736 research outputs found
Self-Assembling of Networks in an Agent-Based Model
We propose a model to show the self-assembling of network-like structures
between a set of nodes without using preexisting positional information or
long-range attraction of the nodes. The model is based on Brownian agents that
are capable of producing different local (chemical) information and respond to
it in a non-linear manner. They solve two tasks in parallel: (i) the detection
of the appropriate nodes, and (ii) the establishment of stable links between
them. We present results of computer simulations that demonstrate the emergence
of robust network structures and investigate the connectivity of the network by
means of both analytical estimations and computer simulations. PACS: 05.65.+b,
89.75.Kd, 84.30.Bv, 87.18.SnComment: 10 pages, 8 figures. A video of the computer simulations can be found
at http://www.ais.fhg.de/~frank/network.html. After publication, this paper
was also included in: Virtual Journal of Biological Physics Research 4/5
(September 1, 2002) and Virtual Journal of Nanoscale Science & Technology
6/10 (September 2, 2002). For related work, see also
http://www.ais.fhg.de/~frank/active.htm
International crop trade networks: The impact of shocks and cascades
Analyzing available FAO data from 176 countries over 21 years, we observe an
increase of complexity in the international trade of maize, rice, soy, and
wheat. A larger number of countries play a role as producers or intermediaries,
either for trade or food processing. In consequence, we find that the trade
networks become more prone to failure cascades caused by exogenous shocks. In
our model, countries compensate for demand deficits by imposing export
restrictions. To capture these, we construct higher-order trade dependency
networks for the different crops and years. These networks reveal hidden
dependencies between countries and allow to discuss policy implications
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