AOA is one of the most important parameters for understanding airplane performance and handling (see What Is Angle of Attack?) because a typical wing has a limited range of angles of attack over which it can function efficiently. In its simplest form, lift is a function of speed, air density, wing area, and AOA.
Day trading is speculation in securities, specifically buying and selling financial instruments within the same trading day. Strictly, day trading is trading only within a day, such that all positions are closed before the market closes for the trading day. Many traders may not be so strict or may have day trading as one component of an overall strategy. Traders who participate in day trading are called day traders.
FINRA and the NYSE define a Pattern Day Trader (PDT) as one who effects four or more day trades (same day opening and closing of a given equity security (stock) or equity option) within a five business day period.