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 number of mass shootings in the US has tripled in recent years, US Attorney General Eric Holder said at an annual conference of police chiefs on Monday. The yearly average of mass shootings has tripled from an average of five per year between the years of 2000 and 2008, the attorney general said. At least 12 mass shootings have taken place in 2013.