WASHINGTON/NEW YORK Supporters of pro-Palestinian activist Mahmoud Khalil gathered Monday outside Columbia University in New York City to mark one year since his detention by US immigration authorities, demanding an end to deportation efforts against him and other pro-Palestinian demonstrators. Students, faculty and activists rallied near the university’s Morningside campus gates carrying banners saying “ICE OUT OF SCHOOLS,” “FIRST THEY CAME FOR MAHMOUD” and “IMMIGRANTS ARE WELCOME HERE.”