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See Inside May 2011

Readers Respond to "Flu Factories" and Other Articles

Letters to the editor from the January 2011 issue of Scientific American


FLU NETWORK
The title of Helen Branswell’s “Flu Factories” is the type of sensationalism that has to be overcome for influenza surveillance to be effective and was in stark contrast to the balanced report that followed. Also, since the article was written, there has been significant progress on the implementation of a national influenza surveillance program in swine. In the program, which started in May 2009, pork producers and their veterinarians submit tissues to one of 37 veterinary diagnostic laboratories nationwide. Genetic sequences of isolated flu virus are entered into a database, then published and made available for review by experts and the public. Should there be a sequence of interest, the public or animal health surveillance systems in the state of origin can be alerted. To educate pork producers about this surveillance plan, direct mailings and other communications have been sent to more than 67,000 producers and to all state animal health officials and public health veterinarians. The results have been remarkable. During November 2010 alone, 490 samples were tested, compared with a previous monthly average of fewer than 200. U.S. pork producers and their families live with these animals, and they take the role they have in protecting public health very seriously.
Paul Sundberg
Vice President, Science and Technology
National Pork Board

GALAXY-WIDE WEB
Tim Folger’s “Contact: The Day After” cites the well-known equation by Frank Drake, which argues for a galaxy full of sentient life. Yet no artificial signal has been detected, and we wonder why. The Drake equation includes a term L, which represents the life span of an alien civilization, but the implicit assumption is that such a civilization would emit signals we could both detect and recognize during its entire life span following its invention of radio. But here on Earth we can already see the failure of that assumption in two ways.

First, after less than 100 years of beacon­like transmissions, the day of the 50-kilowatt broadcast antenna is drawing to a close, as communications technology advances to coaxial, fiber-optic, and short-range, low-power systems. Even geosynchronous satellite communication is aimed down, parsimoniously covering only a portion of Earth’s surface.

Second, every broadcast medium is moving to a digital format, and digital means data compression. Data compression removes redundancies—that is, any recognizable pattern in the signal—and replaces them with a compact digital code. Perfectly compressed digital data are thus indistinguishable from random noise.

These changes have overtaken human communications technology within only a few decades of Guglielmo Marconi’s first work. I can only conclude that we could be sitting in the midst of a “Galaxy-Wide Web” of alien chatter, which to us, without the algorithms to decode it, appears like noise. Perhaps Drake’s L value should be kept to under 50 years, and perhaps SETI could try to think of ways to detect digital signals embodying advanced compression—signals that look just like noise.
Grant Hallman
Huntsville, Ontario

RADIOACTIVE CIGS
The article “Radioactive Smoke,” by Brianna Rego, shed more light on cigarette manufacturers and their not so ethical practices. If tobacco growers are using fertilizer on their plants, it obviously works, even though it is made from uranium-rich phosphate rock and results in polonium 210—a decay product of uranium—being inhaled with cigarette smoke. But as a nonsmoker, I wonder just where else this polonium may lie. Are food growers using the same type of fertilizer? What about cotton growers?
Rachel Allgood
Savannah, Ga.

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