4,954 research outputs found
Coupling the Yoccoz-Birkeland population model with price dynamics: chaotic livestock commodities market cycles
We propose a new model for the time evolution of livestock commodities which
exhibits endogenous deterministic stochastic behaviour. The model is based on
the Yoccoz-Birkeland integral equation, a model first developed for studying
the time-evolution of single species with high average fertility, a relatively
short mating season and density dependent reproduction rates. This equation is
then coupled with a differential equation describing the price of a livestock
commodity driven by the unbalance between its demand and supply. At its birth
the cattle population is split into two parts: reproducing females and cattle
for butchery. The relative amount of the two is determined by the spot price of
the meat. We prove the existence of an attractor and we investigate numerically
its properties: the strange attractor existing for the original
Yoccoz-Birkeland model is persistent but its chaotic behaviour depends also
from the price evolution in an essential way.Comment: 26 pages, 19 figure
Coupling the Yoccoz-Birkeland population model with price dynamics: Chaotic livestock commodities market cycles
We propose a new model for the time evolution of livestock commodities prices which exhibits endogenous deterministic stochastic behaviour. The model is based on the Yoccoz\u2013Birkeland integral equation, a model first developed for studying the time-evolution of single species with high average fertility, a relatively short mating season and density-dependent reproduction rates. This equation is then coupled with a differential equation describing the price of a livestock commodity driven by the unbalance between its demand and supply. At its birth the cattle population is split into two parts: reproducing females and cattle for butchery. The relative amount of the two is determined by the spot price of the meat. We prove the existence of an attractor (theorem A) and of a non-trivial periodic solution (theorem B) and we investigate numerically the properties of the attractor: the strange attractor existing for the original Yoccoz\u2013Birkeland model is persistent but its chaotic behaviour depends also on the time evolution of the price in an essential way
Quantum ratchets in dissipative chaotic systems
Using the method of quantum trajectories we study a quantum chaotic
dissipative ratchet appearing for particles in a pulsed asymmetric potential in
the presence of a dissipative environment. The system is characterized by
directed transport emerging from a quantum strange attractor. This model
exhibits, in the limit of small effective Planck constant, a transition from
quantum to classical behavior, in agreement with the correspondence principle.
We also discuss parameter values suitable for implementation of the quantum
ratchet effect with cold atoms in optical lattices.Comment: Significant changes: Several text improvements and new results.
Figure 2 modified. Figure 4 adde
Driven Tunneling: Chaos and Decoherence
Chaotic tunneling in a driven double-well system is investigated in absence
as well as in the presence of dissipation. As the constitutive mechanism of
chaos-assisted tunneling, we focus on the dynamics in the vicinity of
three-level crossings in the quasienergy spectrum. The coherent quantum
dynamics near the crossing is described satisfactorily by a three-state model.
It fails, however, for the corresponding dissipative dynamics, because
incoherent transitions due to the interaction with the environment indirectly
couple the three states in the crossing to the remaining quasienergy states.
The asymptotic state of the driven dissipative quantum dynamics partially
resembles the, possibly strange, attractor of the corresponding damped driven
classical dynamics, but also exhibits characteristic quantum effects.Comment: 32 pages, 35 figures, lamuphys.st
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