‘Big Bang Machine’ all set to start operations tomorrow

March 29, 2010 By Leave a Comment

London, March 29 (ANI): Reports indicate that the Large Hadron Collider (LHC), popularly known as the ‘Big Bang Machine’, is all set to start operations aimed for record-breaking high-energy particle experiments on March 30, after an 18-month delay for repairs.

According to a report in The Guardian, operators of the LHC have set Tuesday morning as the moment the machine will attempt to steer speeding particles into head-on collisions, creating microscopic bursts of energy that mimic conditions that existed a fraction of a second after the Big Bang.

The start of high-energy operations at the collider marks the end of a frustrating 18-month delay for physicists who saw the machine shut down for essential repair work following an explosion at the laboratory in September 2008, just nine days after it was first switched on.

The 6 billion pounds collider, which occupies a 17-mile (27km) circular tunnel 100m beneath the French-Swiss border, accelerated two counter-rotating beams of protons to an unprecedented energy of 3.5tn electron volts (TeV) last week.

On Tuesday, the beams will be crossed for the first time in the highest-energy man-made collisions ever.

The incident that closed the machine was caused by a short circuit that led to a tonne of liquid helium bursting into the collider tunnel.

Repair work and extra protection systems cost the laboratory 24 million pounds.

The machine was designed to collide two 7 TeV beams of protons, but laboratory managers decided in January to operate the machine at half power until the end of 2011.

The machine will then close for a year of further engineering work to ensure it can run at full power in 2013 without breaking down again.

For scientists at CERN and elsewhere, the beginning of high-energy collisions on Tuesday will end a long period of working without any real data.

Until recently, many physicists have had to make do with computer simulations of particle collisions.

“There’s a lot of anticipation here. Everything’s been pent up for a while and everyone’s ready and eager to get some real data,” said David Wardrope, a British physicist at Cern who completed his PhD at the laboratory last year.

“So far, everything is looking good. We can do some real science now,” he added.

The LHC is expected to make new discoveries about the laws of physics at the highest energies and smallest scales ever probed.

Physicists hope these will help them decide which of their theories of nature are right and which should be junked. (ANI)

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Self-repairing materials may soon make nuclear reactors a whole lot safer

March 26, 2010 By Leave a Comment

Washington, March 26 (ANI): As a result of research by Los Alamos National Laboratory scientists, self-repairing materials within nuclear reactors may one day become a reality.

Los Alamos researchers report a surprising mechanism that allows nanocrystalline materials to heal themselves after suffering radiation-induced damage.

Nanocrystalline materials are those created from nanosized particles, in this case copper particles.

Nanocrystalline materials consist of a mixture of grains and the interface between those grains, called grain boundaries.

When designing nuclear reactors or the materials that go into them, one of the key challenges is finding materials that can withstand an outrageously extreme environment.

In addition to constant bombardment by radiation, reactor materials may be subjected to extremes in temperature, physical stress, and corrosive conditions.

Exposure to high radiation alone produces significant damage at the nanoscale, as it can cause individual atoms or groups of atoms to be jarred out of place.

Each vagrant atom becomes known as an interstitial.

The empty space left behind by the displaced atom is known as a vacancy. Consequently, every interstitial created also creates one vacancy.

As these defects build up over time in a material, effects such as swelling, hardening or embrittlement can manifest in the material and lead to catastrophic failure.

Therefore, designing materials that can withstand radiation-induced damage is very important for improving the reliability, safety and lifespan of nuclear energy systems.

Because nanocrystalline materials contain a large fraction of grain boundaries – which are thought to act as sinks that absorb and remove defects – scientists have expected that these materials should be more radiation tolerant than their larger-grain counterparts.

Recent computer simulations by the Los Alamos researchers describe the never-before-observed phenomenon of a “loading-unloading” effect at grain boundaries in nanocrystalline materials.

This loading-unloading effect allows for effective self-healing of radiation-induced defects.

Using three different computer simulation methods, the researchers looked at the interaction between defects and grain boundaries on time scales ranging from picoseconds to microseconds.

On the shorter timescales, radiation-damaged materials underwent a “loading” process at the grain boundaries, in which interstitial atoms became trapped-or loaded-into the grain boundary.

Under these conditions, the subsequent number of accumulated vacancies in the bulk material occurred in amounts much greater than would have occurred in bulk materials in which a boundary didn”t exist.

After trapping interstitials, the grain boundary later “unloaded” interstitials back into vacancies near the grain boundary.

In doing so, the process annihilates both types of defects – healing the material. (ANI)

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Why nebulae around massive stars don’t disappear

March 17, 2010 By Leave a Comment

Washington, March 17 (ANI): A team of scientists, using computer simulations, has solved a 20-year-old riddle about why nebulae around massive stars don’t disappear.

Massive stars are dense enough to fuse hydrogen while they”re still gathering material from the gas cloud, so it was a mystery why their brilliant radiation does not heat the infalling gas and blow it away.

New simulations by researchers affiliated with the University of Heidelberg, American Museum of Natural History, the National Autonomous University of Mexico, and the Harvard-Smithsonian Center for Astrophysics show that as the gas cloud collapses, it forms dense filamentary structures that absorb the star’s radiation when it passes through them.

A result is that the surrounding heated nebula flickers like a candle flame.

“To form a massive star, you need massive amounts of gas,” said Mordecai-Mark Mac Low, a co-author and curator in the Department of Astrophysics at the Museum. “Gravity draws that gas into filaments that feed the hungry baby stars,” he added.

Stars form when huge clouds of gas collapse.

Once the central density and temperature are high enough, hydrogen begins to fuse into helium and the star begins to shine.

The most massive stars, though, begin to shine while the clouds are still collapsing.

Their ultraviolet light ionizes the surrounding gas, forming a nebula with a temperature of 10,000 degrees Celsius.

This suggests that the growth of a massive star should taper off or even cease because the surrounding gas should be blown away by the heating.

First author Thomas Peters, a researcher at the Center of Astronomy at the University of Heidelberg and a former Annette Kade Fellow at the Museum, and colleagues ran gas dynamical simulations on supercomputers at the Texas Advanced Computing Center funded by the National Science Foundation and at the Leibniz and Juelich Computing Centers in Germany.

The team’s results show that interstellar gas around massive stars does not fall evenly onto the star, but instead forms filamentary concentrations because the amount of gas is so great that gravity causes it to collapse locally while falling to the star.

The local areas of collapse form spiral filaments.

When the massive star passes through them, they absorb its ultraviolet radiation, shielding the surrounding gas.

This shielding explains not only how gas can continue falling in, but why the ionized nebulae observed with radio telescopes are so small.

The nebulae shrink again as they are no longer ionized, so that over thousands of years, the nebula appears to flicker, almost like a candle. (ANI)

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Non-lethal blast waves can cause brain injuries even without direct head impacts

August 27, 2009 By Leave a Comment

Washington, August 27 (ANI): In a new research, scientists have discovered that non-lethal blast waves can cause human brain injury even without direct head impacts, which could lead to an enhanced understanding of head injuries and improved military helmet design.

Using numerical hydrodynamic computer simulations, Lawrence Livermore scientists Willy Moss and Michael King, along with University of Rochester colleague Eric Blackman, have discovered that non-lethal blasts can induce enough skull flexure to generate potentially damaging loads in the brain, even without direct head impact.

Traumatic brain injury (TBI) results from mechanical loads in the brain, often without skull fracture, and causes complex, long-lasting symptoms.

TBI in civilians is usually caused by direct head impacts resulting from motor vehicle and sports accidents. TBI also has emerged among military combat personnel exposed to blast waves.

As modern body armor has substantially reduced soldier fatalities from explosive attacks, the lower mortality rates have revealed the high prevalence of TBI.

But, TBIs resulting from blast waves without head impacts have not been well understood.

To tackle this puzzle, the research team used three-dimensional hydrodynamic simulations to prove that direct action of the blast wave on the head causes skull flexure, producing mechanical loads in brain tissue comparable to those in an injury-inducing impact, even at non-lethal blast pressures as low as 1 bar above atmospheric pressure.

The Army’s Advanced Combat Helmet replaced the older Personal Armor System for Ground Troops helmet.

Its Kevlar shell provides ballistic and impact protection, and its reduced edge cut, although reducing area of coverage, improves soldiers’ field of vision and hearing.

In particular, the team showed that blast waves affect the brain very differently from direct impacts.

The primary source of injury from direct impacts is the force resulting from the bulk acceleration of the head.

In contrast, a blast wave squeezes the skull, creating pressures as large as an injury-inducing impact and pressure gradients in the brain that are much larger.

This occurs even when the bulk head accelerations induced by a blast wave are much smaller than from a direct impact.

“The blast wave sweeps over the skull like a rolling pin going over dough,” said King, LLNL co-principal investigator.

Although the simulations show that the skull is deformed only about 50 microns, “this is large enough to generate potentially damaging loads in the brain,” according to Moss.

“The possibility that blasts may contribute to traumatic brain injury has implications for injury diagnosis and improved armor design,” he added. (ANI)

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Asteroids may have flocked together to build planets

August 18, 2009 By Leave a Comment

London, August 18 (ANI): New computer simulations have suggested that dense swarms of asteroids collapsed under their own gravity to make the building blocks of the planets in our solar system.

The planets are thought to have formed from a disc of dust and gas around the infant sun.

The initial process is well known: dust grains clumped together, forming objects in the millimetre-to-metre range.

However, it is not known how the growth process continued.

The gas in the disc should have put a drag on the new boulders, causing them to spiral into the sun before they could grow further.

According to a report in New Scientist, evidence is now mounting that the next step was a sudden leap forward, skipping intermediate sizes to make asteroids hundreds of kilometers across – massive enough to resist gas drag.

Asteroids hundreds of kilometers across appeared – too massive to be dragged into the sun

This basic idea is decades old, but it attracted renewed attention in 2007 and 2008 following simulations by a team led by Anders Johansen of the Max Planck Institute for Astronomy in Heidelberg, Germany, and by another team led by Jeffrey Cuzzi of NASA’s Ames Research Center in Moffett Field, California.

These showed that turbulence in the nebula could have concentrated objects less than a meter across in dense enough swarms to collapse under their mutual gravity and form large asteroids tens to hundreds of kilometers across.

“If either one of these models turns out to be right, this will be a big step forward,” said John Chambers of the Carnegie Institution in Washington DC.

Now, a new study has found evidence that such a process did occur in our solar system. It is based on the size of objects in the asteroid belt.

Estimates from telescopic surveys suggest there are millions of the smallest asteroids, which are less than a kilometer across, with the numbers of larger ones dropping off sharply.

Yet this size distribution and number would once have been different: asteroids can grow by sweeping up smaller objects, and shatter if they collide with an object of similar size.

Alessandro Morbidelli of the Cote D’Azur Observatory in Nice, France, led a team that simulated the evolution of the asteroid belt, modelling a variety of starting populations.

They did find a good fit when they started with a mixture of sizes between 100 and 1000 kilometers across, suggesting that large asteroids did form spontaneously during the solar system’s development. (ANI)

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Tiger stripes on Enceladus a result of its unusual chemical composition

July 16, 2009 By Leave a Comment

Melbourne, July 16 (ANI): A new study has revealed that the tiger stripes and a subsurface ocean on Enceladus – one of Saturn’s many moons, are a result of the natural satellite’s unusual chemical composition.

“NASA’s Cassini spacecraft recently revealed Enceladus as a dynamic place, recording geological features such as geysers emerging from the ‘tiger stripes’ which are thought to be cracks caused by tectonic activity on the south pole of the moon’s surface,” said Dr Dave Stegman, a Centenary Research Fellow in the School of Earth Sciences at the University of Melbourne.

Enceladus is also one of the brightest objects in our solar system because the ice covering its surface reflects almost 100 percent of the sunlight that strikes it.

It reflects so much of the sun’s energy that its surface temperature is about -201 degrees Celsius.

Grappling with how an inaccessible small moon with a completely frozen interior was capable of displaying geological activity, Dr Stegman and colleagues used computer simulations to virtually explore it.

Ammonia, usually found on Earth as an odorous gas used to make fertilizers, has been indirectly observed to be present in Enceladus and formed the basis of the study, which is the first to reveal the origins of the subsurface ocean.

The model reveals that Enceladus initially had a frozen shell composed of a mixture of ammonia and water ice surrounding a rocky core.

Over time, as Enceladus interacted with other moons, a small amount of heat was generated above the silicate core which made the ice shell separate into chemically distinct layers.

An ammonia-enriched liquid layer formed on top of the core while a thin layer of pure water ice formed above that.

“We found that if a layer of pure water ice formed near the core, it would have enough buoyancy to rise upwards, and such a redistribution of mass can generate large tectonic stresses at the surface,” said Dr Stegman.

“However, the pure water ice rising up is also slightly warmer which causes the separation to occur again, this time forming an ammonia-enriched ocean just under the surface. The presence of ammonia, which acts as an anti-freeze, then helps keep the ocean in its liquid state,” he explained.

“These simulations are an important step in understanding how planets evolve and provide questions to focus future space exploration and observations. It will hopefully progress our understanding of how and why planets and moons are different to each other,” he added. (ANI)

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Now, cheap, efficient, flexible solar cells made from nanopillars

July 10, 2009 By Leave a Comment

Washington, July 10 (ANI): Scientists have found a new way to make cheap, efficient, and flexible solar cells by using nanopillars made of low-cost and flexible materials.

The design by researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and the University of California at Berkeley, grows optically active semiconductors in arrays of nanoscale pillars, each a single crystal, with dimensions measured in billionths of a meter.

“To take advantage of abundant solar energy we have to find ways to mass-produce efficient photovoltaics. Single-crystalline semiconductors offer a lot of promise, but standard ways of making them aren’t economical,” said Ali Javey, lead author of the study.

Solar cell basically converts light energy into charge-carrying electrons and “holes” (the absence of an electron), which flow to electrodes to produce a current.

But, unlike a typical two-dimensional solar cell, a nanopillar array offers much more surface for collecting light.

Computer simulations have indicated that, compared to flat surfaces, nanopillar semiconductor arrays should be more sensitive to light, have a greatly enhanced ability to separate electrons from holes, and be a more efficient collector of these charge carriers.

Thus, Javey created a new, controlled way to use a method called the “vapour-liquid-solid” process to make large-scale modules of dense, highly ordered arrays of single-crystal nanopillars.

Inside a quartz furnace, the researchers grew pillars of electron-rich cadmium sulfide on aluminum foil, in which geometrically distributed pores made by anodization served as a template.

And in the same furnace they submerged the nanopillars, once grown, in a thin layer of hole-rich cadmium telluride, which acted as a window to collect the light.

The two materials in contact with each other form a solar cell in which the electrons flow through the nanopillars to the aluminum contact below, and the holes are conducted to thin copper-gold electrodes placed on the surface of the window above.

The efficiency of the test device was measured at six percent, which while less than the 10 to 18 percent range of mass-produced commercial cells is higher than most photovoltaic devices based on nanostructured materials.

It is possible to make a flexible solar cell, by removing the aluminum substrate, substituting an indium bottom electrode, and embedding the 3-D array in clear plastic. (ANI)

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Galileo may have discovered Neptune 234 years before its official discovery

July 10, 2009 By Leave a Comment

Washington, July 10 (ANI): A new theory by a University of Melbourne physicist has said that Galileo knew he had discovered a new planet, that we now know as Neptune, in the year 1613, 234 years before its official discovery date.

Professor David Jamieson, Head of the School of Physics, has put the theory forward.

He is investigating the notebooks of Galileo from 400 years ago and believes that buried in the notations is the evidence that the astronomer discovered a new planet that we now know as Neptune.

If correct, the discovery would be the first new planet identified by humanity since deep antiquity.

Galileo was observing the moons of Jupiter in the years 1612 and 1613 and recorded his observations in his notebooks.

Over several nights, he also recorded the position of a nearby star which does not appear in any modern star catalogue.

“It has been known for several decades that this unknown star was actually the planet Neptune. Computer simulations show the precision of his observations revealing that Neptune would have looked just like a faint star almost exactly where Galileo observed it,” Professor Jamieson said.

But, a planet is different to a star because planets orbit the Sun and move through the sky relative to the stars.

It is remarkable that on the night of January 28 in 1613, Galileo noted that the “star” we now know is the planet Neptune appeared to have moved relative to an actual nearby star.

There is also a mysterious unlabeled black dot in his earlier observations of January 6, 1613, which is in the right position to be Neptune.

“I believe this dot could reveal he went back in his notes to record where he saw Neptune earlier when it was even closer to Jupiter but had not previously attracted his attention because of its unremarkable star-like appearance,” said Professor Jamieson.

If the mysterious black dot on January 6 was actually recorded on January 28, Professor Jamieson proposes this would prove that Galileo believed he may have discovered a new planet. (ANI)

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Earliest stars in Universe may have been twins

July 10, 2009 By Leave a Comment

Washington, July 10 (ANI): Astrophysicists, using extremely detailed computer simulations, have determined that the earliest stars in the universe formed not only as individuals, but sometimes also as twins.

The robust simulations of the early universe were created by astrophysicists Matthew Turk and Tom Abel of the Kavli Institute for Particle Astrophysics and Cosmology, and Brian O’Shea of Michigan State University.

“We used to think that these stars formed by themselves, but now we see from our computer simulations that sometimes they have siblings,” said Turk.

“These stars provide the seeds of next generation star formation, so by understanding them we can better understand how other stars and galaxies formed,” he added.

To make this discovery, the researchers created an extremely detailed computer simulation of early star formation.

Into this virtual universe, they sprinkled primordial gas and dark matter as it existed soon after the Big Bang, data they obtained from observations of the cosmic microwave background.

This mostly uniform radiation – a faint glow of radio waves spread across the entire sky – contains subtle variations that reflect the beginning of all structure in the universe.

The simulations focused on the first Population III stars: massive, hot stars thought to have formed a mere several hundred million years after the Big Bang.

As the researchers watched their simulated universe evolve, waves of gas and dark matter swirled through the hot, dense universe.

As the universe cooled, gravity began to draw the matter together into clumps. In areas rich with matter, stars began to form.

In one out of the researchers’ five simulations, a single cloud of dust and dark matter formed into “twin” stars: one with a mass equivalent to about 10 suns, and one with a mass equivalent to about 6.3 suns.

Both of them were still growing at the end of the calculation and will likely grow to many times that mass.

“We ran five of these calculations starting from the beginning of the universe, and to our surprise one of them was special,” said Abel.

“This opens a whole new realm of research possibilities. These stars could evolve into two black holes, which could have created gravitational waves we could detect with an instrument like the Laser Interferometer Gravitational Wave Observatory,” he added.

“This will help us fine-tune our models for how structure in the universe formed and evolved. Understanding the very early stars helps us understand what we see today,” Turk said. (ANI)

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Habit of taking turns could be in your genes

July 10, 2009 By Leave a Comment

Washington, July 9 (ANI): The habit of taking turns is more than just good manners – it’s down to evolution, say researchers.

According to University of Leicester psychologists, there is an “invisible hand” that guides our actions in this respect.

“In human groups, turn-taking is usually planned and coordinated with the help of language. For example, people living together often agree to take turns washing up the dishes after meals or taking their children to school,” said Professor Andrew Colman.

And it’s not just in humans, turn-taking has also evolved in animals, including apes, monkeys, birds, and mating pairs of Antarctic penguins that take turns foraging at sea, while their partners incubate eggs or tend to chicks.

Using evolutionary game theory and computer simulations, Professor Colman and Dr. Lindsay Browning have discovered a simple variation of “tit for tat” (copying in each time period whatever the other individual did in the previous period), which can explain how turn-taking evolved in organisms that pursue their individual self-interests robotically.

“Turn-taking is initiated only after a species has evolved at least two genetically different types that behave differently in initial, uncoordinated interactions with others,” said the researchers.

“Then as soon as a pair coordinates by chance, they instinctively begin to play ‘tit for tat’. This locks them into mutually beneficial coordinated turn-taking indefinitely. Without genetic diversity, turn-taking cannot evolve in this simple way.

“In our simulations, the individuals were computer programs that were not only dumb and robotic but also purely selfish. Nevertheless, they ended up taking turns in perfect coordination,” the researchers added.

The study will appear in the journal Evolutionary Ecology Research. (ANI)

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Milky Way survived ancient heat wave because of dark matter

July 1, 2009 By Leave a Comment

Washington, July 1 (ANI): A new theory by scientists says that our Milky Way galaxy survived intense heat generated by the “ignition” of the Universe about half-a-billion years after the Big Bang, because it was already immersed in a large clump of dark matter that trapped gases inside it.

Tiny galaxies, inside small clumps of dark matter, were blasted away by the heat that reached approximate temperatures of between 20,000 and 100,000 degrees centigrade, according to the scientists, including experts at Japan’s University of Tsukuba.

The researchers said that the early Milky Way, which had begun forming stars, held on to the raw gaseous material from which further stars would be made.

This material would otherwise have been evaporated by the high temperatures generated by the “ignition”.

Using computer simulations carried out by the international Virgo Consortium (which is led by Durham), the scientists examined why galaxies like the Milky Way have so few companion galaxies or satellites.

Astronomers have found a few dozen small satellites around the Milky Way, but the simulations revealed that hundreds of thousands of small clumps of dark matter should be orbiting our galaxy.

Dark matter is thought to make up 85 per cent of the Universe’s mass and is believed to be one of the building blocks of galaxy formation.

The scientists said the heat from the early stars and black holes rendered this dark matter barren and unable to support the development of satellite star systems.

According to Joint lead investigator Professor Carlos Frenk, Director of the Institute for Computational Cosmology, at Durham University, “The validity of the standard model of our Universe hinges on finding a satisfactory explanation for why galaxies like the Milky Way have so few companions.”

“The simulations show that hundreds of thousands of small dark matter clumps should be orbiting the Milky Way, but they didn’t form galaxies,” he explained.

“We can demonstrate that it was almost impossible for these potential galaxies to survive the extreme heat generated by the first stars and black holes,” he added.

“The heat evaporated gas from the small dark matter clumps, rendering them barren. Only a few dozen front-runners which had a head start on making stars before the Universe ignited managed to survive,” he further added.

By providing a natural explanation for the origin of galaxies, the simulations support the view that cold dark matter is the best candidate for the mysterious material believed to make up the majority of our Universe. (ANI)

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‘US providing 100-mn aid to Pak to keep its nukes out of extremists reach’

June 29, 2009 By Leave a Comment

Washington, June 29 (ANI): The US is providing technical support at an estimated cost of 100 million dollars to Pakistan in order to keep that country’s nuclear arsenal out of the extremists reach and prevent accidents.

Andrew Cockburn, a renowned author who has written several books on security issues, says that the official aim of US technical support, at an estimated cost of 100 million dollars a year, is to prevent accidents and to ensure that they are out of the extremists’ reach.

But in pursuit of this objective, “it is inevitable that the US is not only rendering the warheads more operationally reliable, we are also transferring the technology required to design more sophisticated warheads without having to test them,” the report adds.

The author quotes a former national security official as saying that if the US is involved, “we can make sure they don’t start testing, or start a war.”

This system known as ‘stockpile stewardship’ was conceived after the US forswore live testing in 1993. It allows scientists to ‘test’ weapons through computer simulations. This vastly expensive programme not only ensures the weapons’ reliability but also the viability of new and improved designs.

The report says that in 2008, the Pakistan military approached Bruce Blair, president of a Washington-based World Security Institute, seeking advice on means to render their weapons more secure.

“Their aim was clearly to render their nuclear force mature and operational,” the Dawn quoted Blair, as saying.

In the same way, Blair said, a few years ago an Indian military delegation turned up at the Russian Impulse Design Bureau in St. Petersburg to ask for help on making their weapons safer to handle.

“They said they wanted to be able to assure their political leadership that their weapons were safe enough to be deployed.”

The author argues that the United States has allowed Pakistan’s nuclear programme to continue because it needs Islamabad’s help in other issues.

Cockburn recalls that when President Ronald Reagan was asked for his views on Pakistan’s nuclear ambitions, he replied “I just don’t think it’s any of our business.”

The author claims that “during the years Dr A. Q. Khan was peddling his uranium enrichment technology around the place, his shipping manager was a CIA agent, whose masters seem to have had little problem with allowing the trade to go forward.”

The Obama administration also has not changed this policy of tolerance towards Pakistan’s nuclear programme, he says. (ANI)

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Dolphins lift their fins in a similar manner to delta wing aircraft

June 27, 2009 By Leave a Comment

Washington, June 26 (ANI): In a new research, scientists have determined that some dolphins’ fins generate lift in the same way as delta wing aircraft.

The research was conducted by Laurens Howle and Paul Weber from Duke University, who teamed up with Mark Murray from the United States Naval Academy and Frank Fish from West Chester University, to find out more about the hydrodynamics of whale and dolphin flippers.

Using Computer tomography scanning of the fins of seven different species ranging from the slow swimming Amazon River dolphin and pygmy sperm whale to the super-fast striped dolphin, the team made scaled models of the flippers of each species.

Then, they measured the lift and drag experienced by the flipper at inclinations ranging from -45degrees to +45degrees in a flow tunnel running at a speed that would have been the equivalent of 2m/s for the full scale fin.

Comparing the lift and drag coefficients that the team calculated for each flipper at different inclination angles, they found that the flippers behave like modern engineered aerofoils.

Defining the flippers’ shapes as triangular, swept pointed or swept rounded, the team used computer simulations of the fluid flows around the flippers and found that sweptback flippers generate lift like modern delta wing aircraft.

Calculating the flippers’ efficiencies, the team found that the bottle nose dolphin’s triangular flippers are the most efficient while the harbour porpoise and Atlantic white-sided dolphin’s fins were the least efficient.

Howle and his colleagues will try to find out more about the link between the flippers’ performances and the environment that whales and dolphins negotiate on a daily basis. (ANI)

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Sea-level rise may pose greatest threat to Northeast US and Canada this century

May 28, 2009 By Leave a Comment

Washington, May 28 (ANI): A new research has suggested that the melting of the Greenland Ice Sheet this century may drive more water than previously thought toward the already threatened coastlines of New York, Boston, Halifax and other cities in the northeastern United States and Canada.

The researchers suggest that moderate to high rates of ice melt from Greenland may shift ocean circulation by about 2100, causing sea levels off the northeast coast of North America to rise by about 30 to 51 centimeters (12 to 20 inches) more than other coastal areas.

The research builds on recent reports that have found that sea level rise could adversely affect North America, and its findings suggest that the situation is even more urgent than previously believed.

“If the Greenland melt continues to accelerate, we could see significant impacts this century on the northeast U.S. coast from the resulting sea level rise,” said scientist Aixue Hu, the research paper’s lead author.

“Major northeastern cities are directly in the path of the greatest rise,” Hu added.

To assess the impact of Greenland ice melt on ocean circulation, Hu and his coauthors used the Community Climate System Model, an NCAR-based computer model that simulates global climate.

They considered three scenarios: the melt rate continuing to increase by 7 percent a year, as has been the case in recent years, or the melt rate slowing down to an increase of either 1 or 3 percent a year.

If Greenland’s melt rate slows down to a 3 percent annual increase, the study team’s computer simulations indicate that the runoff from its ice sheet could alter ocean circulation in a way that would direct about a foot of water toward the northeast coast of North America by 2100.

This would be on top of the average global sea level rise expected as a result of global warming.

Although the study team did not try to estimate that mean global sea level rise, their simulations indicated that melt from Greenland alone under the 3 percent scenario could raise sea levels by an average of 53 centimeters (21 inches).

But if the melt rate continued at its present 7 percent increase per year through 2050 and then leveled off, the study suggests that the northeast coast could see as much as 51 centimeters (20 inches) of sea level rise above a global average that could be several feet.

According to NCAR scientist Gerald Meehl, “Ocean dynamics will push water in certain directions, so some locations will experience sea level rise that is larger than the global average.” (ANI)

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Scientists move closer to “holy grail” of climate change science

May 18, 2009 By Leave a Comment

Washington, May 18 (ANI): A team of atmospheric chemists has moved closer to the first-ever direct detections of biological particles within ice clouds, which is considered the “holy grail” of climate change science.

The team, led by Kimberly Prather and Kerri Pratt of the University of California at San Diego, Scripps Institution of Oceanography, sampled water droplet and ice crystal residues at high speeds while flying through clouds in the skies over Wyoming, US.

Analysis of the ice crystals revealed that the particles that started their growth were made up almost entirely of either dust or biological material such as bacteria, fungal spores and plant material.

This study is the first to yield direct data on how airborne microorganisms work to influence cloud formation.

“If we understand the sources of the particles that nucleate clouds, and their relative abundance, we can determine their impact on climate,” said Pratt, lead author of the research paper.

The effects of tiny airborne particles called aerosols on cloud formation have been some of the most difficult aspects of weather and climate for scientists to understand.

In climate change science, which derives many of its projections from computer simulations of climate phenomena, the interactions between aerosols and clouds represent what scientists consider the greatest uncertainty in modeling predictions for the future.

“By sampling clouds in real time from an aircraft, these investigators were able to get information about ice particles in clouds at an unprecedented level of detail,” said Anne-Marie Schmoltner of NSF’s (National Science Foundation’s) Division of Atmospheric Sciences, which funded the research.

“By determining the chemical composition of the very cores of individual ice particles, they discovered that both mineral dust and, surprisingly, biological particles play a major role in the formation of clouds,” she added.

The Ice in Clouds Experiment – Layer Clouds (ICE-L) team mounted a mass spectrometer onto a C-130 aircraft operated by the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, and made a series of flights through a type of cloud known as a wave cloud.

The researchers performed in-situ measurements of cloud ice crystal residues and found that half were mineral dust and about a third were made up of inorganic ions mixed with nitrogen, phosphorus and carbon, the signature elements of biological matter.

The team demonstrated that both dust and biological material indeed form the nuclei of these ice particles, something that previously could only be simulated in laboratory experiments.

“This has really been kind of a holy grail measurement for us,” said Prather. (ANI)

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Planck satellite all set to measure the Big Bang

May 13, 2009 By Leave a Comment

Berlin, May 13 (ANI): Together with ESA’s (European Space Agency’s) Space Telescope Herschel, Planck is all set to go into orbit on May 14, to begin its studies of the cosmic microwave radiation and of the clues it gives about the Big Bang, the earliest phases of the cosmic history, and the structure and composition of the Universe. ccording to the standard model of cosmology, our Universe began 13.7 billions years ago in a Big Bang, the origin of Space and Time.

The Cosmic Microwave Background (CMB) is the relic heat from this Big Bang, released 380,000 years after beginning and still traveling freely through space today.

At that early time, weak fluctuations of matter density were present, which are seen as variations of temperature in the CMB.

By observing these fluctuations, cosmologists can infer how the large-scale structure of today’s Universe – galaxies, galaxy clusters and filaments – were formed.

The Planck satellite will be placed at the second Lagrangian point of the Sun-Earth-Moon system (L2), located about 1.5 million kilometers away from the Earth – four times the distance to the Moon.

It will spin around its own axis, which will always point towards the Sun, with each rotation recording another strip of the sky and mapping its temperature to an accuracy of about one million of a degree.

The data are sent to Earth and turned into temperature maps of the sky in data processing centers in France and Italy.

What the maps look like depends on certain characteristics of the Universe, for example on the curvature of space.

For hypothetic Universes with specified properties, computer simulations using the MPA software generate virtual maps, which will be compared with maps of the real sky.

“From the comparison, we can draw conclusions about the structure of our own Universe, for example how much ordinary matter and dark energy exist in it,” explained Torsten Ensslin, head of the Planck group at MPA (The Max Planck Institute for Astrophysics).

From their computer simulations, MPA cosmologists have shown how the CMB has influenced the gravitational field of dark matter.

The unseen structures of dark matter can therefore be deduced from temperature variations in the CMB.

The mission is expected to detect thousands of distant objects in a frequency range barely studied so far, and so to offer new insights into the physics of galaxies, Active Galactic Nuclei and quasars in the submillimeter domain.

These will show Planck scientists energetic processes in the immediate vicinity of massive black holes.

Planck may also help us to understand the birth of the first stars in the Universe and the structure of our own galaxy, the Milky Way. (ANI)

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250-mln-yr volcanic shutdown may have led to ‘snowball Earth’

May 11, 2009 By Leave a Comment

London, May 11 (ANI): In a new study, scientists have determined that a 250-million-year shutdown of volcanic activity which is thought to have occurred early in Earth’s history may be what turned the planet into a glacier-covered snowball, and give rise to our oxygen-rich atmosphere.

Previous studies have noted that very little volcanic material has been dated to between 2.45 and 2.2 billion years ago, but it was widely assumed the gap would vanish as more samples were dated.

Now, according to a report in New Scientist, an analysis of thousands of zircon minerals collected from all seven continents indicates that the gap may be real after all.Zircons provide a record of past volcanic activity, as the date they were formed can be calculated from the radioactive isotopes they contain.

The failure of so many samples from all over the world to fill the gap suggests there was a major slowdown in the planet’s volcanic activity during this period, according to Kent Condie of New Mexico Tech in Socorro, who led the study.

“Volcanism didn’t shut off, but it became much, much less widespread during this time,” he added.

“The lull could be tied to a pause in the motion of tectonic plates, which drives much of Earth’s volcanic activity,” said Condie.

Computer simulations suggest this motion, which now takes place continuously, would have been intermittent early in Earth’s history, when the planet’s interior was hotter and less viscous, so less able to drag the plates.

The lull may in turn be a major factor behind a suspected “snowball Earth” event between 2.4 and 2.3 billion years ago, when much of the planet is thought to have been covered with ice.

With no new carbon dioxide (CO2) being spewed from volcanoes, its concentration in the atmosphere would have declined, leading to global cooling.

The lull could also be behind the rise in atmospheric oxygen that is known to have taken place around 2.4 billion years ago.

Prior to the lull, any oxygen produced by marine microorganisms was consumed in reactions with iron in the ocean.

With no fresh volcanic material to replenish the iron, oxygen would have been free to build up in the atmosphere.

This in turn could have further cooled the Earth by removing methane, another powerful greenhouse gas from the atmosphere. (ANI)

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Star crust found to be 10 billion times stronger than steel

May 7, 2009 By Leave a Comment

Washington, May 7 (ANI): A new research by a scientist has shown that the crusts of neutron stars are 10 billion times stronger than steel or any other of the earth’s strongest metal alloys.

The research was done by Charles Horowitz, a professor in the IU (Indiana University) College of Arts and Sciences’ Department of Physics.

He came to came to the conclusion after large-scale molecular dynamics computer simulations were conducted at Indiana University and Los Alamos National Laboratory in New Mexico.

Exhibiting extreme gravity while rotating as fast as 700 times per second, neutron stars are massive stars that collapsed once their cores ceased nuclear fusion and energy production.

The only things more dense are black holes, as a teaspoonful of neutron star matter would weigh about 100 million tons.

Scientists want to understand the structure of neutron stars, in part, because surface irregularities, or mountains, in the crust could radiate gravitational waves and in turn may create ripples in space-time.

“We modeled a small region of the neutron star crust by following the individual motions of up to 12 million particles,” Horowitz said of the work conducted through IU’s Nuclear Theory Center in the Office of the Vice Provost for Research.

“We then calculated how the crust deforms and eventually breaks under the extreme weight of a neutron star mountain,” he added.

Performed on a large computer cluster at Los Alamos National Laboratory and built upon smaller versions created on special-purpose molecular dynamics computer hardware at IU, the simulations identified a neutron star crust that far exceeded the strength of any material known on earth.

The crust could be so strong as to be able to elicit gravitational waves that could not only limit the spin periods of some stars, but that could also be detected by high-resolution telescopes called interferometers, the modeling found.

“The maximum possible size of these mountains depends on the breaking strain of the neutron star crust,” Horowitz said.

“The large breaking strain that we find should support mountains on rapidly rotating neutron stars large enough to efficiently radiate gravitational waves,” he added.

Because of the intense pressure found on neutron stars, structural flaws and impurities that weaken things like rocks and steel are less likely to strain the crystals that form during the nucleosynthesis that occurs to form neutron star crust.

Squeezed together by gravitational force, the crust can withstand a breaking strain 10 billion times the pressure it would take to snap steel. (ANI)

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Ultra fast “Scramjets” can be effectively guided by new control system software

May 2, 2009 By 1 Comment

Washington, April 30 (ANI): Engineers at the Ohio State University, US, have designed control system software that can effectively guide a hypersonic experimental “scramjet”, which is faster than the speed of sound.

Government agencies have been developing faster-than-sound vehicles for decades.

The latest supersonic combustion ramjets, called scramjets, burn air for fuel, and could one day carry people to space or around the world in a matter of hours.

The recent success of NASA’s X-43 hypersonic jet has spurred research into the control systems for these vehicles, according to Lisa Fiorentini, doctoral student in electrical and computer engineering at Ohio State University.

She and associate professor Andrea Serrani are developing a new control system in collaboration with the US Air Force Research Laboratory (ARFL) at Wright-Patterson Air Force Base in Ohio.

The scientists report that their controller performed flawlessly in computer simulations of flight maneuvers.

The controller both guides the jet along its trajectory and keeps it stable during a flight, Fiorentini explained.

Sensors measure factors such as altitude, velocity, and acceleration, and the controller calculates whether any adjustments need to be made to keep the jet stable and on course.

Then, actuators carry out the controller’s commands – for instance, throttling up the engine if the jet needs to accelerate.

“Because these vehicles are unmanned right now, we have to prepare everything ahead of time – anticipate every possible in-flight event,” Fiorentini said.

“And the controller has to work really fast. At 10 times the speed of sound, if you lose just one second, the jet has gone far, far off course,” she added.

What sets the Ohio State control system apart, Serrani explained, is that it allows for flexibility: it adapts to changing conditions during a flight.

“The truly remarkable feature of our approach is that we consider a realistic, physics-based vehicle model within our stability analysis, using a highly sophisticated controller,” he said.

The technology is still under development in military and commercial sectors.

Scramjets could deliver missiles to mobile targets; they could also carry people halfway around the world in less than an hour. (ANI)

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Raindrops splash before they hit the ground

April 27, 2009 By Leave a Comment

London, April 27 (ANI): In a new research that involved the use of computer simulations, scientists have shown that raindrops actually splash just a few microseconds before hitting the ground.

A liquid drop hitting a surface often flattens into a thin sheet that then bounces to form a crown shape.

Previous experiments have suggested the surrounding air plays a role: a droplet doesn’t splash so easily when the air pressure is low, instead spreading out into a thin pancake.

Now, according to a report in New Scientist, Shreyas Mandre of Harvard University and colleagues ran computer simulations of liquid drops hitting a solid surface, accounting for factors such as air pressure and the drop’s surface tension.

Their results showed that a typical raindrop – roughly 2 millimeters wide and traveling at a few meters per second – compresses air in front of it a few microseconds before hitting a solid surface.

This creates an air cushion that causes the raindrop to flatten and spread out, which the team believe would be less likely if the drop was striking a higher friction surface, and may help the splash evolve into a crown.

According to Mandre, splashing is still poorly understood, so describing such processes could help create splash-suppressing materials for use in kitchens, for example. (ANI)

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