The official start of winter brought the colder temperatures, and it looks like they're going to stick around for a while.  That means a renewed call from Shreveport firefighters to use heaters safely.  Chief of Fire Safety Patricia Dyas says space heaters need space...and that you should keep all combustibles -- and yourself -- at least three feet from them.  If you have central air and heat, make sure you have your unit inspected and serviced by a licensed technician.  And above all, you need to have a working smoke detector in your home -- and an escape plan in case your home does catch fire.  If you need a new smoke detector installed, she says you can call the Shreveport Fire Department, which will be happy to install that for you, free of charge.