2,441 research outputs found
Continuous and discontinuous absorbing-state phase transitions on Voronoi-Delaunay random lattices
We study absorbing-state phase transitions in two-dimensional
Voronoi-Delaunay (VD) random lattices with quenched coordination disorder.
Quenched randomness usually changes the criticality and destroys discontinuous
transitions in low-dimensional nonequilibrium systems. We performed extensive
simulations of the Ziff-Gulari-Barshad (ZGB) model, and verified that the VD
disorder does not change the nature of its discontinuous transition. Our
results corroborate recent findings of Barghatti and Vojta [Phys. Rev. Lett.
{\bf 113}, 120602 (2014)] stating the irrelevance of topological disorder in a
class of random lattices that includes VD and raise the interesting possibility
that disorder in nonequilibrium APT may, under certain conditions, be
irrelevant for the phase coexistence. We also verify that the VD disorder is
irrelevant for the critical behavior of models belonging to the directed
percolation and Manna universality classes.Comment: 7 pages, 6 figure
Local vs. long-range infection in unidimensional epidemics
We study the effects of local and distance interactions in the unidimensional
contact process (CP). In the model, each site of a lattice is occupied by an
individual, which can be healthy or infected. As in the standard CP, each
infected individual spreads the disease to one of its first-neighbors with rate
, and with unitary rate, it becomes healthy. However, in our model, an
infected individual can transmit the disease to an individual at a distance
apart. This step mimics a vector-mediated transmission. We observe the
host-host interactions do not alter the critical exponents significantly in
comparison to a process with only L\'evy-type interactions. Our results
confirm, numerically, early field-theoretic predictions.Comment: 8 pages, 6 figures, to appear on Frontiers in Physic
Quantum Dissipation in a Neutrino System Propagating in Vacuum and in Matter
Considering the neutrino state like an open quantum system, we analyze its
propagation in vacuum or in matter. After defining what can be called
decoherence and relaxation effects, we show that in general the probabilities
in vacuum and in constant matter can be written in a similar way, which is not
an obvious result in this approach. From this result, we analyze the situation
where neutrinos evolution satisfies the adiabatic limit and use this formalim
to study solar neutrinos. We show that the decoherence effect may not be
bounded by the solar neutrino data and review some results in the literature.
We discuss the current results where solar neutrinos were used to put bounds on
decoherence effects through a model-dependent approach. We conclude explaining
how and why this models are not general and we reinterpret these constraints.Comment: new version: title was changend and was added a table. To appear at
Nucl. Physic.
Contact process on a Voronoi triangulation
We study the continuous absorbing-state phase transition in the contact
process on the Voronoi-Delaunay lattice. The Voronoi construction is a natural
way to introduce quenched coordination disorder in lattice models. We simulate
the disordered system using the quasistationary simulation method and determine
its critical exponents and moment ratios. Our results suggest that the critical
behavior of the disordered system is unchanged with respect to that on a
regular lattice, i.e., that of directed percolation
An epidemiological model with voluntary quarantine strategies governed by evolutionary game dynamics
During pandemic events, strategies such as social distancing can be
fundamental to curb viral spreading. Such actions can reduce the number of
simultaneous infections and mitigate the disease spreading, which is relevant
to the risk of a healthcare system collapse. Although these strategies can be
suggested, their actual implementation may depend on the population perception
of the disease risk. The current COVID-19 crisis, for instance, is showing that
some individuals are much more prone than others to remain isolated, avoiding
unnecessary contacts. With this motivation, we propose an epidemiological SIR
model that uses evolutionary game theory to take into account dynamic
individual quarantine strategies, intending to combine in a single process
social strategies, individual risk perception, and viral spreading. The disease
spreads in a population whose agents can choose between self-isolation and a
lifestyle careless of any epidemic risk. The strategy adoption is individual
and depends on the perceived disease risk compared to the quarantine cost. The
game payoff governs the strategy adoption, while the epidemic process governs
the agent's health state. At the same time, the infection rate depends on the
agent's strategy while the perceived disease risk depends on the fraction of
infected agents. Results show recurrent infection waves, which were seen in
previous epidemic scenarios with quarantine. Notably, the risk perception is
found to be fundamental for controlling the magnitude of the infection peak,
while the final infection size is mainly dictated by the infection rates. Low
awareness leads to a single and strong infection peak, while a greater disease
risk leads to shorter, although more frequent, peaks. The proposed model
spontaneously captures relevant aspects of a pandemic event, highlighting the
fundamental role of social strategies
A survey of cultural aspects in Human Computer Interaction Research
Considering culture in human computer interaction research is an important issue since culture has a strong impact on many cognitive and affective processes, closed related to the design and evaluation of interactive systems. Also, people with different cultural backgrounds develop alternative interpretations and strategies and do not value their environment in the same way, and this reflects in their interactions and satisfaction with interactive technologies. In this survey we summarize some concepts of the cultural aspects related to human computer interaction research. After we discuss how HCI practices could address these cultural issues. Our intention is to establish background and some basic concepts for helping researchers incorporating cultural issues in their design and evaluation processes
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