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Synchronization in an array of linearly stochastically coupled networks with time delays
This is the post print version of the article. The official published version can be obtained from the link - Copyright 2007 Elsevier LtdIn this paper, the complete synchronization problem is investigated in an array of linearly stochastically coupled identical networks with time delays. The stochastic coupling term, which can reflect a more realistic dynamical behavior of coupled systems in practice, is introduced to model a coupled system, and the influence from the stochastic noises on the array of coupled delayed neural networks is studied thoroughly. Based on a simple adaptive feedback control scheme and some stochastic analysis techniques, several sufficient conditions are developed to guarantee the synchronization in an array of linearly stochastically coupled neural networks with time delays. Finally, an illustrate example with numerical simulations is exploited to show the effectiveness of the theoretical results.This work was jointly supported by the National Natural Science Foundation of China under Grant 60574043, the Royal Society of the United Kingdom, the Natural Science Foundation of Jiangsu Province of China under Grant BK2006093, and International Joint Project funded by NSFC and the Royal Society of the United Kingdom
Reexamining the temperature and neutron density conditions for r-process nucleosynthesis with augmented nuclear mass models
We explore the effects of nuclear masses on the temperature and neutron
density conditions required for r-process nucleosynthesis using four nuclear
mass models augmented by the latest atomic mass evaluation. For each model we
derive the conditions for producing the observed abundance peaks at mass
numbers A ~ 80, 130, and 195 under the waiting-point approximation and further
determine the sets of conditions that can best reproduce the r-process
abundance patterns (r-patterns) inferred for the solar system and observed in
metal-poor stars of the Milky Way halo. In broad agreement with previous
studies, we find that (1) the conditions for producing abundance peaks at A ~
80 and 195 tend to be very different, which suggests that, at least for some
nuclear mass models, these two peaks are not produced simultaneously; (2) the
typical conditions required by the critical waiting-point (CWP) nuclei with the
N = 126 closed neutron shell overlap significantly with those required by the
N=82 CWP nuclei, which enables coproduction of abundance peaks at A ~ 130 and
195 in accordance with observations of many metal-poor stars; and (3) the
typical conditions required by the N = 82 CWP nuclei can reproduce the
r-pattern observed in the metal-poor star HD 122563, which differs greatly from
the solar r-pattern. We also examine how nuclear mass uncertainties affect the
conditions required for the r-process and identify some key nuclei
including76Ni to 78Ni, 82Zn, 131Cd, and 132Cd for precise mass measurements at
rare-isotope beam facilities.Comment: 28 pages,9 figures,1 tabl
Hydrostatic pressure effects on the static magnetism in Eu(FeCo)As
The effects of hydrostatic pressure on the static magnetism in
Eu(FeCo)As are investigated by complementary
electrical resistivity, ac magnetic susceptibility and single-crystal neutron
diffraction measurements. A specific pressure-temperature phase diagram of
Eu(FeCo)As is established. The structural phase
transition, as well as the spin-density-wave order of Fe sublattice, is
suppressed gradually with increasing pressure and disappears completely above
2.0 GPa. In contrast, the magnetic order of Eu sublattice persists over the
whole investigated pressure range up to 14 GPa, yet displaying a non-monotonic
variation with pressure. With the increase of the hydrostatic pressure, the
magnetic state of Eu evolves from the canted antiferromagnetic structure in the
ground state, via a pure ferromagnetic structure under the intermediate
pressure, finally to a possible "novel" antiferromagnetic structure under the
high pressure. The strong ferromagnetism of Eu coexists with the
pressure-induced superconductivity around 2 GPa. The change of the magnetic
state of Eu in Eu(FeCo)As upon the application
of hydrostatic pressure probably arises from the modification of the indirect
Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between the Eu moments
tuned by external pressure.Comment: 9 pages, 6 figure
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