Greg Heyman has departed New York-based Rhombus Capital Management, where he was managing director, to become coo of Miura Global Partners. His duties have been absorbed by Gloria Radeff, a Rhombus founding partner. Heyman and Radeff declined comment. Rhombus, an equity long/short shop with $650 million under management, was started by David Fiszel, a former SAC Capital Advisors portfolio manager.