Biomedical subjects

Takashi Odagaki

Publications and source records attributed to Takashi Odagaki.

4 recordsLinked to original sources

PubMed2006

Dissipative process under a boundary perturbation.

A dissipative process in systems subjected to a boundary perturbation is analyzed on the basis of quantum mechanics. We show that the response of the system to the perturbation can be expressed in terms of the first-passage time defined appropriately by quantum mechanics. In other words, the first-passage-time distribution plays the role of the response function in the linear response theory. We apply this formalism to the one-dimensional Anderson model in which a current is introduced at one end of the system and the other is connected to an absorbing wall. We find that the frequency-dependent oscillations of the susceptibility reflect the narrowness of the first-passage-time distribution in disordered systems.

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PubMed2005

Resonant transmission of a soliton across an interface between two Toda lattices.

The transmission of a single soliton is investigated numerically across an interface between two Toda lattices which are connected by a harmonic spring. We find that a resonant transmission of the soliton occurs when the spring constant of the harmonic spring is adjusted properly. Furthermore, when the amplitude of the incident soliton is large, the soliton transmission coefficient exhibits a local minimum which is due to an emergence of localized waves around the harmonic spring. We propose an experimental test of the results by using a nonlinear LC circuit.

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PubMed2003

Numerical study of soliton scattering in inhomogeneous optical fibers.

Using a variable-coefficient nonlinear Schrödinger equation, transmission profile of a single soliton in the optical fiber with an inhomogeneous region is studied numerically. It is found that the transmitted wave contains two solitons which form a bound state when the difference of the dispersion coefficient between the inhomogeneous and the homogeneous regions is large enough. When the amplitude of the transmitted wave is small, the transmitted wave is apt to contain a bound state soliton. With the increase of the length of the inhomogeneous region, a quantity E3, which is the conserved quantity of the constant-coefficient nonlinear Schrödinger equation, for the transmitted wave converges to an asymptotic value with oscillation. It is found that the nonsoliton wave part of E3 for the transmitted wave converges to an asymptotic value rapidly compared with other contributions to E3. We find the condition for the parameters of the inhomogeneous region that a stable soliton can exist on the entire fiber.

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PubMed2002

Specific heat in a nonequilibrium system composed of Einstein oscillators.

In order to understand the behavior of thermodynamic quantities near the glass transition temperature, we put the energy landscape picture and the particle's jump motion together and calculate the specific heat of a nonequilibrium system. Taking the finite observation time into account, we study the observation time dependence of the specific heat. We assume the Einstein oscillators for the dynamics of each basin in the landscape structure of phase space and calculate the specific heat of a system with 20 basins. For a given observation time, a transition from annealed to quenched system occurs at the temperature when the time scale of jumps exceeds the observation time. The transition occurs at lower temperature and becomes sharper for longer observation time.

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