A South African patient with drug-resistant tuberculosis waits to be seen by a doctor at a Johannesburg hospital. Michele Spatari/AFP/Getty Images hide caption

The remains of Air Force Col. Roy A. Knight Jr. have been returned to Texas by a commercial jet flown by his son. Defense POW/MIA Accounting Agency via AP hide caption

Walmart has instructed employees to remove marketing material that displays violent imagery and to unplug or turn off video game consoles that show violent games. AP hide caption

Airway-irritating acetals seem to form in some types of vape juice even without heat, researchers find — likely a reaction between the alcohol and aldehydes in the liquid. Gabby Jones/Bloomberg via Getty Images hide caption

President Trump's Saturday tweets characterizing the district of Rep. Elijah Cummings, D-Md., as "rodent infested" sparked outrage among Baltimore residents and lawmakers. Above, the Maryland congressman appears during a hearing of the House Oversight and Reform Committee, of which he is the chair, on June 26. J. Scott Applewhite/AP hide caption

Attorney General William Barr, in April at a prison reform meeting at the White House. Yuri Gripas/Reuters hide caption

Sleep scientists say the power of a warm bedtime bath to trigger sleepiness likely has to do, paradoxically, with cooling the body's core temperature. PhotoTalk/Getty Images hide caption

Some of the space food that was scheduled to be carried on the Apollo 11 lunar landing mission included (from left to right): chicken and vegetables, beef hash, and beef and gravy. Bettmann/Bettmann Archive hide caption

Activists from Girl Up. Top row from left: Valeria Colunga, Eugenie Park, Angelica Almonte, Emily Lin. Bottom row from left: Lauren Woodhouse, Winter Ashley, Zulia Martinez, Paola Moreno-Roman. Olivia Falcigno/NPR hide caption

Police Sr. Sgt. Paddy Hannan holds an AR-15 style rifle similar to a weapon a gunman used to kill 51 people at two mosques in Christchurch, New Zealand. Dozens of gun owners handed over their weapons in the first of more than 250 planned buyback events around New Zealand. Nick Perry/AP hide caption

Romania's Simona Halep holds the trophy after defeating United States' Serena Williams during the women's singles final match on day 12 of the Wimbledon Tennis Championships in London on Saturday. Ben Curtis/AP hide caption

Kim Davey (left), a passenger in Menzi Mngoma's Uber, made a video of his in-car opera singing that went viral. Kim Davey/Facebook hide caption

Just a modest reduction in daily caloric intake could have protective benefits for our hearts, new research shows. Sian Irvine/Getty Images/Dorling Kindersley hide caption

Mussels bind to surfaces using byssus threads. Understanding how these threads work may help researchers address water contamination. Paul Kay/Getty Images hide caption

A smoked pulled chicken sandwich from Operation BBQ Relief. Ken Goodman Photography hide caption

Researchers compared Americans' health status today with that of 25 years ago and found that health is worsening among lower-income Americans. Orbon Alija/Getty Images hide caption