WASHINGTON - The government sought to assure airline travelers Tuesday that X-raying shoes at security checkpoints was a reliable way of detecting improvised bombs, a claim contradicted by a Department of Homeland Security study. "Screening shoes by X-ray is an effective way of identifying any anomaly, including explosives," said Kip Hawley, Transportation Security Administration chief, at a news conference at Reagan National Airport just outside Washington. A study by the Homeland Security Department, obtained by The Associated Press, states that X-ray images "do not provide the information necessary to effect detection of explosives." Under new orders this week, all airline...