This type of coma is usually reversible once the blood sugar is corrected. Oxygen deprivation: Oxygen is essential for brain function. Cardiac arrest causes a sudden cutoff of blood flow and oxygen to the brain, called hypoxia or anoxia.
The external power supply is the AC power adapter that converts household AC electricity voltages to the much lower DC voltages needed to charge a mobile phone's internal battery.
Nuclear power. Nuclear power is the controlled use of nuclear energy. Nuclear energy is energy in 'fissionable' elements like uranium that can be released by nuclear reactions in a machine called a nuclear reactor. This energy is made into electricity, which then can be used to power machines and heat homes. In 2007, 14% of the world's electricity came from nuclear power.