Bond vigilantes—investors who, in protest to the government's monetary or fiscal policies policy, sell bonds to purposely drive up yield on U.S. debt—are back after 15 years of remaining on the low-down, according to Bloomberg. Higher yields mean higher interest costs for the government, making the cost of borrowing more expensive and throwing the proverbial wrench in Fed Chairman Ben Bernanke's efforts to keep borrowing costs low for consumers and businesses while also trying to jolt the economy. The 10-year Treasury yield has risen 1.4 percent this year, pushing interest rates on 30-year fixed mortgages to more than 5 percent....