This appears to be a rather than a traditional academic paper.
The string qwertyuiopasdfghjklzxcvbnm is the of a standard QWERTY keyboard in order (left to right), and mnbvcxz is the bottom row reversed, lkjhgfdsa is the middle row reversed, poiuytrewq is the top row reversed. qwertyuiopasdfghjklzxcvbnm mnbvcxz lkjhgfdsa poiuytrewq