Computational Biology Center, T.J. Watson IBM Research Laboratory, Yorktown Heights, New York, USA. gcecchi@us.ibm.com|Computational Biology Center, T.J. Watson IBM Research Laboratory, Yorktown Heights, New York, USA. gcecchi@us.ibm.com|Computational Biology Center, T.J. Watson IBM Research Laboratory, Yorktown Heights, New York, USA. gcecchi@us.ibm.com|Computational Biology Center, T.J. Watson IBM Research Laboratory, Yorktown Heights, New York, USA. gcecchi@us.ibm.com|Computational Biology Center, T.J. Watson IBM Research Laboratory, Yorktown Heights, New York, USA. gcecchi@us.ibm.com|Computational Biology Center, T.J. Watson IBM Research Laboratory, Yorktown Heights, New York, USA. gcecchi@us.ibm.com|Computational Biology Center, T.J. Watson IBM Research Laboratory, Yorktown Heights, New York, USA. gcecchi@us.ibm.com