A study on an active square-law combining method for apolarization-diversity coherent optical receiver

A polarization-diversity coherent optical receiver which realizes ideal square-law combining with active gain control is described. This receiver can suppress the additional power penalty due to the demodulator dynamic range limitation by equivalently expanding the demodulator dynamic range. A low-power penalty less than 1 dB was attained with a 400-Mb/s FSK (frequency-shift keyed) single-filter detection system. Throughout a 25-h 183-km transmission experiment, the stable operation of this receiver was confirmed     

Resection of the trachea infiltrated by thyroid carcinoma

Twenty-four thyroid carcinoma patients with infiltration of the trachea were treated surgically. The histological diagnosis in these cases included papillary adenocarcinoma in 22 different patients, medullary carcinoma in one patient, and undifferentiated carcinoma in one patient. In 19 of the patients hemoptysis was noted, and dyspnea was present in ten patients. In 14 of the 24 patients the carcinoma was diagnosed by radiographs of the neck, while in seven patients it was demonstrated bronchoscopically. In three patients tracheal infiltration by thyroid carcinoma was diagnosed by biopsy of the tracheal wall at operation. When the tracheal wall was infiltrated by thyroid carcinoma, treatment consisted of circumferential resection of the involved segment of the trachea followed by an end-to-end anastomosis. Of the 24 patients, 17 survived and six died. In the 17 patients who survived, 13 were disease free. Of this number, six survived more than five years after the initial tracheal resection.     

P450scc-dependent cholesterol metabolism in rat adrenal mitochondria is inhibited by low concentrations of matrix Ca2+

Pregnenolone formation at P450scc in isolated rat adrenal mitochondria is determined equally by the amount of ACTH-stimulated reactive inner membrane cholesterol and by the matrix generation of NADPH. Evidence is presented here that both are sensitive to an increase in matrix Ca2+ produced by low levels of external Ca2+ (0.4-4 microM). Cholesterol availability to P450scc and intramitochondrial NADPH are shown to be highly interdependent. The proportion of mitochondrial cholesterol which is readily available to P450scc in the intact mitochondria increases as conditions become more favorable for NADPH generation. Preincubation of mitochondria without reductant causes substantial decreases in cholesterol metabolism when weaker reducing conditions are used without effect on NADPH generation as evidenced by unchanged metabolism of 20 alpha-hydroxycholesterol at P450scc or DOC at P450(11) beta. Increased Ca2+free not only increases this sensitivity to preincubation but also inhibits reductant transfer from succinate and isocitrate to both P450scc and P450(11) beta. Succinate activity was inhibited much more than that of isocitrate. These actions of Ca2+, which quantitatively explain the stimulatory characteristics of EGTA in standard media, were reversible providing exposure was short (< or = 3 min). Ruthenium red (inhibits Ca2+ uptake antiporter) is as effective as EGTA in preventing all these effects of Ca2+ while cyclosporin A (prevents opening of Ca(2+)-activated inner membrane channels) is partially effective. Ca2+ entry into the matrix is, therefore a necessary step prior to inhibition of cholesterol metabolism by several mechanisms, including the consequences of changes in inner membrane permeability.     

Influence of thickness on H2 gas sensor properties in polycrystalline SnO x films prepared by ion-beam sputtering

Amorphous SnO _x films were deposited on sintered alumina substrates by ion-beam sputtering. They were annealed at 500° C for 2 h in air and polycrystalline films with thickness varying from about 1 to 700 nm were prepared. Film-sensor properties against 0.47% H₂ gas were measured as a function of thickness and the operating temperature for 150 to 350° C. The film thickness exhibiting a sensitivity maximum increased gradually with temperature. The optimum thickness shifted from 7 nm at 150° C to 175 nm at 350° C. Highly sensitive films lay in a narrow thickness range of 60 to 180 nm and films thinner or thicker than this were relatively insensitive at 300 and 350°C. A model was proposed to interpret the sensitivity behaviour in terms of thickness and grain-boundary effect.     

Over 300 km transmission experiment on an optical FSK heterodyne dual filter detection system

An optical FSK heterodyne dual filter detection system has been developed for the first time at 34 Mbit/s bit rate with a high receiver sensitivity of -61.4 dBm. A 66.9 dB large span loss margin has been achieved with high transmitted power and high receiver sensitivity. As a result, a 301 km transmission experiment has been performed.     

灰色预测模型在纺织工业上的应用

简要介绍了灰色预测模型的原理及方法，就纺织工业中应用灰色预测模型所取得的研究成果作了综述评介，并分析了在纺织工业上进一步应用的前景。     

Absolute-length determination of a long-baseline Fabry-Perot cavity by means of resonating modulation sidebands

A new method has been demonstrated for absolute-length measurements of a long-baseline Fabry-Perot cavity by use of phase-modulated light. This method is based on determination of a free spectral range (FSR) of the cavity from the frequency difference between a carrier and phase-modulation sidebands, both of which resonate in the cavity. Sensitive response of the Fabry-Perot cavity near resonant frequencies ensures accurate determination of the FSR and thus of the absolute length of the cavity. This method was applied to a 300-m Fabry-Perot cavity of the TAMA gravitational wave detector that is being developed at the National Astronomical Observatory, Tokyo. With a modulation frequency of ~12 MHz, we successfully determined the absolute cavity length with resolution of 1 mum (3 x 10(-9) in strain) and observed local ground strain variations of 6 x 10(-8).     

The life evaluation by linear cumulative damage rule for cold dwell fatigue of Ti-6Al-4V alloy

Low cycle fatigue (LCF) life at ambient temperature of Ti alloys is well known to decrease with stress dwell. This phenomenon, called cold dwell fatigue (CDF), is influenced by the peak stress, dwell time, and microstructure. For this study, the CDF life was evaluated by the linear cumulative damage rule. The influence of test conditions and microstructure on the linear cumulative damage rule was also verified. By the linear cumulative damage rule, when creep damage is calculated using the time exhaustion rule, theCDF damage was evaluated by the inequality of D_Total = (D_F, D_C) ≤ (0.01, 10^?6). However, the CDF damage can be evaluated in the range of D_Total = 0.6–1.2 when creep damage was calculated using the ductile exhaustion rule. Results indicate that the evaluation was almost independent of the dwell time, peak stress, and microstructure, so it is also a versatile method for evaluating CDF responses.