Katy Perry's new "Part of Me," which was released digitally to retailers on Monday, Feb. 13, is heading for a debut sales week of around 400,000 to 420,000 downloads by week's end on Sunday, Feb. 19 -- so say industry prognosticators. That would mark the pop diva's best debut sales frame and the highest opening week for any act since Lady Gaga's "Born This Way" sold 448,000 on the chart dated Feb. 26, 2011, according to Nielsen SoundScan 这是原话