290,762 research outputs found
Coupled effects of local movement and global interaction on contagion
By incorporating segregated spatial domain and individual-based linkage into
the SIS (susceptible-infected-susceptible) model, we investigate the coupled
effects of random walk and intragroup interaction on contagion. Compared with
the situation where only local movement or individual-based linkage exists, the
coexistence of them leads to a wider spread of infectious disease. The roles of
narrowing segregated spatial domain and reducing mobility in epidemic control
are checked, these two measures are found to be conducive to curbing the spread
of infectious disease. Considering heterogeneous time scales between local
movement and global interaction, a log-log relation between the change in the
number of infected individuals and the timescale is found. A theoretical
analysis indicates that the evolutionary dynamics in the present model is
related to the encounter probability and the encounter time. A functional
relation between the epidemic threshold and the ratio of shortcuts, and a
functional relation between the encounter time and the timescale are
found
Outline of a multilevel approach of the network society
Social and media networks, the Internet in particular, increasingly link interpersonal, organizational and mass communication. It is argued that this gives a cause for an interdisciplinary and multilevel approach of the network society. This will have to link traditional micro- and meso-level research of social and communication ties (Rogers, Granovetter a.o.) to the macro-level research of the network society at large (Castells a.o.).\ud
Systems theory linked to a theory of communicative action establishes a potential basis for a multilevel theory. The systems theory described uses elements of a biologically inspired analysis of networks as complex adaptive systems and the mathematically inspired theory of random and scale-free networks recently elaborated by Barabási, Strogatz and Watts. The outline of the multilevel theory is summarized in ten statements about changing relationships in the network society: an information society with structures and modes of organization primarily shaped by social and media networks. \ud
In the last section an inventory is made of the theoretical and methodological changes communication science will have to make to develop a general theory of the information and the network society in the perspective of communication
Theories for influencer identification in complex networks
In social and biological systems, the structural heterogeneity of interaction
networks gives rise to the emergence of a small set of influential nodes, or
influencers, in a series of dynamical processes. Although much smaller than the
entire network, these influencers were observed to be able to shape the
collective dynamics of large populations in different contexts. As such, the
successful identification of influencers should have profound implications in
various real-world spreading dynamics such as viral marketing, epidemic
outbreaks and cascading failure. In this chapter, we first summarize the
centrality-based approach in finding single influencers in complex networks,
and then discuss the more complicated problem of locating multiple influencers
from a collective point of view. Progress rooted in collective influence
theory, belief-propagation and computer science will be presented. Finally, we
present some applications of influencer identification in diverse real-world
systems, including online social platforms, scientific publication, brain
networks and socioeconomic systems.Comment: 24 pages, 6 figure
Society seen through the prism of space: outline of a theory of society and space
Two questions challenge the student of space and society above all others: will new technologies
change the spatial basis of society ? And if so, will this have an impact on society itself ?
For the urbanist, these two questions crystallise into one: what will the future of cities have
to do with their past ? Too often these questions are dealt with as though they were only
matters of technology. But they are much more than that. They are deep and difficult questions
about the interdependence of technology, space and society that we do not yet have the
theoretical apparatus to answer. We know that previous �revolutions� in technology such as
agriculture, urbanism and industrialisation associated radical changes in space with no less
radical changes in social institutions. But we do not know how far these linkages were
contingent or necessary. We do not, in short, have a theory of society and space adequate to
account for where we are now, and therefore we have no reasonable theoretical base for
speculating about the future. In this paper, I suggest that a major reason for this theoretical
deficit is that most previous attempts to build a theory of society and space have looked at
society and tried to find space in its output. The result has been that the constructive role of
space in creating and and sustaining society has not been brought to the fore, or if it has, only
in a way which is too general to permit the detailed specification of mechanisms. In this
paper I try to reverse the normal order of things this by looking first at space and trying the
discern society through space: by looking at society through the prism of space. Through this
I try to define key mechanisms linking space to society and then use these to suggest how the
questions about the future of cities and societies might be better defined
The Majority Illusion in Social Networks
Social behaviors are often contagious, spreading through a population as
individuals imitate the decisions and choices of others. A variety of global
phenomena, from innovation adoption to the emergence of social norms and
political movements, arise as a result of people following a simple local rule,
such as copy what others are doing. However, individuals often lack global
knowledge of the behaviors of others and must estimate them from the
observations of their friends' behaviors. In some cases, the structure of the
underlying social network can dramatically skew an individual's local
observations, making a behavior appear far more common locally than it is
globally. We trace the origins of this phenomenon, which we call "the majority
illusion," to the friendship paradox in social networks. As a result of this
paradox, a behavior that is globally rare may be systematically overrepresented
in the local neighborhoods of many people, i.e., among their friends. Thus, the
"majority illusion" may facilitate the spread of social contagions in networks
and also explain why systematic biases in social perceptions, for example, of
risky behavior, arise. Using synthetic and real-world networks, we explore how
the "majority illusion" depends on network structure and develop a statistical
model to calculate its magnitude in a network
Do language change rates depend on population size?
An earlier study (Nettle 1999b) concluded, based on computer simulations and
some inferences from empirical data, that languages will change the more slowly
the larger the population gets. We replicate this study using a more complete
language model for simulations (the Schulze model combined with a
Barabasi-Albert net- work) and a richer empirical dataset (the World Atlas of
Language Structures edited by Haspelmath et al. 2005). Our simulations show
either a weak or stronger dependence of language change on population sizes
depending on the parameter settings, and empirical data, like some of the
simulations, show a weak dependence.Comment: 20 pages including all figures for a linguistic journa
Evolutionary game theory: Temporal and spatial effects beyond replicator dynamics
Evolutionary game dynamics is one of the most fruitful frameworks for
studying evolution in different disciplines, from Biology to Economics. Within
this context, the approach of choice for many researchers is the so-called
replicator equation, that describes mathematically the idea that those
individuals performing better have more offspring and thus their frequency in
the population grows. While very many interesting results have been obtained
with this equation in the three decades elapsed since it was first proposed, it
is important to realize the limits of its applicability. One particularly
relevant issue in this respect is that of non-mean-field effects, that may
arise from temporal fluctuations or from spatial correlations, both neglected
in the replicator equation. This review discusses these temporal and spatial
effects focusing on the non-trivial modifications they induce when compared to
the outcome of replicator dynamics. Alongside this question, the hypothesis of
linearity and its relation to the choice of the rule for strategy update is
also analyzed. The discussion is presented in terms of the emergence of
cooperation, as one of the current key problems in Biology and in other
disciplines.Comment: Review, 48 pages, 26 figure
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