Way out there

NASA’s New Horizons spacecraft zipped by Pluto on July 14 last year, giving astronomers their first close-up look at the far-off dwarf planet. The spacecraft has been beaming data back to Earth ever since. Although only half the information is in, planetary scientists published their initial Pluto discoveries last month.

So far the little world has posed to scientists a multitude of unsolved mysteries.

For example, the smooth, 650-mile-wide icy plain known as Sputnik Planum is unmarred by craters, yet impact depressions pockmark the nearby highlands.

Pluto’s ice mountains present their own conundrum. On the plain, nitrogen, methane, and carbon monoxide cycle between frozen and gaseous states, creating flowing glaciers of mostly nitrogen ice on a foundation of water ice. But scientists can’t explain how the soft nitrogen ice has carved the much harder water ice into towering mountains.

Scientists are also baffled by Pluto’s deep valleys. The dwarf planet’s average temperature of minus 400 degrees Fahrenheit is too cold for nitrogen, Pluto’s main element, to become a fluid that could carve such gorges.

Another mystery: How does such a small dwarf planet retain its atmosphere? Scientists predicted Pluto’s nitrogen would be gushing away into space, but instead New Horizons found a mere trickle, 10,000 times less than expected.

“Pluto’s really tiny, so it doesn’t have the mass to hold on to an atmosphere over the age of the solar system—at least we wouldn’t have thought that,” Randy Gladstone of San Antonio’s Southwest Research Institute told New Scientist.

The recent Pluto studies were published in the March 18 edition of Science. Researchers expect the remaining New Horizons data to be available later this year.

Outgrowing the wiggles

Over 7 percent of children worldwide have attention deficit hyperactivity disorder (ADHD), according to the advocacy group CHADD. In the United States that figure swells to as many as 16 percent of children in grades one through five.

But a new study by Taiwanese researchers suggests some of those squirmy children may simply be acting their age. The study, published online in March by The Journal of Pediatrics, analyzed data from nearly 400,000 children, ages 4 to 17.

In Taiwan the birthday cutoff for school entrance is Aug. 31. When the researchers compared children with August birthdays to children born in September, who had an extra year to mature before entering school, they found the younger students were much more likely to be diagnosed with ADHD and to receive medication. The trend was most obvious among boys: Boys born in August were 60 percent more likely to be diagnosed with ADHD than those born in September. —J.B.

Mixed meds

Nearly 1 in 6 older U.S. adults uses combinations of dietary supplements, prescriptions, and over-the-counter medications that could have harmful or deadly interactions, according to a study published by JAMA Internal Medicine in March.

Researchers conducted in-home interviews with 2,351 participants between the ages of 62 and 85 and found that the prevalence of dangerous drug combinations doubled from 2005 to 2011.

For example, about 1 million older adults use the anti-clotting drug clopidogrel in combination with drugs such as Prilosec (used to treat acid reflux), aspirin, or the pain reliever naproxen. Study author Dima Mazen Qato told CBS News clopidogrel can interact with these medications and increase the risk of heart attacks, bleeding complications, or death. —J.B.