PAHs in Galaxies: their Properties and Evolution, arXiv.org Binarity as a key factor in protoplanetary disk evolution: Spitzer disk census of the eta Chamaeleontis cluster, arXiv.org The Possible Belts for Extrasolar Planetary Systems, arXiv.org On the nature of clumps in debris disks, arXiv.org Planet Formation with Migration, arXiv.org