Chlorine can stop the Ebola virus. So medical workers disinfect their hands often at the Doctors Without Borders treatment center in Kailahun, Sierra Leone. Carl De Souza/AFP/Getty Images hide caption

itoggle caption Carl De Souza/AFP/Getty Images

The photographer Sebastiao Salgado, in New York City on Thursday, says we are at a "special moment" — our world now needs to be protected from climate change and other forces. Misha Friedman for NPR hide caption

itoggle caption Misha Friedman for NPR

President Obama and Vice President Biden on Friday debuted the "It's On Us" campaign to help colleges and universities prevent and respond to sexual assault on campus. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP

Psychologists say spanking and other forms of corporal punishment don't get children to change their behavior for the better. Science Photo Library/Corbis hide caption

itoggle caption Science Photo Library/Corbis

"It's one of those moments in your life where you're so conscious about what you're about to do, and what you're about to do will change your life." --€” Geena Rocero James Duncan Davidson/TED hide caption

itoggle caption James Duncan Davidson/TED

San Francisco Supervisor Scott Wiener (left) says he started taking a drug to prevent HIV infection earlier this year. Lisa Aliferis/KQED hide caption

itoggle caption Lisa Aliferis/KQED