A Colorado inmate involved in the culling of poultry at a farm as part of a pre-release program has the first human case of avian flu in the United States. Here, cage-free chickens walk in a fenced pasture at an organic farm near Waukon, Iowa, in October 2015. Charlie Neibergall/AP hide caption
Oyster harvester Johny Jurisich empties a dredge filled with oysters onto his boat near Texas City, Texas. Lucio Vasquez/Houston Public Media hide caption
Knot research falls into a few categories: knot theory, a mathematical and theoretical look at knots; and a couple areas of research focused more on applications like DNA structures or surgical sutures in medicine Richard Drury/Getty Images hide caption
A border collie in northern England chases after a flock of sheep to herd them. A new study finds that only about 9% of the variation in an individual dog's behavior can be explained by its breed. Edwin Remsberg/Getty Images hide caption
Moderna says its vaccine appears to be about 51 percent effective for children ages 6 months to less than 2 years, and 37 percent effective for those ages 2 to less than 6 years. Ole Spata/dpa picture alliance via Getty Images hide caption
An image of the planet Uranus taken by the spacecraft Voyager 2 as it flew by in January 1986. NASA/JPL hide caption
Rapid tests are effective in detecting BA.2, but the high infectivity of the subvariant means it could jump from person to person before a positive result is detected. Justin Tallis/AFP via Getty Images hide caption
A medical worker administers tests at a Covid-19 testing site in New York City. New York City and other places in the Northeast are seeing an uptick in infection numbers. Spencer Platt / Getty Images hide caption
New research finds that previous studies of mental illness using brain scans may be too small for the results to be reliable. Andrew Brookes/Getty Images/Image Source hide caption
Health care workers during a strike in Palo Alto, Calif., on Monday. About 5,000 nurses at Stanford and Packard Children's Hospital began a strike Monday over a fight for what they describe as fair contracts. David Paul Morris/Bloomberg via Getty Images hide caption
Mask mandates on public transportation are no longer in effect following a ruling by federal judge on April 18, 2022. Patrick T. Fallon/AFP via Getty Images hide caption
