Note: As Mike Yassa, the lead author on the study, pointed out to me, the study did not actually test whether consuming caffeine before a task enhances memory, the problem being that other confounding factors can then lead to difference in performances on the test.
The US debt is more than $20.1 trillion, the largest in the world. Here are the 3 reasons it grew so large, and how it damages U.S. economic growth. The US debt is more than $20.1 trillion, the largest in the world.
The Chinese do own a lot of U.S. debt -- $1.24 trillion as of January 2015. By mid-2015, the total amount of official debt owed by the federal, state and local governments was more than $18.5 trillion. That figure is expected to reach $21.6 trillion by the start of 2016.