Prof. Silvio Ferreira
W. Cota, S. C. Ferreira, R. Pastor-Satorras, and M. Starnini, Quantifying echo chamber effects in information spreading over political communication networks, arXiv:1901.03688
We quantify the effects of echo chambers on the diffusion of information over online communication networks, characterizing the debate about the impeachment process of former Brazilian President Dilma Rousseff. We estimate the capability of users to spread the content they produce, showing that individuals broadcasting pro-impeachment sentiments can break their echo chamber, by reaching a larger and more diverse audience than other users. Figure shows the aggregated network of users expressing majorly pro-impeachment (blue), neutral (white), and anti-impeachment (red) sentiments in the content produced by them.
 A. J. Pereira, S. G. Alves, S. C. Ferreira, Effects of a kinetic barrier on limited-mobility interface growth models, arXiv:1902.03211, to appear in Phys. Rev. E (2019).
We investigate discrete growth models for MBE where the particles moving from the top to the bottom of a terrace follows a random walk instead going directly as usually done. This effectively produces a probability to move downward that plays the role of a step barrier. We see that this simple mechanism is sufficient to destabilize the surface and produce 3d structures in the form of mounds. Figure shows surfaces generated with the Wolf-Villain model considering (right) or not (left) this purely kinetic step barrier.
E. E. M. Luis, T. A. de Assis, S. C. Ferreira, and R. F. S. Andrade, Local roughness exponent in the nonlinear molecular-beam-epitaxy universality class in one-dimension, Phys. Rev. E 99 022801 (2019).
We report local roughness exponents for three different models of surface kinetic roughening which belong to the non-linear molecular beam epitaxy universality class for. Our estimates shows that all investigated models present asymptotic non-anomalous scaling with local roughness exponent consistent with the VLDS equation in two-loop renormalization group analysis.
D. H. Silva, S. C. Ferreira, Activation thresholds in epidemic spreading with motile infectious agents on scale-free networks, Chaos 28, 123112 (2018).
We analyze the effects of two diffusion rules, with and without preference to move towards higher degree vertices, on the epidemic SIS model on scale-free networks. We found standard diffusion yield an optimum diffusion rate, in which the threshold is minimum. Preferential diffusion remarkably changes the activation threshold in both analytical approximations and simulations. Figure shows the dependence with diffusion rate for standard (inset) and preferential (main) models.