A Doctor in the Palm of Your Hand
Suppose you were out on a small boat, 100 mi from shore, with a few friends. Suddenly, one of them begins coughing hard and complaining of aches and pains and chills. It could just be the start of a bad cold, but he also seems to be running a fever, which might signal the onset of the flu. But it could also be something more serious, like bacterial pneumonia, that might require hospital care. How would you know?