Sign up

Hi, all. It's been a while since I've dribbbled. I'm working on a site that is for physician authors in publishing their work. I wanted to share a new Sign Up screen that I'm working on and get your feedback. I'm primarily concerned with the required fields (although I'm open to all critiques). Only one field is optional and labeled as such within the input field – all others are required. What are you thoughts about this layout/flow?

If a user chooses to sign up using LinkedIn, we will prompt the user to add their Affiliation and Specialty as we take the new user to their member profile at first login.

For our purposes, every user must have an Affiliation and a Speciality (not uncommon in the physician's world), to create an account. Thanks in advance.