4 research outputs found
Toy model for molecular motors
A hopping model for molecular motors is presented consisting of a state with
asymmetric hopping rates with period 2 and a state with uniform hopping rates.
State changes lead to a stationary unidirectional current of a particle. The
current is explicitly calculated as a function of the rate of state changes,
including also an external bias field. The Einstein relation between the linear
mobility of the particle and its diffusion coefficient is investigated. The
power input into the system is derived, as well as the power output resulting
from the work performed against the bias field. The efficiency of this model is
found to be rather small.Comment: 11 pages Latex, 7 postscript figures, to be published in Physica
Absence of self-averaging in the complex admittance for transport through random media
A random walk model in a one dimensional disordered medium with an
oscillatory input current is presented as a generic model of boundary
perturbation methods to investigate properties of a transport process in a
disordered medium. It is rigorously shown that an admittance which is equal to
the Fourier-Laplace transform of the first-passage time distribution is
non-self-averaging when the disorder is strong. The low frequency behavior of
the disorder-averaged admittance, where , does not coincide with the low frequency behavior of the admittance for any
sample, . It implies that the Cole-Cole plot of
appears at a different position from the Cole-Cole plots of of any
sample. These results are confirmed by Monte-Carlo simulations.Comment: 7 pages, 2 figures, published in Phys. Rev.