16,256 research outputs found
Hamiltonian formulation of SL(3) Ur-KdV equation
We give a unified view of the relation between the KdV, the mKdV, and
the Ur-KdV equations through the Fr\'{e}chet derivatives and their inverses.
For this we introduce a new procedure of obtaining the Ur-KdV equation, where
we require that it has no non-local operators. We extend this method to the
KdV equation, i.e., Boussinesq(Bsq) equation and obtain the hamiltonian
structure of Ur-Bsq equationin a simple form. In particular, we explicitly
construct the hamiltonian operator of the Ur-Bsq system which defines the
poisson structure of the system, through the Fr\'{e}chet derivative and its
inverse.Comment: 12 pages, KHTP-93-03 SNUTP-93-2
A pairwise maximum entropy model describes energy landscape for spiral wave dynamics of cardiac fibrillation
Heart is an electrically-connected network. Spiral wave dynamics of cardiac
fibrillation shows chaotic and disintegrated patterns while sinus rhythm shows
synchronized excitation patterns. To determine functional interactions between
cardiomyocytes during complex fibrillation states, we applied a pairwise
maximum entropy model (MEM) to the sequential electrical activity maps acquired
from the 2D computational simulation of human atrial fibrillation. Then, we
constructed energy landscape and estimated hierarchical structure among the
different local minima (attractors) to explain the dynamic properties of
cardiac fibrillation. Four types of the wave dynamics were considered: sinus
rhythm; single stable rotor; single rotor with wavebreak; and multiple wavelet.
The MEM could describe all types of wave dynamics (both accuracy and
reliability>0.9) except the multiple random wavelet. Both of the sinus rhythm
and the single stable rotor showed relatively high pairwise interaction
coefficients among the cardiomyocytes. Also, the local energy minima had
relatively large basins and high energy barrier, showing stable attractor
properties. However, in the single rotor with wavebreak, there were relatively
low pairwise interaction coefficients and a similar number of the local minima
separated by a relatively low energy barrier compared with the single stable
rotor case. The energy landscape of the multiple wavelet consisted of a large
number of the local minima separated by a relatively low energy barrier,
showing unstable dynamics. These results indicate that the MEM provides
information about local and global coherence among the cardiomyocytes beyond
the simple structural connectivity. Energy landscape analysis can explain
stability and transitional properties of complex dynamics of cardiac
fibrillation, which might be determined by the presence of 'driver' such as
sinus node or rotor.Comment: Presented at the 62nd Biophysical Society Annual Meeting, San
Francisco, California, 201
Extended nonlocal chiral-quark model for the heavy-light quark systems
In this talk, we report the recent progress on constructing a
phenomenological effective model for the heavy-light quark systems, which
consist of (u,d,s,c,b) quarks, i.e. extended nonlocal chiral-quark model
(ExNLChQM). We compute the heavy-meson weak-decay constants to verify the
validity of the model. From the numerical results, it turns out that (f_D, f_B,
f_{D_s}, f_{B_s})=(207.54,208.13,262.56,262.39) MeV. These values are in
relatively good agreement with experimental data and various theoretical
estimations.Comment: 3 pages, 4 figures, Talk given at the 20th International IUPAP
Conference on Few-Body Problems in Physics (FB20), 20~25 August 2012,
Fukuoka, Japa
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