activator - (biology) any agency bringing about activation; a molecule that increases the activity of an enzyme or a protein that increases the production of a gene product in DNA transcription. 1  substance - the real physical matter of which a person or thing consists; DNA is the substance of our genes.
In 2006, in cases where police officers intentionally fired a gun at a person, they discharged 364 bullets and hit their target 103 times, for a hit rate of 28.3 percent, according to the departmentâs Firearms Discharge Report. The police shot and killed 13 people last year. In 2005, officers fired 472 times in the same circumstances, hitting their mark 82 times, for a 17.4 percent hit rate. They shot and killed nine people that year.
The average gap between murders is 54 hours. But they do not happen in a regular pattern and the gap can be a lot less and a lot more than 54 hours. We can use our probability model to predict how often there will be murders on consecutive days, how often there will be a day without a murder, and so on.