sentences:  In 1913 she celebrated her fiftieth birthday with an exhibition of a series of her German portraits in the Plaza.In 1916 she moved to Park Avenue, commencing her residence with the presentation of a portrait of John Burroughs; that same year she presented her so-called "blue portrait" of the inventor Nikola Tesla in her studio at 109 East 39th Street.This was the only portrait Tesla sat for during his life.