Instanton Number Calculus on Noncommutative R^4

In noncommutative spaces, it is unknown whether the Pontrjagin class gives integer, as well as, the relation between the instanton number and Pontrjagin class is not clear. Here we define ``Instanton number'' by the size of $B_{\alpha}$ in the ADHM construction. We show the analytical derivation of the noncommuatative U(1) instanton number as an integral of Pontrjagin class (instanton charge) with the Fock space representation. Our approach is for the arbitrary converge noncommutative U(1) instanton solution, and is based on the anti-self-dual (ASD) equation itself. We give the Stokes' theorem for the number operator representation. The Stokes' theorem on the noncommutative space shows that instanton charge is given by some boundary sum. Using the ASD conditions, we conclude that the instanton charge is equivalent to the instanton number.Comment: 29 pages, 7 figures, some statements in Sec.4.3 correcte

Threshold voltage instability and hysteresis in gamma-rays irradiated 4H-SiC junction field effect transistors

High dose irradiation effects of gamma-rays up to 17 MGy (H2O) on 4H-SiC JFETs was investigated. Due to the irradiation, gradual positive threshold voltage (Vth) shift as high as 0.5 V and continuous decrease in transconductance gm were observed. In addition, Vth instability and hysteresis appeared for the irradiated JFETs when the gate voltage (VG) sweep direction, sweep interval, i.e. averaged sweeping rate, sweep range and delay time were changed. Increase of VG interval attributed to positive Vth shift for both forward and reverse direction, whereas narrowing of sweep range and increase of delay time resulted in more noticeable negative shift of Vth for reverse direction. Such Vth hysteresis indicates that capture and release of carriers predominantly took place via hole traps formed around the gate region due to high dose gamma-ray irradiation

Acute Effects on Signal-Averaged Electrogram Parameters and Suppressing Premature Ventricular Contractions in Single or Combined Use of Class I Antiarrhythmic Drugs

Disopyramide (DP), mexiletine (MX), and flecainide (FL) are class I antiarrhythmic drugs. However, these drugs exert different effects on the electrocardiogram (ECG) based on their unique actions on cardiac myocytes. The electrocardiographic changes during combination therapy with these drugs are not well understood. The purpose of the present study was to evaluate acute morphologic changes in the ECG based on signal-averaged high resolution ECG (SAECG) after administration of the drugs in relation to their antiarrhythmic eficacy and safety. Twenty-one patients with frequent and stable premature ventricular contractions (PVC) were studied. Changes in the filtered QRS duration (f-QRS) and the root mean square voltage of the last 40 msec of the QRS complex (RMS40) were evaluated. Suppression of PVCs was achieved soon after intravenous administration of the drugs (63% for DP, 43% for MX, 86% for FL and 100% for DP+MX). Although DP and FL significantly prolonged f-QRS, MX had little effect on f-QRS. DP+MX also prolonged f-QRS, but the degree of prolongation was moderate. RMS40 was significantly decreased by DP and FL, but not by MX. DP+MX also decreased RMS40, but the decrease was less than for DP alone. Late potentials were observed after administration in 56% of patients with DP, 0% with MX, 67% with FL and 0% with DP+MX. No adverse events were reported during the study. In summary, the class I antiarrhythmic drugs exerted different acute effects on SAECG parameters. The combination of DP and MX increased the eficacy on suppressing PVC without excess additive changes on SAECG parameters. We conclude that combination therapy with DP and MX is eficacious and safe in patients with PVC and the analysis of SAECG during antiarrhythmic therapy is clinically important