5 junio 2015
Birds use a thumb-like structure on the wing to create a small vortex which makes their turns and landings smooth, new research shows. This is the first time that researchers have found evidence that the effect of the alula is due to a small vortex formed at the tip of the alula feathers.
http://feeds.sciencedaily.com/~r/sciencedaily/~3/dXO9AIJZBCU/150605103008.htm
