Hundred years after the flu pandemic of 1918, the world faces an outbreak of a new severe acute respiratory syndrome, caused by a novel coronavirus. With a high transmissibility, the pandemic spreads worldwide, creating a scenario of devastation in many countries. By the middle of 2021, about 3% of the world population has been infected and more than 4 million people have died. Different from the H1N1 pandemic, which had a deadly wave and cessed, the new disease is maintained by successive waves, mainly produced by new virus variants, and the small number of vaccinated people. In the present work, we create a version of the SIR model with spatial localization of persons, their movements, and taking into account social isolation probabilities. We discuss the effects of virus variants, and the role of vaccination rate in the pandemic dynamics. We show that, unless a global vaccination is implemented, we will have continuous waves of infections.HighlightsThe COVID-19 has infected more than 200 millions and has killed more than 4 million persons.WHO has not been successful in defining a global vaccination policy.Many epidemic scenarios arise when different countries apply different vaccination strategies.Present model can show some insights on how vaccination programs can be managed.Competing Interest StatementThe authors have declared no competing interest.Funding StatementThis research did not receive any specific grant from funding agencies in the commercial, or non-profit sectors. SPR acknowledges grant from Conselho Nacional de Desenvolvimento Cientifico e Tecnologico - CNPq, through proccess 306572/2019-2.Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:The manuscript is a modeling paper, there was no clinical trial of any kind.All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesThe code of model is included in manuscript files.

In this work we apply first principles calculations to investigate the flat band phenomenology in twisted antimonene bilayer. We show that the relatively strong interlayer interactions which characterize this compound have profound effects in the emergence and properties of the flat bands. Specifically, when the moiré length becomes large enough to create well defined stacking patterns along the structure, out-of-plane displacements take place and are stabilized in the regions dominated by the AB stacking, leading to the emergence of flat bands. The interplay between structural and electronic properties allows for detection of flat bands in higher twist angles comparable to other two-dimensional materials. We also show that their energy position may be modulated by noncovalent functionalization with electron acceptor molecules.

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Há poemas que falam do que se sente, do tempo e da perda. E há outros que falam do instante — esse breve espaço em que o sentimento e o tempo se tocam e se desfazem. Em Minas, Bahia & Poesia, Mário Mazzoni e Matheus Matos recolhem esses instantes. Suas palavras escorrem pela clepsidra partida, misturando o efêmero e o eterno, a leveza e o peso da existência, a ternura e a ausência dos amores. Cada poema é um fragmento de tempo quebrado — uma pausa entre o que já se foi e o que ainda pulsa, entre o silêncio e o que mantém o poema vivo. Aqui, o cotidiano ganha densidade poética: o gato na janela, as chuvas de março, as serras de Minas e a terra vermelha da Bahia. Tudo vibra, tudo respira — e tudo passa. Só a poesia fica. Mas se o tempo é o carrasco das certezas, é também o espaço onde os poetas reencontram o sentido de existir. Entre espelhos, reflexos e silêncios, Minas, Bahia & Poesia é um livro sobre o que o tempo não apaga: o gesto de sentir.

 

Sobre os autores: Mário S. C. Mazzoni nasceu em Belo Horizonte, Minas Gerais. É físico e professor da UFMG e do Programa de Pós-Graduação em Física de Materiais da UFOP. Pesquisador na área de Física da Matéria Condensada, publica aqui seu primeiro livro em coautoria. Matheus J. S. Matos nasceu em Aracaju, Sergipe, e cresceu em Irecê -BA, terra que o habita ainda hoje. Físico e professor da UFOP, encontra na poesia um modo de atravessar o tempo e transformá-lo em palavra. Minas, Bahia & Poesia é também o registro dessa travessia.