During deep sleep, waves of cerebrospinal fluid (blue) coincide with temporary decreases in blood flow (red). Less blood in the brain means more room for the fluid to carry away toxins, including those associated with Alzheimer's disease. Fultz et al. 2019 hide caption
Common vampire bats (Desmodus rotundus), such as this group day-roosting in a cave in Mexico, can form cooperative, friendship-like social relationships. B.G. Thomson/Science Source hide caption
Shannan Troncoso, co-owner of Brookland's Finest Bar & Kitchen in Washington, D.C., has turned her customers into fans of Brussels sprouts. Catie Dull/NPR hide caption
A "murder" scene could seem creepy, but what is going on inside these crows' minds may be most unsettling. Dragan Todorovic/Getty Images hide caption
A flyer reminding customers about vaping-related deaths and illnesses, on display in a Seattle vape store. The Washington State Board of Health recently passed a four-month emergency ban on flavored vaping products. It applies to products that contain either THC or nicotine. Jovelle Tamayo/Bloomberg/Getty Images hide caption
This year the Drug Enforcement Administration is accepting electronic vaping devices (provided any lithium ion batteries are removed) during its annual National Prescription Drug Take Back Day event. Lane Turner/The Boston Globe/Getty Images hide caption
At Chicago's McCormick Place, neuroscientists from around the world presented their work to colleagues. But some researchers were denied entry because of the Trump administration's travel ban. Rob Piercy/Allen Institute hide caption
Google's processor, Sycamore, performed a truly random-number generation in 200 seconds. The achievement marks a major breakthrough in the decadeslong quest to use quantum mechanics to solve computational problems. Above, a Google sign at the company's campus in Mountain View, Calif. Jeff Chiu/AP hide caption
A firefighter participates in a controlled burn in a forest outside El Perelló in Catalonia, Spain, on Sept. 27. NPR followed a special unit into the woods in Spain to see how they burn for prevention. Aaron Labaree for NPR hide caption