Zombie' Worms Found in Mediterranean Fossil

 

Races of bizarre, bone-eating 'zombie' worms have been found on a 3-million-year-old fossil whale bone from Tuscany in Italy. It is the first time the genus Osedax has been found in the Mediterranean, and suggests Osedax were widespread throughout the world's oceans 6 million years ago.

The new find, published in the journal Historical Biology, confirms what scientists have long suspected -- that Osedax were likely responsible for erasing parts of the fossil record by destroying bones before they could become fossils.
Worms from the Osedax genus do not have a mouth or gut but consume the bone by growing root-like tissues, which dissolve the bone as they grow.
Lead scientist Nicholas Higgs discovered tell-tale traces of Osedax in the Mediterranean last year using micro-CT (Computed Tomography) scanning technology as part of his PhD at the University of Leeds and the Natural History Museum.
He says: "After several promising leads came to a dead end, the scans from the final sample looked different and I knew that I was on to something."
Osedax were first discovered alive in 2002 in Monterey Bay, California, where they were living on the bones of a decaying gray whale.
Since then, scientists have been curious about how the worms might have affected fossil records, but understanding when Osedax evolved and where they lived in the past has until now remained a problem because actual remains of soft-bodied Osedax do not preserve as fossils.
The only way to tell where and when Osedax have been at work is by distinctive bulb-shaped cavities that they leave behind in a bone -- and it is these borings that have finally been recognised by Higgs.
His research shows how widespread Osedax were millions of years ago.
The only other known evidence of Osedax from the past is in whale bones from the Pacific coast of Washington State in the US -- about as far away as it is possible to get from the Mediterranean in terms of ocean connectedness.
When Mediterranean dried up almost six million years ago most deep sea animals were killed. About half a million years later the sea re-flooded from the Atlantic.
Higgs says: "So finding out that Osedax were feeding on this whale bone three million years ago tell us that their ancestors must have also been living in the Atlantic as well, because the Mediterranean was re-colonised 5.5 million years ago from the Atlantic."
It is now almost certain that the Mediterranean is currently host to undiscovered, living Osedax species, Higgs says.
"There are 20 different species in Monterey, California alone, so it's almost certain there are many more out there. If Osedax were living the Mediterranean three million years ago there's no reason why they aren't living there now."
Last year, Higgs travelled to California to examine living Osedax and their borings to help understand and identify the full range of known species.

Icequake swarms portend some avalanches

Forecasting glacier crack-ups may be possible by keeping an ear to the ice
 

Unless you’re eating breakfast, hearing snap, crackle, and pop may be an early warning sign of an impending avalanche. Geologists listening in on “icequakes” that rumble through glaciers have developed a model that can predict a collapse up to 15 days before it happens, the team reports in a study posted on arXiv.org.
With that kind of heads up, villages could be evacuated and roads closed in avalanche-prone areas.
Though all glaciers groan and creak under stress, glaciers on an incline are especially creaky because gravity tugs on the top of the ice more than the base. Accumulating snow causes even more stress. These forces cause the glacier to fracture, sending tiny icequakes throughout. Eventually, if a glacier can’t handle the stress, a large chunk will fall off, pummeling any unsuspecting villages below with a moving mass of snow and ice.
To find early warning signs of a break-off, scientists in Switzerland placed seismic instruments on a glacier precariously hugging the northeast face of the Weisshorn, a mountain in the Swiss Alps that looms over the 400 inhabitants of the village of Randa, 2,500 meters below. Break-offs in the winter are especially dangerous because the glacier has accumulated snow, so that ruptures trigger avalanches. Weisshorn avalanches have claimed 51 lives since the 17th century.
The team traveled via helicopter in 2003 to plant the instruments — the glacier spans 3,800 to 4,500 meters above sea level on a slope of 45 to 50 degrees. The team also planted seven light reflectors mounted on stakes to help track the glacier’s movement, and left a camera across the valley to film changes in the dynamic landscape.
Researchers froze into the ice a special microphone, called a geophone, to pick up seismic vibrations. Two weeks before the glacier split in 2005, researchers were able to detect a change in the sounds picked up by the microphone.
“As you approach rupture, you hear more sounds,” says geologist and study coauthor Jérome Faillettaz of ETH Zurich. “It’s just like if you break a pen or a cracker. You hear some small noise before it breaks.”
Along with rumbling sounds, the team also saw the reflectors-on-sticks accelerate several days before the rupture. Scientists have known that seismic activity dramatically increases five days before a break-off, but by combining the motion of the glacier with the behavior of the icequakes, the researchers’ model can detect a rupture 15 days in advance.
“It’s the first time icequakes have been used as a precursor to these break-offs,” says glaciologist Fabian Walter of the Scripps Institution of Oceanography in La Jolla, Calif.
Though there are similar hanging glaciers all over the world, says Walter, few are near human settlements with lots of infrastructure.
Icequakes are less complicated to study than earthquakes because waves travel through only one medium, as opposed to several layers of the Earth. But just as scientists haven’t figured out how to predict earthquakes, predicting icequakes isn’t possible either.

Cosmic rebirth

Circular patterns in the universe's pervasive background radiation suggest the Big Bang was only the latest of many


 
Most cosmologists trace the birth of the universe to the Big Bang 13.7 billion years ago. But a new analysis of the relic radiation generated by that explosive event suggests the universe got its start eons earlier and has cycled through myriad episodes of birth and death, with the Big Bang merely the most recent in a series of starting guns.
That startling notion, proposed by theoretical physicist Roger Penrose of the University of Oxford in England and Vahe Gurzadyan of the Yerevan Physics Institute and Yerevan State University in Armenia, goes against the standard theory of cosmology known as inflation.
The researchers base their findings on circular patterns they discovered in the cosmic microwave background, the ubiquitous microwave glow left over from the Big Bang. The circular features indicate that the cosmos itself circles through epochs of endings and beginnings, Penrose and Gurzadyan assert. The researchers describe their controversial findings in an article posted at arXiv.org on November 17.
The circular features are regions where tiny temperature variations in the otherwise uniform microwave background are smaller than average. Those features, Penrose said, cannot be explained by the highly successful inflation theory, which posits that the infant cosmos underwent an enormous growth spurt, ballooning from something on the scale of an atom to the size of a grapefruit during the universe’s first tiny fraction of a second. Inflation would erase such patterns.
“The existence of large-scale coherent features in the microwave background of this form would appear to contradict the inflationary model and would be a very distinctive
signature of Penrose's model” of a cyclic universe, comments cosmologist David Spergel of Princeton University. But, he adds, “The paper does not provide enough detail about the analysis to assess the reality of these circles.”
Penrose interprets the circles as providing a look back, past the glass wall of the most recent Big Bang, into the universe’s previous episode, or “aeon,” as he calls it. The circles, he suggests, were generated by collisions between supermassive black holes that occurred during this earlier aeon. The colliding black holes would have created a cacophony of gravitational waves — ripples in spacetime due to the acceleration of the giant masses. Those waves would have been spherical and uniformly distributed.
According to the detailed mathematics worked out by Penrose, when the uniform distribution of gravitational waves from the previous aeon entered the current aeon, they were converted into a pulse of energy. The pulse provided a uniform kick to the allotment of dark matter, the invisible material that accounts for more than 80 percent of the mass of the cosmos.
“The dark matter material along the burst therefore has this uniform character,” says Penrose. “This is what is seen as a circle in our cosmic microwave background sky, and it should look like a fairly uniform circle.”
Each circle has a lower-than-average variation in temperature, which is just what he and Gurzadyan found when they analyzed data from NASA’s orbiting Wilkinson Microwave Anisotropy Probe, or WMAP, which scanned the entire sky for nine years, and the balloon-borne BOOMERANG experiment, which studied microwave background over a smaller fraction of the heavens.
Because the team found similar circular features with two different detectors, Penrose says it’s unlikely he and his colleagues are being fooled by instrumental noise or other artifacts.
But Spergel says he is concerned that the team has not accounted for variations in the noise level of WMAP data acquired over different parts of the sky. WMAP examined different sky regions for different amounts of time. Maps of the microwave background generated from those regions studied the longest would have lower noise and smaller recorded variations in the temperature of the microwave glow. Those lower-noise maps could artificially produce the circles that Penrose and Gurzadyan ascribe to their model of a cyclic universe, Spergel says.
A new, more detailed map of the cosmic microwave background, now being conducted by the European Space Agency’s Planck mission, could provide a more definitive test of the theory, Penrose says.

Negative temperature, infinitely hot

Physicists propose creating thermodynamics puzzle routinely in the lab

Physicists have described a new way of making one of the most counterintuitive phenomena known: negative temperature, which despite its name means a system that is almost infinitely hot.
Negative temperatures have been seen before, but only in very limited applications. In a paper to appear in Physical Review Letters, theorists propose broader and more intriguing ways to confirm negative temperatures, by taking pictures of atoms as they change from positive to negative temperature.
Such new approaches, scientists say, might reveal previously unknown ways in which matter behaves at the quantum level. “With these atom systems you can mimic various states of matter and do stuff that is otherwise not possible,” says team leader Achim Rosch, a physicist at the University of Cologne in Germany.
To understand negative temperature, think in terms of energy states rather than markings on a thermometer. Atomic particles in what physicists consider positive temperature — which includes most ordinary experiences, from the sun’s surface to Antarctica’s ice — like to be in the lowest energy states possible. But in systems with negative temperature, particles prefer to populate high-energy states instead of low-energy ones.
Scientists have made negative-temperature systems before, using the spins of atomic nuclei. Picture a line of atoms, each with a spin that can point up or down. In the lowest possible energy state, all spins point down. Add energy to the system and the spins will start to flip up — reaching maximum entropy, or disorder, when half the spins are up. Adding more energy after that will shift the system into negative temperature, whose high-energy states are the only way to accommodate the extra energy.
In place of atomic spins, Rosch’s team now proposes using ultracold atoms, like those used in many laboratories to study matter at the quantum level. In such extreme experimental conditions, the atoms lose their collective identities and begin to interact with one another in weird ways. By tweaking energy inputs and other factors, the scientists say, atoms that are millionths of a degree above absolute zero on a thermometer scale could be pushed past maximum entropy into the range of negative temperature.
By making images of the probability of each atom’s location, researchers propose that theoretically they could see the atoms shift from sticking together to flying apart once they crossed the boundary from positive into negative temperature. That change would constitute “a clear signature” of negative temperature, says Immanuel Bloch, an experimental physicist at Ludwig-Maximilians University in Munich and the Max Planck Institute for Quantum Optics in nearby Garching.
Bloch, who works with ultracold atoms, plans to soon try coaxing them into negative temperature and measuring them in the way Rosch’s team suggests. “It’s an exciting proposal which challenges our perception of thermodynamics,” he says.
For instance, if a negative temperature system were plopped down next to a positive one, the heat of the high-energy states would continually flow from the negative to the positive system. In that sense, the negative temperature one is infinitely hot.

The sandman gene

Researchers find another genetic variant linked to sleep duration

Whether people sleep a lot or a little may depend in part on a gene that also determines whether fruit flies snooze all night.

Geneticists studying sleep duration in people scanned the DNA of more than 4,200 Europeans, looking for genes associated with a person’s average nightly sleep time. The team found that people who have one version of a gene called SUR2 sleep about 28 minutes longer than people who have another version of the gene, said Karla Allebrandt of the University of Munich, who presented the research November 5 at the annual meeting of the American Society of Human Genetics.

In order to determine whether SUR2 really affects sleep or was just found by coincidence, the researchers then examined the gene’s function in fruit flies. The team removed the gene from the brains of two strains of fruit flies and then recorded how well the flies slept. Flies without SUR2 didn’t sleep as long at night as flies that have it, Allebrandt said. The gene encodes a protein that forms part of a channel that transports potassium in and out of cells.

Last year researchers from the University of California, San Francisco reported that a rare variation in DEC2, a gene involved in regulating the body’s daily rhythms, is associated with sleeping almost two hours a night less than average (SN: 9/12/10, p. 11)