WALNUT CREEK, Calif. (AP) - A Republican activist has acknowledged sending hundreds of bogus letters to the editorial pages of San Francisco Bay area newspapers over the past decade, many of which were published. Editors at the newspapers involved said Monday that they would intensify efforts to verify that letters to the editor are actually sent by the people who write them. However, technological advances have made bogus letters increasingly difficult to screen out, they said. "It's important to verify the authenticity of the letters we receive," San Francisco Chronicle Editorial Page Editor John Diaz told The Associated Press. "It's...