San Francisco Chronicle: California Democratic Sen. Barbara Boxer told more than 50 Silicon Valley CEOs Tuesday that they need to go to Washington if they want to help improve Americans’ health and end the country’s dependence on foreign oil. Around 40 executives have signed up for the trip in early May through the Silicon Valley Leadership Group, a trade group in San Jose that hosted Boxer’s talk, so they can lobby for the omnibus energy bill, which includes a cap-and-trade plan for greenhouse gas emissions. …