Technology firm Smiths Group posted a rise in pre-tax profits in the six months to January 30 despite flat sales as it benefited from actions taken to increase efficiency, including laying off staff.Pre-tax profits totalled £178m, up from £167m over the same period the previous year. Sales slipped to £1.28bn from £1.29bn.Sales at Smiths Detection, which supplies technology such as X-ray systems for airports, climbed to £266m from £233m. John Crane, a supplier of technology such as mechanical seals and filtration systems, saw sales fall to £358m from £393m. Medical devices supplier Smiths Medical's revenues rose to £414m from £403m.At Smiths Interconnect, which supplies technology to the transport, military and aerospace markets, sales fell to £146m from £152m, but margins benefited from cost savings including staff reductions.'Looking to the balance of the year, Smiths Group is well placed to build on these results to deliver further improvement in margins and returns while continuing to generate strong free cash-flow,' said chief executive Philip Bowman.Smiths also announced that its diagnosis business within Smiths Detection had signed a collaboration agreement with the drug group Novartis to market the Bio-Seeq device, which is used to detect biological warfare agents such as anthrax.