LHC May Have Revealed First Hints of Higgs

Finally, physicists may have gotten a long-awaited prize with the latest data release from the Large Hadron Collider on Dec. 13, which show a possible signal for the elusive Higgs boson at around 125 gigaelectronvolts (GeV).

Two separate experiments confirm a small rise in the number of certain particle decay events occurring in a particular energy range. This could be a sign of the Higgs particle, which is a manifestation of the Higgs field required to give subatomic particles their mass.

The ATLAS experiment sees a signal consistent with a 126 GeV Higgs while the CMS collaboration reports an excess of events at 124 GeV. (A hydrogen atom is approximately 1 GeV, so if this were the Higgs particle it would be roughly equivalent to the mass of a cesium atom.) Even if this signal is not from the Higgs, both experiments narrowed down the range in which the Higgs particle could possibly show up, leaving only a small window between approximately 115 and 130 GeV.

“It’s getting very exciting. We are stepping into an interesting territory and we are starting to see some bumps there,” said physicist Greg Landsberg from Brown University in Providence, Rhode Island, who is a team member of the CMS group.

Even more exciting, a Higgs in this mass range would likely require new physics beyond the Standard Model — which describes the interactions of all known subatomic particles and forces –- in order to be stable. One possible extension, known as supersymmetry, posits the existence of a heavier partner to all known subatomic particles in order to solve certain problems with the Standard Model.

But physicists’ long wait for the Higgs may not quite be over.

As yet, the findings are “not very significant, and at best 50-50 (probably worse) that it is real,” wrote physicist Matt Strassler of Rutgers University, who was not involved with the work, in an e-mail. The observation is not much more than a “vague hint, and it is neither clear nor convincing.”

While both experiments see a similar signal, the observed particle decay events could have occurred by chance so this isn’t yet a discovery.

Next year, experiments will roughly quadruple the LHC dataset, giving an additional 15 percent boost in terms of the quality and power of the data, said Landsberg.

As mathematician Peter Woit of Columbia University wrote on his blog the day before the announcement, “One thing that can be predicted with certainty is a flood of papers from theorists claiming that their favorite model predicts this particular Higgs mass.”

From wired

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Planck Snaps Its First Images Of Ancient Cosmic Light

ScienceDaily (Sep. 20, 2009) — Preliminary results from ESA’s Planck mission to study the early Universe indicate that the data quality is excellent. This bodes well for the full sky survey that has just begun.

Planck started surveying the sky regularly from its vantage point at the second Lagrange point of the Sun-Earth system, L2, on 13 August. The instruments were fine-tuned for optimum performance in the period preceding this date.

ESA's Planck microwave observatory is the first European mission designed to study the Cosmic Microwave Background – the relic radiation from the Big Bang.

Following launch on 14 May, checkouts of the satellite's subsystems were started in parallel with the cool-down of its instruments' detectors. The detectors are looking for variations in the temperature of the Cosmic Microwave Background that are about a million times smaller than one degree – this is comparable to measuring from Earth the body heat of a rabbit sitting on the Moon. To achieve this, Planck's detectors must be cooled to extremely low temperatures, some of them being very close to absolute zero (–273.15°C, or zero Kelvin, 0K).

A map of the sky at optical wavelengths shows a prominent horizontal band which is the light shining from our own Milky Way. The superimposed strip shows the area of the sky mapped by Planck during the First Light Survey.

With check-outs of the subsystems finished, instrument commissioning, optimisation, and initial calibration was completed by the second week of August.

The 'first light' survey, which began on 13 August, was a two-week period during which Planck surveyed the sky continuously. It was carried out to verify the stability of the instruments and the ability to calibrate them over long periods to the exquisite accuracy needed.

This survey was completed on 27 August, yielding maps of a strip of the sky, one for each of Planck's nine frequencies. Each map is a ring, about 15° wide, stretching across the full sky. Preliminary analysis indicates that the quality of the data is excellent.

Routine operations started as soon as the first light survey was completed, and surveying will now continue for at least 15 months without a break. In approximately 6 months, the first all-sky map will be assembled.

Within its allotted operational life of 15 months, Planck will gather data for two complete sky maps. To fully exploit the high sensitivity of Planck, the data will require delicate adjustments and careful analysis. It promises to return a treasure trove that will keep both cosmologists and astrophysicists busy for decades to come.

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How Photon Echoes Can Be Used To Create A Quantum Memory Device

ScienceDaily (Sep. 14, 2009) — A new way of storing and ‘echoing’ pulses of light has been discovered by a team from The Australian National University, allowing bursts of laser to work as a flexible optical memory and potentially assist in extending the range of quantum information systems.

Technologies like quantum cryptography are being developed to send secure information coded onto light beams from one point to another. Yet at present these systems are unable to extend beyond a distance of 50 to 100 kilometres because, beyond that range, too much of the information is lost.

The experiment that generated the photon echo effect. (Credit: Image courtesy of Australian National University)

But a team based at the ARC Centre of Excellence in Quantum-Atom Optics at ANU has demonstrated how photon echoes can be used to create a quantum memory device – meaning that pulses of light can be captured, stored and then released on demand. Such a device would be an important part of a quantum repeater, which could extend the range of secure quantum communication.

“Light can be a fantastic medium for transferring lots of information very quickly, but it doesn’t like to stay in one place for long,” explains team member Dr Ben Buchler. “This is the problem of optical memory – how to keep the information coded on light in one place so you can access it again later. One method is to slow the light down so it’s as good as frozen in place for a while. The way we’ve explored is to absorb the light in a cloud of atoms, which you can then manipulate to release the light at will.”

In experiments performed by PhD candidate Mahdi Hosseini, the ANU research team developed a method where pulses of laser light are absorbed into a cloud of atoms surrounded by a coil of wire. The coil creates a magnetic field that shifts the frequency of the atoms. After absorbing the laser pulses, the atoms all begin to spin at different speeds, depending on their frequency. If the magnetic field is reversed, the atoms all change direction and spin the other way. When the spinning atoms return to the state they were in when they absorbed the light, the laser pulses are released as a photon echo.

“But we take it a few steps further,” explains Dr Buchler. “We can also stretch, compress and split the pulses when we let them out. Best of all, we can recall the pulses in any order, just like a random access memory in a computer can recall electronic information in any order. To do this we use a second control laser beam that can turn the photon echo on and off. In a regular photon echo system, once the atoms all re-align the stored light just comes out – you can’t stop it. In our system, the combination of control beam and magnetic field switching makes it possible to choose exactly when to recall any one of the stored pulses, how much of it to recall and how fast to recall it.”

The research, published in Nature, outlines how the team have managed to store laser pulses with efficiencies above 40 per cent using its technique. The team includes Dr Ben Buchler, Ben Sparkes, Gabriel Hetet, Mahdi Hosseini, Dr Jevon Longdell (now at the University of Otago) and Professor Ping Koy Lam from ANU.

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First Complete Image of a Molecule, Atom by Atom

Researchers at IBM have used an atomic-force microscope to resolve the chemical structure of pentacene.

This image of pentacene, a molecule
made up of five carbon rings, was
made using an atomic-force
microscope. Credit: Science/AAAS

Using an atomic-force microscope, scientists at IBM Research in Zurich have for the first time made an atomic-scale resolution image of a single molecule, the hydrocarbon pentacene.

Atomic-force microscopy works by scanning a surface with a tiny cantilever whose tip comes to a sharp nanoscale point. As it scans, the cantilever bounces up and down, and data from these movements is compiled to generate a picture of that surface. These microscopes can be used to "see" features much smaller than those visible under light microscopes, whose resolution is limited by the properties of light itself. Atomic-force microscopy literally has atom-scale resolution.

Still, until now, it hasn't been possible to use it to look with atomic resolution at single molecules. On such a scale, the electrical properties of the molecule under investigation normally interfere with the activity of the scanning tip. Researchers at IBM Research in Zurich overcame this problem by first using the microscope tip to pick up a single molecule of carbon monoxide. This drastically improved the resolution of the microscope, which the IBM scientists used to make an image of pentacene. They arrived at carbon monoxide as a contrast-enhancing addition after trying many chemicals.

The researchers hope that looking this closely at single molecules will give them a better understanding of chemical reactions and catalysis at an unprecedented level of detail.

source : http://www.technologyreview.com/blog/editors/24040/

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Nitrous oxide fingered as monster ozone slayer

Most people know nitrous oxide as the laughing gas that dentists reserve for drill-phobic patients. But once it enters the atmosphere, N₂O is no laughing matter. New calculations indicate that it has risen to become the leading threat to the future integrity of stratospheric ozone, Earth’s protective shield against the sun’s harmful ultraviolet rays.

Currently, Freon and other chlorofluorocarbons — or CFCs — are the leading source of ozone thinning, especially in the hole that forms annually over Antarctica. The surprise is not that N₂O is also ozone-toxic. That’s been known for decades. What’s new is a measure of how its ozone-destroying potency compares to CFCs, specifically to one known as CFC-11.

Calculations by a trio of scientists from the National Oceanic and Atmospheric Administration in Boulder, Colo., now indicate that each molecule of N₂O is almost one-fiftieth as effective at depleting ozone as is CFC-11.

Which may not sound like much — except it is, the NOAA scientists emphasize. Owing to its roughly 100-year survival time in the atmosphere (a lifespan comparable to CFCs) and the huge quantities released each year, N₂O stands poised to become a potent player in the thinning of global stratospheric ozone. Indeed, “We found that if you look ahead, N₂O will remain the largest ozone-depleting emissions for the rest of the century,” notes team leader A.R. Ravishankara.

A paper describing the new analyses was posted online today in Science.

CFCs not only are very potent agents of ozone destruction, but also have been released in huge quantities and are long-lived. The bottom line: Once these pollutants enter Earth’s upper atmosphere, they linger, catalyzing damage for decades.

As such, they deserve most of the blame for the overall five-to six-percent thinning in stratospheric ozone that has developed in the past half-century or so, the NOAA scientists say. But owing to the 1987 Montreal Protocol, a United Nations treaty that has restricted or banned use of the most ozone-toxic chemicals, stratospheric ozone thinning has peaked and now appears to be falling.

NOAA calculations now suggest that gains made under the Montreal Protocol will slow or halt, owing to the huge and rising contributions of a pollutant that also imperils ozone — but remains ignored by the powerful treaty. Owing to a twist of fate, the treaty’s success in limiting CFC emissions will also begin intensifying N₂O’s potency.

To understand why, Ravishankara says, it helps to know how CFCs and N₂O damage ozone. Solar ultraviolet radiation breaks CFC molecules apart, creating chlorine and chlorine oxides. "These are what destroy ozone," he says, not the parent CFCs. Similarly, N₂O doesn't directly damage ozone. Chemical reactions in the stratosphere must first strip away one of that molecule's nitrogen atoms — forming nitric oxide, or NO. This stripped down molecule, he explains, is what actually wreaks havoc with ozone.

“Nitrogen oxides and chlorine oxides kind of oppose each other in destroying stratospheric ozone,” the scientist explains. “In other words, N₂O offsets the ability of chlorine oxides to destroy ozone. And vice versa.” In the new paper, he says, “We have calculated the ozone-depleting potential of N₂O to be roughly 50 percent larger when chlorine levels return to the year-1960 level.”

As N₂O pollution goes, dentists are very bit players. Deforestation, animal wastes and bacterial decomposition of plant material in soils and streams emit up to two-thirds of atmospheric N₂O.

However, emissions from such natural sources appear fairly static, Ravishankara said at a briefing yesterday. That’s in stark contrast to N₂O releases from processes fostered by human activity, such as the nitrogen fertilization of agricultural soils and fossil-fuel combustion. These anthropogenic emissions of the pollutant have been growing steadily, he says, to where they now boost atmospheric concentrations of N₂O by roughly one percent every four years.

What all this means, the NOAA scientists say, is that N₂O is now a bigger threat to future stratospheric ozone destruction than are CFCs. And if N₂O emissions don’t diminish substantially, Ravishankara says, within a century they could eventually slay 40 percent as much stratospheric ozone each year as CFCs did at their peak.

Reporters asked the NOAA team what can and should be done, but the scientists simply argued that finding answers was the responsibility of policymakers. However, Ravishankara observed that because most N₂O releases are so diffuse, limiting them will prove much more challenging than simply mandating controls on tailpipes or smokestacks.

Yet success would yield a doubly whammy, notes coauthor John Daniel. The reason: N₂O is also a greenhouse gas.

By Janet Raloff

Web edition

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New Way To Reproduce A Black Hole?

ScienceDaily (Aug. 22, 2009) — Despite their popularity in the science fiction genre, there is much to be learned about black holes, the mysterious regions in space once thought to be absent of light. In a paper published in the August 20 issue of Physical Review Letters, Dartmouth researchers propose a new way of creating a reproduction black hole in the laboratory on a much-tinier scale than their celestial counterparts.

The new method to create a tiny quantum sized black hole would allow researchers to better understand what physicist Stephen Hawking proposed more than 35 years ago: black holes are not totally void of activity; they emit photons, which is now known as Hawking radiation.

"Hawking famously showed that black holes radiate energy according to a thermal spectrum," said Paul Nation, an author on the paper and a graduate student at Dartmouth. "His calculations relied on assumptions about the physics of ultra-high energies and quantum gravity. Because we can't yet take measurements from real black holes, we need a way to recreate this phenomenon in the lab in order to study it, to validate it."

In this paper, the researchers show that a magnetic field-pulsed microwave transmission line containing an array of superconducting quantum interference devices, or SQUIDs, not only reproduces physics analogous to that of a radiating black hole, but does so in a system where the high energy and quantum mechanical properties are well understood and can be directly controlled in the laboratory. The paper states, "Thus, in principle, this setup enables the exploration of analogue quantum gravitational effects."

"We can also manipulate the strength of the applied magnetic field so that the SQUID array can be used to probe black hole radiation beyond what was considered by Hawking," said Miles Blencowe, another author on the paper and a professor of physics and astronomy at Dartmouth.

This is not the first proposed imitation black hole, says Nation. Other proposed analogue schemes have considered using supersonic fluid flows, ultracold bose-einstein condensates and nonlinear fiber optic cables. However, the predicted Hawking radiation in these schemes is incredibly weak or otherwise masked by commonplace radiation due to unavoidable heating of the device, making the Hawking radiation very difficult to detect. "In addition to being able to study analogue quantum gravity effects, the new, SQUID-based proposal may be a more straightforward method to detect the Hawking radiation," says Blencowe.

In addition to Nation and Blencowe, other authors on the paper include Alexander Rimberg at Dartmouth and Eyal Buks at Technion in Haifa, Israel.

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Scientists propose lab-grade black holes

One day, scientists may create the ultimate tempest in a teapot — an artificial black hole in a millimeter-long gadget. Such laboratory-grade black holes may illuminate enigmatic physical properties of their wild galactic counterparts, all from the safety of a lab bench, a study to appear in Physical Review Letters suggests.

“For black holes, we just don’t understand the physics at all,” says physicist William Unruh of the University of British Columbia in Vancouver, Canada, who was not involved in the new study. The prospect of conducting actual experiments on systems resembling black holes is exciting, he says. “Belief is not the same as doing an experiment.”

Mysterious black holes were originally thought to gobble up everything around them, including light (hence the name). But in the 1970s, British physicist Stephen Hawking predicted that because of quantum effects, these voracious monsters should emit photons. Right on the brink of the black hole, these photons “are so energetic that they go beyond what we understand,” says study coauthor Miles Blencowe of Dartmouth College in Hanover, N.H. Such emitted photons, known as Hawking radiation, have not yet been caught in the wild, nor have they been simulated in an experiment, leaving knowledge of their basic properties — and existence — in limbo.

In the new study, the researchers propose using a series of tiny, cold superconducting devices called SQUIDs in a linear, train-track–shaped arrangement to create a black hole analog. “But unlike a black hole out in space, we know the physics of this system,” says study coauthor Paul Nation, also of Dartmouth College.

Particles inside a black hole’s boundary, called the horizon, get sucked into the depths of the black hole, while particles outside the horizon can escape. Blencowe likens the horizon to a steep waterfall, where a fish above the drop can swim at normal speeds, but once a fish hits the fast-flowing water in the waterfall, it is swept down into the water below.

Similarly, the proposed system also creates a horizon, in the form of an electromagnetic wave that moves across the device in response to a magnetic pulse. Photons behind this horizon are trapped, while photons ahead of it move normally. By detecting and studying the photons that emerge from the device, researchers hope to have a better idea of what happens to particles near the edge of a black hole, both those that escape and those that are pulled in.

Changing the strength of the horizon-creating magnetic pulse may create conditions that fluctuate, making a system that simulates “shaking spacetime,” Nation says. Watching how photons behave in such a quantum system may answer some basic questions about the quantum nature of gravity, he says.

Building the new system has many challenges. “All of these experiments have a long way to go before they’ll deliver their promise,” comments Unruh, who has proposed a black hole analog that relies on sound waves.

Nation says that stringing together the 4,000 or so SQUIDs needed to create the artificial black hole would be a difficult endeavor. The largest string built so far is only 400 units long. Another hurdle to creating this system is designing a detector sensitive enough to catch single photons that would have a frequency much lower than that of visible light. “People are close to making a detector, but technically, it hasn’t been done,” says Nation.

By Laura Sanders

Web edition : Thursday, August 13th, 2009

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First Black Holes Were Lean and Mean

Like many pioneers in new surroundings, the first black holes found scant pickings, according to new simulations that mimic conditions in the early universe. The findings have scientists puzzling over how early black holes grew into the supermassive beasts they are today without a steady diet of gas, dust, stars, and other fodder.

Today's black holes thrive on recycled goods. Most galaxies abound with interstellar gas and dust, the detritus of countless generations of stars. Black holes grow by consuming material that passes too close to their enormous gravity wells. But fodder in the earliest universe was not nearly as plentiful, researchers at NASA; Stanford University in Palo Alto, California; and the Department of Energy's SLAC National Accelerator Laboratory in Menlo Park, California discovered. The team wanted to see how the earliest black holes grew, so they created simulations based on previous work with the earliest stars, many of which collapsed directly into the first black holes.

The simulations showed that the black holes radiated energy so intensely that they heated surrounding gas far into space--as far as 10,000 light-years away (see a movie here (22Mb)). The heated gas became so diffuse, it could not form nearby stars and solar systems, nor fall back inward to feed black holes. As a result, the team reports online this week in The Astrophysical Journal Letters, the earliest black holes grew less than 1% over 200 million years. It turns out that "a black hole's growth is limited until it is hosted by a larger galaxy," says astrophysicist and co-author John Wise of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

The simulations "highlight for me how complex the processes in the early universe were," says astronomer Steven Willner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. In particular, he says, very little is known about what happened to the first stars or their remnants. "This paper is not the final word" on that process, Willner says, "but it's a very nice start."

By Phil Berardelli
ScienceNOW Daily News
11 August 2009

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Developing A Chemical Hygiene Plan To Keep Everyone In The Lab Safe

Finding work in any kind of laboratory can be an exciting career--but it can also be pretty dangerous, if you aren't careful. Most labs are full of chemicals and precision instruments that can be hazardous if misused.

Knowing little or nothing about what kind of hazards can arise in your workplace can actually make you much more vulnerable to injury, which is the last thing you need at work.

That is why many laboratories develop what are called Chemical Hygiene Plans, often shortened to CHPs to help to inform their workers how to monitor their use of potentially perilous substances in the lab setting.

If the lab in which you work does not have its own CHP, you should sensitively suggest to one of your supervisors that you develop one, and it should include some of the following things.

This may seem like a given, but be sure to have clearly posted the contact information of all important laboratory personnel. Also have easy access to numbers for Poison Control and other emergency services. Do not hesitate to make contact with supervisors or medical services when necessary.

Every member of the laboratory team needs to agree upon a set of procedures to enact when there is an emergency, including an evacuation route. The route should be posted clearly, and there should be frequent reminders of the plan. It should be included in training sessions for new workers.

Be sure to maintain an accurate chemical inventory. Make sure that this inventory is given an easily discernable title and heading. Make sure it includes the room number and building name, the name of the department, the person who is responsible for making the inventory, and the date which it was made.

The list of chemicals itself should in a concise manner identify the chemical name, the approximate amount, the location of that chemical within the lab, any possible quantity changes, and some basic hazard warnings, which can be limited to abbreviations like "TOX," for toxic. Make sure these things are understood by all staff.

All kinds of laboratories across various industries are in need temperature sensors. Make sure that yours are up to date with advancing technology and as sensitive as you need them to be. Teach all employees to pay close attention to them to avoid burns or contact with materials not suitable for handling. When your employees are well-educated and prepared, they will be safer all-around, which continues to make their work more exciting and rewarding. And when their work is rewarding, they will certainly be more productive--and that benefits everybody.

by Art Gib

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Titan may host prebiotic brew

Saturn’s moon Titan has an environment that resembles Earth’s at the time that life first got a foothold, new findings from the Cassini spacecraft suggest.

Two close flybys have gathered fresh evidence that ammonia, most likely mixed with water ice, has recently erupted onto the surface of the moon. The likely presence of ammonia on Titan’s icy surface, combined with the abundance of methane and nitrogen in the moon’s thick atmosphere, together suggest that Titan may host a prebiotic brew, says Cassini scientist Robert Nelson of NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

The findings, reported by Nelson August 5 in Rio de Janeiro at a meeting of the International Astronomical Union, are based on data gathered by Cassini’s Visual and Infrared Mapping Spectrometer during November and December 2008. The spectrometer records emissions from seven different infrared “windows” — wavelength bands at which radiation from material on Titan’s surface can penetrate the moon’s methane-rich shroud and reach the spacecraft.

Previously, more distant flybys of Titan had hinted at the presence of fresh ammonia deposits on the surface. In addition, radar imaging with another Cassini instrument in 2008 had revealed that regions that may harbor ammonia, particularly an area known as Hotei Arcus, have lobe-shaped deposits and flows characteristic of volcanic eruptions.

Ammonia is known to lower the melting point of water and facilitate icy volcanic activity. Such activity might be triggered by heat leftover from the formation of Titan or gravitational flexing of the moon, notes Cassini researcher Rosaly Lopes of the Jet Propulsion Laboratory.

Cassini swooped low enough during the November and December flybys for the spectrometer to obtain higher-resolution spectra of material at Hotei Arcus. The spectra resemble the pattern expected from ammonia, but because the emissions also overlap with that of frozen water, the ammonia detection is “likely” rather than definitive, Nelson said. Those two flybys also enabled the spectrometer to image Hotei Arcus closely enough to find the same lobe-shaped flow pattern, indicative of volcanic terrain, that the radar instrument had found, Nelson reported at the conference. The flows imaged in the infrared bands appear truncated compared with those in earlier radar images, hinting that newly deposited ammonia on the surface might have covered the markings, he said.

The new evidence, combined with the older data, suggests that Titan has a geologically active surface, with ongoing icy volcanic eruptions that carry new deposits of ammonia ice to the surface, Nelson said. Once there, the ammonia may mix with methane and nitrogen — the principal constituents of Titan’s dense atmosphere — to create an environment that could foster life.

Other researchers have suggested that ammonia is present in Titan’s interior and might even help sustain a liquid water ocean within the moon, comments Cassini scientist Jonathan Lunine of the University of Arizona in Tucson. Ammonia recently found on geologically active Enceladus, one of Titan’s small sister moons, argues in favor of ammonia on Titan, he adds (SN Online: 7/22/09).

In addition to lowering the freezing point of liquid water, ammonia also lowers the density of the liquid relative to that of water ice, allowing some liquid to more easily rise to the surface, Lunine says. Adding ammonia to water ice would also create a thick viscous surface flow that might explain the shape and topography of the Hotei Arcus region, he notes.

“We’re very excited by the results,” Nelson said. Titan may indeed support a prebiotic mixture of chemicals similar to those under which life on Earth evolved.

From

Ron Cowen

Web edition : Wednesday, August 5th, 2009

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