Cooperation in public goods games: stay, but not for too long

Cooperation in repeated public goods game is hardly achieved, unless contingent behavior is present. Surely, if mechanisms promoting positive assortment between cooperators are present, then cooperators may beat defectors, because cooperators would collect greater payoffs. In the context of evolutionary game theory, individuals that always cooperate cannot win the competition against defectors in well-mixed populations. Here, we study the evolution of a population where fitness is obtained in repeated public goods games and players have a fixed probability of playing the next round. As a result, the group size decreases during the game. The population is well-mixed and there are only two available strategies: always cooperate (ALLC) or always defect (ALLD). Through numerical calculation and analytical approximations we show that cooperation can emerge if the players stay playing the game, but not for too long. The essential mechanism is the interaction between the transition from strong to weak altruism, as the group size decreases, and the existence of an upper limit to the number of rounds representing limited time availability

Speaking for themselves: observations on a “marginal” tradition in Brazilian Literature

The article discusses “marginal literature” produced in the outskirts of São Paulo by authors who do not “fit” into the symbolic hierarchies of the dominant literary canon. This analysis will be based on a broad overview of the tradition in Brazilian literature that has tried to represent both poverty and marginalisation. Special attention will be paid to the debate on the shift from a “dialectic of malandroism”, proposed by Antonio Candido, towards a “dialectic of marginality”. According to João Cezar de Castro Rocha, the latter involves a variety of art practices that seek to expose social conflict instead of disguising it. Then, an analytical framework on the aesthetics of marginality will be presented, while identifying to what extent literary experiences of the past have influenced the marginal literature movement. Finally, the article concludes with reflections on some strategies authors have been using to overcome prejudices towards their cultural expression, which include attempts to create new narrative forms based on the valorisation of the place of enunciation and the right to speak for themselves

Constant training in direct ophthalmoscopy Reply

Laureate Int Univ, Sch Med, Dept Ophthalmol, Rua Doutor Almeida Lima 1-134, BR-03164000 Sao Paulo, BrazilFed Univ Sao Paulo UNIFESP, Dept Ophthalmol, Sao Paulo, BrazilFed Univ Sao Paulo UNIFESP, Dept Ophthalmol, Sao Paulo, BrazilWeb of Scienc

Ophthalmoscopy simulation: advances in training and practice for medical students and young ophthalmologists

Objective: To describe and appraise the latest simulation models for direct and indirect ophthalmoscopy as a learning tool in the medical field. Methods: The present review was conducted using four national and international databases PubMed, Scielo, Medline and Cochrane. Initial set of articles was screened based on title and abstracts, followed by full text analysis. It comprises of articles that were published in the past fifteen years (2002-2017). Results: Eighty-three articles concerning simulation models for medical education were found in national and international databases, with only a few describing important aspects of ophthalmoscopy training and current application of simulation in medical education. After secondary analysis, 38 articles were included. Conclusion: Different ophthalmoscopy simulation models have been described, but only very few studies appraise the effectiveness of each individual model. Comparison studies are still required to determine best approaches for medical education and skill enhancement through simulation models, applied to both medical students as well as young ophthalmologists in training.Laureate Int Univ, Sch Med, Dept Ophthalmol, Rua Doutor Almeida Lima 1-134, BR-03164000 Sao Paulo, SP, BrazilFed Univ Sao Paulo UNIFESP, Dept Ophthalmol, Sao Paulo, SP, BrazilFed Univ Sao Paulo UNIFESP, Dept Ophthalmol, Sao Paulo, SP, BrazilWeb of Scienc

When Politicians Talk About Politics: Identifying Political Tweets of Brazilian Congressmen

Since June 2013, when Brazil faced the largest and most significant mass protests in a generation, a political crisis is in course. In midst of this crisis, Brazilian politicians use social media to communicate with the electorate in order to retain or to grow their political capital. The problem is that many controversial topics are in course and deputies may prefer to avoid such themes in their messages. To characterize this behavior, we propose a method to accurately identify political and non-political tweets independently of the deputy who posted it and of the time it was posted. Moreover, we collected tweets of all congressmen who were active on Twitter and worked in the Brazilian parliament from October 2013 to October 2017. To evaluate our method, we used word clouds and a topic model to identify the main political and non-political latent topics in parliamentarian tweets. Both results indicate that our proposal is able to accurately distinguish political from non-political tweets. Moreover, our analyses revealed a striking fact: more than half of the messages posted by Brazilian deputies are non-political.Comment: 4 pages, 7 figures, 2 table

Contextualized tasks of Brazilian textbooks from a Critical Mathematics Education perspective

Contexto: Baseado em parte do nosso trabalho no grupo de pesquisa Teorema - Interlocuções entre Geometria e Educação Matemática, sobre análise de livros didáticos brasileiros, este artigo tem como objetivo (objetivos:) propor reflexões sobre se, e como, tarefas contextualizadas podem contribuir para mudar as atitudes e crenças dos estudantes em relação à Matemática e à sociedade. Design: Tendo em vista esse objetivo, com base nos pressupostos da pesquisa qualitativa, analisamos um total de 41 livros didáticos de Matemática, sendo 20 dos Anos Finais do Ensino Fundamental e 21 do Ensino Médio, todos aprovados pelo Programa Nacional do Livro e do Material Didático (PNLD) (Ambiente e participantes - não há participantes). Coleta e análise dos dados: Com os livros em mãos, buscamos tarefas contextualizadas que promovessem reflexões e discussões críticas sobre temas do cotidiano - econômicos, sociais, tecnológicos, sustentáveis, éticos, entre outros - presentes na sociedade. Para analisar as tarefas selecionadas, adotamos a Educação Matemática Crítica como lente teórica, revelando preocupações sociais, políticas e culturais, propondo a leitura do mundo com a Matemática, além de promover uma Pedagogia Libertadora, com base na justiça social. Resultados: Os resultados indicaram que as tarefas selecionadas podem promover reflexões e contribuir para a mudança de atitude dos alunos em relação à Matemática e à sociedade, porém ressaltamos que o papel do professor é fundamental neste processo. Conclusão: Tendo em vista o elevado número de tarefas presentes nos livros didáticos brasileiros, consideramos que elas poderiam apresentar um maior número de situações contextualizadas, aumentando o número de opções para o professor

Contextualized tasks of Brazilian textbooks from a critical mathematics education perspective

Considering the dimension of the National Textbook Program (PNLD) in Brazil, the textbook plays a relevant role in student formation as iy, as in many countries, defines the real curriculum. Objective: to propose reflections on whether, and how, contextualized tasks can contribute to changing students' attitudes and beliefs regarding Mathematics and society. Design: In view of this goal, based on the assumptions of qualitative research. Settings and participants:. we analyzed a total of 41 Mathematics textbooks, 20 of which were Middle School and 21 of High School, all approved by the PNLD. Data collection and analysis: We sought for contextualized tasks that promoted reflections and critical discussions about everyday themes - economic, social, technological, sustainable, ethical, among others - present in society. To analyze the selected tasks, we adopted the Critical Mathematical Education as a theoretical lens, revealing social, political, and cultural concerns, proposing the reading of the world with Mathematics, in addition to promoting a Pedagogy for Liberation, based on social justice. Results: The results indicated that the selected tasks could promote reflections and contribute to the change of students' attitude towards Mathematics and society, however we emphasize that the teacher's role is fundamental in this process. Conclusion: In view of the high number of tasks present in Brazilian textbooks, we consider that they could present a greater number of contextualized situations, increasing the number of options for the teacher

Bipartite Producer-Consumer Networks and the Size Distribution of Firms

A bipartite producer-consumer network is constructed to describe the industrial structure. The edges from consumer to producer represent the choices of the consumer for the final products and the degree of producer can represent its market share. So the size distribution of firms can be characterized by producer's degree distribution. The probability for a producer receiving a new consumption is determined by its competency described by initial attractiveness and the self-reinforcing mechanism in the competition described by preferential attachment. The cases with constant total consumption and with growing market are studied. The following results are obtained: 1, Without market growth and a uniform initial attractiveness $a$, the final distribution of firm sizes is Gamma distribution for $a>1$ and is exponential for $a=1$. If $a<1$, the distribution is power in small size and exponential in upper tail; 2, For a growing market, the size distribution of firms obeys the power law. The exponent is affected by the market growth and the initial attractiveness of the firms.Comment: 13 pages, 3 figure