High-efficiency enhancement-mode power heterojunction FET with buried p/sup +/-GaAs gate structure for low-voltage-operated mobile applications

This letter describes a successfully developed enhancement-mode double-doped AlGaAs/InGaAs/AlGaAs heterojunction FET with a buried p/sup +/-n junction gate structure for low-voltage-operated mobile applications. The buried p/sup +/-GaAs gate structure effectively reduced on-resistance (R/sub on/) and suppressed drain-current frequency dispersion for the device with high positive threshold voltage, resulting in high-efficiency characteristics under low-voltage operation. The fabricated p/sup +/-gate HJFET exhibited a low R/sub on/ of 1.4 /spl Omega//spl middot/mm with a threshold voltage of +0.4 V. Negligible frequency dispersion characteristics were obtained through pulsed current-voltage measurements for the device. Under a single 2.7-V operation, a 19.8-mm gate width device exhibited a power added efficiency of 51.9% with 26.8-dBm output power and a -40.1-dBc adjacent channel power ratio using a 1.95-GHz wideband code-division multiple-access signal.     

A PWM signal processing core circuit based on a switched currentintegration technique

A highly functional circuit for pulse width modulation (PWM) signal processing is proposed as a core of the A-D merged circuit architecture for time-domain information processing. The core circuit employs a switched-current integration technique as its computing architecture and functions as a linear arithmetic operator, a memory, and also a delaying device of PWM signals. A 0.8-μm CMOS test chip includes 110 transistors plus two capacitors and performs parallel additions and multiplications at the accuracy of 1.2 ns. A cumulative property of the technique allows the circuit to serve as a low-power accumulator that consumes 23% of the energy of the full digital 7-b accumulator. A PWM multiply-accumulate unit and a nonlinear operation unit are also proposed to extend functionality of the circuit. Since the PWM signal carries multibit data in a binary amplitude pulse, these circuits can be favorably applicable to low-voltage and low-power designs in the deep submicrometer era     

Rapidly destructive arthropathy of the hip in siblings

A case of rapidly destructive arthropathy of the hip in male siblings aged 74 and 76 years is reported. Hip joints of the brothers were destroyed 12 and 4 months after the onset of symptoms, respectively. Results of clinical and laboratory examinations did not show any features of neuropathic, inflammatory, or septic arthropathy. Pathologically in both patients, osteoarthrotic changes with small foci of bone necrosis and nonspecific inflammation and moderate amount of hemosiderosis in the synovium were observed.     

Tyrosine phosphorylation of Crk-associated substrates by focal adhesion kinase. A putative mechanism for the integrin-mediated tyrosine phosphorylation of Crk-associated substrates

Integrin-ligand binding induces the tyrosine phosphorylation of various proteins including focal adhesion kinase (pp125(FAK)) and Crk-associated substrate (Cas). FAK is activated and autophosphorylated by the ligation of integrins, although the substrate of FAK has not been revealed. We show here that p130(Cas) and Cas-L are FAK substrates. FAK directly phosphorylates Cas proteins primarily at the YDYVHL sequence that is conserved among all Cas proteins. Furthermore, the phosphorylated YDYVHL sequence is a binding site for Src family protein-tyrosine kinases, and the recruited Src family kinase phosphorylates the other tyrosine residues within Cas. The Cas-L YDYVHL sequence is phosphorylated upon integrin-ligand binding, and this integrin-mediated tyrosine phosphorylation is inhibited by the cotransfection of the FAK COOH-terminal domain that does not contain a kinase domain. These findings strongly suggest that FAK initiates integrin-mediated tyrosine phosphorylation of Cas proteins; then, Src family tyrosine kinases, which are recruited to phosphorylated Cas and FAK, further phosphorylate Cas proteins.     

Measurements, analyses and evaluation of residential PV systems by Japanese monitoring program

This paper is about measurements, analyses and evaluation of residential PV systems in the Japanese Monitoring Program, on which JQA was subsidized by NEDO (New Energy Development and Industrial Technology Organization) that is currently proceeding [NSS R&D] from FY1997 to FY 2000.The aim of this investigation refers, through the data evaluation and analyses, to obtain knowledge required for optimizing design of PV systems, such as system performance, characteristics and regional dependency under practical operation and to develop the system evaluation technology on the design parameter method.     

Numerical study of radiation‐convection heat transfer

In this study, the authors attempted to introduce a simulation technique for radiation‐convection heat transfer in the high‐temperature fields of industrial furnaces, boilers, and gas turbine combustors. The convection effect was analyzed by a differential equation, but the radiation effect was analyzed by an integral equation. Thus, it was not easy to arrange both effects using the same type of equations. Then, the authors introduced the zone method and Monte Carlo method for the integral equation of the radiation effect and the finite difference method for the differential equation of the convection effect. A three‐dimensional analysis of the high‐temperature furnace was performed by this simulation technique to obtain its temperature distribution. Furthermore, another radiation‐convection heat transfer analysis in the low‐temperature living room was performed by the same technique. Finally, the authors tried to develop a computer software for radiation‐convection heat transfer and described their idea of software construction for the above. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(5): 391–407, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10042     

Ultrastructural study of the synapses of central chromatolytic anterior horn cells in motor neuron disease

This report deals with an ultrastructural investigation of the synapses on the somata of central chromatolytic anterior horn neurons of seven patients with amyotrophic lateral sclerosis (ALS) and four patients with lower motor neuron disease (LMND) who had no upper motor neuron or corticospinal tract involvement. Specimens from 24 age-matched individuals who died of non-neurological diseases served as controls. We examined a total of 171 anterior horn neurons with central chromatolysis (51 from ALS, 42 from LMND and 78 from controls), and 174 normal-appearing anterior horn neurons as controls. The cross-sectional area, the number of synapses, and the length of active zone were significantly reduced in the chromatolytic neurons of both patients and controls as compared with normal-appearing neurons of the controls (p < 0.0001). However, regarding chromatolytic neurons, no significant differences were seen in the number of synapses, length of each individual synapse, and length of its active zone between patients and controls and also in the frequency of presynaptic alterations on the somata. There was no overall difference between ALS and LMND patients in any of these parameters. Our findings suggest that the flow of electrophysiological information from afferent fibers to the somata may be greatly impaired in central chromatolytic neurons of both control individuals and patients with motor neuron disease (MND), and that the observed synaptic alterations may reflect pathological events resulting from anterior horn neuron degeneration. It may represent a compensatory mechanism of the synapses for diminished synaptic function that synapses were relatively well preserved on the somata of central chromatolytic neurons of the MND patients as compared with those of the chromatolytic neurons of the controls despite of markedly reduced cross-sectional area in the former. It also suggests that the pathomechanism involved in central chromatolysis differs between normal individuals and patients with MND.     

Suppression of cell growth by ectopic expression of N-cadherin

We found that ectopic expression of N-cadherin in 3Y1 caused tight association of cells and, thereby, substantially suppressed cell growth. N-cadherin expression inhibited neither tyrosine phosphorylation of cellular proteins, GTP uptake onto Ras, nor activation of MAP kinase, suggesting that it does not directly interfere the Ras-MAP kinase pathway. However, co-expression of N-cadherin with dominant negative Ras, S17N Ras, showed synergestic growth inhibitory effect, suggesting that N-cadherin signaling antagonizes the Ras-MAP kinase signaling. In addition, we found that N-cadherin yielded cell-cycle arrest at G0/G1 phase. These results strongly suggest that N-cadherin cell adhesion machinery works as a negative controller of cell cycle in 3Y1 and this growth suppressive function of cadherin is distinct from the epithelial morphogenetic function.     

The relationship between deterioration and reversal of optic disc cupping in monkeys with chronic experimental high-pressure glaucoma

PURPOSE: To investigate the correlation between the deterioration in optic disc cupping during the chronic elevation of intraocular pressure (IOP) and the reversal of cupping during a subsequent reduction in IOP in experimental glaucoma. METHODS: We examined changes in the vertical and horizontal cup to disc ratios, the rim area to disc area ratio, and the cup volume to disc area ratio in 11 monkey eyes with laser-induced glaucoma using computerized stereo-image analysis. Correlations between changes in disc parameters during a spontaneous IOP reduction and changes in disc parameters during a period of chronic IOP elevation from baseline before laser exposure (baseline) to before the IOP reduction (pre-IOP reduction) and during the period from baseline to after the reduction in IOP (post-IOP reduction) were determined by linear regression analysis. RESULTS: All disc parameters improved significantly during IOP reduction and deteriorated significantly during the periods from baseline to the pre-IOP reduction and from baseline to the post-IOP reduction. The degree of reversal in disc parameters was correlated with the deterioration from baseline to the pre-IOP reduction and from baseline to the post-IOP reduction in the vertical cup to disc ratio (r = 0.68, P = 0.0218 and r = 0.97, P < 0.0001, respectively), the horizontal cup to disc ratio (r = 0.57, P = 0.0649 and r = 0.98, P < 0.0001, respectively), the rim area to disc area ratio (r = 0.68, P = 0.0227 and r = 0.98, P < 0.0001, respectively), and the cup volume to disc area ratio (r = 0.67, P = 0.0256 and r = 0.88, P = 0.0004, respectively). CONCLUSION: The degree of deterioration in cupping from baseline before the induction of glaucoma may be an important determinant of the degree of cupping reversal during subsequent reductions in IOP in primate glaucoma.     

NiZnCu Ferrite Thick Film with Nano Scale Crystallites Formed by the Aerosol Deposition Method

This paper describes the magnetic properties of NiZnCu ferrite film deposited at room temperature by an aerosol deposition method (ADM). The thickness of the film was 6 μm and the deposition rate was estimated as 2 μm/min. The microstructure of as-deposited at room temperature films consists of randomly oriented nanocrystallites with a size of 20 nm. As-deposited and annealed films exhibited the following magnetic properties: intensity of magnetization M _s= 0.147 T (117 emu/cm³), coercivity H _c= 40.58 kA/m (510 Oe); and M _s= 0.3 T (250 emu/cm³), H _c= 14.95 kA/m (188 Oe), respectively.