Toru Nakamura

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Heart rate variability (HRV) displays scale-invariant fractal properties. Recent studies have revealed multifractal properties in the healthy human HRV, which could be characterized by singularities with various strength of local Hölder exponents embedded in HRV. In this paper, HRV time series from preterm infants, whose autonomic nervous system undergoes(More)
This paper proposes a door access control system with mobile phones which allows off-line delegations of an access. A model of door access control with mobile phones is introduced, and then the delegation is formalized as a copy of a door-key. On the previous model, secure copy by off-line is realized using the essential idea of the proxy signature.(More)
The objective evaluation of depressive mood is considered to be useful for the diagnosis and treatment of depressive disorders. Thus, we investigated psychobehavioral correlates, particularly the statistical associations between momentary depressive mood and behavioral dynamics measured objectively, in patients with major depressive disorder (MDD) and(More)
The purpose of this paper is to realize an authentication system which satisfies four requirements for security, privacy protection, and usability, that is, impersonation resistance against insiders, personalization, unlinkability in multi-service environment, and memory efficiency. The proposed system is the first system which satisfies all the properties.(More)