SHORT PROFILE of Corina Yoris, an 80-year-old university professor who was chosen by Venezuelan opposition leader Maria Corina Machado as her substitute candidate to challenge President Nicolas Maduro in the July 28 presidential election. Yoris, who has never held public office, was part of the commission that organized the opposition primary in October, which Machado easily won, unnerving the Maduro government with her surging popularity. SHORT PROFILE OF Corina Yoris