Jul 11, 2014

Korean Mummy's Hernia Diagnosed 300 Years Later

This diagnosis is 300 years too late.

An autopsy of a Korean mummy entombed in the 17th century shows that the middle-age man suffered from a potentially painful hernia during his lifetime, according to a new study.

The mummy, only discovered last year, had been buried in a royal tomb of Korea's Chosun (or Joseon) Dynasty in Andong, a city in modern-day South Korea. The well-preserved remains belonged to a man who was about 45 years old and 5 feet, 3 inches (160.2 cm), the researchers said in their report published this month in the journal PLOS ONE. Based on his topknot hairstyle, archaeologists concluded that the man was married.

Before he died, the middle-age man may have roamed the streets of Andong with pain in his chest and abdomen. Perhaps he was sometimes short of breath or nauseated. But he wouldn't have known what was wrong with him; doctors have only been able to diagnose his condition, known as Bochdalek-type congenital diaphragmatic hernia (CDH), with the advent of radiological imaging technologies, such as X-ray and computed tomography (CT) scans, in the 20th century.

Bochdalek hernias arises from a birth defect that causes a hole in the diaphragm, the dome-shaped muscle that stetches across the bottom of the lungs. Other organs in the abdomen might push through this hole into the chest cavity, compressing one or both of the lungs and moving the heart.

A computed tomography (CT) scan of the mummy hinted that something was wrong with the placement of the man's organs. An autopsy confirmed that there was indeed a hole in his diaphragm and that several of his organs were herniated, including the right lobe of his liver, part of his stomach and part of his colon, the scientists said.

The researchers, led by Yi-Suk Kim of Ewha Womans University in Seoul, South Korea, looked for other complications that may have been caused by the man's condition, such as perforation or strangulation of his herniated organs, which often causes death in Bochdalek CDH patients today. However, the scientists found no such evidence for these problems.

"This means that the CDH itself might not have been the main cause of death in his case," the authors wrote. "He could have lived with CDH in this lifetime while experiencing a few signs of respiratory disturbances. We suspected that the functional defects caused by the CDH in the present male mummy case might have been largely compensated for as he grew older."

Read more at Discovery News

Were Ancient Child Skulls Gifts to the Lake Gods?

Children's skulls found at the edges of Bronze Age settlements may have been a gruesome gift for the local lake gods.

The children's skulls were discovered encircling the perimeter of ancient villages around lakes in Switzerland and Germany. Some had suffered ax blows and other head traumas.

Though the children probably weren't human sacrifices killed to appease the gods, they may have been offered after death as gifts to ward off flooding, said study co-author Benjamin Jennings, an archaeologist at Basel University in Switzerland.

Lake dwellers
Since the 1920s, archaeologists have known that ancient villages dotted Alpine lakes in Switzerland and Germany. However, it wasn't until the 1970s and 1980s that many of the sites were excavated, yielding hunting tools, animal bones, ceramics, jewelry, watchtowers, gates and more than 160 dwellings. Tree rings on wooden artifacts from the sites suggest people lived there at different periods between 3,800 and 2,600 years ago. [Mummy Melodrama: Top 9 Secrets About Otzi the Iceman]

The Bronze Age lake dwellers regularly faced flooding. Whenever lake levels rose, they would pick up and move to dry land, only to return once the waters receded. To adapt to this watery threat, the people built houses on stilts or on sturdy wooden foundations, and created palisades, or fences, made from bog pine, the researchers wrote in the June issue of the journal Antiquity.

But in addition to finding evidence for such architectural adaptations, archaeologists also unearthed more macabre details of life (and death): children's skulls and skeletal remains encircling the villages at the palisade edges. Many of these ancient skulls were placed there long after their initial burial, at a time when the settlements experienced the worst inundation from rising lake levels, the researchers wrote.

Gift to the gods

In the current study, Jennings and his colleagues took a closer look at the fossil skeletons.

Most were from children under age 10, and though the skeletal remains revealed tooth decay and signs of respiratory ailments, those health troubles would not have been severe enough to warrant a mercy killing, the researchers wrote in the journal article.

The skulls showed evidence of head trauma from battle-axes or clubs, though the injuries don't have the uniformity associated with a ritual killing. As a result, it's more likely the youngsters were felled in warfare, rather than killed as a sacrifice for the gods, the researchers wrote.

Either way, it's clear these weren't ordinary burials, he said.

"Across Europe as a whole there is quite a body of evidence to indicate that throughout prehistory human remains, and particularly the skull, were highly symbolic and socially charged," Jennings told Live Science in an email.

At these sites, "the remains are found at the perimeter of the settlement — not inside and not outside, but at a liminal position on the border between in and out," Jennings added. And at one of the sites, the remains were placed at the high-water mark of the floodwaters. Taken together, the details of the burial suggest the remains were placed as an offering to protect against flooding, Jennings said.

Read more at Discovery News

Baby Thought Cleared of HIV Has the Virus Again

A girl who was born HIV-positive but was treated early and showed no signs of the disease for years has seen her infection return, US doctors said Thursday.

The girl's story had raised hopes that doctors may have found a way to cure young children who are born HIV-positive, simply by giving them strong anti-retroviral drugs shortly after birth.

"Certainly, this is a disappointing turn of events for this young child, the medical staff involved in the child's care and the HIV/AIDS research community," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

Known widely as the "Mississippi baby," she was born to an HIV-positive mother in 2010 and was given a potent dose of anti-retroviral medication 30 hours after birth.

She continued taking the medications until the age of 18 months, when doctors lost track of her. When she returned five months later, doctors could find no sign of the virus, even though she had not been taking her daily pills.

The child continued to stay off treatment and showed no sign of the virus for more than two years.

"Typically, when treatment is stopped, HIV levels rebound within weeks, not years," said Deborah Persaud, professor of infectious diseases at the John Hopkins Children's Center in Baltimore.

Persaud described the child's response as "unprecedented."

Now age four, she was tested during a routine clinical care visit earlier this month, and was found to have detectable HIV levels in her blood.

She also had a decreased T-cell count and the presence of HIV antibodies, signaling that her body was fighting the infection and that HIV was actively replicating again in her body.

The girl, whose identity has not been released, is now being treated once again with anti-retroviral medication and is doing well, Fauci said.

"The case of the Mississippi child indicates that early anti-retroviral treatment in this HIV-infected infant did not completely eliminate the reservoir of HIV-infected cells that was established upon infection but may have considerably limited its development and averted the need for anti-retroviral medication over a considerable period," said Fauci.

Researchers must now turn their attention to understanding why and how the child went into remission, with the hope of extending that time period even further in future cases, he said.

Read more at Discovery News

The Feisty Shrimp That Kills With Bullets Made of Bubbles

This is what it looks like when a pistol shrimp gets stung by a bee. I jest, of course. Everyone knows that bees can’t swim. That giant claw is perfectly natural: The shrimp uses it to snap so hard that it briefly heats the water to 8,000 degrees Fahrenheit.
The greatest, smoothest gunslinger of all time—and I say it knowing full well I’m going to get emails for this opinion—is Clint Eastwood’s Man With No Name, aka Blondie, of Sergio Leone’s classic spaghetti westerns. I mean, at a public hanging the guy sat back and sniped the rope to free the accused, then blasted off the hats of the men in attendance. Because let’s be real: Wearing a hat to an execution is bad form.

But the greatest real-life gunslingers have to be the pistol shrimp, aka the snapping shrimp, hundreds of species with an enormous claw they use to fire bullets of bubbles at foes, knocking them out cold or even killing them. The resulting sound is an incredible 210 decibels, far louder than an actual gunshot, which averages around 150.

Pound for pound, pistol shrimp are some of the most powerful, most raucous critters on Earth. Yet at the same time they are quite vulnerable, allying with all manner of creatures and even forming bizarre societies to protect themselves from the many menaces of the ocean bottom.

The Life Despotic

The pistol shrimp has two claws, a small pincer and an enormous snapper. The snapper, which can grow to up to half the length of the shrimp’s body, does not have two symmetrical halves like the pincer. Instead, half of it is immobile, called a propus, which has a socket. The other half, called a dactyl, is the mobile part. It has a plunger that fits into this socket. The shrimp opens the dactyl by co-contracting both an opener and closer muscle. This builds tension until another closer muscle contracts, setting the whole thing off with incredible force.

“Mama Said Knock You Out” is the anthem of the pistol shrimp, which most of the critters, having never met their mothers, feel somewhat conflicted about.
When the plunger slams into this socket it displaces water that jets out at 105 feet a second, a velocity so high that its pressure drops below the vapor pressure of water. Tiny bubbles already present in the water suddenly swell in this low pressure, then collapse when the pressure climbs again.

“You essentially create this cavitation bubble,” said coral reef biologist Nancy Knowlton of the Smithsonian Institute. “And when the bubble collapses, it generates that snap sound,” as opposed to the impact of the claws themselves making the noise.

More importantly, the collapse of the bubble generates, for a split second, temperatures of 8,000 degrees Fahrenheit, nearly as hot as the surface of the sun, and also, oddly, a flash of light. The resulting shockwave bombards the shrimp’s prey, which if it’s lucky will die instantly because it’s then dragged into the pistol shrimp’s burrow and consumed. That’s not so fun if you’re half-conscious (see the awesome BBC video below). It’s such a powerful blast that some species use it to drill into solid basalt rock, snap after snap, to make a comfy little home, like an aquatic version of Dig Dug, only with fewer dragons, or whatever those things are.

Some species of snapping shrimp take up residence in sponges for protection. I love the expression on this little one’s face more than almost everything.
The creature has weaponized bubbles. (Another ocean critter, the mantis shrimp, produces cavitation bubbles when it rapidly strikes prey with its clubs, though it’s unclear if it evolved to use the bubbles or if they’re just a welcome destructive side effect). And pistol shrimp are far from conservative with their snapping. In fact, vast colonies of them all firing off at each other or their prey have been known to disrupt sonar equipment with a cacophony likened to the crackling of burning twigs. Yet there is an upside to all the racket.

“Anywhere you go swimming in the tropics, if you listen around you, you can hear these things,” said Knowlton. “And some people have argued that instead of thinking about snapping shrimp sounds as an obstacle to hearing what it is you’re trying to hear, you can also use the sounds of snapping shrimp and other things on coral reefs to assess the health of the reefs.” Lots of noise means lots of life (and lots of pissed off sonar operators).

Like many crustaceans, the pistol shrimp will willingly shed its claws if attacked, because it’s better to lose a pincer than your life, but that won’t stop the noise for long. As complicated a structure as its snapping claw is, the shrimp will grow another—in a surprising way.

Relieve a pistol shrimp of its snapping claw and it’ll grow back not another snapper, but a pincer like its remaining claw. But what’s the fun in having two pincers? After the next molting of its exoskeleton, the original pincer starts looking more and more like a snapper, eventually growing to the full size and strength of the lost pistol. The shrimp has switched weapon hands, modifying the existing pincer to more quickly get back into fighting shape.

Things can glitch, though, and a pistol shrimp can end up with two pistols if it loses a pincer and it grows back as the wrong type, according to Knowlton. Dual-wielding snappers sounds awesome, sure, but they need pincers to dig into the stunned prey once they’ve gotten them back into the burrow. Think of the claws as complementary forks and knives … knives that actually are more like guns. OK think of them as forks and guns.

Social Security

For all their orneriness, pistol shrimp are really quite easy to get along with—if you have something to offer them. While many species pair into monogamous lifetime bonds, others have mastered the art of symbiotic relationships, teaming up with all manner of other sea critters. Taking shelter in the three-dimensional maze that is coral, for instance, a shrimp in turn dutifully attacks the giant, voracious crown-of-thorns starfish that come to feed on its host, blasting the fiend’s tube feet to drive it away. Others take shelter in the stinging tentacles of sea anemones, just like the famous clownfish.

Pistol shrimp will pair up with gobies to live in and protect a single burrow. It’s a friendship that at any moment could be undone by the shrimp accidentally snapping the goby in the face and knocking it unconscious. Not unlike most friendships, really.
Another species will dig a sandy burrow and invite a goby over. The lovely new couple will hover at the entrance on the lookout for both prey and predator. “The goby provides advance warning to the shrimp,” said Knowlton. “And in many cases [the shrimp] puts its long antennae, one of them at least, on top of the goby. So if the goby runs back into the burrow, the shrimp withdraws as well.” In exchange, the pistol shrimp, a quite accomplished digger, constantly excavates the burrow to keep it tidy.

But most incredible of all symbiotic snapping shrimp relationships are the handful of species that actually form societies of hundreds of individuals inside sponges, an extremely advanced level of organization known as eusociality. The shrimp are ruled by a larger queen and king, the only ones who breed, surrounded by their doting subjects.

“It’s remarkable in the sense that of all the millions of species in the ocean, a few species of snapping shrimp are the only marine animals that do this,” said marine biologist Emmett Duffy of the Smithsonian Institution, who was the first to describe these societies. “But what in some ways is more remarkable is how similar these things are ecologically to some of the social insects.” Think ant and bee colonies that we know so well, only wetter.

Read more at Wired Science

Jul 10, 2014

Why Some Chimps Are Smarter Than Others

Chimpanzees don't just get their smarts by aping others — chimps, like humans, inherit a significant amount of their intelligence from their parents, new research reveals.

Researchers measured how well 99 captive chimpanzees performed on a series of cognitive tests, finding that genes determined as much as 50 percent of the animals' performance.

"Genes matter," said William Hopkins, a neuroscientist at Georgia State University in Atlanta and co-author of the study published today (July 10) in the journal Current Biology.

"We have what we would call a smart chimp, and chimps we'd call not so smart," Hopkins told Live Science, and "we were able to explain a lot of that variability by who was related to each other."

Animal 'intelligence'

People don't usually talk about animal intelligence, but rather animal learning or cognition. American psychologists John Watson and B.F. Skinner developed the notion of behaviorism in the early 20th century, which said that scientists should study only the behavior of animals, not their mental processes. This was the dominant approach until about 1985.

But in the last few decades, studies have shown convincingly that animals are capable of cognition. What remained unknown was the mechanism behind it, Hopkins said. Many studies of human twins suggest that intelligence is heritable, but few studies have looked at whether this is true in other primates.

In the new study, Hopkins and his colleagues gave chimpanzees at the Yerkes Primate Center, in Atlanta, a battery of cognitive tests adapted from ones developed by German researchers for comparing humans and great apes. The tests measured a range of abilities in physical cognition, such as the ability to discriminate quantity, spatial memory and tool use. The tests also examined aspects of social cognition, such as communication ability.

The researchers created a genetic pedigree of the chimps, showing how they were related to each other. This would be like taking a group of 300 random people, sticking them on another planet where they could breed and have children, and testing their intelligence 50 years later, Hopkins said.

About half of the variability in the chimps' performance on the cognitive tests could be attributed to their relatedness, the results showed. "I was a little surprised by that. It was higher than I thought would be," Hopkins said.

In addition, neither the sex of the animals nor their rearing history (whether they were raised by their mother or by humans) seemed to affect cognitive performance, the researchers found.

Nature vs. nurture

In humans, some people believe that intelligence is primarily a result of schooling. But for chimps, this can't be a factor, since they don't go to school, Hopkins said. "The fact that we can establish this in an organism that has none of the baggage of our social-cultural systems points strongly to the role that genes play in their intelligence," he said.

Alex Weiss, a psychologist who studies nonhuman primates at the University of Edinburgh in Scotland, who was not involved in the study, said the findings were "really interesting, particularly as these findings mirror what has been found for decades in studies of human twins and human families." It provides just one more example of the similarities between chimpanzees and humans, Weiss told Live Science.

But while the results suggest that "nature" matters a bit more than "nurture" for intelligence, Hopkins said other findings don't support that interpretation. Environment and experience still have an influence on cognitive performance. For example, if you compare chimps that have been trained to use sign language to ones that haven't, the trained animals do much better on cognitive tests, he said. "So there's a case where nurture really matters."

Read more at Discovery News

200-Year-Old Bottle of Seltzer Found in Shipwreck

Polish archaeologists have recovered one of the world’s oldest intact bottles of mineral water from a shipwreck lying on the bottom of the Baltic Sea.

Still corked, the perfectly preserved stoneware bottle was produced between 1806 and 1830 by Selters, one of the oldest mineral waters in Europe.

The 12-inch bottle was found during archaeological work on a shipwreck lying at a depth of about 40 feet in the Gdańsk Bay not far from the Polish coast.

Little is known about the wreck. Archaeologists called it F-33-31 or “Głazik,” meaning boulders in Polish. Indeed, its cargo of large stones suggests the vessel was probably used for transporting construction materials along the Baltic coast.

So far, the stoneware bottle is the most valuable find retrieved from the wreck.“Probably we have found the oldest cork bottle from Selters,” Tomasz Bednarz, an underwater archaeologist of Gdańsk’s National Maritime Museum, told Discovery News.

The naturally carbonated water springs of Selters were discovered around the year 1000 on the northern slopes of the Taunus mountain range in Germany. The mineral water source was fully exploited during the mid-19th century.

From St. Petersburg to New York and from London to Florence, Selters “liquid treasure,” delivered in unique clay jugs, became a synonym of the finest mineral water. In North America, Selters was the prototype of “seltzer” artificial soda water.

Read more at Discovery News

Earliest Case of Down Syndrome Found in Medieval Cemetery

The earliest probable case of Down syndrome in the archaeological record comes from a 5- to 7-year-old child who lived in medieval France some 1,500 years ago, new research shows.

The child, who is also the youngest example of the condition in the archaeological record, likely was not stigmatized in life, given that the body was treated in a similar way to others buried at the site, researchers say.

Archaeologists originally discovered the skeleton of the child in 1989, when they excavated it along with 93 other skeletons from a fifth- to sixth-century necropolis located just south of the Abbey of Saint-Jean-des-Vignes in northeastern France. Researchers had suspected the child may have had Down syndrome, but they hadn't performed a rigorous analysis to confirm the diagnosis.

So Maïté Rivollat, an archaeologist at the University of Bordeaux, and her colleagues studied the skull of the child, and took a computed tomography (CT) scan of it to understand its internal features.

"Two earlier publications just mentioned the possibility of Down syndrome without a detailed study," Rivollat told Live Science in an email. "The scan was a new possibility to approach the intracranial aspect of that skull."

An ancient disorder

Down syndrome is a genetic disorder in which a person has an extra copy of chromosome 21. People born with Down syndrome typically have intellectual disabilities, physical growth delays and certain facial features, including a flat nasal bridge and almond-shaped eyes that slant upward.

British physician John Langdon Down first described Down syndrome as a unique disorder in 1866. Despite this relatively recent identification of the condition, paintings and sculptures have depicted Down syndrome for centuries.

For instance, the earliest depiction of Down syndrome may come from Olmec figurines from Mesoamerica that date as far back as 1500 B.C., according to a 2011 study on the history of Down syndrome published in the Journal of Contemporary Anthropology.

In the archaeological record, the oldest probable case of Down syndrome came from a 9-year-old child who lived in England sometime between A.D. 700 and 900. (A skeleton from a Native American cemetery in California, dating to 5200 B.C., may, in fact, be the earliest archaeological case of Down syndrome, but the evidence is less conclusive, the 2011 study notes.)

A normal life?

To see if the Saint-Jean-des-Vignes child really had Down syndrome, Rivollat and her team studied the dimensions and structure of the child's skull and compared it with the skulls of 78 other children of similar ages. Their analysis showed the French child had numerous features indicative of Down syndrome, which the other skulls lacked.

For example, the skull was short and broad, and flattened at the base. In addition, it contained thin cranial bones and certain extra bone pieces. The child also had some sinus and dental abnormalities, which aren't diagnostic of Down syndrome on their own, but are indicative of the disorder when considered along with the other characteristics, the researchers point out in their study, published online last month in the International Journal of Paleopathology.

Read more at Discovery News

Dazzling New View of Europa's Frozen Red Veins

Jupiter’s moon Europa is one of the most fascinating worlds in our solar system. Its cracked icy crust is known to hide vast watery oceans that actively cycle oxygen and nutrients from the surface to its depths, leading astrbiologists to hypothesize about its life-giving potential. And we’re not talking about single-celled bacteria — the moon has the potential to support complex lifeforms.

Now, in a newly released view of Europa’s cracked surface, ruddy veins of hydrated salts mixed with chemicals such as magnesium sulfate or sulfuric acid break up bluish slabs of pure water ice. Compiled from data collected by NASA’s Galileo spacecraft, this image release only amplifies our fascination for the moon.

The colorized version of this observation, which measures 101×103 miles (163×167 kilometers), uses data that was collected in 1997 and 1998 during separate Galileo flybys. The spacecraft ended its mission in 2003 after NASA commanded it to crash into Jupiter’s atmosphere. This kamikaze ending was chosen as the spacecraft ran out of thruster fuel to avoid it crashing with Europa or the other Jovian satellites, potentially contaminating them with hardy Earth bacteria that may have been hiding in the probe’s components.

This view was originally released as a greyscale map after the first 1997 flyby, but after layering lower-resolution color data collected in 1998, a whole new dimension has been revealed. It is thought that the red veins reveal interactions from Europa’s surface ice with the ocean below.

Wouldn’t it be awesome if we could land a robotic mission near one of these veins, potentially finding an open fissure where a robotic Europa submersible could be dropped to seek out the lifeforms that may lie beneath.

From Discovery News

Found! Most Distant Stars in Milky Way Galaxy

The boundaries of our home galaxy may have to be redrawn.

Astronomers have discovered the farthest-flung stars yet known in the Milky Way. The two objects — known as ULAS J0744+25 and ULAS J0015+01 — are about 775,000 and 900,000 light-years from Earth, respectively, making them both about five times more distant than a satellite galaxy known as the Large Magellanic Cloud.

"The distances to these two stars are almost too large to comprehend," study lead author John Bochanski, of Haverford College in Pennsylvania, said in a statement. "To put it in perspective, when the light from ULAS J0015+01 left the star, our early human ancestors were just starting to make fires here on Earth."

The Milky Way extends far beyond its familiar disk, which is just 100,000 light-years or so wide. The galaxy is surrounded by a sparse "halo" of stars — perhaps stragglers left out there after the Milky Way's many mergers with dwarf galaxies over the eons, researchers say.

Scientists know this halo extends to at least 500,000 light-years away, but its exact dimensions are unknown. Bochanski and his colleagues decided to probe the halo's outer reaches, hunting for a type of star called cool red giants.

Cool red giants are much rarer than red dwarfs, which make up about 70 percent of the Milky Way's stars. But they're about 10,000 times brighter, making them much easier to see from a distance.

"It really is like looking for a needle in a haystack," Bochanski said. "Except our haystack is made up of millions of red dwarf stars."

The team pored over images collected by the UKIRT Infrared Deep Sky Survey, which uses the United Kingdom Infrared Telescope in Hawaii, and the Sloan Digital Sky Survey, which employs a telescope in New Mexico. They detected ULAS J0744+25 and ULAS J0015+01 in these data, then confirmed them by taking spectroscopic data with the 6.5-meter telescope at the MMT Observatory in Arizona.

Read more at Discovery News

Jul 9, 2014

Huge Trove of Dinosaur Footprints Found in Alaska

A "world-class" dinosaur track site discovered in Alaska's Denali National Park shows that herds of duck-billed dinosaurs thrived under the midnight sun.

"We had mom, dad, big brother, big sister and little babies all running around together," said paleontologist Anthony Fiorillo, who is studying the dinosaur tracks. "As I like to tell the park, Denali was a family destination for millions of years, and now we've got the fossil evidence for it."

The discovery adds to Fiorillo's growing conviction that dinosaurs lived at polar latitudes year-round during the Late Cretaceous Period, about 70 million years ago.

"Even back then the high latitudes were biologically productive and could support big herds of pretty big animals," said Fiorillo, curator of earth sciences at the Perot Museum of Nature and Science in Dallas.

The dinosaur track site, near Cabin Peak in the park's northeast corner, has thousands of tracks from hadrosaurs, or duck-billed dinosaurs. Many of the deep tracks contain preserved skin and "nail" impressions from the plant-eating hadrosaurs.

"This is definitely one of the great track sites of the world. We were so happy to find it," Fiorillo said.

Fiorillo and his collaborators also found traces from birds, clams, worms and bugs intermingled with the dinosaur tracks. Other dinosaur denizens who left behind footprints in Denali were ceratopsians, therizinosaurs and the flying reptiles called pterosaurs. Ferns and redwood cones complete the picture of a rich Cretaceous ecosystem.

The muddy ground is so rumpled by footprints that the researchers were hard-pressed to pull out tracks from individual hadrosaurs. Instead, they counted each print and grouped them by size. The results were published June 30 in the journal Geology.

There are four distinct size ranges, varying in length from 5 inches (about 12 centimeters) to 24 inches (about 60 cm). More than 80 percent of the tracks are from adults, and 13 percent are from young duckbills less than a year old. Just 3 percent are juvenile hadrosaurs. The researchers think the small number of juvenile prints suggest the young underwent a rapid growth spurt, spending only a short time as tiny, vulnerable dinosaurs (a theory also supported by studies of hadrosaur bones).

Duck-billed dinosaurs are the most common dinosaur fossils from the Late Cretaceous, with a wide range of species found on several continents. Call them the buffalo of the dinosaurs, grazing on the fern prairie and protecting their young in big herds.

The evidence emerging from the Denali hadrosaur tracks show babies and juvenile dinosaurs living in Alaska during the summer. The juveniles probably couldn't endure a long migration, so the tracks suggest the dinosaurs spent their entire lives in the Arctic, rather than migrating from somewhere else, the researchers said.

Some researchers have speculated that dinosaurs migrated north to Alaska, perhaps even coming from Canada like huge caribou herds.

"If you take a great big herd of plains eaters, they have to move at some level, otherwise they strip out all the vegetation," Fiorillo said. "But there's a growing data set that suggests they didn't do the thousand and thousands of miles of migration that was originally considered."

During the Late Cretaceous, Alaska sat at about the same latitude as today, but it was a tectonic jigsaw puzzle that had yet to assemble into today's stunning topography. Mountain-fed rivers and streams flowed through Denali, but not the same mountains: the Alaska Range was just being born. Mount McKinley, now the tallest mountain in North America, didn't exist. The climate was warmer, similar to coastal Washington and Oregon, but sunlight still flipped between extremes, with lengthy summer days and long, dark winters.

Despite the dark winters, scientists such as Fiorillo have uncovered scores of dinosaur fossils and tracks across Alaska in recent decades, from quarries near the North Slope oil fields down to Denali's spectacular mountains.

Fiorillo and colleagues from Texas, Japan and Alaska have been documenting the new Denali track site since 2011. Exhibits featuring copies of the Denali dinosaur fossils and hadrosaur footprints are on display in the park and at the Perot Museum in Texas.

The trampled ground sits at the top of a steep ridge and is exposed on a cliff face about 590 feet (180 meters) long. The tracks were made within a short time range, between 69 million to 72 million years ago, likely in a muddy river or stream bank during the height of summer, the researchers said. (The bugs and plants help pin down the time of year.)

Read more at Discovery News

Giant Ancient Sea Scorpions Had Bad Eyesight

Gigantic sea scorpions that lurked in the ocean more than 400 million years ago weren't as scary as they sound, a new study suggests.

The massive creatures, known as pterygotids, were the largest arthropods that ever lived, growing to be up to 6.5 feet (2 meters) long, with claws measuring up to about 2 feet (0.6 m). But contrary to what scientists thought, these animals may not have been true top predators.

"These things were almost certainly still predators of some kind, but the imagined notion that they were swimming around terrorizing anything that looked edible is probably an exaggeration," said Derek Briggs, a paleontologist at Yale University in New Haven, Connecticut, and co-author of the new study, published today (July 8) in the journal Biology Letters.

Pterygotids were a type of eurypterid, an extinct type of sea scorpion related to arachnids. These ocean-dwelling creatures lived between about 436 million to 402 million years ago, in the Silurian and Devonian periods, Briggs said. Their closest living relatives are horseshoe crabs or modern sea scorpions, he said.

Previously, these spooky sea monsters were thought to be fearsome predators, devouring armored fishes and giant cephalopods (related to modern squids and nautiluses). Their compound eyes and large claws seemed to suggest as much.

But more recently, a study revealed that pterygotid claws wouldn't have been strong enough to break into armored fish or cephalopod shells.

In the recent study, Briggs and his team set out to examine the eyes of these ancient sea scorpions, to determine whether they had good enough vision to be great hunters.

Some of the lenses in the creatures' eyes were big enough for researchers to see them without any help from technology, but others had to be viewed under an electron microscope. The team estimated the angle between the lenses and the size of the lenses, comparing them with the eyes of a smaller eurypterid relative and of modern arthropods.

Read more at Discovery News

Isolated Amazon Tribe Makes Contact With Scientists

A never-before-contacted tribe in Brazil's Amazon voluntarily emerged from the forest and approached scientists, according to an announcement from the country's Indian affairs dapartment (FUNAI).

Science Now reported that on June 29, the group of Brazilian scientists had made the first official contact with an isolated tribe in 18 years.

It wasn't an accident that the scientists were in the area, the Science Now article said. "The event -- Brazil’s first official contact with an isolated tribe since 1996 -- was not entirely unexpected. Since early June, fearful villagers in the region had radioed Brazilian authorities at least twice about a group of some 35 tribal strangers who were raiding their crops and trying to make off with machetes and other tools," it said.

FUNAI quickly sent experts to the Upper Envira River region in case the indigenous tribe wanted to make contact.

According to Science Now, there are at least 70 isolated tribes in the Brazilian Amazon, and many more in the broader rainforest. Most have already made some sort of contact with the outside world, mainly through rubber harvesters and mahogany loggers.

In fact, FUNAI officials think that this indigenous tribe -- whose language is still unknown -- fled mahogany loggers working illegally on protected lands in Peru, some 300 kilometers (ca. 186 miles) away from where they emerged. The loggers could have driven off the animals the tribe hunted, leaving them no choice but to migrate.

Whatever the reason they chose to emerge from the forest on June 29, the most important thing to do now, experts said, is to protect the tribe's members from contracting dangerous diseases they're not protected from, like the flu and whooping cough. The elderly and very young are most at risk.

Between 1983 and 1985, over half of another isolated population in the Peruvian Amazon died from illnesses they contracted from loggers, Science Now said.

From Discovery News

Cosmic Mystery Solved by Supersized Supernova Dust

How cosmic dust is created has been a mystery for some time. Although the textbooks tell us that the dusty stuff that builds the planets — and, ultimately, the complex chemistry that forms life (we are, after all, made of ‘star stuff’) — comes from supernova explosions, astronomers have been puzzled as to how delicate grains of dust condense from stellar material and how they can possibly survive the violent shock waves of the cataclysmic booms.

But now, with the help of a powerful ground-based telescope, astronomers have not only watched one of these supernova ‘dust factories’ in action, they’ve also discovered how the grains can withstand the violent supernova shock.

“The problem has been that even though dust grains composed of heavy elements would form in supernovae, the supernova explosion is so violent that the grains of dust may not survive,” said co-investigator Jens Hjorth, of the Niels Bohr Institute at the University of Copenhagen. “But cosmic grains of significant size do exist, so the mystery has been how they are formed and have survived the subsequent shockwaves.”

Like many astronomical studies, the road to discovery started with a huge stroke of luck. In 2010, a very bright supernova erupted in the nearby galaxy UGC 5189A. The supernova, called SN2010jl, signified the death of a massive star around 40 times the mass of our sun.

Researchers used a special spectrograph called the “X-shooter” attached to the Very Large Telescope (VLT) at the Paranal Observatory in northern Chile to zoom-in on the supernova and, over the following two and a half years, make 10 observations of the supernova aftermath. This work builds on previous observations of the famous supernova 1987A (SN 1987A) remnant made by the by the Atacama Large Millimeter/submillimeter Array (ALMA). These ALMA observations revealed a supernova remnant brimming with fresh dust — but little information about how the dust was formed could be deciphered.

By observing SN2010jl in visible and near-infrared wavelengths simultaneously with the VLT, the researchers were able to detect the absorption of light by newly-formed dust grains immediately after the explosion. These direct measurements of which wavelengths were absorbed by the dust revealed, for the first time, a timeline of how the dust is created by a supernova, the physical size of the dust particles and what material they are made of.

“Previously astronomers have seen plenty of dust in supernova remnants left over after the explosions,” said lead author Christa Gall, of Aarhus University, Denmark. “But they also only found evidence for small amounts of dust actually being created in the supernova explosions. These remarkable new observations explain how this apparent contradiction can be resolved.”

The VLT observations, which have been published in the journal Nature, show that dust formation starts soon after the supernova erupts and continues for a long period after the initial explosion. The researchers discovered that shortly before the main supernova explosion, the star blasts gases (rich in hydrogen, helium and carbon) into space, forming a dense shell around the star.

“When the star explodes, the shockwave hits the dense gas cloud like a brick wall,” said Gall. “It is all in gas form and incredibly hot, but when the eruption hits the ‘wall’ the gas gets compressed and cools down to about 2,000 degrees.

“At this temperature and density elements can nucleate and form solid particles. We measured dust grains as large as around one micron (a thousandth of a millimeter), which is large for cosmic dust grains. They are so large that they can survive their onward journey out into the galaxy.”

Read more at Discovery News

Jul 8, 2014

Long-Lost Iron Age Temple Unearthed in Iraq

Life-size human statues and column bases from a long-lost temple dedicated to a supreme god have been discovered in the Kurdistan region of northern Iraq.

The discoveries date back over 2,500 years to the Iron Age, a time period when several groups — such as the Urartians, Assyrians and Scythians — vied for supremacy over what is now northern Iraq.

"I didn't do excavation, just archaeological soundings —the villagers uncovered these materials accidentally," said Dlshad Marf Zamua, a doctoral student at Leiden University in the Netherlands, who began the fieldwork in 2005. The column bases were found in a single village while the other finds, including a bronze statuette of a wild goat, were found in a broad area south of where the borders of Iraq, Iran and Turkey intersect.

For part of the Iron Age, this area was under control of the city of Musasir, also called Ardini, Marf Zamua said. Ancient inscriptions have referred to Musasir as a "holy city founded in bedrock" and "the city of the raven."

"One of the best results of my fieldwork is the uncovered column bases of the long-lost temple of the city of Musasir, which was dedicated to the god Haldi," Marf Zamuatold Live Science in an email. Haldi was the supreme god of the kingdom of Urartu. His temple was so important that after the Assyrians looted it in 714 B.C., the Urartu king Rusa I was said to have ripped his crown off his head before killing himself.

He "threw himself on the ground, tore his clothes, and his arms hung limp. He ripped off his headband, pulled out his hair, pounded his chest with both hands, and threw himself flat on his face …" reads one ancient account (translation by Marc Van De Mieroop).

The location of the temple has long been a mystery, but with the discovery of the column bases, Marf Zamua thinks it can be narrowed down.

Additionally, Marf Zamua analyzed an ancient carving of Musasir, discovered in the 19th century at Khorsabad. The carving, he found, shows hillside houses with three windows on the second floor and a doorway on the ground floor. Such a design can still be seen today in some villages, the bottom floor being used as a stable and storage area, he noted.

This long-lost temple is just the tip of the archaeological iceberg. During his work in Kurdistan, Marf Zamua also found several life-size human statues that are up to 7.5 feet (2.3 meters) tall. Made of limestone, basalt or sandstone, some of these statues are now partly broken.

They all show bearded males, some of whom "are holding a cup in their right hands, and they put their left hands on their bellies," said Marf Zamua. "One of them holds a hand ax. Another one put on a dagger."

Originally erected above burials, the statues have a "sad moment" posture, Marf Zamua said. Similar statues can be found from central Asia to eastern Europe. "It is art and ritual of nomads/pastorals, especially when they their chieftains," Marf Zamua said.

Mostof the newfound statues date to the seventh or sixth century B.C., after Musasir fell to the Assyrians, and during a time when the Scythians and Cimmerians were advancing through the Middle East.

Over the past few weeks, conflict in Iraq has been increasing as a group called the "Islamic State in Iraq and the Levant" (ISIS) has taken several cities and threatened to march on Baghdad. The Kurdistan area, including this archaeological site, is autonomous, and its militia has been able to prevent ISIS from entering it.

Marf Zamuasaid there are risks associated with living and working in the border area. Due to the conflicts of the past few decades, there are numerous unexploded land mines, one of which killed a young shepherd a month back, he said. Additionally the National Iraqi News Agency reports that Iranian artillery recently fired onto the Iraqi side of the border, and there have been past instances where planes from Turkey have launched attacks into Iraqi Kurdistan.

Read more at Discovery News

Drought Spurs Interest in Water Dowsing

With much of the American southwest in one of the most severe droughts in history, more and more people are turning to the ancient art of water dowsing. Dowsers-for-hire are seeing booming business, hired by farmers, winemakers, and others to help locate new sources of water.

According to an NBC News story, “The ancient method of discovering water underground is finding new life in drought-ridden states such as California.”

Dowsing, also known as rhabdomancy, is a process in which people use a forked branch, pendulum, two L-shaped wires, or other devices to search for hidden or missing objects.

A forked twig is said to suddenly dip downward when over water, while a pendulum is said to swing a certain way, guiding the holder toward hidden water.

Though water dowsing is the best known type of dowsing, dowsers claim to find almost anything they search for, from missing persons to missing jewelry to deposits of oil and gold. Some dowsers even claim to be able to find things never proven to exist, such as ghosts.

Though the practice goes back many centuries, there is no scientific evidence that dowsing actually works. So why do so many people swear by it? The answer lies in statistics and psychology.

The first thing to understand about water dowsing is that dowsers are impressed at their success in finding something that is almost everywhere. Even during surface droughts, the hydrogeology in most parts of the world is such that if you dig deep enough you’ll find water in an underground aquifer just about anywhere.

From a dowser’s perspective it’s easy to see why they claim success: Of course dowsers are convinced of their ability, since they often find water. No one can claim 100 percent accuracy — not even advanced geological analysis can do that. So the occasional wrong predictions are dismissed as normal human fallibility, while the successes are attributed to special water-finding abilities of the dowser or their equipment.

Dowsers and their clients aren’t thinking about water-finding from a statistical point of view; they are more interested in the seemingly mystical, supernatural powers exhibited by swinging pendulums and bobbing twigs.

There are thousands of sincere dowsers who proudly rattle off their success stories to friends, family, and potential clients. Science, however, proves its theories through repeated, well-designed scientifically controlled tests, not personal stories and anecdotes.

The question is not, “Can dowsers find water?” — for they (and anyone else) certainly can — but instead “Can dowsers find water with any better accuracy than random chance?”

A more challenging feat would be for dowsers to consistently locate places where water cannot be found; or to compare their water witching accuracy with a non-dowser who is just guessing; or even use a random-number generator to pick places to drill for water so there is some basis for comparison.

Dowsers have been scientifically tested many times over the years, and have performed no better than chance under controlled conditions. In 1986, for example, university physicists in Munich, Germany, received a $250,000 grant to conduct a large-scale study of water dowsing.

In a review of the study published in Skeptical Inquirer science magazine, J.T. Enright, a professor of behavioral physiology at Scripps Institution of Oceanography, notes that “It is difficult to imagine a set of experimental results that would represent a more persuasive disproof of the ability of dowsers to do what they claim. The experiments thus can and should be considered a decisive failure by the dowsers.”

With some water dowsers charging hundreds of dollars in fees, landowners seeking water would do just as well to pick a convenient place to dig or drill and start there. They will probably find water, but even if they pay a dowser the worst-case scenario is wasted time and money.

A look at the history of dowsing reveals that centuries ago the consequences of bogus dowsing information was far more dire. In “The Book of Divination,” writer Ann Fiery notes that “Rhabdomancy was denounced as the work of the devil at various points in history, but it has been employed almost continuously in Europe since the Middle Ages… The French were… the chief innovators in its development as a policing tool.

In 1692, a peasant named Jacques Aymar used his divining rod to track down the murderers of a local wine merchant. His forked stick bobbed up and down dramatically at the murder site and then led Aymar through town, over the Rhone, and all the way up to Lyons, where he found a hunchback who confessed to taking part in the deed.”

Read more at Discovery News

Ancient Inner Ear Suggests Neanderthals Got Around

The remains of an ancient human in China not thought to be Neanderthal has an inner ear much like that of humans' closest extinct relatives, according to a new study. These new findings could be evidence of interbreeding between Neanderthals and other species of archaic humans in China.

However, the researchers say human evolution could be more complicated than is often thought, and the implications of the new discovery remain unclear.

Although modern humans are the only living members of the human family tree, a number of other human lineages once lived alongside the ancestors of modern humans. These so-called archaic humans included Neanderthals, the closest extinct relatives of modern humans, who lived in Eurasia roughly between 200,000 and 30,000 years ago.

To learn more about human evolution, scientists investigated a 100,000-year-old human skull known as Xujiayao 15, found 35 years ago in northern China alongside human teeth and bone fragments. At first, the researchers thought that the skull belonged to an archaic human. But they discovered that, anatomically, the skull — and the fossils discovered alongside it — had characteristics typical of a non-Neanderthal form of archaic human.

"It's clearly not modern human," said study co-author Erik Trinkaus, an anthropologist at Washington University in St. Louis.

However, micro-CT scans of the skull revealed an inner ear much like those seen in Neanderthals.

"We were very surprised," Trinkaus told Live Science. "I said, 'My God, it looks like a Neanderthal.'"

This image shows the Xujiayao 15 inner ear.
The inner ear, also known as the labyrinth, is located within the skull's temporal bone. It contains the cochlea, which converts sound waves into electrical signals that are transmitted via nerves to the brain, and the semicircular canals, which help people keep their balance as they move. These semicircular canals are often well-preserved in mammal skull fossils, the researchers said.

In the mid-1990s, CT scans revealed that nearly all Neanderthals possessed a specific arrangement of their semicircular canals. The pattern of semicircular canal sizes and positions seen in Neanderthals was often used to set them apart from both earlier and modern humans.

"We fully expected the scan to reveal a temporal labyrinth that looked much like a modern human one, but what we saw was clearly typical of a Neanderthal," Trinkaus said in a statement.

In comparison, none of the three other archaic human skulls they analyzed from different parts of China had this type of inner ear.

But while it is tempting to conclude that these findings demonstrate interbreeding between Neanderthals and archaic humans in China, Trinkaus and his colleagues suggested that the implications of the Xujiayao discovery remain unclear.

"You can't rely on one anatomical feature or one piece of DNA as the basis for sweeping assumptions about the migrations of hominid species from one place to another," Trinkaus said in a statement.

"What these findings say to me are that characteristics were probably more varied in ancient human populations than we think," Trinkaus said. "We see characteristics mix and match in populations across the world nowadays, and I believe that characteristics shuffled back and forth in ancient human populations across the landscape over centuries and millennia. The idea of distinct, separate lineages in this time period in human evolution is meaningless -- it was much more of a labyrinth than that."

Read more at Discovery News

Supermassive Black Hole Jet Mystery Solved

One of the most enduring mysteries behind the dynamics of supermassive black holes, and their impacts on galactic evolution, has been uncovered by an international team of astrophysicists.

Using the ESO’s Very Large Telescope (VLT), located in the Atacama desert in northern Chile, researchers from the UK, Netherlands and the US have studied the core of a nearby galaxy in great detail. The galaxy, called IC5063, has a very active central supermassive black hole that appears to drive rapid outflows of molecular hydrogen from the galaxy. IC5063 is known as a Seyfert galaxy, a very active type of galaxy with a bright core.

Many active galactic nuclei have been observed with these outflow features and, as molecular hydrogen is key to the formation of stars, astronomers have realized that its ejection impacts star formation and, therefore, galactic evolution. As the majority of galaxies are thought to contain supermassive behemoths in their cores, the activity of these black holes (that have masses of tens to hundreds of millions of suns) can control the quantity of gas supplied to star forming regions.

But how do black holes accelerate this cold hydrogen gas to hundreds of thousands of miles per hour? Until now, that has been hard to fathom.

From the VLT observations, astronomers headed by Clive Tadhunter of the University of Sheffield have found that the outflow is driven by jets of relativistic electrons, which are being ejected from the dynamic environment just outside the black hole’s event horizon. Whenever the highly energetic electrons blast through clouds of molecular hydrogen, the gas is transported out of the galaxy, starving it of star-forming material.

“Much of the gas in the outflows is in the form of molecular hydrogen, which is fragile in the sense that it is destroyed at relatively low energies,” said Tadhunter, who collaborated with researchers from the Netherlands Institute of Radio Astronomy and the Center for Astrophysics, Harvard. “It is extraordinary that the molecular gas can survive being accelerated by jets of electrons moving at close to the speed of light.”

The research has been published in the journal Nature.

Read more at Discovery News

Jul 7, 2014

Some Bees Shout 'That Nectar's Ours!'

Imagine you're a bee and you just located a prime nectar source. You want to alert your hivemates, but not attract competitors. What should you do?

Some bees devise a special "whisper" to discretely let bees in their colony know about a food source, but others, new research has shown, "shout" it out loud with a message along the lines of, "This is good nectar and it's all ours or -- watch out!"

In the case of bees, the insects aren't actually shouting, but signalling to each other and outside bees using information-rich pheromone trails.

"It tells nestmates where to find good food and hints at a larger occupying force," explained Elinor Lichtenberg in a press release. Lichtenberg, a postdoctoral researcher at Washington State University, focused on species of singless Brazilian bees for her paper in the journal Current Biology.

The finding, she says, demonstrates how eavesdropping competitors can alter the evolution of animal signals -- even in unexpected ways.

"Our study provides a new way of looking at how eavesdroppers affect the evolution of animal communication signals," she said. "Until now, it was thought that eavesdroppers select against conspicuous signals, for example by more easily finding and eating prey that sings loudly. But our results show that eavesdroppers can help select for the same conspicuous signals that are easiest for intended recipients to detect and understand."

The hunt for good nectar can become fiercely competitive between some bee colonies, requiring bee species to develop critical communication strategies.

Among the Brazilian bees analyzed for the research, the bee species Trigona hyalinata is known to spy on species of Trigona spinipes bees to detect good foraging spots. But invading the other bees' nectar source can come at a price.

If individuals can recruit enough of their colony mates, then honing in on Trigona spinipes' source can be a good bet. But if they only manage to rally a small group of their colony mates to a competitor’s source, they're likely to lose out to the other bees, or, worse, die fighting for it.

Read more at Discovery News

Biggest-Ever Flying Bird Soared With 20-Foot Wingspan

The world’s largest-ever flying bird has just been identified, according to scientists who say the bird’s wingspan was about 24 feet long, which is around the same length as a dance floor suitable for 160 people.

The long-extinct bird, named Pelagornis sandersi in honor of retired Charleston Museum curator Albert Sanders, was appropriately unearthed at what is now the site of the Charleston International Airport. This literal big bird, described in the latest issue of the Proceedings of the National Academy of Sciences, took off from the site in Charleston, S.C., 25 to 28 million years ago.

Its fossils were so big that some of them had to be dug out with a backhoe.

“The upper wing bone alone was longer than my arm,” co-author Dan Ksepka, curator of science at the Bruce Museum in Greenwich, Conn., said in a press release.

Ksepka and his team believe that Pelagornis sandersi was twice as big as the largest flying bird alive today: the royal albatross. It also pushes the current record holder for largest flying bird ever to fly the skies, Argentavis magnificens, into second place.

Analysis of P. sandersi’s remains strongly suggest that it could fly.

The enormous bird had paper-thin hollow bones, stumpy legs and giant wings that would have made it at home in the air, but awkward on land, according to the researchers. They believe its impressive wings would have allowed for efficient gliding.

But how could such a bird have taken off? Its wings were too big to flap and generate lift from a standing position. The wings would have just hit the ground with a thud.

Ksepka and his team created computer simulations and determined that the bird probably ran downhill into a headwind or took advantage of air gusts to get aloft, similar to what hang gliders do.

Once airborne, it must have been quite a sight. Riding on air currents that rise from the ocean’s surface, the big bird could have soared for miles over the open ocean without flapping its wings. It hunted marine life, so it must have occasionally swooped down to the water to feed on soft-bodied prey like squid and eels, according to the new study.

“That’s important in the ocean, where food is patchy,” said Ksepka.

Read more at Discovery News

Sahara Desert Dust Blows Across Atlantic to Americas

If you’re sneezing right now, the cause may on the other side of the planet. In late June, winds began blowing what NASA describes as a “river of dust” from Africa across the Atlantic Ocean to North and South America.

Because of thermal expansion of the atmosphere around the equator, sand and dirt grains are suspended thousands of feet in the air, as a wind carries them westward.

Though Florida usually gets the heaviest dose of African dust, this year the dust seems to be spreading over a much wider swath of the south and southwest, according to Garrett Lewis, a meteorologist at TV News 5 in Fort Smith/Fayettsville, Ark.

A study published in the Journal Environmental Science and Technology in 2008 found that the Saharan dust plume had the ability to double the atmospheric dust in Houston.

Dust events of this sort, which occur every year, can be a problem if you’re an asthmatic or have respiratory problems. But the dust also can have some beneficial effects.

University of Miami researchers note that the suspended dust absorbs and scatters solar radiation over the tropical Atlantic, which can result in cooler ocean temperatures. That, in turn, may reduce the amount of energy available for hurricanes to form and strengthen.

Additionally, the dust itself has value. Each year, about 40 million tons of Saharan dust ends up descending upon the Amazon River Basin, where it replenishes nutrients in the rainforest that have become depleted by tropical rains. The Everglades also has been fertilized for thousands of years by African dust as well.

Read more at Discovery News

Cassini Grand Finale: Saturn Mission's Daring End

Like all good things, epic space missions must come to an end. But in the case of NASA’s Cassini mission around Saturn, it’s going to end in dramatic style.

After a decade in orbit around the ringed gas giant Cassini has revolutionized our understanding of Saturn’s rings, moons and dynamic atmosphere. It’s even put Earth in its place, as a tiny blue dot in the vast expanse of space.

Sadly, Cassini can’t soldier on forever; it will run out of fuel (used by its thrusters for adjustments during orbit) — but that’s not necessarily a bad thing.

Until now, mission managers have tried to protect the spacecraft from any orbital risks in the interest of prolonging Cassini’s life, but as the mission is now coming to a close, they can afford to be a little less careful while looking for awesome science opportunities. Starting in 2016, Cassini will be commanded to carry out a “daring set of orbits that is, in some ways, like a whole new mission,” writes NASA in a recent news release.

Known as “proximal orbits,” the spacecraft will fly high above Saturn’s poles and then fly outside the planet’s narrow F-ring. This orbital path will take it past the icy moon Enceladus, allowing another passage through the moon’s fascinating water-rich plumes that blast into space.

Then, its trajectory will evolve to make a dive between the innermost ring and the planet 22 times. Flying through the ring plane will increase the potential for impacts with ring dust, ice grains and even large rocks, so until now such an orbital profile has been avoided at all costs.

What happens next? Well, assuming it doesn’t hit anything in the meantime, to avoid an end-of-mission collision with Titan or Enceladus — two Saturnian moons with biological potential that scientists do not want to contaminate with any hardy Earth-borne bacteria that may be hitching a ride on the probe — Cassini will plunge into Saturn’s atmosphere, burning up in a fiery final act.

Now that the mission is entering a very final and distinct phase of its decade-long Saturn odyssey, NASA has asked for mission-naming ideas. After the Cassini’s primary mission, it was renamed “Cassini Equinox” (2008) then “Cassini Solstice” (2010) after each mission extension, which related to the changing seasons on Saturn. Now, after considering suggestions from 2,000 members of the public, this final act will be known as the “Cassini Grand Finale.”

Read more at Discovery News

Jul 6, 2014

Who is responsible for climate change?

Calculating the cumulative cost of carbon dioxide emissions gives new insights into the question of who is responsible for climate change.

One of the major reasons for the failure of the 2009 Climate Convention Conference in Copenhagen was the issue of carbon debt. Developed countries called for emission reductions in developing countries, while the latter use the former's historical emissions, their carbon debt, as a reason for inaction. An article recently published in Scandinavian Economic History Review suggests how to finally settle this question of historical responsibility.

Jan Kunnas from the University of Stirling and his colleagues from universities in the UK and New Zealand examined how to incorporate the environmental effects of fossil fuel use into the national accounts and measures of sustainability. They suggest using a single global price for carbon dioxide emissions, as there is in the long term no possibility for a single country to isolate itself from the impacts of climate change. Every country will be affected to some degree, say from increases in food prices as climate change has negative impacts on global food production or from climate refugees. Ethically speaking, the use of a global damage cost indicates a belief that we are all in the same lifeboat when it comes to the long-term effects of climate change. Furthermore, the calculated price should decrease as we move back in time to take into account that carbon dioxide is a stock pollutant, and that one unit added to the present large stock is likely to cause more damage than a unit emitted under the lower concentration levels in the past.

There is a large variation between different estimates of the costs of carbon dioxide emissions, depending on the estimates of future mitigation or a business as usual approach and the damage the estimated emission path will lead to. To account for this variation a low, medium and high price was used to calculate the annual costs of carbon dioxide emissions. This shows how much lower annual GDP would be, if future generations bearing the costs of climate change could demand compensation for this externality. In Britain the costs of carbon dioxide as a share of GDP peaked at the eve of the first oil crisis in 1971 between 0.3% and 4.3% depending on the price used, and in the USA between 0.4% and 5.4% of GDP.

The annual effects of carbon dioxide might be small, but the cumulative effects are not. For Britain the cumulative effects from 1800 to 2000 range from £100 to £1400 billion, and for the USA from $960 to $13,600 billion (in 2000 prices). In other words at most the cumulative carbon debt exceeds, the annual GDP, which in 2000 were £916 billion in the UK and $9951 billion in the USA.

Calculating the cumulative cost of carbon dioxide emissions provides us an opportunity to finally settle the question of historical responsibility for the damages caused by climate change. The choice of price has a big influence on the accumulated costs, but it does not affect the relative position of different countries. With both a constant price and a declining price the USA has the highest cumulative cost of carbon emissions during the period 1902 -- 2009, contributing 24-27% of the cumulative global cost, followed by the EU with 17-19%. China is nowadays the biggest source of carbon dioxide, but the cumulative costs of its emissions are still long behind with 10-12%.

Read more at Science Daily

From pencil marks to quantum computers

One of the hottest materials in condensed matter research today is graphene.

Graphene had an unlikely start: it began with researchers messing around with pencil marks on paper. Pencil "lead" is actually made of graphite, which is a soft crystal lattice made of nothing but carbon atoms. When pencils deposit that graphite on paper, the lattice is laid down in thin sheets. By pulling that lattice apart into thinner sheets -- originally using Scotch tape -- researchers discovered that they could make flakes of crystal just one atom thick.

The name for this atom-scale chicken wire is graphene. Those folks with the Scotch tape, Andre Geim and Konstantin Novoselov, won the 2010 Nobel Prize for discovering it. "As a material, it is completely new -- not only the thinnest ever but also the strongest," wrote the Nobel committee. "As a conductor of electricity, it performs as well as copper. As a conductor of heat, it outperforms all other known materials. It is almost completely transparent, yet so dense that not even helium, the smallest gas atom, can pass through it."

Developing a theoretical model of graphene

Graphene is not just a practical wonder -- it's also a wonderland for theorists. Confined to the two-dimensional surface of the graphene, the electrons behave strangely. All kinds of new phenomena can be seen, and new ideas can be tested. Testing new ideas in graphene is exactly what Perimeter researchers Zlatko Papić and Dmitry (Dima) Abanin set out to do.

"Dima and I started working on graphene a very long time ago," says Papić. "We first met in 2009 at a conference in Sweden. I was a grad student and Dima was in the first year of his postdoc, I think."

The two young scientists got to talking about what new physics they might be able to observe in the strange new material when it is exposed to a strong magnetic field.

"We decided we wanted to model the material," says Papić. They've been working on their theoretical model of graphene, on and off, ever since. The two are now both at Perimeter Institute, where Papić is a postdoctoral researcher and Abanin is a faculty member. They are both cross-appointed with the Institute for Quantum Computing (IQC) at the University of Waterloo.

In January 2014, they published a paper in Physical Review Letters (PRL) presenting new ideas about how to induce a strange but interesting state in graphene -- one where it appears as if particles inside it have a fraction of an electron's charge.

It's called the fractional quantum Hall effect (FQHE), and it's head turning. Like the speed of light or Planck's constant, the charge of the electron is a fixed point in the disorienting quantum universe.

Every system in the universe carries whole multiples of a single electron's charge. When the FQHE was first discovered in the 1980s, condensed matter physicists quickly worked out that the fractionally charged "particles" inside their semiconductors were actually quasiparticles -- that is, emergent collective behaviours of the system that imitate particles.

Graphene is an ideal material in which to study the FQHE. "Because it's just one atom thick, you have direct access to the surface," says Papić. "In semiconductors, where FQHE was first observed, the gas of electrons that create this effect are buried deep inside the material. They're hard to access and manipulate. But with graphene you can imagine manipulating these states much more easily."

In the January paper, Abanin and Papić reported novel types of FQHE states that could arise in bilayer graphene -- that is, in two sheets of graphene laid one on top of another -- when it is placed in a strong perpendicular magnetic field. In an earlier work from 2012, they argued that applying an electric field across the surface of bilayer graphene could offer a unique experimental knob to induce transitions between FQHE states. Combining the two effects, they argued, would be an ideal way to look at special FQHE states and the transitions between them.

Experimental tests

Two experimental groups -- one in Geneva, involving Abanin, and one at Columbia, involving both Abanin and Papić -- have since put the electric field + magnetic field method to good use. The paper by the Columbia group appears in the July 4 issue of Science. A third group, led by Amir Yacoby of Harvard, is doing closely related work.

"We often work hand in hand with experimentalists," says Papić. "One of the reasons I like condensed matter is that often even the most sophisticated, cutting-edge theory stands a good chance of being quickly checked with experiment."

Inside both the magnetic and electric field, the electrical resistance of the graphene demonstrates the strange behaviour characteristic of the FQHE. Instead of resistance that varies in a smooth curve with voltage, resistance jumps suddenly from one level to another, and then plateaus -- a kind of staircase of resistance. Each stair step is a different state of matter, defined by the complex quantum tangle of charges, spins, and other properties inside the graphene.

"The number of states is quite rich," says Papić. "We're very interested in bilayer graphene because of the number of states we are detecting and because we have these mechanisms -- like tuning the electric field -- to study how these states are interrelated, and what happens when the material changes from one state to another."

For the moment, researchers are particularly interested in the stair steps whose "height" is described by a fraction with an even denominator. That's because the quasiparticles in that state are expected to have an unusual property.

There are two kinds of particles in our three-dimensional world: fermions (such as electrons), where two identical particles can't occupy one state, and bosons (such as photons), where two identical particles actually want to occupy one state. In three dimensions, fermions are fermions and bosons are bosons, and never the twain shall meet.

But a sheet of graphene doesn't have three dimensions -- it has two. It's effectively a tiny two-dimensional universe, and in that universe, new phenomena can occur. For one thing, fermions and bosons can meet halfway -- becoming anyons, which can be anywhere in between fermions and bosons. The quasiparticles in these special stair-step states are expected to be anyons.

In particular, the researchers are hoping these quasiparticles will be non-Abelian anyons, as their theory indicates they should be. That would be exciting because non-Abelian anyons can be used in the making of qubits.

Read more at Science Daily