LONDON More than 600 artists and art workers have signed an open letter calling on the Tate in London to sever ties with arts organizations whose founders have financial ties to Israel , Artnews has reported. The letter, addressed to Tate leadership ahead of the Turner Prize ceremony on Dec. 3, calls for the museum to divest from the Zabludowicz Art Trust, Zabludowicz Art Projects and Outset Contemporary Art Fund. The three organizations are run separately by arts philanthropists Anita and Poju