly, and reducing cost. An MRI system comprises a magnet generating a static magnetic field and a gradient coil unit generating a gradient magnetic field superposed on the static magnetic field. The gradient coil unit is formed into a substantially cylindrical shape having an outer circumferential surface, and shields the gradient magnetic field from being leaked out into a radially outer space. The MRI system further comprises a shim coil unit generating a correcting magnetic field homogenizing the static magnetic field. The shim coil unit is mounted on the outer circumferential surface of the gradient coil unit in common serving as a bobbin for the shim coil unit.

Abstract: An active shield gradient coil for a nuclear magnetic resonance imaging, formed by a primary coil having a fingerprint shaped current distribution formed on an inner cylinder in which at least a part of current return lines is cut out, a shield coil having a current distribution formed on an outer cylinder, and a bridging connection member for connecting cut out part of the current return lines of the primary coil with the shield coil, in which the current distribution of the shield coil is a composition of a first shield pattern for cancelling out a magnetic field produced by the primary coil outside the outer cylinder and a second shield pattern for cancelling out a magnetic field produced by the bridging connection member outside the outer cylinder. The current distribution of the primary coil can have turn back current paths for leading the cut out part of the current return lines on one end of the gradient coil to another end of the gradient coil.

Abstract: A nuclear magnetic resonance imaging scheme suitable for three dimensional physiological function imaging such as brain function imaging. In this scheme, the pulse sequence is controlled to realize a three dimensional imaging sequence with a division scan in at least one of a first encoding direction and a second encoding direction. In other words, the pulse sequence is controlled to realize a three dimensional imaging sequence with first encoding gradient field pulses and second encoding gradient field pulses for defining regular sampling pitches in first and second encoding directions, where at least one of the first encoding gradient field pulses and the second encoding gradient field pulses has a lead-in pulse in regularly changing magnitude for each spin excitation.

Abstract: A method for growing a compound semiconductor layer of Al.sub.x Ga.sub.1-x As (0.ltoreq.x.ltoreq.1) on a compound semiconductor substrate uses a molecular beam epitaxial apparatus, the method including the steps of providing the substrate having a GaAs layer on an upper surface thereof, thermally etching the GaAs layer by heating the substrate at a temperature and irradiating the GaAs layer with a gallium molecular beam and an arsenic molecular beam to expose the upper surface of the substrate, and growing the Al.sub.x Ga.sub.1-x As (0.ltoreq.x.ltoreq.1) layer on the upper surface of the substrate.

Abstract: A nuclear magnetic resonance imaging with improved image quality and operation efficiency. It uses an active shield coil with an outer shielding coil having at least two coil turns which are provided on a plurality of separate layers and mutually connected electrically, in order to reduce the heat generation. The eddy current in the shielding coil is reduced by providing a slit portion thereon. The eddy current compensation is achieved by using an appropriate eddy current compensation pulse to minimize a residual eddy current magnetic field within a desired field of view according to a model of a general expression of the residual eddy current magnetic field after the eddy current compensation. The optimum setting of the system parameters for various imaging pulse sequences is achieved for the undetermined gradient coil configuration as well as for the predetermined gradient coil configuration, according to a mathematical model analysis of various imaging pulse sequences.

Abstract: Where an imaging volume of an object under examination is comprised of eight slices with four regions "a", "b", "c", and "d" per slice (on the k space), the RF pulse frequency, the slice-selection gradient magnetic field, and the phase-encoding gradient magnetic field are controlled so as to first acquire data for a region "a" of each of the slices #1 to #8 in sequence and then acquire data for the slices #1 to #8 for each of the regions "b" to "d" in sequence. The data with 4 rows and 8 columns thus obtained for each of the regions of the slices is rearranged into data with 8 rows and 4 columns arranged for each of the slices. Data in each row are subjected to two-dimensional Fourier transformation, so that an MR image corresponding to each slice is reconstructed. This permits the RF pulse repetition time TR to be made long even if a time interval between successive data acquisition is made short.

Abstract: An MR imaging system comprises a first gradient coil unit(first G coil unit) for providing magnetic gradients superimposed in a static magnetic field, a first RF coil unit for transmitting an RF pulse to a patient and receiving a MR signal from the patient, a second gradient coil unit(second G coil unit) and a second RF coil unit. The second G coil unit is located between the patient and the first G coil unit. In a first operating mode(for example, spin echo scan mode), the second G and RF coil units are moved out the first G coil unit and the first RF coil unit is moved into the first G coil unit by guiding these units along a rail or the second G and RF coil units are drawn out from the first G coil unit and the first RF coil unit is inserted into the first G coil unit so that these units are located in predetermined position.

Abstract: A semiconductor laser device which can effectively confine electrons and positive holes is disclosed. The semiconductor laser device includes a semiconductor substrate of a first conductivity type, a current blocking layer of a second conductivity type, a first semiconductor layer of the first conductivity type made of a III-V group compound semiconductor, an active layer made of a III-V group compound semiconductor, and a second semiconductor layer. The semiconductor substrate has a ridge-type mesa having (n11)A planes. The current blocking layer is formed on the semiconductor substrate other than the top face of the mesa. The first semiconductor layer is formed on the entire surface of the current blocking layer and on the top face of the mesa. The active layer is formed on the first semiconductor layer. The second semiconductor layer is formed on the active layer.

Abstract: An MRI system applies a phase encoding gradient field, a read-out gradient field, and an RF field to an object which is placed in a homogeneous static field in accordance with a predetermined pulse sequence so as to excite MR at a specific slice plane of the object, thereby detecting an MR signal from the object and visualizing the slice plane.