62 research outputs found
Optimal diffusion in ecological dynamics with Allee effect in a metapopulation
How diffusion impacts on ecological dynamics under the Allee effect and
spatial constraints? That is the question we address. Employing a microscopic
minimal model in a metapopulation (without imposing nonlinear birth and death
rates) we evince --- both numerically and analitically --- the emergence of an
optimal diffusion that maximises the survival probability. Even though, at
first such result seems counter-intuitive, it has empirical support from recent
experiments with engineered bacteria. Moreover, we show that this optimal
diffusion disappears for loose spatial constraints.Comment: 16 pages; 6 figure
On a comparative study between dependence scales determined by linear and non-linear measures
In this manuscript we present a comparative study about the determination of
the relaxation (\textit{i.e.}, independence) time scales obtained from the
correlation function, the mutual information, and a criterion based on the
evaluation of a nonextensive generalisation of mutual entropy. Our results show
that, for systems with a small degree of complexity, standard mutual
information and the criterion based on its nonextensive generalisation provide
the same scale, whereas for systems with a higher complex dynamics the standard
mutual information presents a time scale consistently smaller.Comment: 14 pages. To appear in Physica
The role of the nature of the noise in the thermal conductance of mechanical systems
Focussing on a paradigmatic small system consisting of two coupled damped
oscillators, we survey the role of the L\'evy-It\^o nature of the noise in the
thermal conductance. For white noises, we prove that the L\'evy-It\^o
composition (Lebesgue measure) of the noise is irrelevant for the thermal
conductance of a non-equilibrium linearly coupled chain, which signals the
independence between mechanical and thermodynamical properties. On the other
hand, for the non-linearly coupled case, the two types of properties mix and
the explicit definition of the noise plays a central role.Comment: 9 pages, 2 figures. To be published in Physical Review
Quantum walks with spatiotemporal fractal disorder
We investigate the transport and entanglement properties exhibited by quantum
walks with coin operators concatenated in a space-time fractal structure.
Inspired by recent developments in photonics, we choose the paradigmatic
Sierpinski gasket. The 0-1 pattern of the fractal is mapped into an alternation
of the generalized Hadamard-Fourier operators. In fulfilling the blank space on
the analysis of the impact of disorder in quantum walk properties --
specifically, fractal deterministic disorder --, our results show a robust
effect of entanglement enhancement as well as an interesting novel road to
superdiffusive spreading with a tunable scaling exponent attaining effective
ballistic diffusion. Namely, with this fractal approach it is possible to
obtain an increase in quantum entanglement without jeopardizing spreading.
Alongside those features, we analyze further properties such as the degree of
interference and visibility. The present model corresponds to a new application
of fractals in an experimentally feasible setting, namely the building block
for the construction of photonic patterned structures.Comment: 16 pages, 9 figure
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