Opinion dynamics: models, extensions and external effects

Recently, social phenomena have received a lot of attention not only from social scientists, but also from physicists, mathematicians and computer scientists, in the emerging interdisciplinary field of complex system science. Opinion dynamics is one of the processes studied, since opinions are the drivers of human behaviour, and play a crucial role in many global challenges that our complex world and societies are facing: global financial crises, global pandemics, growth of cities, urbanisation and migration patterns, and last but not least important, climate change and environmental sustainability and protection. Opinion formation is a complex process affected by the interplay of different elements, including the individual predisposition, the influence of positive and negative peer interaction (social networks playing a crucial role in this respect), the information each individual is exposed to, and many others. Several models inspired from those in use in physics have been developed to encompass many of these elements, and to allow for the identification of the mechanisms involved in the opinion formation process and the understanding of their role, with the practical aim of simulating opinion formation and spreading under various conditions. These modelling schemes range from binary simple models such as the voter model, to multi-dimensional continuous approaches. Here, we provide a review of recent methods, focusing on models employing both peer interaction and external information, and emphasising the role that less studied mechanisms, such as disagreement, has in driving the opinion dynamics. [...]Comment: 42 pages, 6 figure

Transtorno do Déficit de Atenção/Hiperatividade: o que nos informa a investigação dimensional? Attention Deficit/Hyperactivity Disorder: what does the dimensional research inform us?

Investiga-se o Transtorno do Déficit de Atenção/Hiperatividade (TDAH) em contexto escolar adotando a perspectiva dimensional. Participaram 107 crianças com idade média de 12,37 anos. Utilizou-se a Escala de TDAH - versão para professores, uma versão adaptada para pais e tarefas computadorizadas de processamento cognitivo. A prevalência de Hiperatividade pelo relato de professores e pais foi condizente com aquela apontada pela literatura (4,7%). O Déficit de Atenção, avaliado por pais e professores, correlacionou com todas as medidas de processamento de informação. Hiperatividade e Comportamento Anti-social correlacionaram com as medidas de memória de trabalho quando a primeira foi avaliada pelos professores e a segunda pelos pais, refletindo baixa concordância entre o relato de informantes a respeito das dimensões comportamentais do TDAH. Entretanto, as respostas dos professores parecem estar mais de acordo com a literatura. Conclui-se que a perspectiva dimensional de investigação pode fornecer informações relevantes sobre as características demográficas e cognitivas do TDAH.<br>This research investigates the Attention Deficit/Hyperactivity Disorder (ADHD) in a school context from a dimensional perspective. It took part of the study 107 children with mean age of 12,37 years. It was used the ADHD's Scale - teacher's version and an adapted form for parents in addition to computer tasks to measure cognitive processing. The prevalence of Hyperactivity, according to teachers and parent's report, was consistent with the literature (4,7%). Attention deficit correlated with all measures of cognitive processing. Hyperactivity and Antisocial Behavior correlated with working memory measures only when the first was assessed by teachers and the second was assessed by parents. In this sense, it was found low concordance between informants regarding ADHD behavior dimensions. However, teacher's report seems to be according with contemporary literature. It was concluded that dimensional investigation can provides relevant information related to demographic and cognitive characteristic of ADHD

IL-9/IL-9 receptor signaling selectively protects cortical neurons against developmental apoptosis

In mammals, programmed cell death (PCD) is a central event during brain development. Trophic factors have been shown to prevent PCD in postmitotic neurons. Similarly, cytokines have neurotrophic effects involving regulation of neuronal survival. Nevertheless, neuronal PCD is only partially understood and host determinants are incompletely defined. The present study provides evidence that the cytokine interleukin-9 (IL-9) and its receptor specifically control PCD of neurons in the murine newborn neocortex. IL-9 antiapoptotic action appeared to be time-restricted to early postnatal stages as both ligand and receptor transcripts were mostly expressed in neocortex between postnatal days 0 and 10. This period corresponds to the physiological peak of apoptosis for postmitotic neurons in mouse neocortex. In vivo studies showed that IL-9/IL-9 receptor pathway inhibits apoptosis in the newborn neocortex. Furthermore, in vitro studies demonstrated that IL-9 and its receptor are mainly expressed in neurons. IL-9 effects were mediated by the activation of the JAK/STAT (janus kinase/signal transducer and activator of transcription) pathway, whereas nuclear factor-kappaB (NF-kappaB) or Erk pathways were not involved in mediating IL-9-induced inhibition of cell death. Finally, IL-9 reduced the expression of the mitochondrial pro-apoptotic factor Bax whereas Bcl-2 level was not significantly affected. Together, these data suggest that IL-9/IL-9 receptor signaling pathway represents a novel endogenous antiapoptotic mechanism for cortical neurons by controlling JAK/STAT and Bax levels