The purchase of Adaptive Materials is a little different from the 40-odd acquisitions notched up by Ultra Electronics since it was spun out of the merged TI/Dowty in 1993. The American company, based in Ann Arbor, Michigan, has a proven technology but it has yet to turn a profit. Ultra shares were pushing £19 last autumn but have been sent back by a cautious trading statement from Cobham, the closest comparator, and the perception that the premium they enjoy over the rest of the sector had run too far ahead. Ultra shares now sell on less than 15 times this year's earnings. Expensive, but worth it, says the Times.Recruiter Staffline shares have tripled since the summer on the back of those higher forecasts and the perception that growth has further to go as companies continue to outsource large chunks of their workforce, despite some uncertainty over the impact of European legislation on temporary staff, which arrives in October. The shares sell on less than nine times earnings for 2011, though, and remain a firm hold says the Times.The investment case for Yell Group is that it is no longer seen as a grotesquely indebted printer of unread directories and is, instead, an online marketing resource for small and medium-sized businesses. But prospects are not going to improve in the appreciable future and nor, therefore, will that bombed-out share price. Too soon to chase says the Times.Please note: Digital Look provides a round-up of news, tips and information that is impacting share prices and the market. Digital Look cannot take any responsibility for information provided by third parties. This is for your general information only as not intended to be relied upon by users in making an investment decision or any other decision. Please obtain a copy of the relevant publication and carry out your own research before considering acting on any of this information.