Takaomi Shigehara

Learn More
In this Letter, we propose a framework to transform a complex network to a time series. The transformation from complex networks to time series is realized by the classical multidimensional scaling. Applying the transformation method to a model proposed by Watts and Strogatz [Nature (London) 393, 440 (1998)], we show that ring lattices are transformed to(More)
We study the low energy quantum spectra of two-dimensional rectangular billiards with a small but finite-size scatterer inside. We start by examining the spectral properties of billiards with a single pointlike scatterer. The problem is formulated in terms of self-adjoint extension theory of functional analysis. The condition for the appearance of so-called(More)
This paper proposes a novel face detection method intended to be used for practical intelligent environment and human-interactive robot. Face detection and recognition are very crucial for such applications. However, in the real situation, it is not easy to realize the robust detecting function because position, size, and brightness of face image are much(More)
We propose a new method to construct a four parameter family of quantum-mechanical point interactions in one dimension, which is known as all possible self-adjoint extensions of the symmetric operator T = −∆⌈C 0 (R\{0}). It is achieved in the small distance limit of equally spaced three neighboring Dirac’s δ potentials. The strength for each δ is(More)
We examine the spectral properties of three-dimensional quantum billiards with a single pointlike scatterer inside. It is found that the spectrum shows chaotic (random-matrix-like) characteristics when the inverse of the formal strength v̄−1 is within a band whose width increases parabolically as a function of the energy. This implies that the spectrum(More)
Ninety-nine and 476 clones of Myzus persicae (Sulzer) were sampled on tobacco at Kyoto (Shimogamo) (1996-2000) and at 23 other localities (1998-1999) in Japan, respectively. The clones were classified into colour-esterase forms, distinguished by combinations of body colour and electrophoretically detectable esterases, to verify the changes in genotypic(More)
We construct a one-dimensional contact interaction (ε potential) which induces the discontinuity of the wave function while keeping its derivative continuous. By combining the ε potential and the Dirac’s δ function, we construct most general one-dimensional contact interactions allowable under the time reversal symmetry. We present some elementary results(More)
We extend the standard Kronig-Penney model with periodic δ potentials to the cases with generalized contact interactions under the assumption that the system has time-reversal symmetry. By applying Bloch theorem, the eigenvalue equation which determines the dispersion relation for onedimensional periodic array of the generalized contact interactions is(More)
We first give the solution for the local approximation of a four parameter family of generalized one-dimensional point interactions within the framework of non-relativistic model with three neighboring δ functions. We also discuss the problem within relativistic (Dirac) framework and give the solution for a three parameter family. It gives a physical(More)