Quando outros personagens mudam o cenário. Lutas dos movimentos indígenas a partir da Constituição de 1988

Este ensaio - fundamentado em análises historiográfico-bibliográficas e em pesquisa de campo realizada na Terra Indígena Raposa Serra do Sol, no Estado de Roraima enfoca o papel dos movimentos indígenas como relevante e singular protagonista nas lutas pela democratização e participação social no contexto sociopolítico dos últimos 30 anos. A escolha se justifica por três argumentos centrais e interligados: com o processo de elaboração da Constituição Federal de 1988 (que garantiram, ao menos no papel, direitos coletivos e diferenciados aos povos indígenas no Brasil), movimentos indígenas passaram a atuar como uma força social expressiva e propositiva que contribui para a descolonização da profunda e renitente matriz colonial da organização social brasileira; há contribuições diretas das organizações indígenas no que se refere à contestação do sistema liberal-representativo de democracia; assim como aportes substantivos no campo da participação social. Em sentido distinto à politização do cotidiano promovida pelos novos personagens que entraram em cena da clássica obra de Eder Sader, enfatiza-se aqui a atuação descolonial e influente dos movimentos indígenas no sentido da cotidianização do político - que denuncia o caráter etnocêntrico e supostamente universalista das estruturas de poder, democracia e participação vigentes e reivindica o pleno exercício de seus modos de vida

Ferromagnetism in a Hubbard model for an atomic quantum wire: a realization of flat-band magnetism from even-membered rings

We have examined a Hubbard model on a chain of squares, which was proposed by Yajima et al as a model of an atomic quantum wire As/Si(100), to show that the flat-band ferromagnetism according to a kind of Mielke-Tasaki mechanism should be realized for an appropriate band filling in such a non-frustrated lattice. Reflecting the fact that the flat band is not a bottom one, the ferromagnetism vanishes, rather than intensified, as the Hubbard U is increased. The exact diagonalization method is used to show that the critical value of U is in a realistic range. We also discussed the robustness of the magnetism against the degradation of the flatness of the band.Comment: misleading terms and expressions are corrected, 4 pages, RevTex, 5 figures in Postscript, to be published in Phys. Rev. B (rapid communication

Impacts of El Niño Southern Oscillation and Indian Ocean Dipole on dengue incidence in Bangladesh

Dengue dynamics are driven by complex interactions between hosts, vectors and viruses that are influenced by environmental and climatic factors. Several studies examined the role of El Niño Southern Oscillation (ENSO) in dengue incidence. However, the role of Indian Ocean Dipole (IOD), a coupled ocean atmosphere phenomenon in the Indian Ocean, which controls the summer monsoon rainfall in the Indian region, remains unexplored. Here, we examined the effects of ENSO and IOD on dengue incidence in Bangladesh. According to the wavelet coherence analysis, there was a very weak association between ENSO, IOD and dengue incidence, but a highly significant coherence between dengue incidence and local climate variables (temperature and rainfall). However, a distributed lag nonlinear model (DLNM) revealed that the association between dengue incidence and ENSO or IOD were comparatively stronger after adjustment for local climate variables, seasonality and trend. The estimated effects were nonlinear for both ENSO and IOD with higher relative risks at higher ENSO and IOD. The weak association between ENSO, IOD and dengue incidence might be driven by the stronger effects of local climate variables such as temperature and rainfall. Further research is required to disentangle these effects