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  • Item type: Item , Access status: Apenas metadados ,
    Modeling viral mutant-variant dynamics: From continuous optimal control to discrete dosing protocols
    (2026) López-Pedrares, J.; Silva, C. J.; Vázquez-Cendón, M. E.; Muñuzuri, A. P.
    The emergence of viral mutant-variants poses a significant public health challenge, as existing treatments often exhibit reduced efficacy against new lineages compared to the original strains. This paper presents a mathematical framework to model the competitive dynamics between these lineages within a host using a Lotka–Volterra competition scheme. To mitigate the impact of more contagious or resistant microorganisms, we apply optimal control theory to investigate strategies for mutant suppression. We conduct a comparative study between continuous control, representing ideal treatment scenarios, and discrete-time control, which reflects the clinical reality of periodic dosing protocols. We introduce a discrete-time optimal control formulation to connect the theoretical continuous-control framework with periodic dosing protocols. The analytical study identifies the stability conditions for viral extinction under constant and impulsive interventions, while numerical simulations validate the expected behaviors. Our results show that the effectiveness of discrete treatment depends strongly on the dosing interval and treatment intensity, with a transition from effective mutant suppression to loss of control as the dosing interval increases. Specifically, our quantitative results demonstrate that periodic interventions can achieve complete mutant suppression while effectively halving the total cumulative dose compared to continuous protocols. These findings provide quantitative insights into the design of antiviral dosing strategies.
  • Item type: Item , Access status: Acesso aberto ,
    Protestos sem participação popular prévia: Um desafio para o ativismo do Fridays for Future-Brasil
    (2026) Santa Rosa, V.; Üzelgün, M. A.
    As mídias digitais estão sendo utilizadas por movimentos sociais como ferramenta de ação política. No Brasil, o Fridays for Future (FFF) recorreu às affordances do Instagram para reconstruir as práticas do Norte Global, já que as greves climáticas não foram bem-sucedidas no país. Este artigo propõe uma tipologia para as ações contenciosas adotadas pelo FFF-Brasil. Investigamos 177 postagens, entre junho de 2020 e abril de 2022, não relacionadas às greves. Com base na análise de conteúdo e na teoria dos atos pragmáticos, capaz de investigar a linguagem a partir dos efeitos que se pretende imprimir no interlocutor, mostramos que as ações predominantes são aquelas que nomeamos de Protestos sem Participação Popular Prévia (PsPPP). Compreendemos que esse formato foi empregado para realizar denúncias e reivindicações online, sem, no entanto, ter como objetivo principal provocar opositores, mas sim conquistar apoiadores e representatividade.
  • Item type: Item , Access status: Apenas metadados ,
    The future beyond Fridays: The discursive turn of the Fridays for Future movement in Brazil
    (2026) Santa Rosa, V.; Üzelgün, M. A.
    Fridays for Future, founded by young Swedish activist Greta Thunberg, quickly became a transnational movement through its intense use of digital media. This article aims to understand the collective’s formation in Brazil, given the very different discourse production conditions vis-à-vis the Global North. In Study 1, employing content analysis, we identify the quantitative trends in the networked mediation of student climate strikes, demonstrating that this contentious action, unlike in the Europe, did not resonate much in the Brazilian public sphere. In Study 2, supported by French discourse analysis and political process theory, we define the discursive opportunity structures: Identity, Governmental, Ecological, Political-Scientific and Private Initiative. We conclude that Instagram’s affordances enabled the collective in the implementation of a “rooted discourse.” This strategy helped highlight the different consequences and implications of rising global temperatures within the country, avoiding the generalization of a “globalized discourse.”