505 research outputs found
Thermo-kinetic approach of single-particles and clusters involving anomalous diffusion under viscoelastic response
We present a thermo-kinetic description of anomalous diffusion of
single-particles and clusters in a viscoelastic medium in terms of a
non-Markovian diffusion equation involving memory functions. The scaling
behaviour of these functions is analyzed by considering hydrodynamics and
cluster-size space random walk arguments. We explain experimental results on
diffusion of Brownian particles in the cytoskeleton, in cluster-cluster
aggregation and in a suspension of micelles.Comment: To be published in the Journal of Physical Chemistry
Periodic Modulation Induced Increase of Reaction Rates in Autocatalytic Systems
We propose a new mechanism to increase the reactions ratesin multistable
autocatalytic systems. The mechanism is based upon the possibility for the
enhancement of the response of the system due to the cooperative behavior
between the noise and an external periodic modulation. In order to illustrate
this feature we compute the reaction velocities for the particular case of the
Sel'Kov model, showing that they increase significantly when the periodic
modulation is introduced. This behavior originates from the existence of a
minimum in the mean first passage time, one of the signatures of stochastic
resonance.Comment: Submitted to J. Chem. Phy
Self-consistent theory of shot noise in nondegenerate ballistic conductors
A self-consistent theory of shot noise in ballistic two-terminal conductors
under the action of long-range Coulomb correlations is presented. Analytical
formulas for the electron distribution function and its fluctuation along the
conductor, which account for the Coulomb correlations, have been derived. Based
upon these formulas, the current-noise reduction factor has been obtained for
biases ranging from thermal to shot-noise limits as dependent on two
parameters: the ratio between the length of the sample and the Debye screening
length \lambda=d/L_D and the applied voltage qU/k_BT. The difference with the
formulas for a vacuum diode is discussed.Comment: 21 pages, 11 figs, minor change
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