Tech stocks are in demand following strong results from Apple last night driven by iPhone sales. ARM, which reportedly designed the chips for the smartphone, as a strong performer, as is FTSE 250-listed peer Imagination Technologies, whose intellectual property is thought to be used in the iPhone.Updates from aerospace and defence stocks have been given a mixed reception but the sector is lower overall.Car and aeroplane parts supplier Senior is higher after saying it expects profits for 2010 to exceed expectations after trading in the three months to March 31 got a lift from favourable currency movements and cost control and efficiency improvements.But aerospace and defence systems group Meggitt's update has received a poor reception. It said trading since the start of the year has been in line with its expectations of a challenging first half.Top performing sectors so far todayTechnology Hardware & Equipment 441.76 +2.41%Food & Drug Retailers 4,963.47 +1.23%Industrial Transportation 2,473.50 +0.70%Chemicals 5,313.07 +0.62%Forestry & Paper 4,936.51 +0.55%Bottom performing sectors so far todayConstruction & Materials 3,708.73 -2.24%Mining 23,302.23 -2.09%Aerospace and Defence 3,394.51 -1.99%Tobacco 26,028.84 -1.65%General Retailers 1,767.98 -1.23%