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.
Only around 180 impact craters have ever been discovered on Earth and around 30 per cent of them contain important natural resources of minerals or oil and gas. The largest and oldest known crater prior to this study, the 300 kilometre wide Vredefort crater in South Africa, is 2 billion years in age and heavily eroded.
The gaping crater of the 1932 QuizapÃº eruption (left-center) lies below the summit of Cerro Azul stratovolcano. Cerro Azul was constructed to the south of its twin volcano Descabezado Grande, where this photo was taken. Steep-sided Cerro Azul has a 500-m-wide summit crater that is open to the north. QuizapÃº was the source of one of the world's largest explosive eruptions of the 20th century in 1932. This eruption created a 600-700 m wide, 150 m deep crater and ejected 9.5 cu km of dacitic tephra. Photo by Oscar GonzÃ¡lez-FerrÃ¡n (University of Chile).