Sampling and analysis activity picking up in newer shale plays. After a steep drop in stock price, Core's valuation is reasonable once again. Core Laboratories (NYSE: CLB), a mid-cap oil servicer focusing on production enhancement and research optimization, has recently been savaged since giving lower revenue and earnings guidance. Core lowered full-year earnings guidance from $6.00-$6.25 to $5.80-$6.00 per share. Revenue for the second quarter is now estimated to be between $265 and $270 million; a number less than the previous estimate, but still above last year's second quarter results. The analysts estimated revenue to be around $288 million.