Thursday, 28 October 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

Physicists Vote to Run Tevatron for 3 More Years

Posted: 27 Oct 2010 02:40 PM PDT

A group of high-energy particle physicists decided this week to recommend extending the life of the Tevatron, the second-most-powerful particle collider in the world, for 3 years.

The panel's recommendation goes to the Department of Energy, then Congress and ultimately to the White House. The funding decision could determine whether the United States or Europe wins the race to find the theoretical Higgs boson. It all comes down to $105 million, a tiny amount relative to the billions spent building the massive particle colliders competing for the find.

The Tevatron at Fermilab in Batavia, Illinois, is potentially powerful enough to confirm or deny the existence of the Higgs boson, which would help explain the origin of mass in the universe. But the machine needs more time, and its scheduled September 2011 shutdown would almost certainly allow Europe's new, more powerful Large Hadron Collider to get there first.

The LHC, run by CERN in Geneva, will have more than enough energy to find the Higgs, says Robert Roser, an experimental physicist at Fermilab. But mechanical breakdowns set the project's start date back for more than a year, to September 2008, and prompted CERN to ramp the LHC up far more slowly, and to just half its top energy, before a 16-month shutdown to fix faulty magnets planned for December 2011. This leaves a window open for the Tevatron to catch the Higgs first, if it isn't shuttered first.

 

The 15 members of the U.S. particle-physics community who gathered in Washington, D.C., this week voted 14 to 1 in favor of giving the Tevatron 3 more years. The machine costs around $50 million per year to run. Fermilab has agreed to come up with $15 million annually, which will be diverted from other scientific projects.

"Now it's up those people [at the DOE] to work together to figure out how to get $35 million per year out of the budget," Roser said. "With a $4.7 billion total [DOE] Office of Science budget, I'm hoping it won't be that hard. But we'll see."

Ultimately, the decision is up to the Barack Obama administration, whose budget is due out in February 2011. If approved, the 3.9-mile-long circular collider will be allowed to gather data and sift for signs of the Higgs through 2014.

"Finding the Higgs is kind of like a casino. The more chances you have at pulling the slot machine, the more chances you have of winning the jackpot," Roser said. "Data buys us probability, and that will increase our odds of coming up with a significant result."

If the scientists' extension request fails, the LHC can pick up where the Tevatron left off in 2013 with seven times the particle-colliding power, which is more than enough to squeeze the Higgs out of hiding, if it exists. But this could take several more years than it would to find it with the Tevatron, which is running better than it ever has, despite being well beyond its designed life expectancy.

"Right now we have a track record of success. Only in the last year has the Tevatron been in the Higgs game, where we're able to make statements about the Higgs particle," Roser said. "It would be a shame to be in that regime and just turn it off."

Ultimately, finding the Higgs would be the best supporting evidence yet for the Standard Model of Physics — the guidebook to the particles and forces at work in the universe.

"We're trying to understand how mass fits into the Standard Model, and it's perhaps the single most important question facing our field right now," Roser said. "We need to use every tool available to solve it."

Images: Fermilab/Fred Ulrich 1) The Tevatron with Wilson Hall in the background. 2) The Collider Detector at Fermilab, one of the Tevatron's two detectors.

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Monkey Fossils Suggest Primates Came Out of Asia, Not Africa

Posted: 27 Oct 2010 12:22 PM PDT

The discovery of four ancient, lemur-like creatures in what is now Libya suggests the human family tree's taproot is in the Middle East, not Africa.

The conventional narrative of primate development places the origins of anthropoids — monkeys and apes, including humans — in Africa. Some paleontologists, however, think Asia is the more likely cradle for that ur-primate, or what Christopher Beard has called the "Dawn Monkey."

Beard, a paleontologist at the Carnegie Museum of Natural History, is among the co-authors of the paper describing the new primates, published October 28 in Nature. The four species' fossils, representing three distinct taxonomic families, are 40 million years old. Nothing similar was known to have lived in Africa at that time.

The diversity and timing of the new anthropoids raises two scenarios. Anthropoids might simply have emerged in Africa much earlier than thought, and gone undiscovered by modern paleontologists. Or they could have crossed over from Asia, where evidence suggests that anthropoids lived 55 million years ago, flourishing and diversifying in the wide-open ecological niches of an anthropoid-free Africa.

 

That humans may trace their evolutionary lineage to creatures like the newly-discovered anthropoids, which likely weighed between four ounces and one pound and could sit in the palm of your hand, is an intriguing possibility. But other paleontologists warn that more investigation is required.

"These discoveries are exciting and very informative," said Stony Brook University paleoanthropologist William Jungers, who was not involved in the study. But "more than anything else, these discoveries indicate that we still have a lot to learn."

Image: Mark A. Klingler/Carnegie Museum of Natural History.

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Citation: "Late middle Eocene epoch of Libya yields earliest known radiation of African anthropoids." By Jean-Jacques Jaeger, K. Christopher Beard, Yaowalak Chaimanee, Mustafa Salem, Mouloud Benammi, Osama Hlal, Pauline Coster, Awad A. Bilal, Philippe Duringer, Mathieu Schuster, Xavier Valentin, Bernard Marandat, Laurent Marivaux, Eddy Metais, Omar Hammuda & Michel Brunet. Nature, Vol. 467 No. 1095, October 28, 2010.

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Record-Breaking Neutron Star is a Clue to Exotic Physics

Posted: 27 Oct 2010 11:45 AM PDT

A quick-spinning stellar corpse is the most massive of its kind ever seen. The dead star's extra bulk could rule out several theories about what these dense stellar objects are made of, and provide a celestial lab to explore exotic matter.

"For people who work in this field, it's huge," said neutron star astronomer M. Coleman Miller of the University of Maryland, who was not involved in the new study. "It's a big new addition to our information about a state of matter that we cannot explore in labs."

Weighing in at twice the mass of the sun, the new heavyweight champ — a pulsar dubbed J1614-2230 — is 20 percent more massive than any previously measured star of its class.

Pulsars are a special type of neutron star, the dense remains of ordinary stars that exploded as supernovas, that sweep the sky with a lighthouse-like beam of radio waves as they spin. As these radio beams swish past Earth, the stars appear to "pulse" at extremely regular intervals.

Neutron stars, true to their name, are formed almost entirely of neutrons, which can pack tightly into the densest form of matter known to exist without forcing the star to collapse into a black hole. But some theories suggest neutron stars could squish down even further by converting their neutrons to exotic types of matter. If neutron stars were packed with heavy, strange particles like hyperons or kaons, the stars would collapse under their own weight at much lower masses.

"If you're able to establish that there really is an object out there with high mass," Miller said, "it takes a lot of the predictions you would make with the exotic forms of matter and different particles, and says 'I'm sorry, you're wrong. Try again.'"

 

To take the extra-heavy pulsar's measurements, astronomers relied on a relativistic trick of the light.

Pulsars are usually among the most accurate clocks in the universe, blinking regularly tens to thousands of times per second. But J1614-2230 has a companion star, a white dwarf. When the radio pulses brush past the white dwarf, they slow down as if they were swimming through molasses, and take a longer time to get to Earth.

This effect, called the Shapiro delay, is due to Einstein's general relativistic prediction that clocks run slower in a gravitational field, at least as seen from far away. The more massive the white dwarf is, the slower the pulses get.

Astronomer Paul Demorest of the National Radio Astronomy Observatory and colleagues used the Green Bank Telescope in West Virginia to watch how the times between pulses changed at different points in the pulsar's orbit around the white dwarf over the course of 8.7 days. A new instrument called GUPPI (Green Bank Ultimate Pulsar Processing Instrument) provided more precise measurements of the pulse delay than previous attempts could muster.

The astronomers used the mass of the white dwarf plus data on the pulsar's orbit to find the pulsar's mass: A whopping 1.97 times the mass of the sun. The next most-massive neutron star was 1.67 times the mass of the sun, and most neutron stars cluster around 1.25 to 1.44 times the mass of the sun. The results are reported in the Oct. 28 Nature.

"The pulsar mass is quite a bit higher for this system than any that have been previously measured," Demorest said. "That changes our thinking about what is the maximum possible mass a neutron star can have."

Because the team used the Shapiro delay, the measurement is more reliable than previous attempts to measure neutron star mass, Miller added.

"The Shapiro delay depends only on the mass, full stop, no other effects," he said. "It's much easier to interpret than others that have previously suggested higher masses."

The bulky star rules out all but a few models for the composition of neutron stars. Rather than containing exotic particles, the stellar corpses are probably made of plain neutrons and protons.

But that's hardly a disappointment to Miller. "It's cool," he said. "It represents a state of matter and a state of physics that we cannot reproduce on Earth. By these distant and safe observations, we're able to learn things about fundamental physical law that we could not learn otherwise."

One pressing theoretical question remains: How did the pulsar get so big? Is it slowly devouring its companion? Or was it just born this big?

"Either would be a valid explanation," Demorest said. "We just don't know which is correct yet."

Image: Bill Saxton/NRAO/AUI/NSF

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Assassin Bug Eats Spiders After Feigning Capture

Posted: 27 Oct 2010 08:37 AM PDT

By Duncan Geere, Wired UK

A species of assassin bug has been found which creeps onto spiders' webs and pretends to be prey, then devours the spider when it comes to investigate.

The creature, known to entomologists as Stenolemus bituberus, and actually in the spider family itself too, is the subject of a paper just published in Proceedings of the Royal Society B by Annie Wignall from Macquarie University in Sydney, Australia. Wignall describes the exact process of "aggressive mimicry" by which the assassin bug stalks its target.

Most predators conceal themselves in order to capture prey, but the assassin bug takes the opposite approach — overtly advertising its presence in a way that entices its dinner to investigate. Web-building spiders use vibrations in their web to detect when it's caught something, so they can go over, bind it in more web, and eat it.

The assassin bug slowly approaches the spider on its web, using its forelegs to pluck the silk threads in a manner that simulates the vibrations of a fly struggling after being caught. Wignall studied the behavior of the bugs, and found that the response of the spider to the predator was the same as its response to when a vinegar fly or aphid was caught in the web.

 

Once the spider is close enough, the assassin bug lashes out, and eats the poor unsuspecting arachnid. Most of the time, anyway — Wignall also observed a few occasions of spiders counter-attacking the bugs and killing and eating them instead.

Wignall points out that the assassin bug doesn't identically replicate the vibrations caused by prey — there are several higher-amplitude vibrations that prey generate which aren't simulated by the bug. But the spider doesn't seem to be able to generally differentiate between the two.

The work could have implications for the physics of how vibrations propagate through three-dimensional webs.

Images: 1) Flickr/jeffsmallwood. 2) An assassin bug. Flickr/dhobern

Source: Wired.co.uk

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Neuron Recordings Capture Brain Focus on Josh Brolin

Posted: 26 Oct 2010 11:08 AM PDT

By measuring the activity of single neurons, researchers have recorded what happens when people narrow their focus on subjects like Josh Brolin or Marilyn Monroe.

The neuroscientists weren't interested in the actors, however, but rather the dynamics of attention.

"Say you're walking down the street, and there are cars, buildings, trees, people, all competing for your attention. Some stand out more than others, and you don't control that. It just happens. How does this happen in your brain?" said computational neuroscientist Moran Cerf of the California Institute of Technology.

For an experiment published October 28 in Nature, Cerf's team enlisted the help of epileptics whose brains had been temporarily wired to computer monitors, allowing doctors to see where seizure patterns began in anticipation of corrective surgery. Invasive deep-brain procedures aren't allowed for the sake of basic, non-medical research, but since the epileptics' brains are already wired, Cerf's team was able to conduct a unique experiment.

In earlier research, they'd correlated firings of individual neurons in the medial temporal lobes — the brain's processing centers — with individual people (namely, Halle Berry.) In this study, they linked neurons to easily recognizable people like Monroe, Brolin, Venus Williams and Michael Jackson.

 

Cerf's team simultaneously displayed pairs of their pictures on a computer monitor, then asked test subjects to concentrate on one person. As their minds focused, the images flickered back and forth, finally settling on the target image. As this happened, their mental activity was recorded in real-time.

The researchers weren't particularly interested in specific neurons, or even specific brain regions: Each wired neuron was representative of five million more, spread across the brain. Instead, he was looking for patterns of focus.

"The most exciting thing is that patients sometimes fail in the task. Someone sees a picture of Marilyn Monroe and Josh Brolin, and his task is to focus on Brolin. But, somehow, the image of Marilyn Monroe catches his attention more. The image moves away from Brolin. It's 90 percent Marilyn. And then, when he's about to fail, he manages to summon Josh Brolin in his mind," Cerf said.

"There's competition between two senses, between vision and imagery. The eyes bring one image, his mind's eye brings another, and those fight. We can see how one wins over the other. This is a remarkable moment, because it happens every day in our life, and we never saw it first-hand."

Cerf expected focus would result from an increase in target-focused activity, so with people asked to focus on Josh Brolin, the Brolin-linked parts of the brain would fire more. Instead, he found the Marilyn Monroe-linked regions fired less. Brains narrowed focus not by enhancing their targets, but by diminishing distraction.

As for how that selective diminishing was performed, Cerf couldn't tell. He likened the experiment to seeing flows of water at a river's end, without knowing what dam operators were doing upstream. Whatever was responsible for guiding focus wasn't wired with the electrodes in the patients, nor will it be.

"Upstream? I wish," said Cerf. "If I could, I'd put electrodes all the way from the vision area, and look at information flow from the moment you get photons hitting the retina to the point where they become concepts. But there isn't reason" to put those electrons in patients.

In future studies, Cerf hopes to measure associations more completely and see what other parts of the mind are triggered by thinking of larger concepts.

"There's a cloud of associations that surround each concept. We don't know how they're formed, or how far they go. The idea now is to try to find one concept, start moving away from it, and see where the borders are," he said.

Video: After the researchers map neurons to images in study participants' brains, on-screen images change depending on their mental focus./Moran Cerf.

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Citation: "On-line, voluntary control of human temporal lobe neurons." By Moran Cerf, Nikhil Thiruvengadam, Florian Mormann, Alexander Kraskov, Rodrigo Quian Quiroga, Christof Koch & Itzhak Fried. Nature, Volume 467 Number 7319, October 28, 2010.

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Wednesday, 27 October 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

Space Telescope Listens In on Stellar Symphony

Posted: 26 Oct 2010 01:46 PM PDT

The Kepler Space Telescope doesn't just look for planets. By listening to subtle vibrations of the stars in its field of view, the telescope is recording a stellar symphony that gives an unprecedentedly accurate view of the inner lives of stars.

"We can say Kepler is listening to thousands of musicians in the sky," said Daniel Huber, a graduate student at the University of Sydney.

Kepler recorded thousands of red-giant stars humming in response to their internal rumblings. In this recording, which was scaled up to the range of human hearing, the deeper, louder tones correspond to larger stars.

Audio: Daniel Huber/KASC

Huber and members of an international consortium called the Kepler Astroseismic Science Consortium presented the new results in a teleconference Oct. 26. The Kepler chorus could help pin down the properties of planets, predict the future of our own sun and solve century-old stellar mysteries.

To search for planets, Kepler stares unblinkingly at a single patch of sky and waits for a star to slightly dim, a sign that a planet is crossing in front of the star. The telescope's sharp eyes are sensitive enough to detect stars' natural brightness variations, the result of vibrations inside the stars.

"Sound waves travel into the star and bring information up to the surface, which Kepler can see as a tiny flickering in brightness of the star," said astronomer Travis Metcalfe of The National Center for Atmospheric Research.

That flickering "has an underlying order like the notes of a musical instrument," he added. "We essentially measure the tone of these musical notes from the starlight."

In the same way that a cello sounds deeper than a violin, larger stars vibrate with lower frequency — or deeper tone — than smaller stars. These vibrations let astronomers measure the radius of a star to within a few percent.

 

The tones also reveal the stars' ages. Young stars burn brightly by converting hydrogen into helium and energy deep in their cores, but eventually the hydrogen reserves run out. Sound waves pass through dense helium cores more quickly than through hydrogen, changing the tone heard at the surface and giving a good sense of how long the star has been working as a hydrogen furnace.

Metcalfe presented a star with the uninspiring name KIC 11026764 as the most accurately characterized star in the universe, aside from the sun. The star is 5.94 billion years old, more than one billion years older than the sun, and 2.05 times the sun's radius. The measurements also show that this star isn't burning hydrogen fuel anymore — the core is almost entirely helium and is slowly contracting. Over the next several million years, the star will puff off its outer layers of gas until it becomes a bloated red-giant star.

This star does not host any planets, but the same techniques could be used to characterize stars that do. Knowing stars' sizes and ages could help pin down the sizes and ages of their planets.

"Our knowledge of the planets that Kepler discovers is only as good as our knowledge of the stars that they orbit," said Kepler co-investigator Natalie Batalha of San Jose State University in California.

Kepler also listened to the vibrations of more than a thousand red-giant stars ranging from a few to several dozen times bigger than the sun. Red giants are the endgame of stellar evolution. In about 6 billion years, the sun will evolve into a red giant as well.

"Kepler allows us to study the future life of our sun in much greater detail than ever before," Huber said.

Bigger red giants give off a lower, louder tone than smaller red giants, the study confirmed. Huber's results are published in two papers on arXiv.org.

The new observations may also help solve a stellar riddle that has puzzled astronomers for a hundred years. A class of stars called RR Lyrae variable stars can grow brighter or dimmer by a factor of two over just a few hours. Astronomers can measure how bright these stars actually are, as opposed to how bright they look from Earth, making them excellent "standard candles" to determine distances to other objects in the universe.

But some of these stars also show a weird modulation in their brightening and dimming, called the Blazhko effect. When this effect was discovered a century ago, it was thought to be rare and unusual.

The new Kepler data suggests that the effect "may be a rule rather than an exception," said astronomer Katrien Kolenberg of the Institute of Astronomy in Vienna, Austria.

Kepler observed the prime example of these shifty stars, known simply as RR Lyrae, plus 40 of its counterparts: "the most accurate and extensive measurement of these stars ever made," Kolenberg said. The observations showed a second variation in the stars' brightness that happens at ahlf the speed of the main variation, which Kolenberg believes is related to the mysterious Blazhko effect.

"It is striking that only a few months of uninterrupted Kepler data of the star RR Lyrae uncover phenomena that were never detected before, not even with a century of high-quality ground-based data," she said. "This is a dramatic overhaul in our understanding of RR Lyrae stars."

Because the Kepler Astroseismic Science Consortium is an international group, NASA, which operates the telescope, cannot give it funding. Last summer the consortium began raising research funds through an "Adopt a Star" program, in which anyone can claim a star as their own in Google Sky.

Image: Carter Roberts/Eastbay Astronomical Society.

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Shade of Red Preserved in Jurassic Fossils

Posted: 26 Oct 2010 10:28 AM PDT

Most biological colors of past geological ages are lost to time, existing only in the imagination's eye. But one algae's delicate reddish hue has survived intact, appearing in much the same tones as it did 150 million years ago.

Called Solenopora jurassica, the algae is responsible for fossils unearthed in Britain (where they're dubbed Beetroot Stones) and France. According to a new study, their coloration comes from natural pigments in the algae suffused by the element boron.

"It is quite exciting to find anything colorful from organisms that existed at a time when dinosaurs ruled the world," said Klaus Wolkenstein, a chemist at Austria's Johannes Kepler University and co-author of the new analysis, published October 26 in the Proceedings of the National Academy of Sciences.

Wolkenstein cautioned that fossilization may still have altered S. jurassica's pigmentation, changing its hue to something less than exactly original. But it's still close, and no other boron-containing biological pigments have ever been found, making S. jurassica's color truly unique.

Asked whether such pigmentation might be engineered into a modern algae, Wolkenstein preferred to look for it in nature. Perhaps similar pigments still exist in modern red algae and have just been overlooked — a 150 million-year-old color hidden in front of our eyes.

 

Liliocrinus, a Jurassic-era sea lily that's also maintained some of its original pigmentation.

Images: 1) Solenopora jurassica./Klaus Wolkenstein. 2) A Jurassic-era sea lily, its pigmentation also preserved for 150 million years./Klaus Wolkenstein.

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Citation: "Boron-containing organic pigments from a Jurassic red alga." By Klaus Wolkenstein, Jürgen H. Gross, and Heinz Falk. Proceedings of the National Academy of Sciences, Vol. 107 No. 43, October 26, 2010.

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Video: Fingerless Robotic Hand Can Pick Anything

Posted: 26 Oct 2010 07:52 AM PDT

A small bag filled with coffee grounds is lending robots a fingerless hand. The new kind of gripper, described online the week of October 25 in the Proceedings of the National Academy of Sciences, is capable of grasping all sorts of different objects with ease.

"This could be game-changing technology," says mechanical engineer Peko Hosoi of MIT, who was not involved with the new study. "The idea is so simple, yet effective and robust."

The simple gripper is made of a bag of coffee grounds and a vacuum, though other grains such as couscous and sand also work, says study coauthor Eric Brown of the University of Chicago. To pick something up, the bag of loose grounds first melds around the object. Then, as a vacuum sucks air out of the spaces between grains, the gripper stiffens, packing itself into a hard vice molded to the outline of the object. Reducing the bag's starting volume by just a teeny amount — less than 1 percent of the total — was enough to make the gripper latch on, the team found.

This transition from fluidlike behavior (such as dry sand flowing out of a bucket) to solid (a hard-packed sand castle) is a physical process called "jamming." Because the gripper's bulb conforms to any shape evenly before the vacuum jams it, it's extremely versatile. "Our goal was to pick up objects where you don't know what you're dealing with ahead of time," Brown says.

Gripper designs based on rigid metal fingers — like the classic arcade game with a claw that picks up toys — range from two-finger pincers to humanlike hands with five fingers and multiple joints. But all of these designs have to contend with complex finger positioning and forces. "This approach is totally different," says mechanical engineer Mark Yim of the University of Pennsylvania in Philadelphia. "It approaches grasping from a very different angle."

 

In experiments, the gripper started by picking up little things the researchers found lying around the lab: a pen, plastic tubing, a coffee mug, a shock absorber, a jack. The gripper held a cup of water well enough to pour, and a pen well enough to write. In a more daring feat, the gripper lifted a pair of water-filled gallon jugs tied together with a rope by wrapping itself around the handle of one and hoisting. And in one of the ultimate tests for robotic hands the gripper picked up a raw egg, a formidable task because hard metal pincers or fingers can concentrate force in a few small places, shattering the fragile shell.

"One of the tricky things about picking up delicate objects is that you have to know how much pressure to apply: too little and you drop the object; too much and you break it," Hosoi says. "This new gripper works by exactly conforming to the shape of the object so you can manipulate items with very little pressure — and without requiring feedback from sensors."

One kink in the design is that the gripper must apply pressure against an object in order to mold properly. If the gripper were to come at a mug handle from the side, it wouldn't be able to get a grip. Instead, it would scoot the mug along the table and over the edge. Brown says the design could be combined with a more traditional finger-based scaffold to provide more control.

Brown and his colleagues calculated that a similar gripper with a diameter of a meter would be powerful enough to lift an object weighing one metric ton. A scaled-up version might be helpful in search-and-rescue missions, Brown says. "You're posed with a problem of rubble of all sizes and shapes," so having a flexible gripper would be desirable.

Video: A robotic gripper made of a stretchy bag of coffee grounds and a vacuum picks up a shock absorber with ease. Vimeo.com/John Amend

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Signs of Destroyed Dark Matter Found in Milky Way’s Core

Posted: 26 Oct 2010 05:31 AM PDT

Cosmologists say they've found the most compelling evidence of dark matter particles to date, deep inside the Milky Way's core.

There, the thinking goes, the mysterious stuff is colliding to create gamma rays more frequently than anywhere else in the celestial neighborhood.

Similar studies have peppered scientific journals in recent years, but establishing the source definitively has been troublesome. That's not the case in this study, posted Oct. 13 on the preprint server arXiv.org, says Dan Hooper, its lead author and a cosmologist at both Fermilab in Illinois and the University of Chicago.

"We've considered every astronomical source and nothing we know of, except dark matter, can account for the observations," Hooper said. "No other explanation comes anywhere close."

The claim has yet to meet the full scrutiny of other scientists, but those who have read it said they'll be following discussions about the work closely.

"This is the first study I know of that pulls together a few threads of evidence for dark matter together with one simple particle model," said Craig Hogan, an astrophysicist at Fermilab who wasn't involved in the research. "It's not proven, but it's very exciting and deserves follow-up."

 

Dark matter got its start 13.7 billion years ago in a colossal expansion of energy called the Big Bang. That energy cooled down to form normal matter, dark matter and dark energy, which now make up 4 percent, 23 percent and 73 percent of the cosmos, respectively.

Like normal matter, dark matter has gravitational pull, helping to glue billions of stars together into galaxies. But it's called dark for a reason: The stuff hardly interacts with normal matter, making it invisible. Neutrinos are the only type of dark matter particles that have been detected in the laboratory, but they have almost zero mass and make up only a tiny fraction of dark matter's energy-of-the-universe slice.

The huge remaining portion, astrophysicists believe, is made up of weakly interactive massive particles, or WIMPs, some 10 to 1,000 times fatter in energy than a proton. If any two particles collide, the theory goes, they destroy one another and produce gamma rays.

Hooper and his team found such high-energy death knells in more than two years of data beamed back by the Fermi space telescope, NASA's gamma ray observatory that scans the Milky Way for high-energy action. What they found signaled the existence of colliding dark matter particles about eight to nine times heavier than protons — just outside the expected range.

"It's lighter than many of us would have guessed, but only by a little bit," Hooper said. "So far, we don't have any problems with that. The range is mostly sociological and not written in stone."

The team found the signals in data from a 100-light-year-wide zone of the core. They looked there, Hooper explained, because it's one of dark matter's favorite hangout spots and, in the Milky Way's case, the stuff is 100,000 times more concentrated than at the galaxy's outskirts. In short, the galaxy's core is a demolition derby for dark matter.

As tantalizing as the evidence may be, however, other scientists want to see Carl Sagan's bill of "extraordinary claims require extraordinary evidence" fulfilled before they climb on board. In simple terms, that means definitive evidence both in nature and in the laboratory.

"No one has produced Sagan-class evidence," said Michael Turner, a cosmologist at the University of Chicago who wasn't involved with the study. "The hardest part to accepting this is that you have to exclude astrophysical explanations, and nature is very, very clever. It could be something we just haven't thought of yet."

The good news, says Turner, is that several promising dark-matter detection experiments are underway. In particular, deep-underground detectors like CoGeNT, which may have seen signs of WIMPs in recent years, could lend Hooper a hand.

"This decade is the decade of dark matter. The problem is ripe to solve," Turner said. "We've gotten to this point where all of these detectors are looking in the right places."

Hooper agrees on both counts, but says no astrophysicist he spoke with could explain the phenomenon. As for verifying dark matter's existence in the laboratory, he suspects it's only a matter of weeks before his findings are backed up or trounced.

"I haven't been this excited about being a cosmologist ever before," Hooper said.

Image: A gamma-ray map of the Milky Way recorded over the course of 3 months. NASA/DOE/Fermi LAT Collaboration (high-res version)

Via: symmetry breaking

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Posted by johnald

Tuesday, 26 October 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

50-Million-Year-Old Insect Trove Found in Indian Amber

Posted: 25 Oct 2010 01:08 PM PDT

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A collection of amber deposits unearthed in northwest India has opened a spectacular window into insect life some 50 million years ago.

At that time, what's now the Asian subcontinent had just crashed into mainland Asia — about 100 million years after breaking off the coast of east Africa. During its long isolated float, life on that giant island had time to evolve into strange new forms.

That's what's researchers expected, anyway, but not what they found in the amber, described October 26 in the Proceedings of the National Academy of Sciences.

Instead, the insects resemble what's seen in amber deposits from continental landmasses of the time. (Amber is the geological name for fossilized tree resin, which often preserves insects that get stuck in it.) The findings suggest an unexpected transfer of insects, perhaps across chains of volcanic islands.

Although the new amber didn't yield bizarre new species, it's still loaded with fossil treasures. More than 700 insect species representing 55 families of insects have been identified inside. Among them are ancient bees, termites and ants — highly social insects that form some of the world's most complex societies.

In the years to come, scientists will compare these ancient specimens to modern forms and develop a deeper understanding of how these creatures have evolved. Until they do, the bugs are plenty amazing to look at.

Images: Courtesy of David Grimaldi, American Museum of Natural History.

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Citation: "Biogeographic and Evolutionary Implications of a Diverse Paleobiota in Amber from the Early Eocene of India," by Jes Rust, Hukam Singh, Rajendra S. Ran, Tom McCann, Lacham Singh, Ken Anderson, Nivedita Sarkar, Paul C. Nascimbene, Frauke Stebner, Jennifer C. Thomas, Monica Solórzano Kraemer, Christopher J. Williams, Michael S. Engel, Ashok Sahni and David Grimaldi. Proceedings of the National Academy of Sciences, Vol. 107 No. 43, October 26, 2010.

Brandon's Twitter stream, reportorial outtakes and citizen-funded White Nose Syndrome story; Wired Science on Twitter.

Pet Frogs Transmit Salmonella

Posted: 25 Oct 2010 11:47 AM PDT

VANCOUVER, British Columbia — Buying your tyke a pet frog might carry a downside that extends well beyond the "ick" factor, a new study finds. Pet African dwarf frogs harboring salmonella have sickened at least 113 people, most of them children, researchers from the Centers for Disease Control and Prevention report.

"This is the first multistate outbreak of salmonella associated with frogs," says Shauna Mettee, a public health nurse at the CDC in Atlanta who presented the findings October 22 in Vancouver, Canada, at a meeting of the Infectious Diseases Society of America.

CDC investigators became curious when doctors began reporting a spate of cases of the typhimurium subspecies of salmonella in 2009. Between April 2009 and March 2010, Mettee and her colleagues identified 113 cases of this infection, three-fourths occurring in children under age 10. The median age of the patients was 5. A sampling of 54 of these patients showed that about one-third needed hospitalization. Symptoms ranged from cramping to severe and even bloody diarrhea. There were no fatalities.

Bacteria transmission took many forms. For example, one woman cleaned a frog aquarium in the kitchen sink and subsequently bathed a 3-week-old infant in it, Mettee says.

 

The researchers traced the infected frogs to a single breeding facility that houses 800,000 to 1 million African dwarf frogs and sells them. Health authorities are now working with the facility's owner to implement cleanup procedures designed to limit salmonella among the animals.

The facility hasn't been shut down or even identified publicly, Mettee says, because "we have no regulatory authority … regarding the sale of frogs."

But that doesn't stop health officials from weighing in on the topic. "Children should avoid all contact with frogs and keep them out of the home," Mettee says.

James Hughes, an infectious-disease physician at Emory University School of Medicine in Atlanta and incoming president of IDSA, says these findings "should remind us of the importance of good hand hygiene in the kitchen and other areas of the house, especially if there are reptiles or amphibians in the household."

Amphibians and reptiles can carry salmonella bacteria without appearing sick, says Patricia Griffin, a physician and chief of the enteric diseases epidemiology branch at CDC. She notes that pet turtles, which were popular in the 1970s, were found to expose people to salmonella. Small turtles have since been banned as pets, but some street sales continue, Mettee says.

Since March 31, an additional 57 cases of the salmonella subspecies have been reported. Mettee and her colleagues are now checking whether these cases also trace to frogs from the same breeding facility.

Image: Flickr/Kelli Gaskill

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Cooling Lava Flow Spotted on Venus

Posted: 25 Oct 2010 07:45 AM PDT

Beneath its dreary shroud of clouds, Venus could be positively hopping: Planetary geologists have spotted a lava flow they say is just decades old. If confirmed, it would be the youngest evidence for volcanism on Venus.

"The flow we studied seems to be very young — it is still warm inside," says Nataliya Bondarenko, a planetary scientist at the University of California, Santa Cruz. She and her colleagues describe their findings in an upcoming issue of Geophysical Research Letters.

Researchers have long thought that Venus must be geologically active, since more than 1,000 volcanoes dot its surface. But scientists have struggled to gather definitive evidence that the planet is active today, like Earth, and not long dead, like Mars.

The new study builds on recent work suggesting that Venusian volcanoes are indeed a thing of the present.

 

Bondarenko's team analyzed microwave data collected by NASA's Magellan mission, which orbited Venus in the early 1990s. Microwave radiation indicates heat coming from the planet, such as a lava flow in the process of cooling.

In the Bereghinia Planitia region in Venus' northern hemisphere, the team found a flow that appeared up to 85 degrees Celsius hotter than expected. Had the flow been more than a century old, Bondarenko says, it would have cooled down enough that Magellan wouldn't have spotted any excess heat.

The flow must have been at least 15 years old when detected by Magellan, she says, because the Pioneer Venus orbiter photographed it in 1978.

But there's little other evidence supporting Bereghinia Planitia as recently volcanically active, says Suzanne Smrekar, a planetary geologist at the Jet Propulsion Laboratory in Pasadena, California.

In April, Smrekar and colleagues published a paper in Science describing lava flows from three regions in Venus' southern hemisphere. All three were places known to be hot spots of geological activity, similar to Hawaii. Using data from the European Space Agency's Venus Express mission, currently orbiting the second planet, Smrekar's team found several flows that looked fresh. The flows' unweathered appearance, compared with the surrounding landscape, suggests that they formed no more than 2.5 million years ago and probably in the past 250,000 years, the team concluded.

Because the Venus Express data come only from the southern hemisphere, they can't say anything about whether Bereghinia Planitia is also active, Smrekar says. But any claim of a decades-old flow in the north "sort of falls into the 'extraordinary claims require extraordinary proof' category," she says.

For their part, Bondarenko and her colleagues want to expand their research to look for other fresh flows on Venus.

Image: As seen in microwave wavelengths, a lava flow in Venus' northern hemisphere shows hot spots (red) up to 85 degrees Celsius warmer than expected. The flow could be just decades old and still cooling down, a new study suggests. Nataliya Bondarenko et al/GRL

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