The mitral valve, which connects the upper and lower left-side chambers of the human heart, is one of the many pieces of the heart critical to its proper function. Mitral valve prolapse is common, and when it leads to severe leakage over a prolonged period ...

For centuries, people tried to build ornithopters that flapped like birds, but none became a practical path to human flight. The Wright brothers got off the ground not because they simply imitated, but because they moved beyond flapping and focused on the principles of lift and control.