From an analysis of ventricular pressure pulses, inferences were drawn as to basic determinants of cardiac performance in experimental conditions simulating ... aortic and pulmonary stenosis, ...

Conservation photography occupies a unique space, blending the art of visual storytelling with the urgency of environmental ...

National Geographic's enterprising photographers have helped readers explore and learn about our beautiful world through their images for more than a century. Here is their best work from the past ...