In patients greater than age 65, more than 90% of aortic stenosis involves trileaflet valves which have developed heavy calcification. [5] In these instances the calcium deposits are thought to ...

Birds push against the air below them by flapping their wings downward to generate lift. But if the downstroke of a bird’s wing creates lift, why doesn’t the upstroke push the bird back down? Birds ...

The bird’s elbow is a hinged joint that is held in the flexed position at rest. During flight, birds partially flex this joint to reduce air resistance on the upstroke. The elbow is relatively ...