How to close devices which have been left open?

[Erik P. Olsen]

It often happens when I use my scanner that it hits a bug which leaves
it in an open state and thus becomes unavailable until the system has
been rebooted. 

Does a command exist which would take a device such as a scanner out of
the open state?

I am using sane-backends for avision version 1.0.15 and FC3 fully
updated. The scanner is scsi attached as /dev/sg0.

-- 
Regards,
Erik P. Olsen