The number of Americans filing new claims for unemployment benefits rose sharply last week, a potential signal the job market was losing steam although some of the increase might be attributed to temporary holiday factors. Initial claims for state unemployment benefits rose 20,000to a seasonally adjusted 287,000 for the week ended Dec.26, the U.S. Labor Department said on Thursday. Many economists expect a slower pace of job market improvement in 2016 even as the unemployment rate falls further from its current 5 percent.