As the world reels from the New Zealand mosque massacre, it’s worth remembering the many past incidents of murder, assault and other violence that were also streamed live on Facebook. In the past, social media researcher Jennifer Grygiel has called for a time-delay on livestreams to protect children from seeing online horrors. Now, though, Grygiel writes that it’s time for even stronger action.

The search for ways to beat TB continues to preoccupy scientists. The disease still kills more than 1.5 million people a year while 10 million continue to be infected annually. Even more chilling is the fact that a new threat has emerged — a strain of TB that’s resistant to existing drug regimens. There’s some good news on this front, as Andrew Nunn and I.D Rusen explain. Another challenge is that TB doesn’t just affect the lungs. Nazir Ismail sets out what other organs are prone to infection.