Base metal prices are mixed on the London Metal Exchange, with a stronger USD capping the complex’s upside. Three-month copper is trading at $7,687.75 a metric ton, down 0.2% from its previous settlement. Three-month nickel is the strongest performer, trading 0.4% higher at $16,223/ton. The EUR/USD is at 1.2236 from 1.2250 late in New York Friday; dollar-priced commodities become more expensive to investors holding other currencies when the greenback firms. Trading is expected to be thin and choppy in the lead up to Fed Chairman Ben Bernanke’s testimony to U.S. Congress Tuesday and Wednesday, traders say. Any indications of further monetary easing will likely push prices higher, while any lack of stimulus signals would likely spur selling on the LME. Of the base metals, nickel has the least near-term downside due to producer cost pressures, while copper has the furthest to fall as it’s trading far above the cost of production.