High compression ratio backward Raman conversion for highbrightness excimer laser systems

A scheme of backward Raman pulse compression is proposed in which the backward first Stokes pulse is amplified under stationary conditions and the backward second Stokes under transient conditions by choosing an appropriate Raman medium. The compression factor and efficiency are improved by insertion of selective absorbers for the second Stokes component. The feasibility of such a scheme is demonstrated by an experiment in which a 249-nm UV pulse of 20-ns duration has been compressed into a 30-ps pulse with an power gain of 150 and energy conversion efficiency of 22%. Higher compression ratio and higher efficiency is expected under improved conditions     

The capacity of central and peripheral catecholaminergic neurons to innervate the pineal organ and cerebral cortex of the rat: in vitro immunohistochemical observations

The locus coeruleus (LC) or superior cervical ganglion (SCG) of neonatal rats were co-cultured either with the pineal organ or cerebral cortex (CX) to investigate the innervating capacity of central and peripheral catecholamine neurons under these experimental conditions. After 2 weeks of co-culturing, cultures were fixed for tyrosine hydroxylase (TH) immunohistochemistry to examine the distribution of catecholamine neurons and their fibers. Glial fibrillary acidic protein and fibronectin immunohistochemistry was performed to determine the cell types proliferating around the explants. In LC/CX co-cultures, numerous astrocytes spread between the two explants, and TH-immunoreactive neurites were generally seen to invade CX explants. In contrast, neurite extension from LC to pineal explants occurred only when a glial cell sheet grew between the two explants, and when the pineal explants were not surrounded by a tight fibronectin-positive cell layer. Neurites of the SCG usually invaded both CX and pineal explants, regardless of the existence of glial or non-glial cell layer. These results indicate that central and peripheral catecholamine neurites have the potential of invading both the cortex and pineal, although they are distributed only in particular regions of the intact brain. The distribution of LC neurites, however, seems to be profoundly affected by the cell types spreading around the explants; glial cells appear to support LC neurite extension, whereas non-glial cells appear to inhibit it.     

A small glucagonoma of the pancreas with evident ductular and tubular structures

A 54-year-old woman was admitted to our department for assessment of a tumor of the pancreas found incidentally on abdominal ultrasonography. Examination revealed a hypovascular 1-cm sized tumor in the body of the pancreas. Surgical examination revealed that the tumor was solitary and located in the pancreas body, with no invasion to the adjacent organs iof lymph node involvement. Distal pancreatectomy, preserving the spleen, was performed. Histologically, the tumor was a glucagonoma with evident ductular and tubular structures, suggesting that its site of origin was ductal epithelia.     

80-ps and 4-ns pulse-pumped gains in a GaP-AlGaP semiconductor Raman amplifier

The characteristic of 80-ps mode-locked (ML) pulse-pumped gain, which results in a decline that changes from a linear gradient to a square-root gradient at introduced pump densities exceeding 10 dB, makes it difficult to develop pulse-pumped gains for high efficiency amplification. To overcome this disadvantage with pumping, we compared an 80-ps ML pulse and 4-ns Q-switched pulse in a straight waveguide. The amplification of the 4-ns pulse was linear and had a maximum gain of 23.3 dB at an introduced pump density of 1.4 W//spl mu/m/sup 2/ in a straight waveguide. The gain was more efficient than with the 80-ps pulse, which was limited by the optical damage threshold of the input antireflective coating (1.6 W//spl mu/m/sup 2/). These high-gain operations should enable semiconductor Raman amplifiers to be used for detecting signals from chemical or biological materials, in addition to infrared light frequency selective amplification with wavelength-division multiplexing in optical communications.     

Development of a digital real‐time simulator for power electronics systems

A digital real‐time simulator for power electronics systems has been developed using MATLAB^TM/SIMULINK^TM. This paper describes the modeling and calculation accuracy of static synchronous compensator (STATCOM) models. Since the simulator operates in a large time step of 50 µs, compensation processing is implemented with the STATCOM model to improve the simulation accuracy. The calculation result of the real‐time STATCOM model is the same as that of non‐real‐time PSCAD^TM/EMTDC^TM. Stable operation of the newly developed simulator was successfully confirmed when connected to a commercial real‐time digital simulator (RTDS^TM). © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(4): 41–49, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10321     

New UV-curable primary coating material for optical fibre

A new UV-curable primary coating material, polybutadiene acrylate (PBA), has been developed. The new acrylate has much lower modulus at low temperature than epoxy and urethane acrylates. The transmission loss increase at low temperature for coated fibres is related to the modulus value for coatings.     

Straight-line soliton data transmission at 20 Gbit/s beyondGordon-Haus limit

Soliton data signals at 20 Gbit/s have been successfully transmitted over 3000 km with the use of soliton control by synchronous modulation and optical filters. The installation of only one simple modulator makes it possible to extend the maximum transmission distance from 2300 km (without soliton control) to 3000 km which is clearly beyond the Gordon-Haus limit     

Dynamic optical soliton communication

Digitally coded optical solitons at 5 and 10 Gb/s have been successfully transmitted over 400 and 300 km, respectively, using erbium-doped fiber amplifiers and repeaters. The soliton pulse source is a gain-switched distributed-feedback laser diode with spectral windowing. The repeater spacing for the 10-Gb/s transmission with an input soliton of A=1.4 is 25 km, which is extended to 50 km for 5-Gb/s transmission with an input soliton of N=1.8-2.0     

Preservation of Scallop Adductor Muscle in Oxygenated Artificial Seawater

ABSTRACT: Adductor muscles dissected from live scallops ( Patinopecten yessoensis ) were preserved in artificial seawater containing various concentrations of dissolved oxygen at 5°C. The period over that the initial ATP level was maintained decreased with a decrease in oxygen concentration. The K-value, an index of freshness, rose markedly after ATP levels and energy charge decreased. Muscle contraction occurred after 4 to 5 d in 1.0 m M oxygen or after 3 d in 0.07 m M oxygen. Sodium azide and 2,4-dinitrophenol accelerated the decrease in ATP, even in oxygenated seawater. These results suggest that enough oxygen to support aerobic respiration is required to preserve adductor muscles in a vital state for a relatively long period.