Underwater 'microbial mat' size of Greece

A thick mat of microbes the size of a country has been found in the waters off South America, report scientists.

The find is among the most recent discoveries by the decade-long global Census of Marine Life, which involves more than 2000 scientists from over 80 nations and is in its final year.

"The bacterial mat extends over the size of Greece," says Dr Ian Poiner of Australian Institute of Marine Sciences (AIMS) in Townsville, who is involved in the survey.

Spotted off Chile and Peru by a team led by marine biologist Dr Victor Ariel Gallardo, the mats are made of filamentous bacteria that are 2 to 7 centimetres long and big enough to be seen by the naked eye.

The "Goliath" bacteria live in a part of the ocean that has very little oxygen, relying on hydrogen sulphide instead.

This "oxygen minimum zone" is an ecosystem that is reminiscent of the Proterozoic period 2.5 billion to 650 million years ago.

"These things are ancient forms of life," says Poiner.

"The mats are a very interesting phenomenon that we have to understand."

Bacterial mats can also occur in more shallow water that has been polluted by nutrient run-off.

Silk forms 'intimate' brain connection

A brain implant made partly of silk can melt onto the surface of the brain, providing an 'intimate' connection for recording signals, report researchers reported on Sunday.

Tests of their device showed the thin, flexible electrodes recorded signals from a cat's brain more accurately than thicker, stiff devices.

Such devices might help people with epilepsy, spinal cord injuries and even help operate artificial arms and legs, the researchers report in the journal Nature Materials.

John Rogers of the University of Illinois, Urbana and colleagues at the University of Pennsylvania and Tufts University in Boston made the electrode arrays using protein from silk and thin metal electrodes.

The silk is biocompatible and water-soluble, dissolving into the brain and leaving the electrodes draped over its contours, the researchers report.

The material is also transparent, strong and flexible, and it is possible to control the rate at which it dissolves.

They tested the silk on cats who were anesthetised but whose eyes were functioning. The electrodes recorded the signals from the eyes of the cats as they were shown visual images.

Microbial life discovered in asphalt lake

Scientists have discovered life in a liquid asphalt lake that is the closest thing on Earth to the hydrocarbon seas of the Saturnian moon Titan.

The find raises questions about the sort of environments capable of supporting life, and whether or not liquid water should still be considered the prerequisite for life to exist.

The discovery was made at Pitch Lake, a poisonous, foul smelling pond on the Caribbean island of Trinidad and Tobago.

Reporting in the physics blog ArXiv, Dr Dirk Schulze-Makuch of Washington State University and colleagues found Pitch Lake teeming with microbial life.

Schulze-Makuch says despite the lake being filled with hot asphalt and bubbling with noxious hydrocarbon gases and carbon dioxide, it's full of life.

"Water is scarce in the lake and certainly below the levels normally thought of as a threshold for life to exist," he says. "Yet on average, each gram of 'goo' in the lake contains tens of millions of living cells."
Strange life forms

Schulze-Makuch says his analysis of gene sequences shows many different kinds of microbial species of single-celled organisms such as archea and bacteria.

"Some are methanogens, others thrive on sulfur or iron, and many have never been seen before. They make a living in an oxygen-free environment full of nasty heavy metals, with very little water, eating hydrocarbons and in some cases breathing out metals," he syas.

"They're very different from microbes found in places like the LaBrea tar pits in Los Angeles. Similar strange life forms have previously been seen in hydrocarbon samples from sub sea oil wells. Which is another reason they are of interest.

Schulze-Makuch says how microbial organisms degrade and process oil reservoirs is poorly understood.

"A better understanding could lead to a number of advances in techniques for things like microbial remediation."

Flight Risk

In space gamma rays—the most energetic forms of light—are created by violent events, such as supernovae, and powerful objects, such as neutron stars.

Scientists have known for decades that thunderstorms on Earth can also create gamma rays, possibly during lightning production. Storms that make gamma rays usually hover about 9 miles (15 kilometers) above Earth, about the same altitude at which many commercial planes fly.

The new study shows that just one of these terrestrial gamma ray flashes, or TGFs, can equal the radiation dosage of about 400 chest x-rays—creating potential hazards for frequent flyers. (Related: "Gamma Ray Burst Caused Mass Extinction?")

In theory, stray gamma rays can alter the structure of human DNA, possibly triggering cancer.

Still, much is unknown about TGFs, including how likely it is for an airplane to fly close to gamma ray sources in storms, noted study co-author Joseph Dwyer, a space scientist at the Florida Institute of Technology.

"I would put this pretty far down on the list [of airplane hazards]," Dwyer said. "I've worked a lot on this, and I would not hesitate to hop on an airplane and fly with my kids across the country."

In fact, people are probably at bigger risk just driving their cars, said Brant Carlson, a TGF expert at Stanford University in California.

"I would say this is a very, very unlikely event, much less likely than many other flight hazards, or the hazards involved in getting to the airport in the first place," said Carlson, who was not involved in the study.

Apollo Moon Rocks

Hints of water in moon samples first surfaced in a 2008 study in the journal Nature, in which scientists reported having detecting water molecules in lunar glasses from the Apollo missions.

That team, however, hadn't been able to prove the water hadn't been introduced to the moon rocks on Earth, perhaps through sloppy handling.

One way to determine a water sample's birthplace is to measure the amounts of different hydrogen isotopes inside the water—a technique unavailable to the Nature team, said James Greenwood, a professor of Earth and environmental sciences at Wesleyan University in Middletown, Connecticut.

Isotope measurements can serve as fingerprints. Water from Earth's mantle has a different isotope ratio than water from a comet, for example.

When the Nature study came out, Greenwood was pioneering a technique that allowed him to study the chemical makeups of Martian meteorites. He later applied his method to samples of the mineral apatite, culled from a variety of moon-rock types, to determine the fingerprint of the water molecules inside.

The work proves that the moon-rock water "is not from us," he said at a presentation of his findings at the 41st Lunar and Planetary Science Conference in Houston, Texas.

Cosmic Scale

The finding suggests that the invisible substance called dark matter and the even more mysterious force known as dark energy are not just figments of physicists' imaginations.

For centuries Isaac Newton's law of universal gravitation worked well enough to explain gravity on Earth. But astronomers eventually saw discrepancies in the way larger objects such as planets interacted.

Einstein's general theory of relativity, published in 1916, proposed that gravity works on large scales because matter warps the fabric of space and time, also known as space-time. (See "Einstein and Beyond" in National Geographic magazine.)

This notion has been used to successfully explain phenomena in our solar system, such as the slight alterations in Mercury's orbit around the sun, which Newton's gravity couldn't account for.

The existence of dark matter and dark energy is based on the assumption that Einstein's gravity is affecting galaxies billions of light-years from Earth in the same way that it affects objects in our solar system.

Based on general relativity, for example, scientists think dark matter exists because some cosmic objects behave as if they have more mass than we can see.

But until now, tests of general relativity on galactic scales have been inconclusive.

Vision Invented

The trick is knowing exactly how materials alter light that enters them.

In experiments, the researchers shone a green laser beam at a roughly 80-micrometer-thick layer—that's 80 thousandths of a millimeter—of zinc oxide, a common ingredient in white paints. On the unseen side of the zinc layer were a series of tiny dots.

By analyzing the patterns of light that came through, the physicists generated a complex model called a transmission matrix—essentially a formula decoding the seemingly chaotic way light travels within the opaque material.

By applying the formula, the researchers say, they were able "translate" the green light coming through the zinc oxide, resulting in a digital camera image of dots in shades of green—revealing exactly what was behind the "wall."

(Read about the power of light.)

The team is now attempting to make out far more complex images of familiar objects, though they're awaiting publication before giving specific examples, ESPCI physicist Sylvain Gigan told National Geographic News.

The see-through vision isn't perfect, though, since a lot of light never makes it through to the other side of the opaque material. In more complex, future experiments, this missing "information" might result in grainy images, said Gigan, who co-authored the new study.

Should miaow-miaow be banned

The "legal high" mephedrone – also known as M-Cat, plant food, and miaow miaow – is getting a lot of attention because a series of deaths have been linked to the drug. Most recently, two teenaged men in the UK died after taking it on Sunday night, although the results of medical tests to determine the causes of their deaths will not be known for several weeks.

It has become the fourth most popular drug in the UK behind cannabis, ecstasy and cocaine over the past year. The British government's official drug advisers are expected to recommend that it be banned, but some drugs policy experts say criminalisation could do more harm than good. Now New Scientist cuts through the hype.

What is mephedrone?

The leaves of the khat plant, Catha edulis, are chewed for the stimulant, amphetamine-like properties of its active ingredients cathinone and cathine, mostly in east Africa and in migrant groups elsewhere. Mephedrone – more properly 4-methylmethcathinone – is the best known of a family of synthetic or substituted cathinones. It is commonly sold as a white powder or in capsules and is usually snorted or swallowed.

Where does it come from?

The vast majority is produced by Chinese chemical companies, which sell it for around £4,000 a kilogram, mostly to European dealers who sell it online for £10 to £15 per gram or less for larger quantities.

Point of nuclear weapons on instant alert

The NPR is expected to state that the US will not use its nukes to attack a country that does not itself have nuclear weapons - as long as that country complies with the Nuclear Non-Proliferation Treaty - and it may renounce nuclear weapons as a response to chemical or biological attack. It may also say 2500 "spare" US nuclear warheads will be destroyed.

But it is not expected to pledge that the US will never be first to launch a nuclear strike, nor that nuclear weapons are only for deterrence or response to nuclear attack. This policy means that the US, along with Russia, will continue to keep 1000 to 1200 nuclear missiles "on alert". For those who support the elimination of nuclear weapons that is a cause for concern. "De-alerting is the key problem," says Ivan Oelrich of the pressure group Federation of American Scientists.

To deter or respond to an attack, nations don't need to keep weapons on alert, says Oelrich. No country could take out all US missiles in a first strike, so a reprisal would not need to be speedy. The only reason to have so many on alert would be to pre-empt a large imminent attack by Russia, says policy analyst James Acton of the Carnegie Endowment for International Peace, a Washington DC-based think tank.

Missiles on alert are a worry, partly because a malfunction could lead to accidental launch, or they could be hijacked - but mostly because they could be launched by misinformed or pressurised military leaders or politicians during a fast-evolving situation, Oelrich says.

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Insect semen kills rival sperm

If you've only got one shot, you better make it count. For some social insects, with only one chance to impregnate their queen, things can get nasty, but it's not the males that try to harm each other: it's their ejaculate.

Some female insects, such as honeybeesMovie Camera and leafcutter ants, have sex on only one day in their life. But what a day: they mate with multiple males and store enough sperm to fertilise eggs throughout their lives.

Now it seems that when honeybees and leafcutter ants inseminate the queen, their seminal fluid is harmful to rival sperm. Researchers looking at sexual selection often focus on the all-important sperm, says Boris Baer of the University of Western Australia. The seminal fluid tends to be discounted as merely a sugary liquid which provides energy, he says.

Baer and colleagues from the University of Copenhagen, Denmark, exposed the sperm of honeybees and leafcutter ants to their own seminal fluid, and the secretions of other males of the same species. The seminal fluid killed more than 50 per cent of the rival sperm within 15 minutes. "The males seemed to use the seminal fluid to harm the sperm," says Baer.