1,346 research outputs found
Transition Phenomena Induced by Internal Noise and Quasi-absorbing State
We study a simple chemical reaction system and effects of the internal noise.
The chemical reaction system causes the same transition phenomenon discussed by
Togashi and Kaneko [Phys. Rev. Lett. 86 (2001) 2459; J. Phys. Soc. Jpn. 72
(2003) 62]. By using the simpler model than Togashi-Kaneko's one, we discuss
the transition phenomenon by means of a random walk model and an effective
model. The discussion makes it clear that quasi-absorbing states, which are
produced by the change of the strength of the internal noise, play an important
role in the transition phenomenon. Stabilizing the quasi-absorbing states
causes bifurcation of the peaks in the stationary probability distribution
discontinuously.Comment: 6 pages, 5 figure
Switching Dynamics in Reaction Networks Induced by Molecular Discreteness
To study the fluctuations and dynamics in chemical reaction processes,
stochastic differential equations based on the rate equation involving chemical
concentrations are often adopted. When the number of molecules is very small,
however, the discreteness in the number of molecules cannot be neglected since
the number of molecules must be an integer. This discreteness can be important
in biochemical reactions, where the total number of molecules is not
significantly larger than the number of chemical species. To elucidate the
effects of such discreteness, we study autocatalytic reaction systems
comprising several chemical species through stochastic particle simulations.
The generation of novel states is observed; it is caused by the extinction of
some molecular species due to the discreteness in their number. We demonstrate
that the reaction dynamics are switched by a single molecule, which leads to
the reconstruction of the acting network structure. We also show the strong
dependence of the chemical concentrations on the system size, which is caused
by transitions to discreteness-induced novel states.Comment: 11 pages, 5 figure
Bulk and surface-sensitive high-resolution photoemission study of Mott-Hubbard systems SrVO and CaVO
We study the electronic structure of Mott-Hubbard systems SrVO and
CaVO with bulk and surface-sensitive high-resolution photoemission
spectroscopy (PES), using a VUV laser, synchrotron radiation and a discharge
lamp ( = 7 - 21 eV). A systematic suppression of the density of states
(DOS) within 0.2 eV of the Fermi level () is found on decreasing
photon energy i.e. on increasing bulk sensitivity. The coherent band in
SrVO and CaVO is shown to consist of surface and bulk derived
features, separated in energy. The stronger distortion on surface of CaVO
compared to SrVO leads to higher surface metallicity in the coherent DOS
at , consistent with recent theory.Comment: 4 pages 5 figures (including 2 auxiliary figures); A complete
analysis of the spectra based on the surface and bulk analysis shows in
auxiliary figures Fig. A1 and A
Unbounded autocatalytic growth on diffusive substrate: the extinction transition
The effect of diffusively correlated spatial fluctuations on the
proliferation-extinction transition of autocatalytic agents is investigated
numerically. Reactants adaptation to spatio-temporal active regions is shown to
lead to proliferation even if the mean field rate equations predict extinction,
in agreement with previous theoretical predictions. While in the proliferation
phase the system admits a typical time scale that dictates the exponential
growth, the extinction times distribution obeys a power law at the parameter
region considered
Image Analysis of Intractable Epilepsy:18F-FDG PET Scan of the Cortical Dysplasia
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