The authors acknowledge ICIST-IST Research Institute for supporting research at Florida International University,
the Calouste Gulbenkian Foundation Grant supporting research at Ryerson University,
the Fulbright Commission for the award of a Fulbright/ FLAD Grant supporting research at UCDavis and the Portuguese National Science Foundation for the Grants SFRH/BD/35925/2007 and SFRH/BD/39923/2007.