New York Times: Earlier this month, the US Department of Defense released its annual census of the nation’s nuclear arsenal through the end of the 2015 fiscal year. At that point, the US possessed 4571 warheads, down 109 from the previous year and down 702 since 2008, the last year of President George W. Bush’s term in office. The disarming of 109 warheads was the lowest annual rate of disarmament during President Obama’s tenure, and the total reduction since 2008 accounted for just 13.3% of the stockpile, the smallest reduction by any administration since the end of the Cold War. According to Hans M. Kristensen of the Federation of American Scientists, the slower rate of disarmament is the result of various factors. Congress has opposed much of Obama’s disarmament efforts, and Russia has rejected additional cuts beyond those agreed to in the 2010 New Start treaty. There is also a potential effect from the three-decade arsenal modernization effort that Obama initiated at an estimated cost of $1 trillion.
Modeling the shapes of tree branches, neurons, and blood vessels is a thorny problem, but researchers have just discovered that much of the math has already been done.