University of Chicago officials say classes will resume today, one day after a 21-year old black student was arrested and charged for allegedly threatening to kill 16 white males on campus in response to the killing of a black teenager by a white city police officer.  University President Robert Zimmer wrote in an email Monday that in light of the arrest, classes and activities would resume Tuesday.  The campus was almost desolate aside from police and campus security on Monday after university officials canceled classes due to an FBI tip of a threat of gun violence.  Zimmer called Monday a “challenging day.”  He says the university will keep additional security presence in place through the quarter, which ends December 12^th.  Jabari R. Dean of Chicago, who’s accused of making the threat, had his initial court appearance Monday.  A University of Illinois at Chicago spokeswoman confirmed that Dean is a freshman majoring in electrical engineering.  A prosecutor said Jabari cooperated after federal agents confronted him and that he didn’t appear to pose a threat.  Dean didn’t enter a plea and his lawyer declined comment afterward.