Burp of Arctic laughing gas is no joke

It seems the Arctic is belching out nitrous oxide – commonly known as laughing gas. Unfortunately, the punchline is that it is a powerful greenhouse gas.

Previously, emissions of N2O were thought to enter the atmosphere mainly from tropical forests and intensively managed farmland, with only a negligible amount from northerly environments.

Maija Repo and colleagues from the University of Kuopio, Finland, measured emissions from peat circles in northern Russia. These sit on peatland plateaux, which are widespread throughout the Arctic, covering 20% of the total land surface. The bare surfaces of peat circles develop because cycles of freezing and thawing churn up the peat, preventing plant growth.

During the snow-free season, they found the peat circles emitted 1.2 grams/m2 of N2O, which is just as much as tropical forests release in a year. The team reckons that a lack of plants decreases competition for the mineral nitrogen. This allows nitrate to accumulate in the soil which is then metabolised by bacteria to produce N2O.

Although this means N2O remains a small contributor to the greenhouse effect, compared with methane and carbon dioxide, the gas persists unaltered in the atmosphere for over 110 years, compared with around 10 years for methane – which is also periodically released by the tundra.

Unfortunately, global warming may promote churning, and expand bare areas. Since the flow of the gas from the peat circles is so high, even a small increase in bare surfaces would cause significant changes in N2O emissions, says Repo.

First gravity map of Moon's far side unveiled

The first detailed map of the gravity fields on the Moon's far side shows that craters there are different than those on the near side. The results could reveal more about the Moon as it was billions of years ago, when magma flowed across its surface.

The new gravity map was collected by the Japanese lunar satellite Kaguya, which released two small probes into orbit around the Moon in 2007.

The motions of the three spacecraft, which are sensitive to variations in the Moon's gravity field, were measured by tracking their radio signals.

Crucially, while the main Kaguya spacecraft was on the far side of the Moon and therefore out of direct contact with Earth, one of the small probes relayed its signals to Earth.

The resulting map - the first detailed one completed of the Moon's far side - shows that craters on the far side have a markedly different gravity signature from those on the side that always faces Earth.
'Fabulous data'

That suggests that billions of years ago, there might have been large differences in the temperature or thickness of the Moon's two halves.

"It's fabulous new data," says Walter Kiefer, a planetary geophysicist with the Lunar and Planetary Institute in Houston, Texas, who was not part of the study. "We haven't been able to get a good look at the far side until now."

Most of the large craters on the Moon formed more than 3.8 billion years ago. These were partly filled in by magma that flowed on the surface before the Moon cooled and its geological activity died down.

But a number of craters also seem to have been filled in from below. Researchers believe material from the mantle also rose up in craters, since these are sites where impacts had thinned the Moon's crust.

The new Kaguya measurements reveal some craters on the far side that seem to have been filled only with mantle. These craters have higher-than-normal gravity at the centre, surrounded by a thick ring of low gravity that closely matches the original low elevation of the crater.
Opposite conclusions

It is not yet clear what these new crater measurements suggest about the early Moon. In order for these structures to survive, the lunar far side must have been too cool and stiff to allow the mantle at the craters' centres to smooth out much over time, says team leader Noriyuki Namiki, of Japan's Kyushu University. "The surface had to be very rigid to support these structures," Namiki says.

But Keifer says the low gravity rings could argue for the opposite scenario. The structures in the centres of the craters might be narrow because the top layer of the Moon's far side was too thin and warm to be able to hold up anything larger. Comparing the Kaguya observations with models could help settle the question, Kiefer says.

The Moon's two halves also show other striking differences. NASA's Lunar Prospector, which operated in the late 1990s, found that radioactive elements seem to be concentrated on the near side. The far side also shows less evidence of past volcanic activity.

Twisted radio beams could untangle the airwaves

The human race is not only exhausting tangible resources such as oil. The radiofrequency spectrum available for wireless communication is becoming the increasingly crowded, with virgin "veins" of frequency running short.

However, Swedish physicists say that twisting radio beams into a helical shape as they are transmitted could help ease the congestion.

Radio frequency encompasses electromagnetic waves between 3 kilohertz and 300 gigahertz, and as wireless communications technology advances much of that range is being used.

Satellite TV, wireless computer networks and cellphones are among the growing technologies vying for space up to 30 gigahertz, with some technology even beginning to extend beyond 100 gigahertz leaving a dwindling supply of virgin terrain to exploit.

Physicist Thomas Leyser at the Swedish Institute of Space Physics in Uppsala, Sweden, thinks he has a novel solution. Along with an international team of physicists, he has demonstrated that it is possible to put a spin on radio beams during their transmission to produce a twisted beam.

"Twisted laser beams have been researched since the 1990s, but it has only now become possible to create twisted beams at the much lower radio frequencies," he says.
Radio twister

That advance could prove important as it provides a new way to encode information into radio transmissions. Leyser says that "the information encoded in the twist is independent of the amplitude and frequency of the radio waves" - the features of a radio wave more normally used to encode data. "It is a feature of radio waves that has not been utilised before."

Leyser and his co-workers created the first twisted radio beams at the HAARP facility of 48 radio antennas in Alaska, normally used to investigate the aurora borealis and other features of the atmosphere. "In order to transmit a radio beam, one needs an array of antennas," he explains.

The signal is twisted by firing antennas in sequence to describe a circle, instead of having all of them transmit the same signal at once. "What we did was to feed all the antennas in the array with slightly different currents," says Leyser.

Each antenna received an alternating current slightly delayed from the adjacent antenna in the circle. The time delay ripples around the array so that the beam emerges to describe a helical wave front.
Digital bits

To confirm that the radio beam had this characteristic shape, the team studied the effects it had on the ionosphere above the array. "The twisted beams excited plasma turbulence in the ionosphere that was consistent with the ring-shaped beams and different from that excited by regular beams," Leyser says.

The twists remain coherent across vast distances - light years, even - and can store information in the form of digital bits (1s and 0s), encoded into the pitch of the twist.

What's not yet clear is how much extra information can be transmitted using twisted beams. In theory, huge amounts of data could be sent, says Leyser.

It is possible to use a much smaller array to produce twisted signals, he adds, although most consumer technologies such as cellphones use dipole antennas that cannot produce twisted beams.

Larger tripole antennas that can twist their transmissions might be suitable for linking fixed points, though, for example between cellphone towers.

Robot uses human mind tricks to navigate

Engineers in Germany have been studying human brain activity to improve the way moving robots avoid obstacles. Watch our exclusive video above to see the system in action.

The team at Ulm University lead by Heiko Neumann and Cornelia Beck analysed how human brains respond to visual information as they move around, and designed software that does the same thing for a wheeled robot with a human-like head with two cameras for eyes.

The robot head was built at Scuola Superiore Sant'Anna, Italy. When it is using the new brain-inspired software, the robot chooses similar paths to humans around obstacles. It could help create systems that can guide visually-impaired people and eventually help robots make their way through cluttered environments as well as we do.

A stellar factory millions of times larger than anything comparable in the Milky Way has been identified in a galaxy in the very early universe. The work bolsters the case that massive galaxies formed very quickly - in spectacular bursts of star formation - soon after the big bang.

Regions of intense star formation, called starbursts, span a few light years at most in the Milky Way, and less than a few hundred light years in nearby, bright galaxies such as Arp 220 (pictured). But it has not been clear how large the stellar nurseries were in the early universe.

To find out, researchers led by Fabian Walter of the Max Planck Institute for Astronomy in Heidelberg, Germany, carefully scrutinised a distant galaxy whose light has taken so long to reach Earth that it appears as it was just 870 million years after the big bang.

Warm dust

It is visible at such distances because it hosts a beacon-like quasar, a bright region created by superheated gas falling towards a colossal black hole at the galaxy's core.

The quasar, called J114816.64+525150.3, is so bright that it overwhelms the surrounding galaxy's light at visible and near-infrared wavelengths. But the galaxy's gas and warm dust can be detected at radio and far-infrared wavelengths.

Using an array of telescopes in the French Alps, the team measured the galaxy's ionised carbon, which emits a strong signal at far-infrared wavelengths. Far-infrared radiation is thought to be a signature of dust that has been heated up by nearby star formation.

Maximum rate

The ionised carbon spanned a region at the heart of the galaxy about 5000 light years across. Based on the galaxy's brightness at far-infrared wavelengths, this starburst region is thought to produce an astounding 1000 Sun-like stars every year.

That is "about 1000 times higher than the star-formation rate of the Milky Way", says team member Chris Carilli, chief scientist at the National Radio Astronomy Observatory in Socorro, New Mexico.

"It's forming stars at the maximal rate allowed . . . on scales that are 106 or 108 times larger in volume" than similar regions in the Milky Way, he continues. "That's remarkable."

Merging galaxies?

The immense scale of the stellar factory is probably due to the fact that there was a lot more gas around in the early universe, Carilli says. Matter in the universe was indeed much denser soon after the big bang, since space itself has expanded over time.

But researchers don't know what ignited the star birth in the first place. Mergers between galaxies can trigger gas clouds to collapse into stars (and cause matter to fall into a galaxy's central black hole, turning on a quasar). However, it's not clear from the observations whether or not a merger was involved in this case.

An alternative theory, put forward recently by a team led by Avishai Dekel of Hebrew University, suggests that cold gas flowing into galaxies - in either smooth streams or clumps - may trigger starbursts. "This may be an example of this phenomenon," Dekel told New Scientist.

crazy thinking

The idea which I am thinking mainly relates to guided vehicles which run on rubber tires with guide wheel in the centre and more particularly to GLT.

It mainly helps in

• Avoiding friction between guide wheel and guide rail.
• Avoiding slowing down of vehicle while taking curves (with perfect contact between guide wheel and guide rail)
• Helps in taking Deep curves than normal.
• Passenger convince

The ideology is to provide automated tilting mechanism to wheels.

Sensors are placed on the guide wheel which measures the force and depending upon the force acting on guide wheel the tilting of rubber wheel takes place at the axle of the respective rubber wheel.

When taking a right hand curve the inner side of the left hand side of the guide wheel flange will be subjected to force as it is pushed inward and so the left rubber wheel will be tilted (Top portion inwards and bottom portion Out wards) to some angle depending on the force on guide wheel so that the guide wheel and guide rail will be in perfect contact and this tilting of rubber wheel helps in taking smooth curve and it helps in avoiding slowing down of train during the curve

And vice versa when taking a left hand curve, right end rubber wheel will be tilted for the operation.

Tilting mechanism is restricted to some angle only.

And when one wheel is tilted it s made sure that the other wheel will be in normal position to avoid collapsing of vehicle due to weight imbalance.