circle. It was introduced by Jakob Steiner in 1826. Specifically, the power Π ( P ) {\displaystyle \Pi (P)} of a point P {\displaystyle P} with respect
π-helix) is a type of secondary structure found in proteins. Discovered by crystallographer Barbara Low in 1952 and once thought to be rare, short π-helices
(pronounced /ˈpiː/), plural pees. The Semitic Pê (mouth), as well as the Greek Π or π (Pi), and the Etruscan and Latin letters that developed from the former