First Glimpse Into Birth of the Milky Way

For almost 20 years astrophysicists have been trying to recreate the formation of spiral galaxies such as our Milky Way realistically. Now astrophysicists from the University of Zurich present the world's first realistic simulation of the formation of our home galaxy together with astronomers from the University of California at Santa Cruz. The new results were partly calculated on the computer of the Swiss National Supercomputing Center (CSCS) and show, for instance, that there has to be stars on the outer edge of the Milky Way.

The aim of astrophysical simulations is to model reality in due consideration of the physical laws and processes. Astronomical sky observations and astrophysical simulations have to match up exactly. Being able to simulate a complex system like the formation of the Milky Way realistically is the ultimate proof that the underlying theories of astrophysics are correct. All previous attempts to recreate the formation of spiral galaxies like the Milky Way faltered on one of two points: Either the simulated spiral galaxies displayed too many stars at the center or the overall stellar mass was several times too big.

A research group jointly run by Lucio Mayer, an astrophysicist at the University of Zurich, and Piero Madau, an astronomer at University of California at Santa Cruz, is now publishing the first realistic simulation of the formation of the Milky Way in the Astrophysical Journal. Javiera Guedes and Simone Callegari, who are PhD students at Santa Cruz and the University of Zurich respectively, performed the simulation and analyzed the data. Guedes will be working on the formation of galaxies as a postdoc in Zurich from the fall.

Removing standard matter central to formation of spiral galaxies

For their study, the scientists developed a highly complex simulation in which a spiral galaxy similar to the Milky Way develops by itself without further intervention. Named after Eris, the Greek goddess of strife and discord, because of the decades of debate surrounding the formation of spiral galaxies, the simulation offers a glimpse in time lapse into almost the entire genesis of a spiral galaxy. Its origins date back to less than a million years after the Big Bang. "Our result shows that a realistic spiral galaxy can be formed based on the basic principles of the cold dark matter paradigm and the physical laws of gravity, fluid dynamics and radiophysics," explains Mayer.

The simulation also shows that in an entity that is supposed to develop into a spiral galaxy, the stars in the areas with giant cloud gas complexes have to form. In these cold molecular giant clouds, the gases exhibit extremely high densities. The star formation and distribution there does not occur uniformly, but rather in clumps and clusters. This in turn results in a considerably greater build-up of heat through local supernova explosions. Through this massive build-up of heat, visible standard matter is removed at high redshift. This prevents the formation of a concave disk in the center of the galaxy. The removal of baryonic matter, as the visible standard matter is also known, also reduces the overall mass of the gas present at the center. This results in the formation of the correct stellar mass, as can be observed in the Milky Way. At the end of the simulation, a thin, curved disk results that corresponds fully to the astronomical observations of the Milky Way in terms of the mass, angular momentum and rotation velocity ratios.

Read moer at Science Daily

Pioneering Ants Challenge Self-Organization Assumptions

Some worker ants are more equal than others.

As with other social insects, it was once thought that workers were essentially equivalent in ant colony hierarchies. But it appears that a few well-informed individuals shape group decisions by leading nestmates to new homes.

The findings could add a new dimension to ant-derived models of self-organization.

“Although self-organized systems appear very effective under the assumption that all individuals follow the same simple set of rules, the presence of key, well-informed individuals altering their behavior according to their prior experience might generally enhance performance even further,” wrote biologists from the University of Bristol and the University of Toulouse in an Aug. 24 Journal of Experimental Biology paper.

To study nest-hunting, Nathalie Stroeymeyt and colleagues Nigel Franks and Martin Giurfa collected “house-hunting” ants, or Temnothorax albipennis, from the southern coast of the United Kingdom. These small, light-brown ants make simple sand-enclosed nests in the cracks of rocks.

Moving the ants into the lab, Stroeymeyt gave them a well-supplied artificial nest. She then placed an identical empty nest site at the opposite end of the ants’ territory. Each ant’s back was painted with individually-identifiable colored spots. Webcams and motion-detection software allowed the researchers to keep track of the movements of specific ants.

One week later Stroeymeyt placed a second unfamiliar nest site in the territory and destroyed their original home. Though some ants began to run around randomly in all directions, a few ants who had already explored the alternate nest site headed directly to it.

Those ants then quickly returned to the destroyed nest to recruit followers. They repeated the process until enough had gathered at the new nest site to relocate the entire colony.

Most studies of how ants find new nest sites use colonies unfamiliar with a new territory, and assume that all workers follow the same rules. But that’s not realistic, and as a model for self-organization and distributed decision-making — ants have inspired various forms of traffic coordination, from cars to data — it might not be optimally efficient.

More at Wired Science

New Monkey and American Bird Species Found

This has been a great week for animal discoveries. A unique new primate was recently found in the Amazon and, for the first time in decades, the United States has a new bird species.

In both cases, the animals previously slipped under the radar of scientists, perhaps because the bird and the primate so closely resemble other documented species.

The new avian is a seabird, Bryan's Shearwater (Puffinus bryani), from the Hawaiian Islands, according to a paper in the journal The Condor. It's the first new species reported from the United States and Hawaiian Islands since the Po' ouli, another bird, was discovered in the forests of Maui in 1974.

DNA testing determined Bryan's Shearwater is a new species.

"It's very unusual to discover a new species of bird these days and especially gratifying when DNA can confirm our original hypothesis that the animal is unique. This bird is unique, both genetically and in appearance, and represents a novel, albeit very rare, species," said Rob Fleischer, head of the Smithsonian Conservation Biology Institute's Center for Conservation and Evolutionary Genetics.

The Bryan's Shearwater is the smallest known shearwater in the world. As you can see from the photo, it's black and white with a black or blue-gray bill and blue legs.

One of the birds was found by biologists in 1963 during the Pacific Ocean Biological Survey Program in 1963. Peter Pyle, an ornithologist at the Institute for Bird Populations, recently examined the specimen and found that it was too small to be a little shearwater (P. assimilis) and that it has a distinct appearance. Pyle's observation then prompted the genetic analysis.

As Fleischer said, this is a rare bird, so the race is already on now to protect it.

"If we can find where this species breeds, we may have a chance to protect it and keep it from going extinct,” said Andreanna Welch, an SCBI predoctoral fellow. "Genetic analysis allows us to investigate whether an animal represents an entirely different species, and that knowledge is important for setting conservation priorities and preventing extinction."

Planning is also underway to protect the new monkey species recently found in Mato Grosso, the Brazilian state with the highest rates of deforestation in the Amazon. Often these days, if a new species is identified, it's extremely rare and possibly on the road to extinction.

The monkey is "a variation" of the titi monkey. Both the titi monkey and this new one are small, long-tailed and covered with soft fur. But the new primate sports its own unique look.

"This primate has features on its head and tail that have never been observed before in other titi monkey species found in the same area," biologist Júlio Dalponte said in a World Wildlife Fund press release.

Read more at Discovery News

Exotic Galaxy Reveals Tantalizing Tale

A galaxy with a combination of characteristics never seen before is giving astronomers a tantalising peek at processes they believe played key roles in the growth of galaxies and clusters of galaxies early in the history of the Universe.

The galaxy, dubbed Speca by the team of researchers, is only the second spiral, as opposed to elliptical, galaxy known to produce large, powerful jets of subatomic particles moving at nearly the speed of light. It also is one of only two galaxies to show that such activity occurred in three separate episodes. The scientists publish their results in the journal Monthly Notices of the Royal Astronomical Society.

Giant jets of superfast particles are powered by supermassive black holes at the cores of galaxies. Both elliptical and spiral galaxies harbour such black holes, but only Speca and one other spiral galaxy have been seen to produce large jets. The jets pour outward from the poles of rapidly-rotating disks of material orbiting the black hole. The on-and-off jet episodes have been seen in a dozen ellipticals, but only one other elliptical shows evidence, like Speca, for three such distinct episodes.

"This is probably the most exotic galaxy with a black hole ever seen. It has the potential to teach us new lessons about how galaxies and clusters of galaxies formed and developed into what we see today," said Ananda Hota, of the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), in Taiwan.

The scientists believe that Speca, about 1.7 billion light-years from Earth, and the 60-some other galaxies in a cluster with it are providing a look at what young galaxies and clusters may have been like when the Universe was much younger. In the young Universe, galaxies in such clusters would have been gathering up additional material, colliding with each other, undergoing bursts of star formation, and interacting with primordial material falling into the cluster from outside.

"Speca is showing evidence for many of these phenomena," Ananda said, adding that "We hope to find many more galaxies like it with future observations, and to learn more about the processes and an environment that were much more common when the Universe was a fraction of its current age."

Speca (an acronym for Spiral-host Episodic radio galaxy tracing Cluster Accretion) first came to Ananda's attention in an image that combined data from the visible-light Sloan Digital Sky Survey and the FIRST survey done with the National Science Foundation's Very Large Array (VLA) radio telescope. Follow-up observations with the Lulin optical telescope in Taiwan and ultraviolet data from NASA's GALEX satellite confirmed that the giant lobes of radio emission, usually seen coming from elliptical galaxies, were coming from a spiral galaxy with ongoing star formation.

Ananda's team also examined the galaxy in images from the NRAO VLA Sky Survey (NVSS), then made new observations with the Giant Meterwave Radio Telescope (GMRT) in India, which observes at longer wavelengths than the VLA and is the premier telescope for observing at those long wavelengths.

With this impressive variety of data from across the electromagnetic spectrum, the researchers unravelled the galaxy's complex and fascinating history.

The radio images from the VLA FIRST survey had shown one pair of radio-emitting lobes. The VLA's NVSS images showed another, distinct pair of lobes farther from the galaxy. The GMRT images confirmed this second pair, but showed another, smaller pair close to the galaxy, presumably produced by the most-recently ejected jet particles.

"By using these multiple sets of data, we found clear evidence for three distinct epochs of jet activity," Ananda explained.

The biggest surprise -- the low-frequency nature of the oldest, outermost lobes -- gave a valuable clue about the galaxy's -- and the cluster's -- environment. The outermost radio-emitting lobes are old enough that their particles should have lost most of their energy and ceased to produce radio emission.

"We think these old, relic lobes have been 're-lighted' by shock waves from rapidly-moving material falling into the cluster of galaxies as the cluster continues to accrete matter," said Ananda.

"All these phenomena combined in one galaxy make Speca and its neighbours a valuable laboratory for studying how galaxies and clusters evolved billions of years ago," Ananda said.

Read more at Science Daily

Scientists Still Struggle to ID 9/11 Remains

In a laboratory in the center of Manhattan scientists continue to struggle to put names to the remains of victims from the September 11, 2001 attacks, some 40 percent of which are still unidentified.

"It's not a legal obligation because everybody has a death certificate. It's an ethical-moral decision," said Mechthild Prinz in the department of forensic biology at the city's Chief Medical Examiner office.

The names of the people who died in the explosions, fires and collapse in the Twin Towers on 9/11 are known, but the violence was so extreme that even a decade later it takes painstaking forensic work to match those identities to the human fragments found at the site.

The latest match made was just this week: Ernest James, who was 40 years old. He was the 1,629th victim identified out of 2,753 people killed at the World Trade Center, or 59 percent of the total.

Initially, traditional methods such as dental records, photographs and finger prints were used to identify the bodies and remains pulled from the rubble. But as the easier batches of remains were dealt with the gruesome task turned into something more akin to serious detective work -- and even that is not enough in many cases.

"We did collect 21,817 remains, so you can imagine obviously that a lot of people were fragmented in many different body parts. And since we haven't identified over a thousand people, some of them really disappeared," said Prinz, 53, who comes from Germany but has been working as a forensic scientist in New York since 1995.

Amid strict security and sanitation conditions, a team of five scientists continues to deal with 6,314 fragments of bones found in the World Trade Center area.

An AFP journalist was shown the work underway through a window in a door before being told to put on gloves and taken into a large room, where robots clean the remains before they are tested for DNA against a databank created by relatives of the deceased.

"I remember a case a few years ago which was a small piece of bone on the roof of the Deutsche Bank building. It was the size of a coin and we were able to identify someone who worked in the towers at that time," recalled Taylor Dickerson, a criminalist in the forensic biology department.

However in most cases the DNA found in the fragments turns out to be just another piece of a person already identified. As a result, the work is painfully slow: fewer than three dozen people have been identified since 2006.

Read more at Discovery News

Horses Domesticated 9,000 Years Ago in Saudi Arabia

Saudi Arabia has found traces of a civilization that was domesticating horses about 9,000 years ago, 4,000 years earlier than previously thought, the kingdom said.

"This discovery shows that horses were domesticated in the Arabian Peninsula for the first time more than 9,000 years ago, whereas previous studies estimated the domestication of horses in Central Asia dating back 5,000 years, Ali al-Ghabban, vice-chairman of the Department of Museums and Antiquities, said at a news conference late Wednesday.

The remains of the civilization were found close to Abha, in southwestern Asir province, an area known to antiquity as Arabia Felix.

The civilization, given the name al-Maqari, used "methods of embalming that are totally different to known processes," Ghabban said.

Among the remains found at the site are statues of animals such as goats, dogs, hawks, and a three foot-tall bust of a horse, Ghabban said.

"A statue of an animal of this dimension, dating back to that time, has never been found anywhere in the world," Ghabban said.

He added that archaeologists also found arrowheads, stone tools, weaving tools and mortars for pounding grain, reflecting the development of that civilization.

Read more at Discovery News

Black Hole Behemoth Found Guilty of Star's Murder

For the first time, astronomers have witnessed the violent death of a star as it happened. But this star didn't die from natural causes; it died as a result of straying too close to a black hole, whose immense tidal forces tore the unfortunate star to shreds before eating the remains.

The accused supermassive black hole resides in the center of a galaxy some 3.9 billion light-years away in the constellation Draco.

This violent event was noticed on March 29 after NASA's Swift space telescope detected X-rays being generated in the center of a distant galaxy, a galaxy with a supermassive black hole in its core that has, until now, remained dormant. Astronomers initially assumed that the X-ray signal was the onset of a gamma-ray burst, but they were wrong.

Something was strange about these emissions -- a source named Swift J1644+57 -- and after follow-up observations by the Japan-led Monitor of All-sky X-ray Image (MAXI) instrument aboard the International Space Station (ISS) and, in a separate study, the National Radio Astronomy Observatory's Expanded Very Large Array (EVLA) near Socorro, N.M., it quickly became apparent that the emissions were originating from the death throes of a star being eaten.

The two Swift J1644+57 studies appear in the Aug. 25 issue of the journal Nature.

"Incredibly, this source is still producing X-rays and may remain bright enough for Swift to observe into next year," said David Burrows, professor of astronomy at Penn State University and lead scientist for the mission's X-Ray Telescope instrument. "It behaves unlike anything we've seen before."

The working theory is that the star in question strayed too close to a supermassive black hole, approximately twice the mass of the four-million-solar-mass supermassive black hole residing in the center of the Milky Way.

As the tidal shear is so powerful close to the black hole's event horizon, the star's structure would have warped dramatically. Very quickly, the stellar plasma will have streamed around the spinning black hole, forming a superheated disk of plasma. The plasma closest to the black hole then got pulled into the event horizon, accelerating as it did so.

The rapid acceleration and complex magnetic fields nearest to the black hole then funneled the matter into the event horizon, but some of the matter escaped as jets, blasting into space at relativistic speeds (exceeding 90 percent the speed of light) from the black hole's spin axis.

Read more at Discovery News

Cod’s Surprising Immune System

Norwegian research has revealed that the immune system of cod is very different from other fish and from mammals -- a discovery that may shed light on the human immune system as well. The discovery was made after scientists sequenced the entire cod genome.

Lacks part of immune system

Up to now, scientists have believed that all higher animals (including fish) share the same basic type of immune system as humans, assumed to have stemmed from a single common origin. Now it appears that cod are lacking in that part of the immune system that normally combats infection from bacteria and parasites.

"This was a very surprising finding," says Professor Kjetill S. Jakobsen, who headed the cod-sequencing project. "Conventional wisdom holds that cod should be dead. Yet it is very much alive -- a very successful species, in fact, quite widespread in the northern seas."

Alternative immunity

One of the genes that cod lack, known as MHC II, is responsible for detecting hostile microorganisms and initiating the immune response to fight off bacteria and parasites. Cod, however, have developed an entirely different way of battling bacteria and other infections. To compensate for a lack of MHC II, cod have a higher number of another gene, MHC I. Other parts of the cod immune system are different as well.

"This is a milestone in Norwegian biological research that will have both a social and an economic impact," emphasises Professor Jakobsen.

The results from the project have recently been published in the journal Nature.

New light on autoimmune disorders

"The unique immune system of cod gives us a new perspective on the human immune system as well," asserts Professor Jakobsen. "This discovery could also provide new insight into how to combat autoimmune disorders such as psoriasis, asthma and allergies."

The sequencing of the cod genome was hosted and coordinated by the Centre for Ecological and Evolutionary Synthesis (CEES), based at the Department of Biology, University of Oslo. Activities were carried out in collaboration with other Norwegian universities and with international research institutes in Norway and abroad.

Important for aquaculture industry

With the entire cod genome sequenced, scientists are able to identify genetic variations among individual cod. This will enhance their understanding of not only the immune system but also traits such as growth rate, sexual maturation, tolerance for temperature fluctuations, and oxygen uptake.

This kind of information will benefit both the aquaculture and fisheries industries. Fish farmers are looking to selectively breed cod that is adapted to production conditions -- fish that are both resistant to disease and an attractive commercial product. Additionally, vaccines can now be developed specifically for cod.

"The challenge now," says Anne Kjersti Fahlvik, Executive Director of the Research Council's Division for Innovation, "is to realise the true potential of detailed knowledge about the cod genome. This should be approached as a joint effort between the aquaculture industry and the relevant research communities."

Read more at Science Daily

Clever Dolphins Use Shells to Catch Fish

Already famed as Earth’s first tool-using marine mammals, the bottlenose dolphins of Australia’s Shark Bay have proved handy yet again, by using conch shells to trap tasty fish, then shaking them into their mouths like sardines from a tin.

Unlike sponging, however, in which dolphins use sponges to find fishes hiding in mud, conching isn’t yet widespread in Shark Bay. It appears to be a relatively new innovation, pioneered by a few individuals and finally catching on.

“The extent to which the conch shell is manipulated and the rarity of the behavior suggest that ‘conching’ takes some skill and practice and might thus be another rare individual foraging tactic in Shark Bay,” wrote biologists led by the University of Zurich’s Michael Krutzen in Marine Mammal Science.

While that study came out in April, an August 24 press release from Australia’s Murdoch University, home of co-authors Simon Allen and Lars Bejder, reported that conching has been observed at least 6 times in the last four months. That’s as often as conching was seen between the first sighting in December 1996 and the afternoon of July 31, 2007, when during a survey of western Shark Bay the researchers spotted an unfamiliar dolphin.

As they lingered nearby, hoping to dart a biopsy sample from her skin, the dolphin dived and then surfaced with her beak lodged in a conch shell, which she waved back and forth above the water. She dove again. Before she surfaced, four more dolphins arrived. When she returned with the conch, they were waiting and watching. So were the researchers.

“Photographs were taken, with two of these clearly revealing the posterior portion of a fish protruding from the conch aperture and held in the dolphin’s jaws,” they wrote in Marine Mammal Science. “The dolphin lifted the conch out of the water and manipulated it in such a manner as to drain the water and the fish from the shell.” It appeared to be an emperor fish.

Until the researchers photographed CON — sort for “Concher,” as they code-named the dolphin — the purpose of conch-wielding was unknown. From their handful of fleeting glimpses over the years, the researchers thought it likely that dolphins were simply eating conch snails inside their shells, or perhaps showing off, as do stick-wielding, clay-throwing dolphins in the Amazon.

Almost two years later, in April 2009, the researchers saw another conching dolphin, this time in a shallow, seagrass-covered spot where a wildlife observer had seen dolphins digging through seabed with shells of baler, another large marine mollusc.

Exactly how the shells are used underwater isn’t yet known. Fish might swim into them while being chased, unwittingly turning themselves into packaged snacks. The dolphins could also use the shells like nets or containers, a possibility suggested by the wildlife observer’s report of seabed-digging.

Read more at Wired Science

Sex with Neanderthals Made Us Stronger

Mating with Neanderthals and another group of extinct hominids, Denisovans, strengthened the human immune system and left behind evidence in the DNA of people today, according to new research.

The findings add to the growing body of evidence that modern humans who left Africa around 65,000 years ago mated with Neanderthals and Denisovans -- two archaic species that lived in Europe and Asia.

The study, which appears in this week's Science, is among the first to show how the interbreeding shaped modern human genes and the attributes they pass to us.

Peter Parham, a professor of cell biology, microbiology and immunology at the Stanford University School of Medicine, and his team focused their analysis on "HLA" genes, which are fast-evolving vital components of the human immune system.

"The modern human populations who left Africa to colonize other continents were likely to have been small groups who started off with limited HLA diversity and suffered further reduction of HLA diversity due to disease," Parham told Discovery News. "Interbreeding with archaic humans introduced additional HLA variants into the modern human population that increased their genetic viability and capacity to resist infection."

He and his colleagues studied the genomes for Neanderthals and Denisovans, as well as the DNA of modern human populations. The organization Bone Marrow Donors Worldwide, as well as bone marrow registries from several countries, provided data on HLA genes.

The analysis shows that Neanderthal and Denisovan HLA genes now represent more than half of such immune system-related DNA in modern European and Asian populations. They also appear to have been later introduced into Africans.

The specific gene HLA-A, for example, is present in the Neanderthal and Denisovan genomes. It contributed this much to the following modern human populations: Up to 95.3 percent for Papua New Guineans, 80.7 percent for Japanese people, 72.2 percent for Chinese people, 51.7 percent for Europeans, and 6.7 percent for Africans.

Such percentages provide clues on how modern humans migrated and interbred. The scientists believe some modern humans migrated out of Africa 67,500 years ago. Interbreeding became evident 50,000 years ago.

"Because archaic humans had lived in Asia and Europe for hundreds of thousands of years before the modern humans arrived, their HLA alleles almost certainly were adapted to the local infections and in this way further invigorated the immune systems of the recent modern migrants," Parham said.

Some of the Europeans and Asians then went back to Africa around 10,000 years ago, bringing the newly acquired genes and their associated immunity boost with them.

Human history was "a lot more complex and interesting" than previously thought, Svante Paabo, director of the Department of Genetics at the Max Planck Institute for Evolutionary Anthropology, told Discovery News.

In separate research, Paabo and his team found that about 4 percent of the genomes of non-Africans are derived from Neanderthals and 4 to 6 percent of modern Melanesian genomes are derived from Denisovans.

This earlier research and the new study then suggest at least two possible scenarios: Either interbreeding was frequent and widespread, involving a lot of individuals, or the majority of native modern populations from certain regions are descended from individuals that did interbreed, even if such "seed" groups were relatively small. Parham suspects the latter is what happened.

Read more at Discovery News