There’s a new art and literary magazine — one with a twist: Everyone connected with it — the artists, writers, editors and producers — are presently or were recently guards at the Metropolitan Museum of Art. The guards you see at museums may seem like ciphers standing silently in their blue uniforms, and only speaking when you ask a question or get too near that work of art. But the 35 artists showcased in this journal give the world a very different picture of themselves.