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Science 20 October 2006:
Vol. 314. no. 5798, p. 403
DOI: 10.1126/science.314.5798.403

Voilà! Cloak of Invisibility Unveiled
Just 5 months after predicting it should be possible, a team of physicists has produced a cloaking device that renders an object invisible--at least when viewed in microwaves of a particular wavelength.The cloak is hardly perfect: Instead of an all-concealing sphere, it's a ring that works only for microwaves zipping along in a plane. The microwaves must also be polarized perpendicular to the plane. And even then, the cloak reflects some of the waves and casts a slight shadow. Nevertheless, "it's a very good achievement," says Ulf Leonhardt, a theorist at the University of St. Andrews in the United Kingdom. "It's surprising that it's as simple as it is and that it works so well."

The cloak embodies the theory laid out by theorist John Pendry of Imperial College London and experimenters David Schurig and David Smith, who work in the electrical and computer engineering department at Duke University in Durham, North Carolina. In May, the team showed that, in principle, it's possible to ferry electromagnetic waves such as light around an object by surrounding it with a "metamaterial": an assemblage of tiny rods and C-shaped rings (Science, 26 May, p. 1120). The waves would then pass as if the object weren't there, rendering it invisible.

The electromagnetic waves cause the electrons in the rings and rods to slosh, and the sloshing, in turn, affects the speed at which the waves travel through the material. If the speed varies in the right way within the cloak, the waves will curve around the object. The theory predicts only how the speed of the waves must vary; it leaves it to experimenters to design the material.

When Schurig, Smith, and colleagues worked out the details, they found that their two-dimensional device required only C-shaped copper rings nestled side by side. The team also simplified the parameters specified by the theory. The changes made the metamaterial easier to build but also left the cloak slightly reflective, as the team reports online this week in Science (www.sciencemag.org/cgi/content/abstract/1133628). "The goal of this paper was to demonstrate that we more or less have the mechanism and that we can design the materials to the parameters," Schurig says.

Even the simplified cloak is a significant advance, says Costas Soukoulis, a theorist at Iowa State University in Ames and the U.S. Department of Energy's Ames Laboratory. "This is very, very important that experiments have produced what theorists had predicted," Soukoulis says. Microwave cloaks might be useful for eluding radar, he says.

It may take years for researchers to make a cloak for visible light. Still, most believe such a thing should be possible now that a cloak for microwaves has been built. After all, not seeing is believing.

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REPORTS
Metamaterial Electromagnetic Cloak at Microwave Frequencies
D. Schurig, J. J. Mock, B. J. Justice, S. A. Cummer, J. B. Pendry, A. F. Starr, and D. R. Smith (10 November 2006)
Science 314 (5801), 977. [DOI: 10.1126/science.1133628]

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Science 15 December 2006:
Vol. 314. no. 5806, p. 1672
DOI: 10.1126/science.314.5806.1672a
There's More Than One Way to Have Your Milk and Drink It, Too
The adage that milk does a body good may be true for American celebrities wearing milk mustaches in ad campaigns: Many Americans and northern Europeans descend from cattle herders and carry an ancient mutation that allows them to tolerate milk at any age. But milk gives cramps and diarrhea to roughly half the world's adults, especially in Asia and West Africa. That's why lactose tolerance has been held up as a classic example of human evolution, in which some people inherited the trait to digest milk, and some didn't.

Now, an international team reports a revealing twist on this evolutionary story. In this week's issue of Nature Genetics, researchers describe three new genetic variants that arose independently in groups of Africans; each variant allows carriers to drink milk and eat dairy products as adults. The study shows that lactose tolerance evolved more than once in response to culture, says team leader Sarah Tishkoff of the University of Maryland, College Park.

It's also an elegant example of how evolution can find several solutions to the same problem, especially in the face of strong selection, says molecular anthropologist Kenneth Weiss of Pennsylvania State University in State College. "There is not just one way to tolerate milk but several ways," he says. "It's very nice work because it shows that evolution isn't just about picking one gene and driving it."

The textbook tale of lactose tolerance runs this way: All humans digest mother's milk as infants. But for most of human history, weaned children didn't drink milk. So they shut down the enzyme lactase, which breaks lactose into sugars. With the domestication of cattle 9000 years ago, it became advantageous to digest milk, and lactose tolerance evolved in people who raised cattle.

In 2002, researchers identified a genetic mutation that regulates the expression of lactase and allows Finns and other northern Europeans to drink milk as adults. But researchers were surprised that the mutation appeared at lower frequency in southern Europe and the Middle East, and it was missing in most African pastoralists.

Tishkoff organized a team to collect blood samples from 470 Tanzanians, Kenyans, and Sudanese from 43 ethnic groups. Her team sequenced the DNA of 110 individuals who also were tested for milk tolerance.
They found three new mutations in the same stretch of DNA as the European variant. The mutations turned up in varying frequencies in the Maasai and other Nilo- Saharan populations in Tanzania and Kenya, in Afro-Asiatic-speaking Kenyans, and in the Beja from Sudan; some people had all three mutations. People with any of the variants had higher blood sugar levels after drinking milk, a sign that lactose was being digested.

The researchers also found that the most common variant arose as recently as 3000 to 7000 years ago and spread rapidly. "This is extremely significant because it shows the speed with which a genetic mutation can be selected," says zooarchaeologist Diane Gifford-Gonzalez of the University of California, Santa Cruz. Indeed, the data suggest that humans who could digest milk had a huge reproductive advantage. "This is the strongest signature of recent positive selection yet observed," says Tishkoff.

The new data may also help explain why people tolerate milk to varying degrees. The ability to drink milk is "not a qualitative trait that you have or you don't," says Weiss. Tishkoff thinks there are yet more variants, and her team is seeking them.

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Hey all..
I haven't been contributing to WGB much lately- mostly because of pathetic excuses like too much work to do.

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btw- at one time there were five different girls in my department (of 1100) named Tequila (all with various spellings).

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Originally posted by L_Han:
I will have to read that, since I have a virtually unpronounceable name in English.

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But i have to ask

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btw- at one time there were five different girls in my department (of 1100) named Tequila (all with various spellings).

really? And what was their ethnicity?

I mean- the only one I heard was from The Diamond Age

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Originally posted by editengine:
I wonder if there is a similar issue with meat that people experience with milk. I have known a woman who was never fed meat as a child, her family grew up in an area where it was not available at a price they could afford is what she told me. She claimed to now be a vegetarian by default because her system could not digest meat (specifically beef, I don't know about other meats) While not evolutionary like lactose intolerance might be is the ability to eat beef a "learned" function or is it innate in us as omnivores?

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Nature Genetics
Published online: 29 December 2006; | doi:10.1038/news061225-3
Cloned animals deemed safe to eat
US regulators prepare to OK food made from cloned animals.
The US government has released a draft proposal declaring that food from cloned cattle, pigs and goats is "likely to be as safe as" food from their non-cloned counterparts. The draft, released yesterday, arrives more than five years after the US Food and Drug Administration (FDA) requested a voluntary moratorium on the use of cloned animals or their offspring for food until their safety could be assessed.

The proposal is now open to a 90-day public comment period, after which the FDA is widely expected to officially approve food from some cloned animals for human consumption (for sheep, they say, there is still not enough data); the draft states that the FDA has few concerns about the health of cloned animals or the food that they produce.

Industry has been awaiting these findings for years. The FDA released a summary proposal in 2003, but the administration took three more years to produce a full document, citing a lack of sufficient scientific evidence. Since then, the FDA has been gathering data from peer-reviewed studies and unpublished reports from commercial cloning companies. The results of that effort are published in the January 2007 edition of Theriogenology, now available online.

FDA approval is unlikely to unleash a flood of food from cloned animals — cloning is still too expensive to be used regularly for food production. Instead, the technique will initially be used primarily to clone elite animals for breeding. The offspring of those clones will probably be the first to arrive at the dinner table, although a few clones may wend their way directly into the food supply when they are no longer useful for breeding.

Clones without borders

The impact of the FDA's decision will be felt beyond US borders. Chikara Kubota, an animal-cloning researcher at Kagoshima University in Japan, says he was relieved to hear of the FDA's decision and he expects the announcement to affect the status of moratoriums in other countries, including Japan.

Mal Brandon, chairman of Clone International, an animal cloning company based in Australia and New Zealand, says the FDA's announcement is "fantastic news". "It means we can officially open for business," says Brandon, "and draw up contracts with animal breeders and livestock owners worldwide, confident that the offspring of cloned livestock can enter the food chain."

But not everyone is enthusiastic about allowing cloned animals into the food supply. A 2006 survey conducted by the Pew Initiative on Food and Biotechnology found that 64% of Americans are uncomfortable with the notion of animal cloning, raising concerns that allowing products from such animals into the food supply could hurt US dairy and meat industries.

The International Dairy Foods Association, an organization of US dairy lobbyists, issued a response to the FDA's draft proposal, calling cloning a "niche-market technology" that offers no current consumer benefit.

Concerns about the US meat and dairy industry have also worked their way to the US Congress. In an 11 December letter to the US Department of Health and Human Services, Senator Patrick Leahy of Vermont — a state that has a large dairy industry — and six other senators urged caution and cited concerns about consumer acceptance of products from cloned animals. "Clearly, consumers are not clamouring for this new food technology," the senators wrote.

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Science Magazine
Volume 315, Number 5810, Issue of 19 January 2007

APPLIED PHYSICS: Eavesdropping Foiled by Decoys
Secure communication between a sender and a receiver generally requires the message to be encrypted, with the sender and recipient sharing a secret key that encodes and deciphers the message. Ideally, the key should be changed often, and so for practical reasons the key should be distributable over normal communication channels. However, the possibility of the interception of the key by an eavesdropper would compromise security. There is, therefore, a need for a method to distribute the key to the recipient securely so that any attack on the communication channel by a potential eavesdropper can be detected and appropriate action taken.

Yuan et al. use a combination of signal and decoy optical pulses sent over a 25-km optic fiber to demonstrate unconditionally secure quantum-key distribution to a recipient. Because the decoy pulses are weaker than the signal pulses, interception by an eavesdropper considerably reduces their transmission rate to the receiver, thereby revealing the existence of an eavesdropper. Although the use of decoy pulses does provide for secure communication, it also places stringent requirements on the calibration of the sources and the detectors so that artifacts do not compromise security.

Appl. Phys. Lett. 90, 011118 (2007).

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In a study of non-human primates infected with the influenza virus that killed 50 million people in 1918, an international team of scientists has found a critical clue to how the virus killed so quickly and efficiently.

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Instead, the ulcerated lesion on the emperor's stomach suggests a history of chronic H. pylori gastritis, which might have increased his risk of gastric cancer, Dr. Genta said. The risk might have been further increased by his diet full of salt-preserved foods but sparse in fruits and vegetables -- common fare for long military campaigns.

"Even if treated today, he'd have been dead within a year," he said.

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Researchers Have Sequenced 2,000 Flu Genomes; Data in GenBank

NEW YORK (GenomeWeb News) — Researchers have sequenced the genomes of more than 2,000 influenza viruses and have deposited the data in GenBank, according to the National Institutes of Health.

The Institute for Genomic Research led the Influenza Genome Sequencing Project, which took place at the Microbial Sequencing Centers. The MSCs are part of the National Institutes of Allergy and Infectious Disease.

Other project collaborators include the National Center for Biotechnology Information, the Centers for Disease Control and Prevention, and several academic and clinical research institutions.

NIAID’s Maria Giovanni said that the influenza genome project has “vastly increase[ed] the amount of influenza sequence data,” and has led to more researchers putting more sequence data back into the public domain.

Additional information can be found here .