There is some legal dispute as to the definition of "death." This answer focuses on the anatomical definition of brain death: Death has occurred once the brain ceases to generate any neuronal activity.
The fastest mechanism of death, then, would be any injury that destroys the critical centers of the brain. The brainstem plays a significant role in maintaining consciousness and controlling cardiac and respiratory functions, so devastating injury to the brain stem could cause immediate death. Any global injury to the brain, such as diffuse axonal injury, can cause a coma or death; the most severe of these injuries can cause immediate death.
Of course, the most rapid mechanism of death would be the immediate and total destruction of the critical life tissues. For example, a large proximal explosion could immediately destroy the entire brain, thus causing instantaneous death.
carbon dioxide
Death of all cells will occur in about 7 seconds.
facilitated diffusion
myelianation
The mechanism for determining evolution of life were fossils, egg, scales and footprints. Most of the knowledge comes from fossils. They tell us about the shape and size of that animal.
Arrhythmia
more rapid, most rapid
more rapid, most rapid
more rapid, most rapid
More quickly is the comparative and Most quickly is the superlative.
bike
negative feed back
The most rapid urbanization in Eurasia is happening along the coasts and near most rivers.
Injection tends to lead to the most rapid action of drugs.
Yes it is the oldest and most primitive coding mechanism
carbon dioxide
The cast of Love and Death on Rapid Transit - 1997 includes: Liz Byrne Shimmy Marcus Paul Roe Stephanie Serge Vincent Walsh