119,242 research outputs found
Validation of a model of regulation in the tryptophan operon against multiple experiment data using global optimisation
This paper is concerned with validating a mathematical model of regulation in the tryptophan operon using global optimization. Although a number of models for this biochemical network are proposed, in many cases only qualitative agreement between the model output and experimental data was demonstrated, since very little information is currently available to guide the selection of parameter values for the models. This paper presents a model validating method using both multiple experimental data and global optimization
Quantum Dynamics for de Sitter Radiation
We revisit the Hamiltonian formalism for a massive scalar field and study the
particle production in a de Sitter space. In the invariant-operator picture the
time-dependent annihilation and creation operators are constructed in terms of
a complex solution to the classical equation of motion for the field and the
Gaussian wave function for each Fourier mode is found which is an exact
solution to the Schr\"odinger equation. The in-out formalism is reformulated by
the annihilation and creation operators and the Gaussian wave functions. The de
Sitter radiation from the in-out formalism differs from the Gibbons-Hawking
radiation in the planar coordinates, and we discuss the discrepancy of the
particle production by the two methodComment: LaTex 12 pages, no figure; CosPA2011, Peking Univ., Oct. 28-31, 2011;
references added; to be published in International Journal of Modern Physics:
Conference Serie
Renormalization analysis of intermittency in two coupled maps
The critical behavior for intermittency is studied in two coupled
one-dimensional (1D) maps. We find two fixed maps of an approximate
renormalization operator in the space of coupled maps. Each fixed map has a
common relavant eigenvaule associated with the scaling of the control parameter
of the uncoupled one-dimensional map. However, the relevant ``coupling
eigenvalue'' associated with coupling perturbation varies depending on the
fixed maps. These renormalization results are also confirmed for a
linearly-coupled case.Comment: 11 pages, RevTeX, 2 eps figure
The quantization of the chiral Schwinger model based on the BFT-BFV formalism II
We apply an improved version of Batalin-Fradkin-Tyutin (BFT) Hamiltonian
method to the a=1 chiral Schwinger Model, which is much more nontrivial than
the a>1.\delta\xi$ in the measure. As a result, we explicitly
obtain the fully gauge invariant partition function, which includes a new type
of Wess-Zumino (WZ) term irrelevant to the gauge symmetry as well as usual WZ
action.Comment: 17 pages, To be published in J. Phys.
Competition between superconductivity and charge density waves
We derive an effective field theory for the competition between
superconductivity (SC) and charge density waves (CDWs) by employing the SO(3)
pseudospin representation of the SC and CDW order parameters. One important
feature in the effective nonlinear model is the emergence of Berry
phase even at half filling, originating from the competition between SC and
CDWs, i.e., the pseudospin symmetry. A well known conflict between the previous
studies of Oshikawa\cite{Oshikawa} and D. H. Lee et al.\cite{DHLee} is resolved
by the appearance of Berry phase. The Berry phase contribution allows a
deconfined quantum critical point of fractionalized charge excitations with
instead of in the SC-CDW quantum transition at half filling. Furthermore,
we investigate the stability of the deconfined quantum criticality against
quenched randomness by performing a renormalization group analysis of an
effective vortex action. We argue that although randomness results in a weak
disorder fixed point differing from the original deconfined quantum critical
point, deconfinement of the fractionalized charge excitations still survives at
the disorder fixed point owing to a nonzero fixed point value of a vortex
charge.Comment: adding a renormalization group analysis with a random fugacity term
as an effect of randomness on a deconfined quantum critical poin
Steering effects on growth instability during step-flow growth of Cu on Cu(1,1,17)
Kinetic Monte Carlo simulation in conjunction with molecular dynamics
simulation is utilized to study the effect of the steered deposition on the
growth of Cu on Cu(1,1,17). It is found that the deposition flux becomes
inhomogeneous in step train direction and the inhomogeneity depends on the
deposition angle, when the deposition is made along that direction. Steering
effect is found to always increase the growth instability, with respect to the
case of homogeneous deposition. Further, the growth instability depends on the
deposition angle and direction, showing minimum at a certain deposition angle
off-normal to (001) terrace, and shows a strong correlation with the
inhomogeneous deposition flux. The increase of the growth instability is
ascribed to the strengthened step Erlich Schwoebel barrier effects that is
caused by the enhanced deposition flux near descending step edge due to the
steering effect.Comment: 5 page
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