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Concerned about cocoa

High doses of a cocoa antioxidant boost blood flow in the hippocampus, an important brain area for learning and memory. In “Cocoa antioxidant sweetens cognition in elderly” (SN: 12/27/14, p. 5), Bethany Brookshire described how these molecules, called flavanols, also improve older people’s ability to tell complex visual patterns apart.

Commenters on the medical journal site PubMed expressed concerns that the study did not meet standards for clinical trial reporting. Before performing a study with human volunteers, scientists must register their experiments on ClinicalTrials.gov, an online database maintained by the National Institutes of Health. But Hilda Bastian and others pointed out that the experiment described in the cocoa study didn’t match the one submitted to the website: The researchers reported giving high and low doses of flavanols to participants, while the clinical trial initially set out to compare high doses of flavanols to no flavanols at all.

Study author Scott A. Small of Columbia University says that he and his team have submitted an update to ClinicalTrials.gov and that the submission is awaiting approval. As for the flavanol doses, Small says that the beverage used to deliver the high dose contained a number of other components, such as potassium, caffeine and calcium. The low-flavanol beverage had all the same components, he says, and was included to show that only the flavanols had an effect on cognition. “The levels of flavanols in the low-flavanol condition were so low that they have no known effect on the body,” he explains.

Monitoring Mount Nyiragongo

Geologists are keeping an eye on Mount Nyiragongo, an active Congolese volcano that sits perilously close to a growing city. Violent conflicts in the area make this important job difficult, as Thomas Sumner reported in “War zone volcano” (SN: 12/13/14, p. 26).

Researchers occasionally descend into the sweltering crater of the volcano to scoop up fresh lava samples for study. That’s very exciting, Tom Ostwald wrote in an e-mail, but “is it really necessary to get ’em while they’re hot? It would seem that any lava with an accurate birth date would suffice.”

A freshly deposited lava sample offers benefits beyond just a known birth date, explains Sumner. “The rising magma fueling Nyiragongo contains a baseline mix of the radioactive isotopes the researchers use to date flows. This mixture will vary depending on whether radioactive daughter products in the magma are whisked away as gas. Without this information from a newborn rock, the researchers couldn’t tell if a certain pair of isotopes in a lava sample had reached equilibrium over several years or whether they’d already been in balance when they were first spat from the volcano.”

He adds that this baseline is especially important for shorter-lived isotopes such as polonium-210, which has a half-life of just 138 days.

Playing with science

In “Evolve and Linkage turn science into games” (SN: 12/27/14, p. 32), Tina Hesman Saey and a competitive group of Science News staffers tested out a pair of biology-based card games.

“I love hearing about others who are creating science-based games,” wrote John J. Coveyou. “Are there any other science-themed games that I should know about?”

One reader-supplied suggestion was Go Extinct, developed by STEAM Galaxy Studios. “Like Go Fish, but with species,” explained Andy Hall. “Light on the science concepts, but it does teach a bit about the tree of life, and the rules are easy — which is a big plus.”

Commenter jmcnichols added another game to the list: “Evolution is similar in theme to Evolve but looks more polished. I can’t speak for the game-play differences but Evolution had plenty of strategy. It doesn’t teach about evolution either, but uses the relationships between species in an interesting way.”