2,321 research outputs found
Corporate competition: A self-organized network
A substantial number of studies have extended the work on universal properties in physical systems to complex networks in social, biological, and technological systems. In this paper, we present a complex networks perspective on interfirm organizational networks by mapping, analyzing and modeling the spatial structure of a large interfirm competition network across a variety of sectors and industries within the United States. We propose two micro-dynamic models that are able to reproduce empirically observed characteristics of competition networks as a natural outcome of a minimal set of general mechanisms governing the formation of competition networks. Both models, which utilize different approaches yet apply common principles to network formation give comparable results. There is an asymmetry between companies that are considered competitors, and companies that consider others as their competitors. All companies only consider a small number of other companies as competitors; however, there are a few companies that are considered as competitors by many others. Geographically, the density of corporate headquarters strongly correlates with local population density, and the probability two firms are competitors declines with geographic distance. We construct these properties by growing a corporate network with competitive links using random incorporations modulated by population density and geographic distance. Our new analysis, methodology and empirical results are relevant to various phenomena of social and market behavior, and have implications to research fields such as economic geography, economic sociology, and regional economic development.Organizational networks; Interfirm competition; Economic geography; Social networks; Spatial networks; Network dynamics; Firm size dynamics
Modeling the IPv6 Internet AS-level Topology
To measure the IPv6 internet AS-level topology, a network topology discovery
system, called Dolphin, was developed. By comparing the measurement result of
Dolphin with that of CAIDA's Scamper, it was found that the IPv6 Internet at AS
level, similar to other complex networks, is also scale-free but the exponent
of its degree distribution is 1.2, which is much smaller than that of the IPv4
Internet and most other scale-free networks. In order to explain this feature
of IPv6 Internet we argue that the degree exponent is a measure of uniformity
of the degree distribution. Then, for the purpose on modeling the networks, we
propose a new model based on the two major factors affecting the exponent of
the EBA model. It breaks the lower bound of degree exponent which is 2 for most
models. To verify the validity of this model, both theoretical and experimental
analyses have been carried out. Finally, we demonstrate how this model can be
successfully used to reproduce the topology of the IPv6 Internet.Comment: 15 pages, 5 figure
Link creation and profile alignment in the aNobii social network
The present work investigates the structural and dynamical properties of
aNobii\footnote{http://www.anobii.com/}, a social bookmarking system designed
for readers and book lovers. Users of aNobii provide information about their
library, reading interests and geographical location, and they can establish
typed social links to other users. Here, we perform an in-depth analysis of the
system's social network and its interplay with users' profiles. We describe the
relation of geographic and interest-based factors to social linking.
Furthermore, we perform a longitudinal analysis to investigate the interplay of
profile similarity and link creation in the social network, with a focus on
triangle closure. We report a reciprocal causal connection: profile similarity
of users drives the subsequent closure in the social network and, reciprocally,
closure in the social network induces subsequent profile alignment. Access to
the dynamics of the social network also allows us to measure quantitative
indicators of preferential linking.Comment: http://www.iisocialcom.org/conference/socialcom2010
Evolution of networks
We review the recent fast progress in statistical physics of evolving
networks. Interest has focused mainly on the structural properties of random
complex networks in communications, biology, social sciences and economics. A
number of giant artificial networks of such a kind came into existence
recently. This opens a wide field for the study of their topology, evolution,
and complex processes occurring in them. Such networks possess a rich set of
scaling properties. A number of them are scale-free and show striking
resilience against random breakdowns. In spite of large sizes of these
networks, the distances between most their vertices are short -- a feature
known as the ``small-world'' effect. We discuss how growing networks
self-organize into scale-free structures and the role of the mechanism of
preferential linking. We consider the topological and structural properties of
evolving networks, and percolation in these networks. We present a number of
models demonstrating the main features of evolving networks and discuss current
approaches for their simulation and analytical study. Applications of the
general results to particular networks in Nature are discussed. We demonstrate
the generic connections of the network growth processes with the general
problems of non-equilibrium physics, econophysics, evolutionary biology, etc.Comment: 67 pages, updated, revised, and extended version of review, submitted
to Adv. Phy
Properties of Healthcare Teaming Networks as a Function of Network Construction Algorithms
Network models of healthcare systems can be used to examine how providers
collaborate, communicate, refer patients to each other. Most healthcare service
network models have been constructed from patient claims data, using billing
claims to link patients with providers. The data sets can be quite large,
making standard methods for network construction computationally challenging
and thus requiring the use of alternate construction algorithms. While these
alternate methods have seen increasing use in generating healthcare networks,
there is little to no literature comparing the differences in the structural
properties of the generated networks. To address this issue, we compared the
properties of healthcare networks constructed using different algorithms and
the 2013 Medicare Part B outpatient claims data. Three different algorithms
were compared: binning, sliding frame, and trace-route. Unipartite networks
linking either providers or healthcare organizations by shared patients were
built using each method. We found that each algorithm produced networks with
substantially different topological properties. Provider networks adhered to a
power law, and organization networks to a power law with exponential cutoff.
Censoring networks to exclude edges with less than 11 shared patients, a common
de-identification practice for healthcare network data, markedly reduced edge
numbers and greatly altered measures of vertex prominence such as the
betweenness centrality. We identified patterns in the distance patients travel
between network providers, and most strikingly between providers in the
Northeast United States and Florida. We conclude that the choice of network
construction algorithm is critical for healthcare network analysis, and discuss
the implications for selecting the algorithm best suited to the type of
analysis to be performed.Comment: With links to comprehensive, high resolution figures and networks via
figshare.co
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