58 research outputs found
Networks and Cities: An Information Perspective
Traffic is constrained by the information involved in locating the receiver
and the physical distance between sender and receiver. We here focus on the
former, and investigate traffic in the perspective of information handling. We
re-plot the road map of cities in terms of the information needed to locate
specific addresses and create information city networks with roads mapped to
nodes and intersections to links between nodes. These networks have the broad
degree distribution found in many other complex networks. The mapping to an
information city network makes it possible to quantify the information
associated with locating specific addresses.Comment: 4 pages, 4 figure
Hide and seek on complex networks
Signaling pathways and networks determine the ability to communicate in
systems ranging from living cells to human society. We investigate how the
network structure constrains communication in social-, man-made and biological
networks. We find that human networks of governance and collaboration are
predictable on teat-a-teat level, reflecting well defined pathways, but
globally inefficient. In contrast, the Internet tends to have better overall
communication abilities, more alternative pathways, and is therefore more
robust. Between these extremes the molecular network of Saccharomyces cerevisea
is more similar to the simpler social systems, whereas the pattern of
interactions in the more complex Drosophilia melanogaster, resembles the robust
Internet.Comment: 5 pages, 5 figure
A simple model for self organization of bipartite networks
We suggest a minimalistic model for directed networks and suggest an
application to injection and merging of magnetic field lines. We obtain a
network of connected donor and acceptor vertices with degree distribution
, and with dynamical reconnection events of size occurring
with frequency that scale as . This suggest that the model is in
the same universality class as the model for self organization in the solar
atmosphere suggested by Hughes et al.(PRL {\bf 90} 131101)
Information Horizons in Networks
We investigate and quantify the interplay between topology and ability to
send specific signals in complex networks. We find that in a majority of
investigated real-world networks the ability to communicate is favored by the
network topology on small distances, but disfavored at larger distances. We
further discuss how the ability to locate specific nodes can be improved if
information associated to the overall traffic in the network is available.Comment: Submitted top PR
Self-organization of structures and networks from merging and small-scale fluctuations
We discuss merging-and-creation as a self-organizing process for scale-free
topologies in networks. Three power-law classes characterized by the power-law
exponents 3/2, 2 and 5/2 are identified and the process is generalized to
networks. In the network context the merging can be viewed as a consequence of
optimization related to more efficient signaling.Comment: Physica A: Statistical Mechanics and its Applications, In Pres
Measuring information networks
Abstract. Traffic and communication between different parts of a complex system are fundamental elements in maintaining its overall cooperativity. Because a complex system consists of many different parts, it matters where signals are transmitted. Thus signaling and traffic are in principle specific, with each message going from a unique sender to a specific recipient. In the current paper we review some measures of network topology that are related to its ability to direct specific communication
Extracting the hierarchical organization of complex systems
Extracting understanding from the growing ``sea'' of biological and
socio-economic data is one of the most pressing scientific challenges facing
us. Here, we introduce and validate an unsupervised method that is able to
accurately extract the hierarchical organization of complex biological, social,
and technological networks. We define an ensemble of hierarchically nested
random graphs, which we use to validate the method. We then apply our method to
real-world networks, including the air-transportation network, an electronic
circuit, an email exchange network, and metabolic networks. We find that our
method enables us to obtain an accurate multi-scale descriptions of a complex
system.Comment: Figures in screen resolution. Version with full resolution figures
available at
http://amaral.chem-eng.northwestern.edu/Publications/Papers/sales-pardo-2007.pd
Self Organized Scale-Free Networks from Merging and Regeneration
We consider the self organizing process of merging and regeneration of
vertices in complex networks and demonstrate that a scale-free degree
distribution emerges in a steady state of such a dynamics. The merging of
neighbor vertices in a network may be viewed as an optimization of efficiency
by minimizing redundancy. It is also a mechanism to shorten the distance and
thus decrease signaling times between vertices in a complex network. Thus the
merging process will in particular be relevant for networks where these issues
related to global signaling are of concern
The Network of Scientific Collaborations within the European Framework Programme
We use the emergent field of Complex Networks to analyze the network of
scientific collaborations between entities (universities, research
organizations, industry related companies,...) which collaborate in the context
of the so-called Framework Programme. We demonstrate here that it is a
scale--free network with an accelerated growth, which implies that the creation
of new collaborations is encouraged. Moreover, these collaborations possess
hierarchical modularity. Likewise, we find that the information flow depends on
the size of the participants but not on geographical constraints.Comment: 13 pages, 6 figure
Hierarchical characterization of complex networks
While the majority of approaches to the characterization of complex networks
has relied on measurements considering only the immediate neighborhood of each
network node, valuable information about the network topological properties can
be obtained by considering further neighborhoods. The current work discusses on
how the concepts of hierarchical node degree and hierarchical clustering
coefficient (introduced in cond-mat/0408076), complemented by new hierarchical
measurements, can be used in order to obtain a powerful set of topological
features of complex networks. The interpretation of such measurements is
discussed, including an analytical study of the hierarchical node degree for
random networks, and the potential of the suggested measurements for the
characterization of complex networks is illustrated with respect to simulations
of random, scale-free and regular network models as well as real data
(airports, proteins and word associations). The enhanced characterization of
the connectivity provided by the set of hierarchical measurements also allows
the use of agglomerative clustering methods in order to obtain taxonomies of
relationships between nodes in a network, a possibility which is also
illustrated in the current article.Comment: 19 pages, 23 figure
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