Complex sentence: Ubiratan worked as economist for Banco Central do Brasil and Instituto Brasileiro de Economia (IBRE) of FGV-RJ, besides being an researcher of Instituto Brasileiro de Mercados e Capitais (IBMEC).
Split into simpler sentences: Ubiratan worked as economist for Banco Central do Brasil and Instituto Brasileiro de Economia (IBRE) of FGV-RJ. He also worked as a researcher for the Instituto Brasileiro de Mercados e Capitais (IBMEC).