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.
Callisto is without a doubt the most heavily cratered object in the known solar system. This suggests that the surface is very old and inactive. The largest impact crater on Callisto is known as Valhalla. It is 2,485 miles (4,000 km) in diameter. Another large crater, Asgard, has a diameter of 994 miles (1,600 km).It appears that Callisto's surface has undergone very little change since its formation over four billion years ago.he largest impact crater on Callisto is known as Valhalla. It is 2,485 miles (4,000 km) in diameter. Another large crater, Asgard, has a diameter of 994 miles (1,600 km). It appears that Callisto's surface has undergone very little change since its formation over four billion years ago.