Science & TechnologyS


Ark

Ancient Mass Graves of Soldiers, Babies Found in Italy

mass grave
© National Geographic

More than 10,000 graves containing ancient amphorae, "baby bottles," and the bodies of soldiers who fought the Carthaginians were found near the ancient Greek colony of Himera, in Italy, archaeologists announced recently. (See photos.)

"It's probably the largest Greek necropolis in Sicily," said Stefano Vassallo, the lead archaeologist of the team that made the discoveries, in September.

Ark

Archeologists unearth ancient city in Peru

Lima - Researchers digging at the Cerro Patapo archeological site in northern Peru have discovered the ruins of an entire city, which may provide the "missing link" between two ancient cultures, investigators said on Tuesday.

Magnify

How Mosquitoes Avoid Succumbing To Viruses They Transmit

Mosquitoes are like Typhoid Mary. They can spread viruses which cause West Nile fever, dengue fever, or yellow fever without themselves getting sick. Scientists long thought that the mosquito didn't care whether it had a virus hitchhiker, but have now discovered, "There is a war going on," said Zach Adelman, assistant professor of entomology at Virginia Tech.

The war is at the cellular level, between the host and invading RNA - the strands of code that produce different kinds of viral proteins.

The mediators that balance the interactions between mosquito and virus are virus-derived short-interfering RNAs (viRNAs), which are generated by the mosquito's immune response to infection. "If the mosquito is not able to cut up the virus genome into viRNAs, an otherwise invisible infection becomes fatal-- for both the mosquito and the virus. In other words, to complete the circle and be transmitted back to a vertebrate host, the virus must submit, to some extent, to the mosquito's antiviral response," said Kevin M. Myles, assistant professor of entomology at Virginia Tech.

Compass

Tiny Magnetic Crystals In Bacteria Are A Compass

tiny magnetic crystals help the bacteria to navigate
These tiny magnetic crystals (figures a, b,c and d) help the bacteria to navigate.
Scientists have shown that tiny crystals found inside bacteria provide a magnetic compass to help them navigate through sediment to find the best food.

Researchers say their study could provide fresh clues to explain biomagnetism - a phenomenon in which some birds, insects and marine life navigate using the magnetic field that encompasses the Earth.

The study focuses on magnetotactic bacteria, which contain chains of magnetic crystals, called magnetosomes. They exist all over the globe, living in lake and pond sediments and in ocean coastal regions.

Since the discovery of magnetotactic bacteria in the 1970s, it has not been clear exactly what magnetosomes were for. Previous research suggested that some magnetosome chains would not be useful for navigation because their crystal sizes did not possess the right magnetic qualities.

Telescope

Where Did Venus's Water Go?

Interaction between Venus and the solar wind
© ESA / C. CarreauInteraction between Venus and the solar wind.
Venus Express has made the first detection of an atmospheric loss process on Venus's day-side. Last year, the spacecraft revealed that most of the lost atmosphere escapes from the night-side. Together, these discoveries bring planetary scientists closer to understanding what happened to the water on Venus, which is suspected to have once been as abundant as on Earth.

The spacecraft's magnetometer instrument (MAG) detected the unmistakable signature of hydrogen gas being stripped from the day-side. "This is a process that was believed to be happening at Venus but this is the first time we measured it," says Magda Delva, Austrian Academy of Sciences, Graz, who leads the investigation.

Thanks to its carefully chosen orbit, Venus Express is strategically positioned to investigate this process; the spacecraft travels in a highly elliptical path sweeping over the poles of the planet.

Water is a key molecule on Earth because it makes life possible. With Earth and Venus approximately the same size, and having formed at the same time, astronomers believe that both planets likely began with similar amounts of the precious liquid. Today, however, the proportions on each planet are extremely different. Earth's atmosphere and oceans contain 100 000 times the total amount of water on Venus. In spite of the low concentration of water on Venus Delva and colleagues found that some 2x1024 hydrogen nuclei, a constituent atom of the water molecule, were being lost every second from Venus's day-side.

Satellite

Flaw may have sent Beagle 2 to a fiery doom

The mystery over what happened to the Beagle 2 spacecraft may have been solved, five years after contact with it was lost as it entered the Martian atmosphere on Christmas Day 2003. An Australian team of hypersonics engineers say a flawed calculation probably resulted in Beagle 2 tumbling out of control as it descended.

Until now, the loss of the probe has been attributed to the general failings of a poorly funded mission: despite an exhaustive enquiry by the European Space Agency, no single cause for the loss of the £50 million spacecraft has been identified.

Beagle 2
© ESAWhy did Beagle 2 disappear?
Beagle 2 was designed to self-stabilise during its descent through the Martian atmosphere. This was to be achieved through careful design of the spacecraft's aerodynamics and centre of gravity, and by spinning the craft as it was released from the European Space Agency's Mars Express orbiter. This generated a gyroscopic force for correcting wobbles as it descended.

The ideal spin rate was difficult to determine because the forces on a spacecraft change sharply as it plunges from the thin upper atmosphere to the denser gas closer to the surface. The Beagle 2 team simulated the forces in both these regimes but could not afford to simulate the way the forces change during the transition between the two. Instead, they estimated the forces using a mathematical process called a bridging function, and settled on a rate of 14 revolutions per minute.

Info

'Evil water' linked to mysterious drownings

It may sound like a superstitious excuse for a poor day's swimming, but it is not uncommon for triathletes to complain that the water is behaving badly - even that it is "evil". Now a study suggests what they are feeling is real.

Leo Maas, a fluid dynamicist at the Royal Netherlands Institute for Sea Research, and colleagues found that "dead water" - an obstructive effect encountered by ships at sea - can strike swimmers too.

As ships sail over a layer of warm water sitting over saltier, or colder, layers, waves form in the boundary between the two layers. As these waves grow, they form a gulf beneath the ship, sucking away its speed. This effect can stall boats at sea, reducing their speed by up to 80%.

Maas and his colleagues ran two experiments see if dead water could strike swimmers too.

Target

Scientists seek ways to ward off killer asteroids

A blue-ribbon panel of scientists is trying to determine the best way to detect and ward off any wandering space rocks that might be on a collision course with Earth.

Clock

Calls to scrap the 'leap second' grow

clock
© Joe Cornish/GETTY10, 9, 8, 7, 6, 5, 4, 3, 2, 1, and 1 again, happy new year!
At midnight on New Year's Eve, time will stop momentarily. Guardians of atomic clocks around the world will add an extra "leap second" to 2008 to keep time synched with the Earth's rotation. Arguably, the rise of GPS makes this tweak unnecessary.

In 1972, global commerce began to set its clocks by Coordinated Universal Time (UTC), based on the oscillations of the caesium atom. The snag was that other things, such as shipping and aircraft navigation, still relied on UT1 time, which divides one rotation of the Earth into 86,400 seconds. But the Earth's spin is slowing, so the two systems gradually go out of synch. "Over the course of a millennium, the differences would accumulate to about an hour," says Robert Nelson of the Satellite Engineering Research Corporation in Bethesda, Maryland.

To compensate, the ITU, or International Telecommunications Union, adds a leap second to atomic time every few years. However, many argue that we should stop tinkering with time, not least because of the glitches it causes (see "Add second...").

Now a group within the ITU, called Working Party 7A - after deliberating over the leap second for years - has told New Scientist that it recommends abolishing the leap second. Group member Elisa Felicitas Arias, of the International Bureau of Weights and Measures in Paris, France, argues that a timescale that doesn't need regular tweaking is essential in an increasingly interconnected world. What's more, she says, ships and aircraft now navigate via GPS rather than the old time system. GPS runs on a version of atomic time.

Info

First cases of touch-emotion synaesthesia discovered

For a 22-year-old woman known as AW, denim evokes feelings of depression, disgust and worthlessness. Corduroy causes confusion, and silk provides utter contentment. She is one of two people known to experience a newly discovered form of synaesthesia, where textures give rise to strong emotions.

HS, another young woman who experiences tactile-emotion synaesthesia, gets no kick out of denim. Fleece and dry leaves disgust her, while the touch of tennis balls, fresh leaves and sand are heaven.

Other forms of synaesthesia include numbers and letters that evoke colours, shapes that evoke tastes shapes and colours with their very own fragrances.

AW and HS's sensations, unusual though they may seem, are an extreme form of the positive feelings most people associate with a soft blanket or the aversion to sharp knives and jagged rocks, says V. S. Ramachandran, a neuroscientist at the University of California, San Diego.

"We have an affinity for fur because when were evolving in the ice age, we needed coats," he says. "This is the architecture on which [tactile-emotion synaesthesia] is built."