We would like to thank:
Arantza Illarramendi and Serena Sorrentino, for their valuable comments and support.
The anonymous reviewers of our papers, for their useful suggestions, that helped us to improve our work.
Víctor Martínez-Burgos, for his work on the graphical user interface.
Graphics designer José Ilarri, for developing the logo of Doctopush.
Last but not least, this work was partially supported by the MUR FIRB Network
Peer for Business project, the IST FP6 STREP project
2006 STASIS, and the CICYT project TIN2007-68091-C02-02.