He has published over 170 articles in refereed journals and international conferences in the above areas and has been invited speaker in major international events. Prof. Sellis is a recipient of the prestigious Presidential Young Investigator (PYI) award given by the President of USA to the most talented new researchers (1990), and of the VLDB 1997 10 Year Paper Award for his work on spatial databases. He was the president of the National Council for Research and Technology of Greece (2001-2003) and a member of the VLDB Endowment (1996-2000). Prof. Sellis has a long background and experience in research and technology, by actively participating in important projects funded from the European Union and the General Secretariat of Research and Technology. In November 2009, he was awarded the status of IEEE Fellow, for his contributions to database query optimization, and spatial data management.