2,234 research outputs found
Collective intelligence: aggregation of information from neighbors in a guessing game
Complex systems show the capacity to aggregate information and to display
coordinated activity. In the case of social systems the interaction of
different individuals leads to the emergence of norms, trends in political
positions, opinions, cultural traits, and even scientific progress. Examples of
collective behavior can be observed in activities like the Wikipedia and Linux,
where individuals aggregate their knowledge for the benefit of the community,
and citizen science, where the potential of collectives to solve complex
problems is exploited. Here, we conducted an online experiment to investigate
the performance of a collective when solving a guessing problem in which each
actor is endowed with partial information and placed as the nodes of an
interaction network. We measure the performance of the collective in terms of
the temporal evolution of the accuracy, finding no statistical difference in
the performance for two classes of networks, regular lattices and random
networks. We also determine that a Bayesian description captures the behavior
pattern the individuals follow in aggregating information from neighbors to
make decisions. In comparison with other simple decision models, the strategy
followed by the players reveals a suboptimal performance of the collective. Our
contribution provides the basis for the micro-macro connection between
individual based descriptions and collective phenomena.Comment: 9 pages, 9 figure
Competition in the presence of aging: order, disorder, and synchronized collective behavior
We study the stochastic dynamics of coupled states with transition
probabilities depending on local persistence, this is, the time since a state
has changed. When the population has a preference to adopt older states the
system orders quickly due to the dominance of the old state. When preference
for new states prevails, the system can show coexistence of states or
synchronized collective behavior resulting in long ordering times. In this
case, the magnetization of the system oscillates around .
Implications for social systems are discussed.Comment: 5 pages, 5 figures, lette
Hypoxic Cell Waves around Necrotic Cores in Glioblastoma: A Biomathematical Model and its Therapeutic Implications
Glioblastoma is a rapidly evolving high-grade astrocytoma that is
distinguished pathologically from lower grade gliomas by the presence of
necrosis and microvascular hiperplasia. Necrotic areas are typically surrounded
by hypercellular regions known as "pseudopalisades" originated by local tumor
vessel occlusions that induce collective cellular migration events. This leads
to the formation of waves of tumor cells actively migrating away from central
hypoxia. We present a mathematical model that incorporates the interplay among
two tumor cell phenotypes, a necrotic core and the oxygen distribution. Our
simulations reveal the formation of a traveling wave of tumor cells that
reproduces the observed histologic patterns of pseudopalisades. Additional
simulations of the model equations show that preventing the collapse of tumor
microvessels leads to slower glioma invasion, a fact that might be exploited
for therapeutic purposes.Comment: 29 pages, 9 figure
Nondiffractive sonic crystals
We predict theoretically the nondiffractive propagation of sonic waves in
periodic acoustic media (sonic crystals), by expansion into a set of plane
waves (Bloch mode expansion), and by finite difference time domain calculations
of finite beams. We also give analytical evaluations of the parameters for
nondiffractive propagation, as well as the minimum size of the nondiffractively
propagating acoustic beams.Comment: 7 figures, submitted to J. Acoust. Soc. A
Driving defect modes of Bose-Einstein condensates in optical lattices
We present an approximate analytical theory and direct numerical computation
of defect modes of a Bose-Einstein condensate loaded in an optical lattice and
subject to an additional localized (defect) potential. Some of the modes are
found to be remarkably stable and can be driven along the lattice by means of a
defect moving following a step-like function defined by the period of Josephson
oscillations and the macroscopic stability of the atoms.Comment: 4 pages, 5 figure
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