I'm applying to PhD programs and I've gotten in touch with a couple of prospective faculty. If they sign their emails with their first name, is it good to assume that they're okay with being called by their first name? Or should I play it safe and wait until they invite me to do so? Or should I simply ask? I don't want to come off as disrespectful, but I don't want to be regarded as not being able to take a hint either. I have a master's degree and know at a LOT of, if not most, grad students ca