A typical ECG in AF shows no P waves and an irregular ventricular rate. AF is often treated with medications to slow the heart rate to a near normal range (known as rate control) or to convert the rhythm to normal sinus rhythm (known as rhythm control). Electrical cardioversion can also be used to convert AF to a normal sinus rhythm and is often used emergently if the person is unstable.
How does a water tower work? Water towers provide extra water storage for a town's water supply. They hold about a day's worth of water, so if the town's pumps fail (like during a power outage), the water tower acts as a backup water supply.
The Department of Energy's Hydropower 101 video explains how hydropower works and highlights some of the Water Power Program's efforts in R&D in this area (to see how a hydroelectric system works, see our How Hydropower Works page):