Market timing e avaliação de desempenho dos fundos brasileiros

Este trabalho avalia o desempenho de fundos de investimento brasileiros pelo seu market timing, ou seja, pela capacidade de os gestores anteciparem diferenças de retorno das ações em relação a um ativo de renda fixa. Utilizam-se testes - paramétrico e não-paramétrico - desenvolvidos por Henriksson e Merton para a análise do desempenho de 243 fundos, no período de setembro de 1998 a outubro de 2003. Encontra-se evidência de habilidade de market timing para uma minoria de gestores de fundos, resultado que aparentemente se deve à maior facilidade de se preverem grandes diferenças de retorno entre o mercado acionário e a taxa de juros livre de risco.

Genomic rearrangements in trypanosomatids: an alternative to the "one gene" evolutionary hypotheses?

Most molecular trees of trypanosomatids are based on point mutations within DNA sequences. In contrast, there are very few evolutionary studies considering DNA (re) arrangement as genetic characters. Waiting for the completion of the various parasite genome projects, first information may already be obtained from chromosome size-polymorphism, using the appropriate algorithms for data processing. Three illustrative models are presented here. First, the case of Leishmania (Viannia) braziliensis/L. (V.) peruviana is described. Thanks to a fast evolution rate (due essentially to amplification/deletion of tandemly repeated genes), molecular karyotyping seems particularly appropriate for studying recent evolutionary divergence, including eco-geographical diversification. Secondly, karyotype evolution is considered at the level of whole genus Leishmania. Despite the fast chromosome evolution rate, there is qualitative congruence with MLEE- and RAPD-based evolutionary hypotheses. Significant differences may be observed between major lineages, likely corresponding to major and less frequent rearrangements (fusion/fission, translocation). Thirdly, comparison is made with Trypanosoma cruzi. Again congruence is observed with other hypotheses and major lineages are delineated by significant chromosome rearrangements. The level of karyotype polymorphism within that "species" is similar to the one observed in "genus" Leishmania. The relativity of the species concept among these two groups of parasites is discussed.