30 June 2012 | NewScientist | 15

WANT ultra-fast wireless internet? Just get light to do the twist.

The wireless and fibre-optic links that make up the internet use electromagnetic waves to carry data as a series of pulses at a specific frequency. It is possible to increase the amount of data transmitted at a given frequency by twisting light beams in different ways. Each beam has a different angular momentum and

acts as an independent channel in a larger, composite beam.

Now Jian Wang, Alan Willner and colleagues at the University of Southern California in Los Angeles have used the twisting technique to transmit over a terabit of data per second. By comparison, home Wi-Fi routers run at around 50 megabits per second. Because there are many ways to twist light, the team was

Cobwebs in the gut ensnare bacteria

JUST like spiders, we weave webs – microscopic ones that capture and prevent microbes from irritating the lining of the small intestine.

Charles Bevins at the University of California, Davis, found that human alpha defensin 6 (HD6) molecules bind together to form a web after they have ensnared bacterial or fungal cells. The web prevents the cells from entering intestinal crypts – recesses lying at the bottom of villi that line the small intestine (Science, DOI: 10.1126/science.1218831).

Inside the crypts, stem cells regenerate the lining of the gut about every three days. “Anything that gets into the crypt is a potential threat to this process,” says Bevins.

HD6 is found at low levels in people with inflammatory bowel diseases, Bevins says, suggesting that reduced crypt protection may be a contributing factor.

Ethiopian genes hint at truth to Queen of Sheba story

THE genomes of Ethiopian people hold echoes of the meeting between a legendary king and queen.

About 3000 years ago, the Queen of Sheba purportedly travelled from what is now Ethiopia to meet King Solomon in Israel. Ethiopian folklore even tells of a child between the pair. But that’s just a story, right?

Perhaps not entirely. Luca Pagani of the Wellcome Trust Sanger Institute in Hinxton, UK, examined samples of Ethiopian genomes and noticed that some individuals had components of both African and non-African lineages. Delving deeper, Pagani and his colleagues

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Twist again to send a terabit a second able to combine beams with eight different types of twist, each carrying its own independent sequence of pulses (Nature Photonics, DOI: 10.1038/nphoton.2012.138).

Willner says the technique could be used between satellites in space, or over shorter distances on Earth. “It’s another dimension by which you can transmit data,” he says. Right now, it works only in free-space as current fibre-optic technology distorts twisted light.

discovered that the non-African genetic components had much more in common with people living in Syria and around the eastern Mediterranean than in the nearer Arabian peninsula. What’s more, the gene flow probably took place around 3000 years ago (The American Journal of Human Genetics, DOI: 10.1016/j.ajhg.2012.05.015).

The finding is backed by linguistic research, which shows that one of the four language families of Ethiopia migrated from the same region about 3000 years ago. “Middle Eastern language came to Ethiopia along with Middle Eastern genes,” Pagani says. “And that is when the Queen of Sheba legend is supposed to have happened.”

The meeting between the queen and Solomon remains a story, but the populations they came from did meet around that time, says Pagani.

DOES belief in heaven and a forgiving god make people less worried about breaking the law?

Azim Shariff at the University of Oregon in Eugene and his colleagues compared crime data from 67 countries with people’s beliefs in the afterlife. Even after controlling for crime-related factors including GDP, national crime rates were typically higher in countries with particularly strong beliefs in heaven but weak beliefs in hell (PLoS One, DOI: 10.1371/journal.pone.0039048).

“Belief in a benevolent, forgiving god could license people to think they can get away with things,” says Shariff, although he stresses that the results do not necessarily imply causality between religious beliefs and crime rates.

Is god’s mercy to blame for crime?

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