Letters from the May 12, 2007, issue of Science News

Saw right through it

E. Fred Schubert and his colleagues are to be congratulated for developing an improved antireflective coating (“The New Black: A nanoscale coating reflects almost no light,” SN: 3/3/07, p. 132). But the coating would not make a lens “absorb” more light. Rather, it would help the lens “propagate” the light.

Nathaniel L. Cohen
San Diego, Calif.

“Absorb” probably was a poor word choice in reference to a lens. The point is that the coating reduces the amount of light reflected at the lens’ surface, thereby increasing the transmission of light through the lens.—P. Barry

Like dog years?

You report on new age dates for Clovis sites (“New age for ancient Americans,” SN: 3/3/07, p. 141). It may be of interest to your readers that the dates given (11,050 to 10,900 years ago) are in “radiocarbon years” and are not in real or “calendar years.” As a result of variations in the production of carbon-14 in the atmosphere through time, radiocarbon years have a certain percentage of error, depending on age and type of material. For example, the radiocarbon date of 11,000 years is actually equal to approximately 13,000 calendar years.

Bruce Bartleson
Gunnison, Colo.

Poacher prevention

To discourage poaching, authorities in Zambia should subdue every elephant they can find, sedate it, harvest the ivory themselves, and sell it for revenue for animal-protection programs (“DNA pinpoints poached ivory tusks,” SN: 3/10/07, p. 158). That’s better than dead.

Buz Craft
Wills Point, Texas

A lot of living to do

Regarding “Living Long on Less? Mouse and human cells respond to slim diets” (SN: 3/10/07, p. 147), what were the ages of the people in the study?

Henry Dieter Weinschel
Las Cruces, N.M.

The participants, whose muscle cells showed several more-youthful signs if they ate fewer calories, were 35 to 38 years old.—P. Barry

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