Livia Sauvage carefully placed her hand on a sheet painted with a tree and lifted it, leaving an orange handprint. Sauvage, a second-year student at the University of Virginia, attended a letter-writing event Wednesday at the McIntire Amphitheatre. Dozens of students clustered around tables writing notes of support and encouragement to members of the Tree of Life Synagogue in Pittsburgh, where a gunman killed 11 people on Saturday, as well as to Pittsburgh Jewish students and police.