Quantal release at a neuronal nicotinic synapse from rat adrenal gland

The neuronal nicotinic synapse in tissue slices of the adrenal medulla was studied with whole-cell patch-clamp. Excitatory postsynaptic currents (EPSCs) were evoked by local field stimulation or occurred spontaneously especially when external [K+] was increased. EPSCs were carried by channels sharing biophysical and pharmacological properties of neuronal-type nicotinic receptors (nAChRs). A single-channel conductance (gamma) of 43-45 pS was found from nonstationary variance analysis of EPSCs. Spontaneous EPSCs were tetrodotoxin-insensitive and Ca(2+)-dependent and occurred in burst-like clusters. Quantal analysis of spontaneous EPSCs gave a quantal size of 20 pA and amplitude histograms were well described by binomial models with low values of quantal content, consistent with a small number of spontaneously active release sites. However, rare large amplitude EPSCs suggest that the total number of sites is higher and that extrajunctional receptors are involved. Our estimates of quantal content and size at the chromaffin cell neuronal nicotinic synapse may be useful in characterizing central neuronal-type nicotinic receptor-mediated cholinergic synaptic transmission.     

Parallel simulated annealing for power system decomposition

This paper proposes a parallel optimization approach to power system decomposition for voltage control. In this paper, a parallel simulated annealing (PSA) technique is developed to decompose power systems so that subsystems are equally separated in terms of the number of nodes and control variables. System decomposition is one of difficult discrete number combinatorial problems. The PSA technique provides better solutions than the conventional SA because of searching a solution near a global minimum over a wide range. The proposed method is tested in IEEE 30, 57, and 118 node systems     

Effects of crystallographic misorientation on power loss in

The effects of the inclination angle β of the [001] axis out of the sheet plane on the thickness dependence of the power losses in     

New protection method for HVDC lines including cables

For the third project of the Hokkaido-Honshu HVDC Link in Japan, called the HVDC Link III project (rated at 250 kVDC-1200 A-300 MW), we developed an HVDC transmission line protection method based on a new working principle that allows high-speed and highly sensitive detection of faults, enhancing reliability in the supply of electric power. In general, increasing the sensitivity of relays will lead to an increased likelihood of undesired operation whereas lowering the sensitivity will impair the responsiveness of the relays. Our proposed method meets these apparently incompatible requirements very well. Basically classified as a differential scheme, the HVDC transmission line protection method compensates for a charging and discharging current that flows through the line-to-ground capacitance at times of voltage variations caused by a line fault or by the operation of DC power systems. The developed protection method is also characterized in that it uses current changes induced by voltage variations to restrain the operation of a relay. This configuration has made the proposed method far superior in responsiveness and sensitivity to the conventional protection method. A simulation using an EMTP (Electro-Magnetic Transients Program) was conducted on this method. Developed relay equipment embodying the new protection method was subjected to various verification tests, where this equipment was connected to a power system simulator, before being delivered to the HVDC Link III facility     

Expression of V642 APP mutant causes cellular apoptosis as Alzheimer trait-linked phenotype

APP is a transmembrane precursor of beta-amyloid. In dominantly inherited familial Alzheimer's disease (FAD), point mutations V6421, V642F and V642G have been discovered in APP695. Here we show that expression of these mutants (FAD-APPs) causes a clone of COS cells to undergo apoptosis associated with DNA fragmentation. Apoptosis by the three FAD-APPs was the highest among all possible V642 mutants; normal APP695 had no effect on apoptosis, suggesting that apoptosis by APP mutants in this system is phenotypically linked to the FAD trait. FAD-APP-induced apoptosis was sensitive to bcl-2 and most probably mediated by heteromeric G proteins. This study presents a model system allowing analysis of the mechanism for FAD-APP-induced cytotoxicity.     

Integrated optical devices of InGaAsP/InP heterojunction phototransistor and inner stripe light-emitting diode

New integrated optical devices combining an InGaAsP/InP HPT and an inner-stripe LED are proposed and their fabrication processes are described. The device functions of light amplification, optical bistability, and optical switching are demonstrated in the 1-μm wavelength region.     

High performance liquid chromatographic separation of stereoisomeric bile acids as their UV-sensitive esters

High performance liquid chromatographic separation of a series of mono-, di- and trihydroxylated 5β-cholanic acids which differ only in position and configuration of hydroxyl groups at positions C-3, C-7 and/or C-12, is reported. The C-24 free acids were derivatized to four different classes of UV-sensitive esters, i.e.,p-bromophenacyl (BP),m-methoxyphenacyl (MP), 4-nitrophthalimidemethyl (NPM) and 9-anthrylmethyl (AM) esters, and chromatographed on two, variants of C₁₈ reversed-phase columns (Nova-Pak C₁₈ and Zorbax ODS) with methanol-water systems as mobile phase. Separation efficiency and elution order of some isomeric pairs were influenced by both the structure of the C-24 ester groups and the nature of the columns used. Excellent chromatographic properties were found for those derivatives, particularly for the NPM esters.     

Photoinduced bidirectional phase transitions in single crystals of polydiacetylenes

Photoinduced phase transitions have been observed between the two phases in single crystals of polydiacetylenes with side-groups of alkylurethanes. The threshold of the excitation intensity for the photochromism is extremely low, one absorbed photon per 140 repeated backbone units, indicating a collective nature of the photoconversion. The excitation spectra for the converted fraction clearly show that the photoinduced phase transition is mediated by photogeneration of polaronic species and not of singlet excitons.