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Solvation model dependency of helix-coil transition in polyalanine
Helix-coil transitions in poly-alanine molecules of length 10 are studied by
multicanonical Monte Carlo simulations. The solvation effects are included by
either a distance-dependent dielectric permittivity or by a term that is
proportional to the solvent-accessible surface area of the peptide. We found a
strong dependence of the characteristics of the helix-coil transition from the
details of the solvation model.Comment: to appear in Biophysical Journa
Time-reversal Characteristics of Quantum Normal Diffusion
This paper concerns with the time-reversal characteristics of intrinsic
normal diffusion in quantum systems. Time-reversible properties are quantified
by the time-reversal test; the system evolved in the forward direction for a
certain period is time-reversed for the same period after applying a small
perturbation at the reversal time, and the separation between the time-reversed
perturbed and unperturbed states is measured as a function of perturbation
strength, which characterizes sensitivity of the time reversed system to the
perturbation and is called the time-reversal characteristic.
Time-reversal characteristics are investigated for various quantum systems,
namely, classically chaotic quantum systems and disordered systems including
various stochastic diffusion systems. When the system is normally diffusive,
there exists a fundamental quantum unit of perturbation, and all the models
exhibit a universal scaling behavior in the time-reversal dynamics as well as
in the time-reversal characteristics, which leads us to a basic understanding
on the nature of quantum irreversibility.Comment: 21pages, 25figure
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