The Fertittas say it is this rule, and the fighter's ability to quit at any time, that makes mixed martial arts safer than boxing because it limits the numberofblows a fighter takes.
The researchers modeled their study on the electric grid in Illinois, which depends on a large numberof coal and gas plants, and where the wind blows strongest at night, when demand is lowest.
Dr Charmian Goldwyn said the "number, pattern and distribution of injuries is in my opinion typical of their attribution to deliberate blows to the face caused during a recent assault".