Conditions Implying Self-adjointness of Operators

In this paper, we show that if is a quasi-class A operator and S is an arbitrary operator for which and ST = T*S, then T is self-adjoint, and we also show that quasisimilar quasi-class A operators have equal spectra and essential spectra. This work of the second author was supported by the University of Incheon Research Grant in 2008.     

Monocular viewing prolongs reversal interval of perceptual rival figure

The authors examined whether the perceptual reversal rate changes under monocular versus binocular viewing conditions. Our results suggest that the perceptual reversal interval increases during monocular viewing. The ratio of the reversal rate (1/interval) for the two viewing conditions (binocular/monocular) was 1.28 over a wide range of pattern luminance levels. The quoted ratio was 1.40 when the luminance was high. Such a ratio parallels the value of a well-known binocular summation index $(\sqrt 2 )$ , which was derived from the signal detection theory. The binocular summation index shows that the strength of an input signal is enhanced by binocular viewing. However, how the binocular summation shortens the perceptual reversal interval is unclear. This issue can be resolved if the perceptual reversal is derived by integrating the strength of an unconscious image signal. Thus, we discussed the mechanism of perceptual switch by associating two classical, well-studied phenomena, binocular summation and perceptual switch.     

Angular cutting for log-hyponormal operators

We define an angular section for a log-hyponormal operator on a Hilbert space, cut by an arc on the unit circle, and establish various spectral properties for it, which correspond to the properties of an angular section for ap-hyponormal opertor.Dedicated to Professor Norio Shimakura on the occasion of his sixtieth birthdayThis research was supported by Grant-in-Aid Research 1 No. 12640187.