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  1. Book ; Online: Recent violent political extremist events in Brazil and epidemic modeling

    Crokidakis, Nuno

    The role of a SIS-like model on the understanding of spreading and control of radicalism

    2023  

    Abstract: In this work we study a simple mathematical model to analyze the emergence and control of radicalization phenomena, motivated by the recent far-right extremist events in Brazil, occurred in January 8, 2023. For this purpose, we considered a compartmental ...

    Abstract In this work we study a simple mathematical model to analyze the emergence and control of radicalization phenomena, motivated by the recent far-right extremist events in Brazil, occurred in January 8, 2023. For this purpose, we considered a compartmental SIS-like model that takes into account only the right electors, for simplicity. The model considers radical and moderated right electors, and the transitions between the two compartments are ruled by probabilities, taking into account pairwise social interactions and the important influence of social media through the dissemination of fake news. The role of the Brazilian Federal Supreme Court on the control of such violent activities is also considered in a simple way. The analytical and numerical results show that the influence of social media is essential for the spreading and prevalence of radicalism in the population. In the presence of such social media, we show that radicalism can be controlled, but not extincted, by an external influence, that models the acting of the Federal Supreme Court over the violent activities of radicals. If the social media effect is absent, the radicalism can disappear of the population, and this phenomenon is associated with an active-absorbing nonequilibrium phase transition, like the one that occurs in the standard SIS model.

    Comment: 12 pages, 3 figures
    Keywords Physics - Physics and Society ; Computer Science - Social and Information Networks
    Subject code 300
    Publishing date 2023-03-21
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Book ; Online: Radicalization phenomena

    Crokidakis, Nuno

    Phase transitions, extinction processes and control of violent activities

    2022  

    Abstract: In this work we study a simple mathematical model to analyze the emergence and control of radicalization phenomena. The population consisits of core and sensitive subpopulations, and their ways of life may be at least partially incompatible. In such a ... ...

    Abstract In this work we study a simple mathematical model to analyze the emergence and control of radicalization phenomena. The population consisits of core and sensitive subpopulations, and their ways of life may be at least partially incompatible. In such a case, if a conflict exist, core agents act as inflexible individuals about the issue. On the other hand, the sensitive agents choose between two options: live peacefully with core population, or oppose it. This kind of modeling was recently considered by Galam and Javarone (2016) with constant pairwise couplings. Here, we consider the more general case with time-dependent transition rates, with the aim of study the impact of such time dependence on the critical behavior of the model. The analytical and numerical results show that the nonequilibrium active-absorbing phase transition can be suppressed in some cases, with the destruction of the absorbing phase where the radical agents disappear of the population in the stationary states.

    Comment: 12 pages, 5 figures, to appear in IJMPC
    Keywords Physics - Physics and Society ; Condensed Matter - Statistical Mechanics
    Subject code 612
    Publishing date 2022-12-21
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article: COVID-19 spreading in Rio de Janeiro, Brazil: Do the policies of social isolation really work?

    Crokidakis, Nuno

    Chaos, solitons, and fractals

    2020  Volume 136, Page(s) 109930

    Abstract: The recent Coronavirus has been spreading through all the world fastly. In this work we focus on the evolution of the COVID-19 in one of the most populous Brazilian states, namely the Rio de Janeiro state. The first case was reported in March 5, 2020, ... ...

    Abstract The recent Coronavirus has been spreading through all the world fastly. In this work we focus on the evolution of the COVID-19 in one of the most populous Brazilian states, namely the Rio de Janeiro state. The first case was reported in March 5, 2020, thus we have a considerable amount of available data to make a good analysis. We study the dynamics of COVID-19 through a Susceptible-Infectious-Quarantined-Recovered (SIQR) model with an additional mechanism that represents the implementation of public policies of social isolation. Based on the data collected from the Rio de Janeiro state Department of Health from March 5, 2020 through April 26, 2020, we observed that the implementation of social distancing policies changed the initial exponential growth to a sub-exponential one. The SIQR model with the above-mentioned mechanism is capable of reproducing the data of confirmed cases in Rio de Janeiro, and it explains how that change occurred. The model also predicts an important mitigation effect, namely the flattening effect, i.e., the considerably decrease of the maximum number of confirmed cases. Through the results of the model, this effect can be directly related to the social isolation policies. Finally, we consider the relaxation of such policies, and discuss about the ideal period of time to release people to return to their activities.
    Keywords covid19
    Language English
    Publishing date 2020-05-23
    Publishing country England
    Document type Journal Article
    ZDB-ID 2003919-0
    ISSN 1873-2887 ; 0960-0779
    ISSN (online) 1873-2887
    ISSN 0960-0779
    DOI 10.1016/j.chaos.2020.109930
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: COVID-19 spreading in Rio de Janeiro, Brazil

    Crokidakis, Nuno

    Chaos, Solitons & Fractals

    Do the policies of social isolation really work?

    2020  Volume 136, Page(s) 109930

    Keywords General Mathematics ; covid19
    Language English
    Publisher Elsevier BV
    Publishing country us
    Document type Article ; Online
    ZDB-ID 2003919-0
    ISSN 1873-2887 ; 0960-0779
    ISSN (online) 1873-2887
    ISSN 0960-0779
    DOI 10.1016/j.chaos.2020.109930
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Double transition in kinetic exchange opinion models with activation dynamics.

    Pires, Marcelo A / Crokidakis, Nuno

    Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

    2022  Volume 380, Issue 2224, Page(s) 20210164

    Abstract: In this work, we study a model of opinion dynamics considering activation/deactivation of agents. In other words, individuals are not static and can become inactive and drop out from the discussion. A probability [Formula: see text] governs the ... ...

    Abstract In this work, we study a model of opinion dynamics considering activation/deactivation of agents. In other words, individuals are not static and can become inactive and drop out from the discussion. A probability [Formula: see text] governs the deactivation dynamics, whereas social interactions are ruled by kinetic exchanges, considering competitive positive/negative interactions. Inactive agents can become active due to interactions with active agents. Our analytical and numerical results show the existence of two distinct non-equilibrium phase transitions, with the occurrence of three phases, namely ordered (ferromagnetic-like), disordered (paramagnetic-like) and absorbing phases. The absorbing phase represents a collective state where all agents are inactive, i.e. they do not participate in the dynamics, inducing a frozen state. We determine the critical value [Formula: see text] above which the system is in the absorbing phase independently of the other parameters. We also verify a distinct critical behaviour for the transitions among different phases. This article is part of the theme issue 'Kinetic exchange models of societies and economies'.
    MeSH term(s) Humans ; Kinetics ; Phase Transition ; Probability
    Language English
    Publishing date 2022-04-11
    Publishing country England
    Document type Journal Article
    ZDB-ID 208381-4
    ISSN 1471-2962 ; 0080-4614 ; 0264-3820 ; 0264-3952 ; 1364-503X
    ISSN (online) 1471-2962
    ISSN 0080-4614 ; 0264-3820 ; 0264-3952 ; 1364-503X
    DOI 10.1098/rsta.2021.0164
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: COVID-19 spreading in Rio de Janeiro, Brazil: do the policies of social isolation really work?

    Crokidakis, Nuno

    medRxiv

    Abstract: The recent Coronavirus (COVID-19) has been spreading through all the world fastly. In this work we focus on the evolution of the COVID-19 in one of the most populous Brazilian states, namely the Rio de Janeiro state. The first case was reported in March ... ...

    Abstract The recent Coronavirus (COVID-19) has been spreading through all the world fastly. In this work we focus on the evolution of the COVID-19 in one of the most populous Brazilian states, namely the Rio de Janeiro state. The first case was reported in March 5, 2020, thus we have a considerable amount of available data to make a good analysis. First we study the early evolution of the disease, considering a Susceptible-Infectious-Quarantined-Recovered (SIQR) model. This initial phase shows the usual exponential growth of the number of confirmed cases. In this case, we estimate the parameters of the model based on the data, as well as the epidemic doubling time. After, we analyze all the available data, from March 5, 2020 through April 26, 2020. In this case, we observe a distinct behavior: a sub-exponential growth. In order to capture this change in the behavior of the evolution of the confirmed cases, we consider the implementation of isolation policies. The modified model agrees well with data. Finally, we consider the relaxation of such policies, and discuss about the ideal period of time to release people to return to their activities.
    Keywords covid19
    Language English
    Publishing date 2020-05-03
    Publisher Cold Spring Harbor Laboratory Press
    Document type Article ; Online
    DOI 10.1101/2020.04.27.20081737
    Database COVID19

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  7. Article: Data analysis and modeling of the evolution of COVID-19 in Brazil

    Crokidakis, Nuno

    Abstract: The world evolution of the Severe acute respiratory syndrome coronavirus 2 (SARS-Cov2 or simply COVID-19) lead the World Health Organization to declare it a pandemic. The disease appeared in China in December 2019, and it spread fast around the world, ... ...

    Abstract The world evolution of the Severe acute respiratory syndrome coronavirus 2 (SARS-Cov2 or simply COVID-19) lead the World Health Organization to declare it a pandemic. The disease appeared in China in December 2019, and it spread fast around the world, specially in european countries like Italy and Spain. The first reported case in Brazil was recorded in February 26, and after that the number of cases growed fast. In order to slow down the initial grow of the disease through the country, confirmed positive cases were isolated to not transmit the disease. To better understand the evolution of COVID-19 in Brazil, we apply a Susceptible-Infectious-Quarantined-Recovered (SIQR) model to the analysis of data from the Brazilian Department of Health. Based on analyical and numerical results, as well on the data, the basic reproduction number is estimated to $R_{0}=5.25$. In addition, we estimate that the ratio unidentified infectious individuals and confirmed cases is about $10$, in agreement with previous studies. We also estimated the epidemic doubling time to be $2.72$ days.
    Keywords covid19
    Publisher ArXiv
    Document type Article
    Database COVID19

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  8. Article: Modeling the early evolution of the COVID-19 in Brazil: Results from a Susceptible–Infectious–Quarantined–Recovered (SIQR) model

    Crokidakis, Nuno

    International Journal of Modern Physics C: Computational Physics & Physical Computation

    Abstract: The world evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-Cov2 or simply COVID-19) led the World Health Organization to declare it a pandemic The disease appeared in China in December 2019, and it has spread fast around the world, ... ...

    Abstract The world evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-Cov2 or simply COVID-19) led the World Health Organization to declare it a pandemic The disease appeared in China in December 2019, and it has spread fast around the world, especially in European countries like Italy and Spain The first reported case in Brazil was recorded in February 26, and after that the number of cases grew fast In order to slow down the initial growth of the disease through the country, confirmed positive cases were isolated to not transmit the disease To better understand the early evolution of COVID-19 in Brazil, we apply a Susceptible–Infectious–Quarantined–Recovered (SIQR) model to the analysis of data from the Brazilian Department of Health, obtained from February 26, 2020 through March 25, 2020 Based on analytical and numerical results, as well on the data, the basic reproduction number is estimated to R 0 = 5 2 5 In addition, we estimate that the ratio between unidentified infectious individuals and confirmed cases at the beginning of the epidemic is about 10, in agreement with previous studies We also estimated the epidemic doubling time to be 2 7 2 days [ABSTRACT FROM AUTHOR] Copyright of International Journal of Modern Physics C: Computational Physics & Physical Computation is the property of World Scientific Publishing Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission However, users may print, download, or email articles for individual use This abstract may be abridged No warranty is given about the accuracy of the copy Users should refer to the original published version of the material for the full abstract (Copyright applies to all Abstracts )
    Keywords covid19
    Publisher WHO
    Document type Article
    Note WHO #Covidence: #879649
    Database COVID19

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  9. Article ; Online: COVID-19 spreading in Rio de Janeiro, Brazil

    Crokidakis, Nuno

    reponame:Expeditio Repositorio Institucional UJTL ; instname:Universidad de Bogotá Jorge Tadeo Lozano

    Do the policies of social isolation really work?

    2020  

    Abstract: The recent Coronavirus has been spreading through all the world fastly. In this work we focus on the evolution of the COVID-19 in one of the most populous Brazilian states, namely the Rio de Janeiro state. The first case was reported in March 5, 2020, ... ...

    Abstract The recent Coronavirus has been spreading through all the world fastly. In this work we focus on the evolution of the COVID-19 in one of the most populous Brazilian states, namely the Rio de Janeiro state. The first case was reported in March 5, 2020, thus we have a considerable amount of available data to make a good analysis. We study the dynamics of COVID-19 through a Susceptible-Infectious-QuarantinedRecovered (SIQR) model with an additional mechanism that represents the implementation of public policies of social isolation. Based on the data collected from the Rio de Janeiro state Department of Health from March 5, 2020 through April 26, 2020, we observed that the implementation of social distancing policies changed the initial exponential growth to a sub-exponential one. The SIQR model with the above-mentioned mechanism is capable of reproducing the data of confirmed cases in Rio de Janeiro, and it explains how that change occurred. The model also predicts an important mitigation effect, namely the flattening effect, i.e., the considerably decrease of the maximum number of confirmed cases. Through the results of the model, this effect can be directly related to the social isolation policies. Finally, we consider the relaxation of such policies, and discuss about the ideal period of time to release people to return to their activities.
    Keywords Dynamics of social systems ; Epidemic modeling ; Collective phenomena ; Data analysis ; Síndrome respiratorio agudo grave ; COVID-19 ; SARS-CoV-2 ; Coronavirus ; covid19
    Publisher Chaos, Solitons and Fractals
    Publishing country co
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Book ; Online: Modeling the early evolution of the COVID-19 in Brazil

    Crokidakis, Nuno

    results from a Susceptible-Infectious-Quarantined-Recovered (SIQR) model

    2020  

    Abstract: The world evolution of the Severe acute respiratory syndrome coronavirus 2 (SARS-Cov2 or simply COVID-19) led the World Health Organization to declare it a pandemic. The disease appeared in China in December 2019, and it has spread fast around the world, ...

    Abstract The world evolution of the Severe acute respiratory syndrome coronavirus 2 (SARS-Cov2 or simply COVID-19) led the World Health Organization to declare it a pandemic. The disease appeared in China in December 2019, and it has spread fast around the world, specially in european countries like Italy and Spain. The first reported case in Brazil was recorded in February 26, and after that the number of cases growed fast. In order to slow down the initial growth of the disease through the country, confirmed positive cases were isolated to not transmit the disease. To better understand the early evolution of COVID-19 in Brazil, we apply a Susceptible-Infectious-Quarantined-Recovered (SIQR) model to the analysis of data from the Brazilian Department of Health, obtained from February 26, 2020 through March 25, 2020. Based on analyical and numerical results, as well on the data, the basic reproduction number is estimated to $R_{0}=5.25$. In addition, we estimate that the ratio unidentified infectious individuals and confirmed cases at the beginning of the epidemic is about $10$, in agreement with previous studies. We also estimated the epidemic doubling time to be $2.72$ days.

    Comment: 8 pages, 2 figures, updated version (v2, with a different title) will appear in IJMPC
    Keywords Quantitative Biology - Populations and Evolution ; Physics - Physics and Society ; covid19
    Publishing date 2020-03-26
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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