MANHATTAN—Columbia University president Minouche Shafik again set a deadline for unsanctioned student protesters to vacate their "Gaza Solidarity" encampment. Hours after that deadline passed, the encampment still stands. Shafik sent students a Monday morning letter asking them to "voluntarily disperse" from the encampment by 2 p.m. or face suspension. The students refused, voting unanimously to remain. Some wrote messages on the letters such as "COLUMBIA WILL BURN" and "I AINT READING ALL THAT