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721.
S.?Petrovskii A.?Morozov H.?Malchow M.?Sieber 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,73(2):253-264
Many theoretical approaches predict the dynamics of interacting populations to be chaotic but that has very rarely been observed
in ecological
data. It has therefore risen a question about factors that can prevent the onset of chaos by, for instance, making the population
fluctuations
synchronized over the whole habitat. One such factor is stochasticity. The so-called Moran effect predicts that a spatially
correlated noise can
synchronize the local population dynamics in a spatially discrete system, thus preventing the onset of spatiotemporal chaos.
On the whole,
however, the issue of noise has remained controversial and insufficiently understood. In particular, a well-built nonspatial
theory infers that
noise enhances chaos by making the system more sensitive to the initial conditions. In this paper, we address the problem
of the interplay
between deterministic dynamics and noise by considering a spatially explicit predator-prey system where some parameters are
affected by noise.
Our findings are rather counter-intuitive. We show that a small noise (i.e. preserving the deterministic skeleton) can indeed
synchronize the
population oscillations throughout space and hence keep the dynamics regular, but the dependence of the chaos prevention probability
on the
noise intensity is of resonance type. Once chaos has developed, it appears to be stable with respect to a small noise but
it can be suppressed
by a large noise. Finally, we show that our results are in a good qualitative agreement with some available field data. 相似文献
722.
Inga M. Aladzheva Dmitrii I. Lobanov Ol'ga V. Bykhovskaya Pavel V. Petrovskii Konstantin A. Lyssenko Tatyana A. Mastryukova 《Heteroatom Chemistry》2003,14(7):596-602
A novel facile one‐pot synthesis of the 1,2‐azaphospholanes by intramolecular alkylation of 3‐halopropyl amides of tricoordinate phosphorus has been suggested. Using this method, a series of the differently N‐substituted 1,2‐azaphospholanium salts were synthesized. 3‐Aminopropylphosphine oxides were obtained by hydrolysis of the salts. A probable mechanism of the 1,2‐azaphospholanium salts formation is discussed. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:596–602, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10209 相似文献
723.