Robert Kelly is managing director of XTS Energy LLC, and has more than three decades of experience as a business executive. He is a professor of economics and has raised more than $4.5 billion in ...

A pulse oximeter measures blood oxygen levels at home and in healthcare settings. Abnormally low readings on a pulse oximeter might require medical care, especially if they are below 92%. Skin color ...

If you have trouble breathing, your doctor may recommend a few tests to figure out what’s causing it. Some measure how much air you breathe in or out or how much oxygen is going from your lungs to the ...

The velocity of light in vacuum, c, is approximately 3 × 10 8 m s −1, fast enough to make 7.5 round-the-world trips in a single second, and to move a distance of 300 mm in 1 ns. This ultrahigh speed ...