Carlos writes a really good paper for his class. His professor encourages him to submit it to a journal for publication and it gets accepted. Who would own the copyright?
Carlos would own the copyright. According to the University of California Office of the President:
"A student work is a work produced by a registered student without the use of University funds (other than Student Financial Aid), that is produced outside any University employment, and is not a sponsored, contracted facilities, or commissioned work.
Ownership of copyrights to student works shall reside with the originator."