Web edition: March 10, 2008
Print edition: March 15, 2008; Vol.173 #11 (p. 175)

Alpha bird(s)

There is a detail not explicit in the article "Birds network too" (SN: 2/23/08, p. 125) that fits the computer network analogy. By its flight path, each bird adds its personal input and helps guide the course of the flock.

Don Burnap
Rapid City, S.D.

Andrea Cavagna, a physicist at Italy's National Research Council, says that those studying how flocks of starlings coordinate flight have long debated whether a few birds lead in setting the course of the flock. Simulations show that the flock's decisions could indeed emerge from systemwide self-organization principles, he says, rather than from individual actions of a few birds. He adds that further analysis of the data he and his collaborators collected may help settle the question.—Davide Castelvecchi

Seeing is believing

"Extreme Measures" (SN: 2/16/08, p. 107) was wonderful. We have had light and electron microscopes. Can we look forward to atom-wave microscopes?

Bill Schindele
Thousand Oaks, Calif.

Yes. A team led by Bodil Holst at Graz University of Technology in Austria has built a microscope that bombards a sample with helium waves and then measures how the waves reflect to create a picture. In late 2007, Holst's team took the first-ever two-dimensional picture with a helium atom microscope: a blurry image of a tiny, honeycomb-shaped grating.—Ewen Callaway

More Web threads

Regarding "Biological Moon Shot" (SN: 2/2/08, p. 72), there is already a Web site that also aims to answer "What's in my backyard?" At ZipcodeZoo.com, David Stang has assembled close to 3 million pages of information (one species per page) based on more than 37 million field observations that include latitude and longitude. Taxonomic information is provided, and there are more than 250,000 photographs on the site. The organisms covered by the site include plants, animals, fungi, Protozoa, bacteria, and Chromista, and coverage is constantly increasing.

Maren H. Brown
Syracuse, N.Y.