Importance of the organic aerosol fraction for modeling aerosol hygroscopic growth and activation: a case study in the Amazon Basin - Mircea, M; Facchini, M C; Decesari, S; Cavalli, F; Emblico, L; Fuzzi, S; Vestin, A; Rissler, J; Swietlicki, E; Frank, G; Andreae, M O; Maenhaut, W; et al. (Atmospheric chemistry and physics, 2005)