74 research outputs found
A model for cross-cultural reciprocal interactions through mass media
We investigate the problem of cross-cultural interactions through mass media
in a model where two populations of social agents, each with its own internal
dynamics, get information about each other through reciprocal global
interactions. As the agent dynamics, we employ Axelrod's model for social
influence. The global interaction fields correspond to the statistical mode of
the states of the agents and represent mass media messages on the cultural
trend originating in each population. Several phases are found in the
collective behavior of either population depending on parameter values: two
homogeneous phases, one having the state of the global field acting on that
population, and the other consisting of a state different from that reached by
the applied global field; and a disordered phase. In addition, the system
displays nontrivial effects: (i) the emergence of a largest minority group of
appreciable size sharing a state different from that of the applied global
field; (ii) the appearance of localized ordered states for some values of
parameters when the entire system is observed, consisting of one population in
a homogeneous state and the other in a disordered state. This last situation
can be considered as a social analogue to a chimera state arising in globally
coupled populations of oscillators.Comment: 8 pages and 7 figure
Emergence and persistence of communities in coevolutionary networks
We investigate the emergence and persistence of communities through a
recently proposed mechanism of adaptive rewiring in coevolutionary networks. We
characterize the topological structures arising in a coevolutionary network
subject to an adaptive rewiring process and a node dynamics given by a simple
voterlike rule. We find that, for some values of the parameters describing the
adaptive rewiring process, a community structure emerges on a connected
network. We show that the emergence of communities is associated to a decrease
in the number of active links in the system, i.e. links that connect two nodes
in different states. The lifetime of the community structure state scales
exponentially with the size of the system. Additionally, we find that a small
noise in the node dynamics can sustain a diversity of states and a community
structure in time in a finite size system. Thus, large system size and/or local
noise can explain the persistence of communities and diversity in many real
systems.Comment: 6 pages, 5 figures, Accepted in EPL (2014
Against mass media trends: minority growth in cultural globalization
We investigate the collective behavior of a globalized society under the
influence of endogenous mass media trends. The mass media trend is a global
field corresponding to the statistical mode of the states of the agents in the
system. The interaction dynamics is based on Axelrod's rules for the
dissemination of culture. We find situations where the largest minority group,
possessing a cultural state different from that of the predominant trend
transmitted by the mass media, can grow to almost half of the size of the
population. We show that this phenomenon occurs when a critical number of
long-range connections are present in the underlying network of interactions.
We have numerically characterized four phases on the space of parameters of the
system: an ordered phase; a semi-ordered phase where almost half of the
population consists of the largest minority in a state different from that of
the mass media; a disordered phase; and a chimera-like phase where one large
domain coexists with many very small domains.Comment: 7 pages and 7 figure
General coevolution of topology and dynamics in networks
We present a general framework for the study of coevolution in dynamical
systems. This phenomenon consists of the coexistence of two dynamical processes
on networks of interacting elements: node state change and rewiring of links
between nodes. The process of rewiring is described in terms of two basic
actions: disconnection and reconnection between nodes, both based on a
mechanism of comparison of their states. We assume that the process of rewiring
and node state change occur with probabilities Pr and Pc respectively,
independent of each other. The collective behavior of a coevolutionary system
can be characterized on the space of parameters (Pr, Pc). As an application,
for a voterlike node dynamics we find that reconnections between nodes with
similar states lead to network fragmentation. The critical boundaries for the
onset of fragmentation in networks with different properties are calculated on
this space. We show that coevolution models correspond to curves on this space
describing functional relations between Pr and Pc. The occurrence of a
one-large-domain phase and a fragmented phase in the network is predicted for
diverse models, and agreement is found with some earlier results. The
collective behavior of system is also characterized on the space of parameters
for the disconnection and reconnection actions. In a region of this space, we
find a behavior where different node states can coexist for very long times on
one large, connected network.Comment: 6 pages, 6 figure
Co-evolutionnary network approach to cultural dynamics controlled by intolerance
Starting from Axelrod's model of cultural dissemination, we introduce a
rewiring probability, enabling agents to cut the links with their unfriendly
neighbors if their cultural similarity is below a tolerance parameter. For low
values of tolerance, rewiring promotes the convergence to a frozen monocultural
state. However, intermediate tolerance values prevent rewiring once the network
is fragmented, resulting in a multicultural society even for values of initial
cultural diversity in which the original Axelrod model reaches globalization
Ordering dynamics and aging in the Symmetrical Threshold model
The so-called Granovetter-Watts model was introduced to capture a situation
in which the adoption of new ideas or technologies requires a certain
redundancy in the social environment of each agent to take effect. This model
has become a paradigm for complex contagion. Here we investigate a symmetric
version of the model: agents may be in two states that can spread equally
through the system via complex contagion. We find three possible phases: a
mixed one (dynamically active disordered state), an ordered one, and a
heterogeneous frozen phase. These phases exist for several configurations of
the contact network. Then we consider the effect of introducing aging as a
non-Markovian mechanism in the model, where agents become increasingly
resistant to change their state the longer they remain in it. We show that when
aging is present, the mixed phase is replaced, for sparse networks, by a new
phase with different dynamical properties. This new phase is characterized by
an initial disordering stage followed by a slow ordering process towards a
fully ordered absorbing state. In the ordered phase, aging modifies the
dynamical properties. For random contact networks, we develop a theoretical
description based on an Approximate Master Equation that describes with good
accuracy the results of numerical simulations for the model with and without
aging.Comment: 17 pages, 15 figure
Hydrogen-free SiCN films obtained by electron cyclotron resonance plasma: a study of composition, optical and luminescent properties
The Electrochemical Society, Inc. 2007. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Journal of the Electrochemical Society Vol. 154 Issue 4 (2007): H325-H33
General coevolution of topology and dynamics in networks
We present a general framework for the study of coevolution in dynamical
systems. This phenomenon consists of the coexistence of two dynamical processes
on networks of interacting elements: node state change and rewiring of links
between nodes. The process of rewiring is described in terms of two basic
actions: disconnection and reconnection between nodes, both based on a
mechanism of comparison of their states. We assume that the process of rewiring
and node state change occur with probabilities Pr and Pc respectively,
independent of each other. The collective behavior of a coevolutionary system
can be characterized on the space of parameters (Pr, Pc). As an application,
for a voterlike node dynamics we find that reconnections between nodes with
similar states lead to network fragmentation. The critical boundaries for the
onset of fragmentation in networks with different properties are calculated on
this space. We show that coevolution models correspond to curves on this space
describing functional relations between Pr and Pc. The occurrence of a
one-large-domain phase and a fragmented phase in the network is predicted for
diverse models, and agreement is found with some earlier results. The
collective behavior of system is also characterized on the space of parameters
for the disconnection and reconnection actions. In a region of this space, we
find a behavior where different node states can coexist for very long times on
one large, connected network.Comment: 6 pages, 6 figure
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