Tetsuya Kawanishi

Learn More
We propose a method for controlling modal gain in a multimode Erbium-doped fiber amplifier (MM-EDFA) by tuning the mode content of a multimode pump. By adjusting the powers and orientation of input pump modes, modal dependent gain can be tuned over a large dynamic range. Performance impacts due to excitation of undesired pump modes, mode coupling and(More)
The effect of the selective 5-HT(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) on stress-induced anorexia and serotonin (5-HT) release in the rat hypothalamus was studied with brain microdialysis. Subcutaneous injection of 8-OH-DPAT (1 mg/kg) significantly attenuated the immobilization-induced anorexia for 3 h, but had no effect(More)
Several kinds of nonlinear optical effects have been observed in recent years using silicon waveguides, and their device applications are attracting considerable attention. In this review, we provide a unified theoretical platform that not only can be used for understanding the underlying physics but should also provide guidance toward new and useful(More)
Isolated rat hepatocytes were loaded with the Ca2+ indicator fura-2 to measure cytosolic free Ca2+ concentrations ([Ca2+]i) in individual cells by digital ratio imaging microscopy. Stimulation with 0.1 nM vasopressin, 0.5 microM phenylephrine, or 0.5 microM ATP caused repetitive spikes of high [Ca2+]i in a high percentage of cells, in agreement with Woods(More)
We demonstrate highly broad-band frequency conversion via four-wave mixing in silicon nanowaveguides. Through appropriate engineering of the waveguide dimensions, conversion bandwidths greater than 150 nm are achieved and peak conversion efficiencies of-9.6 dB are demonstrated. Furthermore, utilizing fourth-order dispersion, wavelength conversion across(More)
There has been an increasing interest in the application of terahertz (THz) waves to broadband wireless communications. In particular, use of frequencies above 275 GHz is one of the strong concerns among radio scientists and engineers, because these frequency bands have not yet been allocated at specific active services, and there is a possibility to employ(More)
As the bit rates of routed data streams exceed the throughput of single wavelength-division multiplexing channels, spectral and spatial traffic aggregation become essential for optical network scaling. These aggregation techniques reduce network routing complexity by increasing spectral efficiency to decrease the number of fibers, and by increasing(More)
1. Line-scan analyses of spontaneous Ca2+ sparks, non-propagating local rises in Ca2+ concentration, and the early phase of Ca2+ transients in cardiomyocytes were performed with a rapid-scanning laser confocal microscope (Nikon RCM8000) and fluo-3. 2. On electrical stimulation, points at which rise in Ca2+ began earliest were observed at regular spacings of(More)
Two-dimensional images of cytoplasmic and nuclear free Ca2+ movements in cardiac myocytes were obtained at 67-msec intervals using a Ca(2+)-sensitive fluorescence probe, indo-1, and a rapid scanning confocal laser microscope, Nikon RCM8000. Isolated guinea pig ventricular cells were loaded with indo-1 and stimulated at 0.5 Hz through patch pipettes. On(More)