NEW YORK (Reuters) - The chief executive and a managing partner of the collapsed Dubai private equity firm Abraaj Capital Ltd were arrested on U.S. charges that they defrauded their investors, including the Bill & Melinda Gates Foundation, a federal prosecutor said on Thursday. Abraaj founder and Chief Executive Arif Naqvi was arrested in the United Kingdom last Friday, while managing partner Mustafa Abdel-Wadood was arrested at a New York hotel on Thursday, Assistant U.S. Attorney Andrea Griswold said at a hearing in Manhattan federal court. Abdel-Wadood appeared at the hearing and pleaded not guilty to securities fraud, wire fraud...