Self-duality of Riemannian manifolds and connections

A container defining a chamber partially filled with a liquid such as water is provided with a pair of pressurized oxygen flow inlet ports and an outlet port from which humidified or nebulized oxygen flow is discharged for breathing. A humidifying device connected to one of the inlet ports includes a diffuser immersed in the water and provided with relatively small slots through which pressurized oxygen is forced to form minute bubbles that rise through the water to provide humidified oxygen flow which passes out of the outlet port. A nebulizing device connected to the second inlet port includes a tube having one end extending into the water and an opposite end exposed to a low pressure region generated by high velocity oxygen flow through an orifice. Water thereby aspirated through the tube is broken up and entrained by the oxygen flow and the resulting mixture discharged into an enlarged volume chamber and directed against a fixed pin or baffle in the chamber to further break up the entrained water particles. An adjustable inlet port communicates the chamber with room or ambient air to provide preselected dilution of the nebulized oxygen flow with room air which room air is aspirated into the chamber by sub-atmospheric pressure generated therein. The diluted nebulized oxygen flow subsequently passes out of the outlet port. The humidifying and nebulizing devices are independently operatively depending upon which one of the pair of inlet ports is connected to a suitable pressurized oxygen source.