Continuous positive airway pressure (CPAP) machines are used to maintain an open airway in patients diagnosed with obstructive sleep apnea. The machine functions by blowing pressurized air into the airway via mask at a setting determined by sleep study and prescribed by a physician.
Also the second largest impact structure on Earth, the 1.85 billion years old Sudbury crater in Canada, hosts world-class mineral deposits - in this case nickel-rich minerals that were melted and concentrated by the extreme heating caused by the impact.
The largest volcano on Earth is Mauna Loa, Hawaii, with an  area of 5271 km2, more than half of the big island of Hawaii. It  is also the largest in volume, at more than 7â¦5,000 km3. The Mauna  Loa (long island) ridge extends for more than 120 km, but at  a slightly lower elevation than Mauna Kea to the north.    The largest volcanic crater in the continental US is the  Yellowstone supervolcano in Yellowstone National Park, in NW  Wyoming in the US.