She was one of the Clinton 12, Black students who broke a race barrier by entering a Tennessee high school in 1956 in the face of harassment by white segregationists.
An urban planner who specialized in disaster recovery, he was brought in to revive the city after the 2005 storm. The task proved larger than one man could handle.
In the wake of a revolution, he helped found a leading political party and tried to conciliate warring left and right factions, although his success was limited.
An African American who spent much of her career based in the Netherlands, she said her race was less of a factor in Europe when being considered for a wide variety of opera roles.
In Mexico, where the cult of machismo has long held sway, she waged a lonely, sometimes dangerous and often single-handed fight against prostitution and organized sex rings.
En México, donde durante mucho tiempo ha prevalecido el machismo, Ulloa libró una lucha solitaria, a veces peligrosa, contra la prostitución y las redes organizadas de explotación sexual.