President Obama's bus tour continues through Iowa today as he addresses rural farmers and small business owners in the state. The UN's latest global food report finds food prices worldwide are one-third higher than this time last year, threatening billions and contributing to famine in the Horn of Africa. US Customs and Border Protection officials are increasingly turning their attention to checking for undocumented immigrants on trains and buses. Norway's state oil company has discovered a "giant" North Sea oil field off the coast that could contain 1.2 billion barrels. Researchers are finding that the biggest bottleneck in human multitasking is the way the brain processes multiple streams of information.