SELF-ORGANIZED CRITICALITY IN AN ASEXUAL MODEL?

2000 ◽  
Vol 11 (06) ◽  
pp. 1257-1262 ◽  
Author(s):  
COLIN CHISHOLM ◽  
NAEEM JAN ◽  
PETER GIBBS ◽  
AYŞE ERZAN

Recent work has shown that the distribution of steady state mutations for an asexual "bacteria" model has features similar to that seen in Self-Organized Critical (SOC) sandpile model of Bak et al. We investigate this coincidence further and search for "self-organized critical" state for bacteria but instead find that the SOC sandpile critical behavior is very sensitive; critical behavior is destroyed with small perturbations effectively when the absorption of sand is introduced. It is only in the limit when the length of the genome of the bacteria tends to infinity that SOC properties are recovered for the asexual model.

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Andrey Dmitriev ◽  
Victor Dmitriev ◽  
Stepan Balybin

Recently, there has been an increasing number of empirical evidence supporting the hypothesis that spread of avalanches of microposts on social networks, such as Twitter, is associated with some sociopolitical events. Typical examples of such events are political elections and protest movements. Inspired by this phenomenon, we built a phenomenological model that describes Twitter’s self-organization in a critical state. An external manifestation of this condition is the spread of avalanches of microposts on the network. The model is based on a fractional three-parameter self-organization scheme with stochastic sources. It is shown that the adiabatic mode of self-organization in a critical state is determined by the intensive coordinated action of a relatively small number of network users. To identify the critical states of the network and to verify the model, we have proposed a spectrum of three scaling indicators of the observed time series of microposts.


2020 ◽  
pp. 42-50
Author(s):  
Helmut Satz

Complex systems and critical behavior in complex system are defined in terms of correlation between constituents in the medium, subject to screening by intermediate constituents. At a critical point, the correlation length diverges—as a result, one finds the scale-free behavior also observed for bird flocks. This behavior is therefore possibly a form of self-organized criticality.


Fractals ◽  
1996 ◽  
Vol 04 (03) ◽  
pp. 339-348 ◽  
Author(s):  
KYOZI KAWASAKI ◽  
TOHRU OKUZONO

A simple dynamical model for two-dimensional dry foam rheology is constructed for which surface tension effects and viscous dissipation at Plateau borders (intersections of three cell boundaries) are taken into account and is studied by computer simulation. Under externally applied shear strain increasing at small rates, the system exhibits avalanche-like release of stress that has been accumulating under increasing strain. There is a close similarity with earthquake models that show self-organized criticality (SOC). We discuss related simulation of two-dimensional wet foams under statically applied strain by Hutzler et al. [Phil. Mag. B71, 277 (1995)] showing critical behavior.


Author(s):  
Paul Charbonneau

This chapter describes a simple computational idealization of a sandpile. When sand trickles slowly through your fingers, a small conical pile of sand forms below your hand. Sand avalanches of various sizes intermittently slide down the slope of the pile, which is growing both in width and in height but maintains the same slope angle. The pile of sand is a classic example of self-organized criticality. The chapter first provides an overview of the sandpile model before discussing its numerical implementation and a representative simulation involving a small 100-node lattice. It then examines the invariant power-law behavior of avalanches and the self-organized criticality of a sandpile. The chapter includes exercises and further computational explorations, along with a suggested list of materials for further reading.


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