Global warming unpaused, how space affects the brain and more reader feedback

Space travel vs. the brain

Getting to Mars may leave a mark on astronauts’ minds. In “Trip to Mars could damage brain cells” (SN: 5/30/15, p. 11), Laura Sanders explained that high-energy particles smash into nerve cells and leave laboratory mice with memory deficits.  

“Most recent science fiction gives the impression that spaceflight is easy and the universe is filled with life-friendly environments. In reality, human spaceflight is almost impossibly dangerous, and beyond our blue sphere the universe is downright hostile to life,” remarked Mark S. He wondered if lead-lined helmets could shield space travelers from brain-damaging radiation.

Depending on the thickness, such helmets might provide some protection against lighter particles such as protons and helium, says study co­author Charles Limoli of the University of California, Irvine. But thick helmets might be too cumbersome for astronauts, who need to be nimble, and too heavy to wear constantly. So far, says Sanders, there’s no perfect solution to avoid brain damage, but scientists are exploring ways to protect delicate tissues, including new ways of shielding a Mars-bound spacecraft and even drugs that could combat radiation’s damage.

No pause for warming

A curious 15-year slowdown in rising global temperatures may not have happened after all. Incomplete and biased data might be behind the apparent trend, Thomas Sumner reported in “Global warming ‘hiatus’ an artifact” (6/27/15, p. 6).

William Hopkins questioned the idea that 2014 was the hottest year on record. “If I asserted that in my graduate statistics course, I’d get a failing grade,” he wrote. “The mean temperature value for 2015 may be greater than the mean value for all previous years, but the associated variability does not allow for 2014 to be differentiated from multiple prior years.”

Managing editor Tom Siegfried explains that calling 2014 the hottest year on record was a concise way of conveying that its average temperature was the highest measured. Statistical uncertainties make it possible that the actual mean temperature, as opposed to the mean as measured, might not necessarily have been higher than for any other year. In this case, though, it’s by far the strongest candidate for the top spot. Accounting for the uncertainties, the National Oceanic and Atmospheric Administration calculates a 48 percent probability that 2014 was in fact the hottest; probabilities for the next four hottest years combined are less than the probability for 2014.

One-way proteins

In “Twisty chains of proteins keep cells oriented” (SN: 6/27/15, p. 32), Tina Hesman Saey explained how the fibers that make up the scaffolding of a cell develop a distinctive counterclockwise twirl.

The article reminded Lillian Greeley of an experience with evolutionary biologist Stephen Jay Gould. “During the ’80s, he would have open office hours on Friday afternoon from 12 to 3 p.m. and anyone could drop in and discuss anything, which was great fun. One afternoon, he passed around a shell whose pattern wound around in the opposite direction [from most] and told us that there were very few in the world, and this was one of them. It was thrilling for each of us to hold that shell,” she wrote. “The basic question of your article and professor Gould’s fascination is, why do some things go this way and not that way? Hopefully, this century’s neuro-physicist-philosophers may be able to answer this question for us.”

Correction

A caption on Page 26 of “Life’s Cycles” (SN: 7/25/15, p. 24) stated that the last universal common ancestor of all living things may have had a primitive circadian clock. Instead, researchers have evidence that the first circadian clocks evolved more than a billion years later in a common ancestor of eukaryotes, organisms that have a nucleus where DNA is stored and organelles that carry out cellular processes.