Cellular array processor CAP and applications

The general-purpose, highly parallel, cellular array processor (CAP) we developed features multiple-instruction stream, multiple-data stream (MIMD) processing and image display. Processor elements can number in several hundreds. The present system uses 256 processors. Each processor element consists of a general-purpose microprocessor, memory, and a special VLSI chip that performs parallel-processing-specific functions such as processor communication and synchronization. The VLSI has two 2M byte/s independent common bus interfaces for data broadcating and six 15M bit/s serial communication ports for local data communication. The chip also can process image data in real time for multiple processors. Use of the communication interfaces enables a variety of processor networks to be configured. One CAP application has been computer graphics, in which ray tracing is used to generate quality images.     

Meniscal cyst in the posterior intercondylar space found by magnetic resonance imaging

We report a rare case of meniscal cyst from the posterior horn of the lateral meniscus, extending in the posterior intercondylar space of the right knee of a 15-year-old boy, in whom magnetic resonance imaging was very useful for evaluation. A cyst in this location has not been reported previously. The cyst was removed surgically, while preserving the lateral meniscus. A good result was obtained, and no recurrence has been seen in 12 months.     

Dissolution and Absorption of Nipedipine from Nifedipine-Polyvinylpyrrolidone Coprecipitate

Attempt was made to develop the solid dosage form of nifedipina which showed good absorption rate and total bioavailability. Nifedipine is a poorly water-saluble drug, whom bioavailability is low when administered orally in the crystalline form. Solutions of nifedipine were well absorbed from the gastrointestinal tract. The dissolution rate of PVP-nifedipine coprecipitates exhibited rapid dissolution rate. X-ray diffraction data suggested the lack of crystallinity in the coprecipitate. The relation between the dissolution rates and average molecular weights of PVP was studied. Nifedipine in the copretipitate was chemically stable to heat and humidity, but the dissolution rate of nifedipine from the coprecipitate stored at 21° and 75% R.H. markedly decreased. X-ray diffraction data revealed that it might be due to the transformation of amorphous form of nifedipine to crystalline form under higher relative humidity. The gastrointestinal absorption of nifedipine in beagle dogs after oral administration of the coprecipitate was increased than that after oral adniniatration of the physical mixture.     

Creep strength of magnesium-based alloys

The high-temperature creep resistance of magnesium alloys was discussed, with special reference to Mg-Al and Mg-Y alloys. Mg-Al solid-solution alloys are superior to Al-Mg solid-solution alloys in terms of creep resistance. This is attributed to the high internal stress typical of an hcp structure having only two independent basal slip systems. Although magnesium has a smaller shear modulus than aluminum, the inherent creep resistance of Mg alloys is better than that of Al alloys. The creep resistance of Mg alloys is improved substantially by the addition of Y. Solid-solution hardening is the principal mechanism of the strengthening, but the details of the mechanism have not been elucidated yet. Forest dislocation hardening in concentrated alloys and dynamic precipitation in a Mg-2.4 pct Y alloy also contribute to the strengthening. An addition of a very small amount of Zn raises the dislocation density and significantly improves the creep resistance of Mg-Y alloys. This article is based on a presentation made in the symposium entitled “Defect Properties and Mechanical Behavior of HCP Metals and Alloys” at the TMS Annual Meeting, February 11–15, 2001, in New Orleans, Louisiana, under the auspices of the following ASM committees: Materials Science Critical Technology Sector, Structural Materials Division, Electronic, Magnetic & Photonic Materials Division, Chemistry & Physics of Materials Committee, Joint Nuclear Materials Committee, and Titanium Committee.     

Interframe Coding for 4-MHz Color Television Signals

An interframe coding system is described which is capable of transmitting a 4-MHz National Television System Commission (NTSC) color television signal. 6.3 Mbit/s transmission gives acceptable picture quality for video telephone or conference TV use. The NTSC color television signal is converted into a timedivision multiplex (TDM) signal which is composed of time-compressed chrominance and luminance signal in sequence. This signal is encoded using a frame-difference coder of the kind that has been used for black-and-white television signals. A field-repeating technique is introduced into the coder, to prevent a buffer memory from overflowing and to improve picture quality. Statistical investigations show that the presence of the timecompressed chrominance signal gives less than 10 percent increase in the amount of information generated by picture movements; this increase scarcely affects the picture quality.     

A Barium-Titanate-Ceramics Capacitive-Type EEG Electrode

A capacitive-type electrode using barium titanate ceramics is described. This electrode is not affected by the polarization potential. Because its surface is chemically inactive and mechanically strong, its noise voltage is minimum from the beginning of its installation. This device is especially suitable for EEG recording.     

Electron spin resonance investigation of small spin probes in aqueous and vesicle phases of mixed membranes made from poly(oxyethylene) hydrogenated castor oil and hexadecane

Small spin probes in the vesicle and aqueous phases of mixed membranes made from poly(oxyethylene) hydrogenated castor oil (HCO) and hexadecane were investigated by ESR (electron spin resonance) spectroscopy. Partitioning (partition coefficients), rotational correlation times, and activation energies of the spin probes in the vesicle phase were determined. The quantitative results obtained by an ESR simulation indicated that the spin probe DTBN (di-tert-butyl nitroxide), in the vesicle of the mixed membrane, was partitioned similar to that of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) at 50 degrees C, and the partitioning for both probes showed no abrupt change across the temperatures examined. The results differed considerably from conventional analyses of the high-field signal intensities. Activation energies obtained by the simulation for DTBN and TEMPO were 21 and 20 kJ/mol, respectively. In addition, the hyperfine values of 15.8 (DTBN) and 16.1 G (TEMPO) in the vesicle phase were consistent with the activation energies and supported the probe environments in the membrane. Thus, the present ESR results provided detailed information regarding the probe behavior in the membrane.     

Power and energy measurements of transient electric discharge

A simple and inexpensive calculating device for electrical power and energy of transient electric discharges is described. The calculation is made by multiplication of the voltage and current of the discharge by use of wideband integrated circuits.     

High-speed digital-signal transmission experiments by optical wavelength-division multiplexing

The letter reports results obtained with laboratory transmission experiments on high-speed digital signals by optical wavelength-division multiplexing, using a newly developed optical multiplexer and demultiplexer, as well as other high-performance optical devices and fibres.