Soft paywalls retain more users than hard paywalls - by a big margin.

Aortic coarctation is congenital focal narrowing of the aorta in the region of the ductus arteriosus. It may be preductal (proximal to the ductus, illustrated on the right [in the original]), periductal, or postductal.

What is the Feynman Point? The Feynman Point was named after Nobel Prize-winning physicist Richard Feynman (1918–1988), who once joked he wanted to memorize pi up to 999999 ... and so on and so on, as if to say pi continues from the Feynman Point with nines forever. This is not true, of course, and the sequence of nines is a mere coincidence—thus, the joke of the Feynman Point.

An effective analysis of some of the structural limitations that exist in people's lives with particular reference to the problems experienced by Status Zer0 youth.