This research was developed at CGUL with support from the Portuguese Science Foundation under the project PREDATOR—POCTI/CTE-ATM/62475/2004, co-financed by the European Union under program FEDER. Thanks are due to an anonymous referee, Timothy DelSole, Dinis Pestana, Aapo Hyvärinen, Marc Hulle, and Ricardo Trigo, for their constructive comments and criticisms.
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