8,123 research outputs found
Hyperbolic chaos in self-oscillating systems based on mechanical triple linkage: Testing absence of tangencies of stable and unstable manifolds for phase trajectories
Dynamical equations are formulated and a numerical study is provided for
self-oscillatory model systems based on the triple linkage hinge mechanism of
Thurston -- Weeks -- Hunt -- MacKay. We consider systems with holonomic
mechanical constraint of three rotators as well as systems, where three
rotators interact by potential forces. We present and discuss some quantitative
characteristics of the chaotic regimes (Lyapunov exponents, power spectrum).
Chaotic dynamics of the models we consider are associated with hyperbolic
attractors, at least, at relatively small supercriticality of the
self-oscillating modes; that follows from numerical analysis of the
distribution for angles of intersection of stable and unstable manifolds of
phase trajectories on the attractors. In systems based on rotators with
interacting potential the hyperbolicity is violated starting from a certain
level of excitation.Comment: 30 pages, 18 figure
Low Temperature Electronic Transport through Macromolecules and Characteristics of Intramolecular Electron Transfer
A theory of electronic transport through molecular wires is applied to
analyze characteristics of a long-range electron transfer (ET) through
molecular bridges in macromolecules with complex donor/acceptor subsystems.
Assuming a coherent electron tunneling through the bridge to be the predominant
mechanism of ET at low temperatures it is shown that low temperature
current-voltage curves can exhibit a step-like structure, which contains
information concerning intrinsic features of ET processes such as the effect of
donor/acceptor coupling to the bridge and primary pathways of electrons
tunneling through the bridge. By contacting the proposed theoretical analysis
with such experimental data a variety of valuable characteristics of long-range
intramolecular ET can be identified. Analytical and numerical results are
presented. Using the Buttiker dephasing model within the scattering matrix
formalism we analyze dephasing effects, and we show that these effects could be
reduced enough to allow the structure of the electron transmission function to
be exposed in the experiments on the electronic transport through
macromolecules.Comment: 9 pages, 2 figures, text revise
K*-couplings for the antidecuplet excitation
We estimate the coupling of the K* vector meson to the N-->Theta+ transition
employing unitary symmetry, vector meson dominance, and results from the GRAAL
Collaboration for eta photoproduction off the neutron. Our small numerical
value for the coupling constant is consistent with the non-observation of the
Theta+ in recent CLAS searches for its photoproduction. We also estimate the
K*-coupling for the N-->Sigma* excitation, with Sigma* being the Sigma-like
antidecuplet partner of the Theta+-baryon.Comment: 9 pages, 1 figure. Minor changes in text and abstract, references
added; version to appear in Phys. Rev.
Lyapunov exponents of quantum trajectories beyond continuous measurements
Quantum systems interacting with their environments can exhibit complex
non-equilibrium states that are tempting to be interpreted as quantum analogs
of chaotic attractors. Yet, despite many attempts, the toolbox for quantifying
dissipative quantum chaos remains very limited. In particular, quantum
generalizations of Lyapunov exponent, the main quantifier of classical chaos,
are established only within the framework of continuous measurements. We
propose an alternative generalization which is based on the unraveling of a
quantum master equation into an ensemble of so-called 'quantum jump'
trajectories. These trajectories are not only a theoretical tool but a part of
the experimental reality in the case of quantum optics. We illustrate the idea
by using a periodically modulated open quantum dimer and uncover the transition
to quantum chaos matched by the period-doubling route in the classical limit.Comment: 5 pages, 4 figure
Behavior of radiation belts anomalous cosmic radionoise absorption in the aurora zone during the magnetic storms of 12-14 and 20-21 February 1964
Characteristics of radiation belt and ionospheric absorption of cosmic radio noise in auroral zone during geomagnetic storm
Formation of singularities on the surface of a liquid metal in a strong electric field
The nonlinear dynamics of the free surface of an ideal conducting liquid in a
strong external electric field is studied. It is establish that the equations
of motion for such a liquid can be solved in the approximation in which the
surface deviates from a plane by small angles. This makes it possible to show
that on an initially smooth surface for almost any initial conditions points
with an infinite curvature corresponding to branch points of the root type can
form in a finite time.Comment: 14 page
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