A crosstalk model considering leakage fluxes and methods to reducecrosstalk between read/write head and pre-erase head

A head combined with a read/write (R/W) and a pre-erase gap is adopted for 4 MB flexible disk drives. Reducing the crosstalk coupling between the erase head and the R/W head is an important factor in the design. We developed a simple design method to analyze the crosstalk using a three-dimensional finite-element method (3D-FEM). We found that there are two flux paths contributing to the crosstalk in the reproducing process: one is the path through the ferrite cores, and another is the path fringing and reentering into the R/W core. Balancing the fluxes through these two paths, it was possible to realize both high efficiency and low crosstalk simultaneously, Furthermore, the crosstalk during the recording process was analyzed using dc-bias recording theory     

Effects of interfacial thin metal layer for high-performance Pt-Au-based Schottky contacts to AlGaN-GaN

Schottky diodes with Ni-Ti-Pt-Au Schottky electrodes on AlGaN-GaN heterostructures were fabricated and subjected to rapid thermal annealing. The electrical influence on them was investigated in terms of the existence of a thin Ni or Ti layer. The diodes of the Ni-Pt-Au system showed a drastic improvement in their electrical properties, such as an increase in the Schottky barrier height and a decrease in the leakage current, after the 600/spl deg/C treatment whereas the thermal annealing effect was found to be small in the Ti-Pt-Au and the Pt-Au systems. The Ni was considered to play a significant role in realizing a clean Pt contact to AlGaN and reducing surface traps, which were revealed from Auger electron spectroscopy measurement and frequency-dependent capacitance-voltage measurement, respectively. The thermally-treated Ni-Pt-Au gate electrode was concluded to be practicable for realizing high performance HEMTs.     

Multidrug resistance-associated protein and mutant p53 protein expression in non-small cell lung cancer

Multidrug resistance-associated protein (MRP) is one of the major factors for non-P-glycoprotein (PGp)-mediated multidrug resistance. We reported previously that overexpression of the MRP gene was related to the prognosis of non-small cell lung cancer (NSCLC). It is unclear how MRP expression is regulated in NSCLC. In this study, we examined MRP and mutant p53 expression in 107 NSCLCs by immunohistochemical procedures. Forty-seven (43.9%) of these 107 NSCLCs were positive for MRP in the cytoplasm. Mutant p53-positive NSCLC showed a significant correlation with MRP overexpression (P=.011). Coexpression of MRP and p53 in the same cells of NSCLC was confirmed by double-staining procedures. Twenty-six patients with MRP-positive tumors who underwent postoperative chemotherapy with MRP-related anticancer drugs (vindesine and etoposide) had significantly poorer prognoses than did those with MRP-negative tumors (P=.017). This correlation between MRP expression and prognosis was also seen in Stage III patients (P=.022) and in patients with squamous cell carcinoma (P=.062). NSCLC patients with coexpression of MRP and p53 showed poorer prognoses than did those without MRP and p53 (P=.014). These results suggested that MRP overexpression affected by mutant p53 had a significant effect on prognosis through atypical non-PGp-mediated multidrug resistance in NSCLC.     

Simultaneous compensation of laser chirp, Kerr effect, anddispersion in 10-Gb/s long-haul transmission systems

The effects of chirp and fiber nonlinearity in a directly modulated 10-Gb/s intensity-modulated direct-detection (IM-DD) fiber transmission system are investigated by simulation, and a simple and flexible technique for compensating these effects is discussed. Self-phase-modulation (SPM) in optical fiber can be equalized by an anomalous dispersion fiber, whereas pulse broadening caused by laser transient chirp can be compensated by normal dispersion. Using these characteristics, laser transient chirp, SPM, and fiber dispersion can be simultaneously compensated by equalizing fibers inserted within certain intervals. Optimum compensation is always realizable for such fixed equalizing fibers, since the magnitude of SPM can be controlled by changing the optical power in the fiber. Simulation suggests that this technique enables 10-Gb/s, 100-km fiber transmission by direct modulation     

Pyroelectric detector coupled with ultrasonic parametric amplifier

It is pointed out that responsivity can be improved by mechanical resonances. The enhancement factor of responsivity of a trigricyne sulphate (TGS) pyroelectric detector is measured as 40 ∼ 50 at the mechanical resonances whose modes are assigned to dilational modes of a rectangular-plate vibrator. Also, a pyroultrasonic parametric amplifier is demonstrated, which can show further improvement of responsivity of the pyroelectric detector by amplifying the strain that accompanies pyroelectricity. Gain and an equivalent circuit are derived using a simplified parametrically coupled multimode vibrator model. A pyroultrasonic parametric amplifier using lead zirconate titanate (PZT) ceramic is demonstrated, and an improvement of about 5 dB is shown. Obtaining the gain stability is one of the serious problems of a pyroultrasonic parametric amplifier.     

Integrated intensity changes of X-ray diffraction lines for crystalline powders by grinding and compression. Relations between effective Debye parameter and lattice strain

The relations between the effective Debye parameter and lattice strain are investigated on some non-metallic crystalline powders, CoO, Co_0.5 Mg_0.5O, CoAl₂O₄, TiO₂, CaF₂, BaTiO₃ and graphite. The effective Debye parameter B _eff was determined from the integrated intensities of X-ray diffraction lines with different sin /-values and the lattice strain, , was determined from the half-widths of the diffraction lines. Both B _eff and increased with increase in grinding time and pressure. B _eff showed a relatively sharp increase, but tended to saturation. However, increased slowly even after prolonged grinding, and B _eff increased with increase in . When >0.2×10^–2, however, B _eff tended to a limit. The limiting values of B _eff were varied from sample to sample. An attempt was made to explain the changes of B _eff and with grinding and compression to large shear by the introduction of various defects into the structure. B _eff was found to give some information on the deformed structure of crystalline powders.     

Direct measurements of gas diffusivity in a washcoat layer under steady state conditions at ambient temperature

A method for directly measuring gas diffusivity in a washcoat layer was established by preparing a simulated washcoat layer and modifying a Wicke–Kallenbach type counter-current diffusion cell. Three pairs of gases, N₂Ar, CO₂Ar and C₃H₈Ar, were used in the measurements. It was found to be possible to evaluate the pore-transport parameters of the washcoat layer based on the mean transport pore model and the modified Stefan–Maxwell equation. Analysis of the gas diffusion mechanism in the washcoat layer showed that bulk and Knudsen diffusion took place simultaneously, and the percentage value of the contribution by Knudsen transport to net diffusion transport was evaluated.     

Development of a kW Level-200 GHz Gyrotron FU CW GI with an Internal Quasi-optical Mode Convertor

Development of gyrotrons with an internal mode convertor has started in Research Center for Development of Far-Infrared Region, University of Fukui (FIR FU). As the first gyrotron of such a kind, we have designed and manufactured Gyrotron FU CW GI. It operates at 203 GHz at fundamental cyclotron resonance. We have designed a cavity and a mode convertor under some constraints such as reuse of an electron gun and small diameter of a magnet bore. Designed output power is about 1 kW. We have succeeded in observation of a circular radiation pattern. The maximum observed output power is 0.5 kW for the setting cathode voltage of 20 kV and the beam current of 0.5 A. This success makes gyrotron development in FIR FU to proceed to a new stage.