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Haroldo V. Ribeiro
Universidade Estadual de Maringá
74Publications
14H-index
626Citations
Publications 74
Newest
Published on Feb 5, 2019in Scientific Reports4.01
Higor Y. D. Sigaki1
Estimated H-index: 1
(UEM: Universidade Estadual de Maringá),
Matjaz Perc74
Estimated H-index: 74
(University of Maribor),
Haroldo V. Ribeiro14
Estimated H-index: 14
(UEM: Universidade Estadual de Maringá)
The efficient market hypothesis has far-reaching implications for financial trading and market stability. Whether or not cryptocurrencies are informationally efficient has therefore been the subject of intense recent investigation. Here, we use permutation entropy and statistical complexity over sliding time-windows of price log returns to quantify the dynamic efficiency of more than four hundred cryptocurrencies. We consider that a cryptocurrency is efficient within a time-window when these two...
Published on Dec 1, 2019in Nature Communications11.88
Haroldo V. Ribeiro14
Estimated H-index: 14
(UEM: Universidade Estadual de Maringá),
Diego Rybski21
Estimated H-index: 21
(PIK: Potsdam Institute for Climate Impact Research),
Jürgen P. Kropp22
Estimated H-index: 22
(PIK: Potsdam Institute for Climate Impact Research)
The question of whether urbanization contributes to increasing carbon dioxide emissions has been mainly investigated via scaling relationships with population or population density. However, these approaches overlook the correlations between population and area, and ignore possible interactions between these quantities. Here, we propose a generalized framework that simultaneously considers the effects of population and area along with possible interactions between these urban metrics. Our result...
Published on Feb 1, 2019in Physica A-statistical Mechanics and Its Applications2.50
Luiz G. A. Alves9
Estimated H-index: 9
(USP: University of São Paulo),
José S. Andrade5
Estimated H-index: 5
(UFC: Federal University of Ceará)
+ 1 AuthorsHaroldo V. Ribeiro14
Estimated H-index: 14
(UEM: Universidade Estadual de Maringá)
In spite of the considerable progress towards reducing illiteracy rates, many countries, including developed ones, have encountered difficulty achieving further reduction in these rates. This is worrying because illiteracy has been related to numerous health, social, and economic problems. Here, we show that the spatial patterns of illiteracy in urban systems have several features analogous to the spread of diseases such as dengue and obesity. Our results reveal that illiteracy rates are spatial...
Published on Jan 22, 2019in Physical Review E2.35
Higor Y. D. Sigaki1
Estimated H-index: 1
,
R. F. de Souza2
Estimated H-index: 2
+ 2 AuthorsHaroldo V. Ribeiro14
Estimated H-index: 14
Imaging techniques are essential tools for inquiring a number of properties from different materials. Liquid crystals are often investigated via optical and image processing methods. In spite of that, considerably less attention has been paid to the problem of extracting physical properties of liquid crystals directly from textures images of these materials. Here we present an approach that combines two physics-inspired image quantifiers (permutation entropy and statistical complexity) with mach...
Published on Dec 1, 2018in Journal of Complex Networks
Haroldo V. Ribeiro14
Estimated H-index: 14
(UEM: Universidade Estadual de Maringá),
Luiz G. A. Alves9
Estimated H-index: 9
(USP: University of São Paulo)
+ 2 AuthorsMatjaz Perc74
Estimated H-index: 74
(University of Maribor)
Corruptive behaviour in politics limits economic growth, embezzles public funds, and promotes socio-economic inequality in modern democracies. We analyse well-documented political corruption scandals in Brazil over the past 27 years, focusing on the dynamical structure of networks where two individuals are connected if they were involved in the same scandal. Our research reveals that corruption runs in small groups that rarely comprise more than eight people, in networks that have hubs and a mod...
Higor Y. D. Sigaki1
Estimated H-index: 1
(UEM: Universidade Estadual de Maringá),
Matjaz Perc2
Estimated H-index: 2
(University of Maribor),
Haroldo V. Ribeiro14
Estimated H-index: 14
(UEM: Universidade Estadual de Maringá)
Art is the ultimate expression of human creativity that is deeply influenced by the philosophy and culture of the corresponding historical epoch. The quantitative analysis of art is therefore essential for better understanding human cultural evolution. Here, we present a large-scale quantitative analysis of almost 140,000 paintings, spanning nearly a millennium of art history. Based on the local spatial patterns in the images of these paintings, we estimate the permutation entropy and the statis...
Published on Sep 1, 2018in Physica A-statistical Mechanics and Its Applications2.50
Luiz G. A. Alves9
Estimated H-index: 9
(USP: University of São Paulo),
Haroldo V. Ribeiro14
Estimated H-index: 14
(UEM: Universidade Estadual de Maringá),
Francisco Aparecido Rodrigues19
Estimated H-index: 19
(USP: University of São Paulo)
Abstract Understanding the causes of crime is a longstanding issue in researcher’s agenda. While it is a hard task to extract causality from data, several linear models have been proposed to predict crime through the existing correlations between crime and urban metrics. However, because of non-Gaussian distributions and multicollinearity in urban indicators, it is common to find controversial conclusions about the influence of some urban indicators on crime. Machine learning ensemble-based algo...
Published on Aug 1, 2018in Applied Mathematics and Computation3.09
E. K. Lenzi22
Estimated H-index: 22
(NIST: National Institute of Standards and Technology),
Mauricio A. Ribeiro1
Estimated H-index: 1
+ 2 AuthorsHaroldo V. Ribeiro14
Estimated H-index: 14
(UEM: Universidade Estadual de Maringá)
We investigate a process obtained from a combination of nonlinear diffusion equations with reaction terms connected to a reversible process, i.e., 1⇌2, of two species. This feature implies that the species 1 reacts producing the species 2, and vice-versa. A particular case emerging from this scenario is represented by 1 → 2 (or 2 → 1), characterizing an irreversible process where one species produces the other. The results show that in the asymptotic limit of small and long times the behavior of...
Published on Jul 1, 2018in Physics Letters A2.09
D. Marin1
Estimated H-index: 1
,
Mauricio A. Ribeiro1
Estimated H-index: 1
+ 1 AuthorsE. K. Lenzi22
Estimated H-index: 22
(NIST: National Institute of Standards and Technology)
Abstract We investigate the solutions for a set of coupled nonlinear Fokker–Planck equations coupled by the diffusion coefficient in presence of external forces. The coupling by the diffusion coefficient implies that the diffusion of each species is influenced by the other and vice versa due to this term, which represents an interaction among them. The solutions for the stationary case are given in terms of the Tsallis distributions, when arbitrary external forces are considered. We also use the...
Published on May 1, 2018in Physica A-statistical Mechanics and Its Applications2.50
Max Jauregui3
Estimated H-index: 3
(UEM: Universidade Estadual de Maringá),
Luciano Zunino22
Estimated H-index: 22
(CONICET: National Scientific and Technical Research Council)
+ 2 AuthorsHaroldo V. Ribeiro14
Estimated H-index: 14
(UEM: Universidade Estadual de Maringá)
Abstract One of the most useful tools for distinguishing between chaotic and stochastic time series is the so-called complexity–entropy causality plane. This diagram involves two complexity measures: the Shannon entropy and the statistical complexity. Recently, this idea has been generalized by considering the Tsallis monoparametric generalization of the Shannon entropy, yielding complexity–entropy curves. These curves have proven to enhance the discrimination among different time series related...
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