Fusion reactions It is not true that fusion packs the highest punch of any known energy-generating process (“Ignition failed,” SN: 4/20/13, p. 26). Matter-antimatter annihilation far exceeds it (Star Trek had it right back in the 1960s). I believe that under certain conditions, matter falling into a black hole can also yield more energy than fusion. Bobby Baum, Bethesda, Md. The reader is right on both counts. But those approaches are impractical. Scientists have harnessed energy from fusion, even if it has not produced net energy. Energy has never been harnessed from matter-antimatt... (p. 31)

Ethics of humanized mice The recent stories “Human cells rev up mouse brains” (SN: 4/6/13, p. 16) and “Of mice and man” (SN: 3/23/13, p. 22) drove home to me that human-animal hybrids are now reality. In science fiction stories with such hybrids, a big part of the plot is the resultant ethical gray area: There are certain standards for animal research, and much stricter standards for human research. What standards apply to animals that have a significant payload of human cells? Brain research has the most obvious ethical implications, but what makes a “human” is complex and prob... (p. 31)

Faux pas on fashion In “Students honored for research,” (SN: 4/6/13, p. 28), the female winner got singled out as “decked out in a lavender satin dress.” Didn’t Hillary Clinton recently point out to an interviewer that he asked her about her clothes, whereas he wouldn’t ask a man that? What are you trying to convey? Irena Swanson, Portland, Ore. While editing this story, we did ask ourselves whether we might mention the first-place winner’s tuxedo were he a young man. Our answer, and the reason we kept the phrase in the story, was yes. The writer was trying to use detail t... (p. 35)

Pacing Alzheimer’s Science Stats “Alzheimer’s Advancing” (SN: 3/9/13, p. 4) reports a new analysis extrapolating from 2010 U.S. Census data that concludes Alzheimer’s disease will triple by 2050. Omitted in such an analysis is the accelerating advance of science and medicine over the next 40 years. The gloomy prediction makes little sense unless science stops short while the disease continues to progress. Michael Edelstein, San Francisco, Calif. Researchers are working hard on treatments for Alzheimer’s. But until they find ways to prevent the disease, more people will conti... (p. 31)

Get a grip The article “Pruney fingers get better grip” (SN: 2/9/13, p. 11) indicated that skin wrinkling in response to extended exposure to water was the result of constricting blood vessels. I was waiting to read about the possibility that this was the body’s response to prevent heat loss. Water has a high heat capacity, and therefore I might expect that blood vessel constriction is to minimize heat transfer from the body to the water. Perhaps the wrinkling is a secondary, albeit advantageous, effect. Jim Marrone, Pinole, Calif. Cat controversy As a conservation biologist, I... (p. 31)

Grand Canyon rising If the geology of the Grand Canyon dates back to 70 million years ago “Grand Canyon’s age pushed back,” (SN: 1/12/13, p. 15), that would be around the same time the Rocky Mountains were being pushed up by the subduction process originating off the western continental coast. Could the lifting of the Colorado Plateau be related to the lifting of the Colorado Rockies? Joe Flynn, Spanaway, Wash. The timing of the Colorado Plateau’s uplift remains fairly controversial, including whether it occurred all at once or in several discrete stages. But many geologists thi... (p. 31)

Scrutinizing baseball’s streaks My family owned the Oakland A’s, formerly the Kansas City Athletics, from 1960 to 1980. During this period, our team won three consecutive World Series (1972 – 74) and five consecutive division titles (1971 – 75). I personally witnessed that one player would be on a streak and his attitude appeared to raise his teammates’ spirits “Hitting streaks may be contagious,” (SN: 1/26/13, p. 13). I also saw the opposite: If a player was having a bad day, this also seemed to be contagious. Nancy H. Finley, Dublin, Calif. On the other hand, you... (p. 31)

Dark matter enlightened Tom Siegfried’s article on dark matter “Light in the Dark,” (SN: 1/12/13, p. 18) reminded me of the 19th century search for the luminiferous ether. One can only wonder if history will repeat itself in the 21st century search for dark matter. Jeffery Miller, Los Angeles, Calif. The difference is that the ether was only surmised; attempts to observe its effects failed. There is abundant observational evidence for the existence of dark matter. Its actual identity could still, of course, turn out to be very surprising. — Tom Siegfried Where did the figure th... (p. 31)

Weighing factors in obesity In “Obesity research gets weightier” (SN: 12/29/12, p. 28) Nathan Seppa says that green space and a nearby grocery store reduce the incidence of obesity. I think I understand how the green space affects it (clean air, physical activity, et cetera), but I don’t understand how the grocery store does. Is there anything showing a connection? Ted Grinthal, Berkeley Heights, N.J. The connection lies in access to fresh fruits and vegetables, which fight obesity. The researchers counted grocery stores that sold fruits and veggies within a half mile of neighborh... (p. 31)

Early puberty’s cause Regarding “Early Arrival” (SN: 12/1/12, p. 26): In 1960 I left the Ohio Valley of grass- and corn-fed cows to teach in the Los Angeles area. When I arrived, I found that eighth- and ninth-grade girls looked physically like 25-year-old women in Ohio. I asked the other teachers what was going on. They all responded, “beef growth hormones.” If researchers would track earlier puberty in preteen girls alongside the use of growth hormones in cattle, they would most likely find matching graphs. Is this another horror of fast food such as hormone-laden hamburgers? ... (p. 31)