2,338 research outputs found
The notion of persistence applied to breathers in thermal equilibrium
We study the thermal equilibrium of nonlinear Klein-Gordon chains at the
limit of small coupling (anticontinuum limit). We show that the persistence
distribution associated to the local energy density is a useful tool to study
the statistical distribution of so-called thermal breathers, mainly when the
equilibrium is characterized by long-lived static excitations; in that case,
the distribution of persistence intervals turns out to be a powerlaw. We
demonstrate also that this generic behaviour has a counterpart in the power
spectra, where the high frequencies domains nicely collapse if properly
rescaled. These results are also compared to non linear Klein-Gordon chains
with a soft nonlinearity, for which the thermal breathers are rather mobile
entities. Finally, we discuss the possibility of a breather-induced anomalous
diffusion law, and show that despite a strong slowing-down of the energy
diffusion, there are numerical evidences for a normal asymptotic diffusion
mechanism, but with exceptionnally small diffusion coefficients.Comment: submitted to Physica
Boron in groundwater of the Island of Cyprus
Boron can be found in high concentrations in the groundwater of the Island of Cyprus, especially in the central part of the island. Boron in high concentrations is of major concern due to its toxicity to both animals and irrigated plants. The origin of the phenomenon is not very well understood and is usually explained as remains of seawater. This work quantifies the boron content through analytical techniques and provides more information on the levels found
Discrete breathers in thermal equilibrium: distributions and energy gaps
We study a discrete two-dimensional nonlinear system that allows for discrete
breather solutions. We perform a spectral analysis of the lattice dynamics at
thermal equilibrium and use a cooling technique to measure the amount of
breathers at thermal equilibrium. Our results confirm the existence of an
energy threshold for discrete breathers. The cooling method provides with a
novel computational technique of measuring and analyzing discrete breather
distribution properties in thermal equilibrium.Comment: 20 pages, 14 figure
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