Reuters: U.S. government scientists on Thursday doubled their estimate of the amount of oil gushing out of a ruptured Gulf of Mexico oil well as British energy giant BP scrambled to stem the leak. The news that the flow rate may be as high 40,000 barrels (1.68 million gallons/6.36 million liters) per day came after U.S. markets closed. BP shares closed 6.65 percent down in London at 365.50 pence while in New York they rebounded from 14-year lows to end 12.3 percent higher at …