Curvy: It's a catenary, not an arch    Q. The breathtaking
630-foot-high 44,000-ton concrete and steel St. Louis Gateway
Arch has a nifty curve. Is it a) a semicircle b) a parabola c) a
catenary d) part of an ellipse? –M. van de Rohe  A. C, but make
that an inverted catenary– like the droop of a rope hung loosely
from pole to pole, then frozen and turned upside down. If you
picked parabola, you're in good company, for Galileo himself
mistakenly believed this. But it's a more special type of curve.
Key fact about an inverted catenary like the Gateway Arch is
that every point on it is in compression, making for an
extremely strong and stable architectural structure.  Q. "Brain
death" seems like a pretty modern concept. Where did the idea
come from? –M. DeBakey  A. It was 1973, and the medical
community was already unequivocal about the brain being "the
seat of the soul," though the old idea of the heart as the
source of emotion and intellect refused to die, says Mary Roach
in Stiff: The Curious Lives of Human C