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We study an evolutionary dynamics for the contributions by agents to a common/public good in a generalized version of Baliga and Maskin's environmental protection model. The dynamical equilibria consist of three scenarios: a single agent contributing to preserve the good with its optimal contribution level, and all the other agents being free-riders: a group of agents with the same optimal contribution level contributing to preserve the good, and all the other agents being free-riders; one where no agents contribute. The dynamics of the contributions can be complex but we prove that each trajectory converges to the equilibrium associated to the single agent (or group of agents) with the highest preference for the good that are contributing since the beginning. We note that while the aggregate contribution is below the optimal contribution level of the agent with the smallest preference for the good, then the aggregate contribution is increasing and there is no free-riding. Hence, if the optimal contribution level of the agent with the smallest preference is enough to not exhaust the good too quickly and the optimal contribution level of the agent with the greatest preference is enough to preserve the good, then, in spite of the appearance of free-riding in the contributions, the good might not be exhausted.

Abstract
Resumo   Ao considerar diversos desafios que surgiram e que contribuíram para (re) significar o ensino e a aprendizagem no campo dos estudos com surdos, no âmbito das tecnologias digitais em rede, muitas vezes pensadas para a produção e o consumo de ouvintes tendo, portanto, características baseadas nas experiências de quem percebe o mundo pela audição, surgiu a necessidade de experimentar e refletir sobre as possibilidades de engajar os surdos em interações que promovam o desenvolvimento das aprendizagens em redes digitais. Diante de tal desafio e a aproximação com Seminário Práticas de Pesquisa, desenvolvida no âmbito da Pós-graduação em Educação da UNISINOS (PPGEDU) e Pós-Graduação em Linguística Aplicada (PPGLA), tivemos a oportunidade de ter contato com ações de co-criação de uma rede internacional que objetiva conectar crianças e adolescentes em diferentes lugares do mundo para desenvolver ações reticulares de Educação OnLIFE. Como resultado desta aproximação, vimos a necessidade de problematizar práticas pedagógicas para surdos, por meio da Libras para oportunizar aos ouvintes reflexões sobre o papel da Libras nas interações e potencializar o desenvolvimento de ações conjuntas e de transformações sociais numa perspectiva que considere, tanto a cultura surda quanto a cultura ouvinte em rede.

Abstract
Cloud computing is becoming a very popular form of distributed computing, in which digital resources are shared via the Internet. The user is provided with an overview of many available resources. Cloud providers want to get the most out of their resources, and users are inclined to pay less for better performance. Task scheduling is one of the most important aspects of cloud computing. In order to achieve high performance from cloud computing systems, tasks need to be scheduled for processing by appropriate computing resources. The large search space of this issue makes it an NP-hard problem, and more random search methods are required to solve this problem. Multiple solutions have been proposed with several algorithms to solve this problem until now. This paper presents a hybrid algorithm called GSAGA to solve the Task Scheduling Problem (TSP) in cloud computing. Although it has a high ability to search the problem space, the Genetic Algorithm (GA) performs poorly in terms of stability and local search. It is therefore possible to create a stable algorithm by combining the general search capacities of the GA with the Gravitational Search Algorithm (GSA). Our experimental results indicate that the proposed algorithm can solve the problem with higher efficiency compared with the state-of-the-art.

Abstract
The purpose of this article is to identify the most impactful research on customer churn and to map the conceptual and intellectual structure of its field of study. Data were collected from the WoS database, comprising 338 articles published between 1995 and 2020. Several bibliometric techniques were applied, including analysis of co-words, co-citation, bibliographic coupling, and co-authorship networks. R software and the Bibliometrix/Biblioshiny package were used to perform the analyses. The results identify the most active and influential authors, articles, and journals on the topic. More specifically, through co-citations and bibliographic coupling, it was possible to map the oldest articles (retrospective analysis) and the current research front (prospective analysis). The retrospective analysis, based on co-citations, revealed that the foundations of this research field are constructs such as quality of service, satisfaction, loyalty, and changing behaviors. The prospective analysis, performed through bibliographic coupling, revealed that current research is embedded in predictive analysis, clusters, data mining, and algorithms. The results provide robust guidance for further investigation in this field.