A Star Trek convention beamed down to Des Moines last week. Today, it’s the start of the Science Fiction Society Convention in Iowa’s capitol. Jon Mohning is organizing “DemiCon the 13th: Con of the Living Dead” which features guest authors and artists with a supernatural theme.Mohning says the 13th annual gathering will bring in hordes of people from across the state who love science fiction and fantasy in movies, books, comic books, T-V shows and in artwork. He says attendees will include doctors, lawyers and “lots of normal people” who want to be authors or artists themselves or who are just sci-fi fans. He says there will also be panels and discussion groups.The convention is being held at the University Park Holiday Inn in West Des Moines through Sunday. The big event tonight is a dance which Mohning says won’t be any sock hop.”Prom of the Living Dead” will bring out many ghastly apparitions along with other people dressed in Star Trek uniforms, with others decked out as medieval knights, princesses, warriors and Xena-wanna-bes. For more information, surf to “www.demicon.org” or “www.dmsfs.org”.