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Gravity may venture where matter fears to tread

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© UnknownIf gravity can sneak into dimensions that are closed to us, it might explain some puzzling cosmic anomalies

There is nothing certain in this world, US founding father Benjamin Franklin once wrote, except death and taxes. As a scientist, he might have added a third inescapable force: gravity, the unseen hand that keeps our feet on the ground.

Gravity is the universal force. Not only does it stop us getting above ourselves, it keeps Earth orbiting around the sun, our sun swinging around the centre of the Milky Way, the Milky Way in a merry dance around its neighbours, and so on upwards. It is actually the weakest of nature's four forces, but whereas the other three - electromagnetism and the strong and weak nuclear forces - unleash their full strength only at the scales of atoms and particles, gravity conserves its power to trump all comers in the cosmos at large. Just take any two things that have mass, and whatever their size, wherever they are, they will feel gravity's grasp in exactly the same way.

Or will they? Justin Khoury, now of the University of Pennsylvania in Philadelphia, and his colleagues Niayesh Afshordi and Ghazal Geshnizjani of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, are not so sure. They have listed a series of cosmological observations that cannot readily be explained with a one-size-fits-all gravity. None of these effects on its own, they stress, necessarily indicates anything amiss. But intriguingly, all of them melt away if you make just one assumption, albeit a controversial one: that how gravity works depends on the scale on which you look at it.

Light Saber

Scientists convert sound into light

U.S. scientists say they have, for the first time, changed high frequency sounds into light by reversing a process that converts electrical signals to sound.

The Lawrence Livermore National Laboratory researchers said their new tool enhances the way computer chips, LEDs and transistors are build.

Commonly used piezo-electric speakers, such as those found in a cell phone, operate at low frequencies that human ears can hear, the scientists from LLNL and the Nitronex Corp. said. But by reversing that process, lead researchers Michael Armstrong, Evan Reed and Mike Howard used a very high frequency sound wave -- about 100 million times higher frequency than what humans can hear -- to generate light.

Info

Galactic Dust Bunnies Found To Contain Carbon After All

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© NASAThe "Cat’s Eye" nebula, or NGC 6543, is a well-studied example of a "planetary nebula." Such objects are the glowing remnants of dust and gas expelled from moderate-sized stars during their last stages of life. Our own sun will generate such a nebula in about five billion years.

Using NASA's Spitzer Space Telescope, researchers have found evidence suggesting that stars rich in carbon complex molecules may form at the center of our Milky Way galaxy.

This discovery is significant because it adds to our knowledge of how stars form heavy elements - like oxygen, carbon and iron - and then blow them out across the universe, making it possible for life to develop.

Astronomers have long been baffled by a strange phenomenon: Why have their telescopes never detected carbon-rich stars at the center of our galaxy even though they have found these stars in other places? Now, by using Spitzer's powerful infrared detectors, a research team has found the elusive carbon stars in the galactic center.

Magnify

Prion discovery gives clue to control of mass gene expression

The discovery in common brewer's yeast of a new, infectious, misfolded protein -- or prion -- by University of Illinois at Chicago molecular biologists raises new questions about the roles played by these curious molecules, often associated with degenerative brain diseases like "mad cow" and its human counterpart, Creutzfeldt-Jakob. Susan Liebman, distinguished university professor of biological sciences, and postdoctoral research associate Basant Patel propagated the new prion from a normal yeast protein called Cyc8. They note that like the Cyc8 protein, the prion of Cyc8 can affect the expression of a large number of yeast genes.

"We know this prion turns on the expression of genes but we don't know if the prion forms naturally," said Liebman. "If it were to form, it would have this effect. But whether it happens out in the wild all the time, we don't know."

Einstein

The unexpected is a key to human learning

Learn more about: basal ganglia dopaminergic neurons pennsylvania researchers substantia nigra unexpected rewards university of pennsylvania

The human brain's sensitivity to unexpected outcomes plays a fundamental role in the ability to adapt and learn new behaviors, according to a new study by a team of psychologists and neuroscientists from the University of Pennsylvania. Using a computer-based card game and microelectrodes to observe neuronal activity of the brain, the Penn study, published this week in the journal Science, suggests that neurons in the human substantia nigra, or SN, play a central role in reward-based learning, modulating learning based on the discrepancy between the expected and the realized outcome.

"This is the first study to directly record neural activity underlying this learning process in humans, confirming the hypothesized role of the basal ganglia, which includes the SN, in models of reinforcement including learning, addiction and other disorders involving reward-seeking behavior," said lead author Kareem Zaghloul, postdoctoral fellow in neurosurgery at Penn's School off Medicine. "By responding to unexpected financial rewards, these cells encode information that seems to help participants maximize reward in the probabilistic learning task."

Telescope

A curious pair of galaxies

Curious Galaxies
© European Space AgencyThis color composite image of Arp 261 was created from images obtained using the FORS2 instrument on the ESO Very Large Telescope (VLT), at the Paranal Observatory in Chile. This image was created from images through blue, green, red and infrared filters and the total exposure time was 45 minutes.

Sometimes objects in the sky that appear strange, or different from normal, have a story to tell and prove scientifically very rewarding. This was the idea behind Halton Arp's catalogue of Peculiar Galaxies that appeared in the 1960s. One of the oddballs listed there is Arp 261, which has now been imaged in more detail than ever before using the FORS2 instrument on ESO's Very Large Telescope. The image proves to contain several surprises. Arp 261 lies about 70 million light-years distant in the constellation of Libra, the Scales. Its chaotic and very unusual structure is created by the interaction of two galaxies that are engaged in a slow motion, but highly disruptive close encounter. Although individual stars are very unlikely to collide in such an event, the huge clouds of gas and dust certainly do crash into each other at high speed, leading to the formation of bright new clusters of very hot stars that are clearly seen in the picture. The paths of the existing stars in the galaxies are also dramatically disrupted, creating the faint swirls extending to the upper left and lower right of the image. Both interacting galaxies were probably dwarfs not unlike the Magellanic Clouds orbiting our own galaxy.

The images used to create this picture were not actually taken to study the interacting galaxies at all, but to investigate the properties of the inconspicuous object just to the right of the brightest part of Arp 261 and close to the centre of the image. This is an unusual exploding star, called SN 1995N, that is thought to be the result of the final collapse of a massive star at the end of its life, a so-called core collapse supernova. SN 1995N is unusual because it has faded very slowly - and still shows clearly on this image more than seven years after the explosion took place! It is also one of the few supernovae to have been observed to emit X-rays. It is thought that these unusual characteristics are a result of the exploding star being in a dense region of space so that the material blasted out from the supernova plows into it and creates X-rays.

Meteor

Best of the Web: Discovery nears space station as debris nears, too

Discovery
© ESA
Seven astronauts raced to the international space station aboard space shuttle Discovery on Monday, while NASA debated whether the orbiting outpost will need to move aside to dodge part of an old Soviet satellite.

Space station astronauts had a close call last week with a small piece of orbiting junk, and NASA said Monday that debris from a satellite that broke apart in 1981 could come within about half a mile of the station early Tuesday.

NASA will decide later Monday whether to fire the space station's engines to nudge the complex out of the path of the debris.

Comment: Last month we were told that two satellites collided over Siberia. A few days later, fireballs were caught on video over Texas. Now in a week time we have heard twice of astronauts having to dodge 'space junk'.

Is there something we are not being told about what is going on in our atmosphere?


Pharoah

German researchers aim to recreate ancient Egyptian perfume

egypt
© Unknown
Researchers at Bonn University's Egyptian Museum aim to recreate a perfume used by Egypt's best-known female pharaoh, by analyzing residue from a well-preserved flacon, the museum said in a statement.

The 3,500-year-old filigree flacon bears the name of Hatshepsut, an 18th-dynasty pharaoh who ruled from around 1479 BC.

Michael Hoveler-Muller, the museum's curator, said: "The desiccated residues of a fluid can be clearly discerned in the x-ray photographs... Our pharmacologists are now going to analyze this sediment".

Magic Wand

Good as gold--What alchemists got right

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Three hundred years ago, more or less, the last serious alchemists finally gave up on their attempts to create gold from other metals, dropping the curtain on one of the least successful endeavors in the history of human striving.

Centuries of work and scholarship had been plowed into alchemical pursuits, and for what? Countless ruined cauldrons, a long trail of empty mystical symbols, and precisely zero ounces of transmuted gold. As a legacy, alchemy ranks above even fantasy baseball as a great human icon of misspent mental energy.

But was it really such a waste? A new generation of scholars is taking a closer look at a discipline that captivated some of the greatest minds of the Renaissance. And in a field that modern thinkers had dismissed as a folly driven by superstition and greed, they now see something quite different.

Alchemists, they are finding, can take credit for a long roster of genuine chemical achievements, as well as the techniques that would prove essential to the birth of modern lab science. In alchemists' intricate notes and diagrams, they see the early attempt to codify and hand down experimental knowledge. In the practices of alchemical workshops, they find a masterly refinement of distillation, sublimation, and other techniques still important in modern laboratories.

Bulb

Lasers provide antimatter bonanza

Hui Chen
© J. McBride/LLNLHui Chen of the Lawrence Livermore National Laboratory adjusts equipment inside a vacuum chamber at Livermore's Jupiter laser facility. She and her colleagues used Jupiter's Titan laser to produce the highest density of antimatter ever created in a lab.
A research team used lasers to produce more positrons (anti-electrons) inside a solid than any previous experiment, according to the researchers involved. In the 13 March Physical Review Letters, the team describes firing short pulses from an intense laser onto thin gold targets and creating a high-density positron source that could be used to investigate exotic phenomena near black holes or supernovae.

Researchers currently produce positrons using one of two methods. At low energies, from a few to a few thousand electron-volts, they are obtained from radioactive isotopes, as in positron emission tomography (PET), a medical imaging technique. Alternatively, particle accelerators can produce positrons with energies of billions of electron-volts.

Hui Chen and Scott Wilks of the Lawrence Livermore National Laboratory in California and their colleagues now report that they have generated copious amounts of positrons with intermediate energies--in the range of a million electron-volts. They fired picosecond pulses with intensities of around 1020 watts per square centimeter from the Titan laser at Livermore's Jupiter laser facility onto millimeter-thick gold targets. Positrons were produced via the "Bethe-Heitler" process, in which part of each laser pulse creates a plasma on the surface of the target, and the remaining part of the pulse then blasts electrons from the plasma into the solid. Next, the electrons are slowed down by gold nuclei, an interaction that generates gamma-ray photons. The gamma rays then interact with more gold nuclei and transform into electron-positron pairs.