One tried-and-true way to buy a stock is during a rebound off the 10-week moving average. As longtime chart readers know, you want to see the stock draw strong volume as it lifts off that key support level. Investment bank and asset manager Piper Jaffray (PJC), featured in this column Tuesday, is working on a 10-week rebound. So is another stock that's earned a place in IBD's Stock Spotlight screen: Parexel (PRXL). Parexel is actually well on its