sentences:  They also called for a boycott of elections in Cuba's one-party system and for investors to avoid Cuba, giving several news conferences to discuss their concerns.A "The Los Angeles Times" columnist described Roca and Bonne's criticism carrying extra weight as "the only known black dissidents in Cuba", stating that "Given Castro's claim that the revolution has ended racial discrimination, he can ill afford to let well-educated blacks challenge him, even as gently as the four defendants had done.