Mar 16, 2013

How Can We Stlil Raed Words Wehn Teh Lettres Are Jmbuled Up?

Researchers in the UK have taken an important step towards understanding how the human brain 'decodes' letters on a page to read a word. The work, funded by the Economic and Social Research Council (ESRC), will help psychologists unravel the subtle thinking mechanisms involved in reading, and could provide solutions for helping people who find it difficult to read, for example in conditions such as dyslexia.

In order to read successfully, readers need not only to identify the letters in words, but also to accurately code the positions of those letters, so that they can distinguish words like CAT and ACT. At the same time, however, it's clear that raeders can dael wtih wodrs in wihch not all teh leettrs aer in thier corerct psotiions.

"How the brain can make sense of some jumbled sequences of letters but not others is a key question that psychologists need to answer to understand the code that the brain uses when reading," says Professor Colin Davis of Royal Holloway, University of London, who led the research.

For many years researchers have used a standard psychological test to try to work out which sequences of letters in a word are important cues that the brain uses, where jumbled words are flashed momentarily on a screen to see if they help the brain to recognise the properly spelt word.

But, this technique had limitations that made it impossible to probe more extreme rearrangements of sequences of letters. Professor Davis's team used computer simulations to work out that a simple modification to the test would allow it to question these more complex changes to words. This increases the test's sensitivity significantly and makes it far more valuable for comparing different coding theories.

"For example, if we take the word VACATION and change it to AVACITNO, previously the test would not tell us if the brain recognises it as VACATION because other words such as AVOCADO or AVIATION might start popping into the person's head," says Professor Davis. "With our modification we can show that indeed the brain does relate AVACITNO to VACATION, and this starts to give us much more of an insight into the nature of the code that the brain is using -- something that was not possible with the existing test."

The modified test should allow researchers not only to crack the code that the brain uses to make sense of strings of letters, but also to examine differences between individuals -- how a 'good' reader decodes letter sequences compared with someone who finds reading difficult.

Read more at Science Daily

Bat-Eating Spiders Are Everywhere

There's only one place in the world to escape bat-catching spiders: Antarctica. These arachnids ensnare and pounce on bats everywhere else in the world, researchers say.

Bats rank among the most successful groups of mammals, with the more than 1,200 species of bats comprising about one-fifth of all mammal species. Other than owls, hawks and snakes, bats have few natural enemies.

Still, invertebrates — creatures without backbones — have been known to dine on bats. For instance, giant centipedes in a cave in Venezuela were seen killing and eating bats, and the arachnids known as whip spiders were spotted feeding on dead bats in caves of the Caribbean. Cockroaches have been observed feeding on bat pups that have fallen to the floor of caves.

Spider-eat-bat world

Accidental deaths of bats in spiderwebs were known as well, but were thought to happen very rarely. Still, spiders are known to occasionally dine on a variety of vertebrates — creatures with backbones. For instance, fishing spiders capture and devour fish and frogs; some species of wolf spiders, huntsman spiders, tarantulas and related spiders have been seen killing and eating frogs and lizards; and tarantulas and comb-footed spiders have apparently fed on snakes and mice. There are also numerous reports of spiders killing other flying vertebrates, snagging birds with large orb webs.

Recent studies of a web-building spider species (Argiope savignyi) and a tarantula species (Poecilotheria rufilata) both killing small bats led researchers to suggest that bat captures and kills due to spiders might be more frequent than previously thought. So they analyzed 100 years' worth of scientific reports, interviews of bat and spider researchers and the staff of bat hospitals, and scans of image and video sites. The search revealed 52 cases of bat-catching spiders worldwide.

Giant webs

Approximately 90 percent of known bat-catching spiders live in the warmer areas of the globe, in the third of the Earth surrounding the equator. About 40 percent live in the neotropics — the whole of South America, and the tropical regions of North America — while nearly a third live in Asia and more than a sixth live in Australia and Papua New Guinea.

Eighty-eight percent of the reported cases of bat catches were due to web-building spiders, with giant tropical orb-weaving spiders with a leg-span of 4 to 6 inches (10 to 15 centimeters) seen catching bats in huge, strong orb-webs up to 5 feet (1.5 meters) wide.

In instances seen in Costa Rica and Panama, the spiders had built their webs near buildings inhabited by bat colonies. Bat-catching via spiderwebs was also witnessed particularly often in the parks and forests of the greater Hong Kong area. Future research may investigate whether the huge webs that sometimes block the entrances of tropical bat caves in east and southeast Asia and the neotropics may occasionally snag any members of the giant swarms of bats that emerge from the caves at night.

The other 12 percent of cases of spider kills of bats were from spiders that hunt without webs. For instance, tarantulas were seen eating small bats in tropical rainforests in Peru and eastern Ecuador and on the forest floor in northeastern Brazil. A reddish parachute tarantula (Poecilotheria rufilata) was also seen predating on a small bat in Kerala, India, while a huntsman spider (Heteropoda venatoria) was observed capturing and killing a small bat in a shed near Kolkata, India. An attempt by a large fishing spider (Dolomedes triton) to kill a bat pup was also witnessed below a bridge in Indiana.

The victims

Most bat prey of spiders are small or juvenile insect-eating bats, and usually are among the most common bat species of their areas. Bats entangled in webs were usually 4 to 9.5 inches (10 to 24 cm) in wingspan, including some of the smallest species of bats in the world, and they sometimes died of exhaustion, starvation, dehydration or overheating — but there were many cases where spiders were seen actively attacking, killing and eating these victims.

Bats are likely capable of detecting spiderwebs via echolocation, their biological sonar. Even if bats do collide with spiderwebs, only the strongest traps are likely capable of withstanding the energy of such an impact without breaking. As such, bat captures are likely rare.

Read more at Discovery News

Mar 15, 2013

New Pope: It's Francis, Not Francis I

The new pope should be called Francis, not Francis I, the Vatican clarified yesterday.

Father Federico Lombardi, the Vatican spokesperson, remarked that the new pontiff was presented to the world with these Latin words: “Cardinalem Bergoglio, qui sibi nomen imposuit Franciscum ” (Cardinal Bergoglio, who takes for himself the name of Francis).

The word “Primum” (the first), wasn’t added.

“It will remain Francis until a successor calls himself Francis II,” Lombardi said.

Bergoglio’s decision to become the first pope ever to be known by the name Francis is almost unprecedented.

Before him, the last pope to assume a name which wasn’t already used by his predecessors was Landus (913–914). He reigned only six months during the period known as the saeculum obscurum (the dark age) when the papacy was in complete decline.

More recently, Albino Luciani combined two familiar names for popes, making the unused name of John Paul I for what would be a short-lived, 33-day papacy in 1978.

He was the first pontiff to intentionally add “the first” to his name — a move that was considered a formal error.

Until the first millennium, popes were called by their first plain names. An exception was the 6th century Mercurius, who was the first to pick a papal name. Rather than taking the papacy with the unappropriate name of a pagan god, he chose the name John II.

But the ordinal numbers weren’t added to his name. The custom was that a second pope of the same name was called by the term junior and the third, if there were three, secundus junior. Thus, Pope Gregory II was known as Pope Gregory, Jr., while Pope Gregory III as Pope Gregory Secundus, Jr.

As the system was too confusing, in the eighth century, an ordinal number was appended to the pope’s name. Ordinal numbers became common only under Leo IX (1049–54) papacy.

Even today, the ordinal number is omitted in the solemn papal signature.

Since the 11th century, only two popes — Julius II (1503-13) and Hadrian VI (1522-23) — have refrained from changing their names.

John remains the most popular papal name in the history of the Catholic Church, followed by Gregory, Benedict, Clement, Innocent, Leo, and Pius.

Apart from Landus, John Paul I and Francis, other popes may have wished to pick a unique name, but their choice was considered incongruous or unappropriate.

It is said that John Paul II, born with the name Karol Wojtyla, had initially chosen the name Stanislaw, out of respect for the patron saint of his native Poland. The cardinals would have dissuaded him, as the name did not belong to the Roman tradition.

In other cases, the chosen name, even if was previously used, wasn’t just considered appropriate.

The vain Pietro Balbo, who became Paul II, wished to adopt the name Formosus II for his election in 1417. Meaning “beautiful” in Latin, the name wasn’t however the best one to invoke as it would have reminded the so-called Cadaver Synod, where Pope Formosus I, exhumed nearly a year after his death, was put on trial by his successor Stephen VI.

The rotting corpse, clothed with the pontifical vestments, was seated in the papal throne, put on trial and condemned. Three of his fingers were ripped off and he was tossed into the Tiber river. Retrieved by a monk, Formosus’ body was reinterred in St Peter’s Basilica at the death of Stephen VI.

The last pontiff to shock the church was John XXIII (1958-63), the “Good Pope.” In chosing his name, he went back to the Middle Ages. Many of the previous Johns had been disreputable, and it wasn’t even clear how many of them there had been.

Read more at Discovery News

Black Death Skeletons Unearthed by Crossrail Workers

Thirteen skeletons thought to be victims of the Black Death plague which swept Britain over 600 years ago have been dug up by workers on the £15 billion Crossrail project in London, archaeologists said Friday.

Up to 50,000 people may have been buried at the site in Charterhouse Square in Farringdon if it proves to be the location of a plague cemetery mentioned in ancient records.

The records refer to a burial ground in the Farringdon area that opened during the Black Death in 1348.

Over the past two weeks, the archaeologists have uncovered 13 skeletons in two carefully laid out rows 2.5 metres below the road that surrounds the gardens in Charterhouse Square.

"The depth of burials, the pottery found with the skeletons and the way the skeletons have been set out all point towards this being part of the 14th century emergency burial ground," said Jay Carver, Crossrail's lead archaeologist.

"This is a highly significant discovery and at the moment we are left with many questions that we hope to answer," he said.

"We will be undertaking scientific tests on the skeletons over the coming months to establish their cause of death, whether they were plague victims from the 14th century or later London residents, how old they were and perhaps evidence of who they were," Carver added.

The skeletons are being carefully excavated and taken to the Museum of London Archaeology for laboratory testing.

The scientists are hoping to map the DNA signature of the plague which could help uncover the cause of the Black Death.

The bones may also be radio carbon-dated to try and establish the burial dates.

These are not the first skeletons found on the Crossrail project, with archaeologists already having uncovered more than 300 at the New Cemetery near the site of the Bedlam Hospital at Liverpool Street from the 1500s to 1700s.

Read more at Discovery News

Medieval Knight's Tomb Found Under Parking Lot

A medieval headstone and skeleton have been found underneath a parking lot in Scotland, and researchers believe they might belong to a knight.

Archaeologists who were on hand during the construction of a new building in Edinburgh uncovered a carved sandstone slab, decorated with markers of nobility -- a Calvary cross and a sword. Nearby, the team found an adult skeleton, which is thought to have once occupied the grave. Scientists plan to analyze the bones and teeth to learn more about this possible knight or nobleman.

"We hope to find out more about the person buried in the tomb once we remove the headstone and get to the remains underneath, but our archaeologists have already dated the gravestone to the thirteenth century," Richard Lewis, a member of the City of Edinburgh Council, said in a statement.

"This find has the potential to be one of the most significant and exciting archaeological discoveries in the city for many years, providing us with yet more clues as to what life was like in medieval Edinburgh."

Builders at the site expected they would find historic objects during construction. Before it became a parking lot (coincidentally, once used by the University of Edinburgh's archaeology department), the site housed the 17th-century Royal High School, the 16th-century Old High School, and the 13th-century Blackfriars Monastery, researchers said. Archaeologists also apparently uncovered some medieval remains of the monastery, which had been destroyed and somewhat lost since the Protestant Reformation in the 16th century.

"We always knew that the building retrofit might uncover historical artifacts — given the site's history — but this knight is an extraordinary and exciting find," said Andy Kerr, director of the Edinburgh Center for Carbon Innovation, which is undertaking the construction at the site.

Read more at Discovery News

What Is A Sinkhole?

Following the tragic death of a Florida man who was swallowed by the Earth in his sleep, the geologic phenomena of sinkholes has gained a great deal of national attention. But what are they, exactly?

The U.S. Geological Survey classifies three types of sinkholes. The scariest is the type that killed Jeff Bush as it opened up under his bedroom: a cover-collapse sinkhole, where the surface sediment is mostly clay and remains intact as the bedrock and lower levels of the clay are dissolved beneath it. In these situations, a sinkhole can form suddenly and catastrophically over the course of a few hours, with little to no earlier signs of danger.

Two aspects of the geology are important in identifying sinkhole risk: bedrock and surface sediment.

If the bedrock is one of two types, or rock that can be easily dissolved by groundwater, then what type of surface sediment above it is critical in evaluating risk.

Bedrocks made of salt, gypsum and anhydrite are known as evaporates, whereas bedrock made of limestone and dolomite are known as carbonates. Evaporates dissolve easily because they were originally formed from minerals precipitating out of solution during periods of drought. Adding groundwater then puts the minerals back into solution, eroding the bedrock and leaving divots, cavities and even chasms of space for the surface sediment to fall into and fill.

Carbonates are especially vulnerable to acidic groundwater the same way that oyster and other seashells are vulnerable to ocean acidification. In this case, we can blame carbon pollution.

Increasing carbon dioxide in the atmosphere leads to rainwater containing higher levels of carbon dioxide, otherwise known as acid rain. When carbon dioxide in water is given a carbonate ion, it prefers to make bicarbonate ions rather than staying happily in the water minding its own business. Any rock or shell made of carbonate then becomes more at risk of dissolution as the ocean and rainwater become more acidic, much like tooth enamel dissolves away when soaked in a glass of soda pop.

Once the bedrock starts to dissolve and erode away, the type of surface sediment makes the difference as to whether the sinkhole will be catastrophic or not.

If little to no surface sediment covers the bedrock, for example, then the consequence is likely to be noticed immediately as the hole first begins forming; usually because drainage patterns in the area change. Rainwater that used to wash away will begin to collect, forming ponds and wetlands. This type of sinkhole is a called a dissolution sinkhole.

In cases where the bedrock is overlaid with sand or another type of permeable layer, the surface will collapse at the same time as the hole is forming. Like sands in an hourglass, the surface will fall in to fill the opening as it is made in the bedrock. This type of sinkhole is called a cover-subsidence sinkhole.

Read more at Discovery News

Have TED Talks Jumped the Shark?

TED is a nonprofit organization devoted to the dissemination of, as their slogan says,  “Ideas Worth Spreading.” Supported by many prominent thinkers, scientists, and entrepreneurs including Bill Gates, evolutionary biologist Steven Pinker, and philosopher Daniel Dennett, TED began in 1984 as a collaboration between thinkers from three enterprises — technology, entertainment, and design — and has since broadened its scope globally.

“The two annual TED conferences, on the North American West Coast and in Edinburgh, Scotland, bring together the world’s most fascinating thinkers and doers,” according to the website, “who are challenged to give the talk of their lives.”

TED talks have been popular for years, highlighting interesting and thought-provoking speakers on a wide variety of social and scientific issues. However, TED has increasingly come under fire for promoting pseudoscience and misinformation.

A spin-off department of TED, TEDx, licenses individuals across the country and around the world to stage similar events, record the talks on video, and submit the videos to TED for inclusion on their website. As TED and TEDx talks became more and more popular, the standards began slipping.

Bad Science

One notorious series of TEDx talks in Spain invited speakers to discuss a long list of conspiracy and New Age topics such as “Basic Mind Control,” rebirthing therapy, “Angelic Reiki,” and even something called “Egyptian Psycho-Aromatherapy and Transpersonal Homeotherapy.”

This list of pseudoscience apparently did not set off any red flags for TEDx organizers at the time, but it did for scientists and journalists who demanded to know why these were considered to be “ideas worth spreading.”

Concerns that the once-prestigious TED brand was being diluted and contaminated by sloppy scholarship and bad science grew so loud that in December 2012, TED representatives issued a letter to TEDx affiliates about it.

The letter noted that as “TEDx organizers, your audience’s trust is your top priority, over and above any other personal or business relationship that may have brought this speaker to your attention. It is not your audience’s job to figure out if a speaker is offering legitimate science or not. It is your job. 

The consequence of bad science and health hoaxes are not trivial. As an example, Andrew Wakefield’s attempt to link autism and vaccines was exposed as a hoax last year. But while his work was being investigated, millions of children went without vaccines, and many contracted deadly illnesses as a result. We take this seriously. Presenting bad science on the TEDx stage is grounds for revoking your license.”

It went on to offer an excellent discussion about how to tell good science from pseudoscience.

Noted astronomer and former TEDx speaker Phil Plait recently addressed the issue in a Slate column: “It’s simply not possible to be an expert in every field of science, so guidelines are needed. The letter gives excellent advice to people on being skeptical in the first place, and then follows up with actual research to back up that skepticism. This letter is a gold-star winner in how to communicate skepticism. It applies equally well to those well-versed in it and to those who may not have any experience in pseudoscientific fluffery. While it’s directed at TEDx organizers, it should be required reading for everybody.”

It seems that not everyone got the memo, however, because another TEDx speaker was recently called out for promoting bad science. This time it was a talk by a man named Rupert Sheldrake, a British biochemist who has written several books about telepathic dogs, crystal healing and other paranormal phenomena.

In a TEDx talk, Sheldrake discussed what he sees as dogmatism in science, scientists’ irrational devotion to materialism and his belief in what he calls “morphic resonance,” an unknown force that he claims somehow molds the collective unconscious of all members of a species.

Sheldrake made several factual errors in his talk, including stating that governments do not fund research into alternative medicine — in fact the National Institutes of Health have spent millions of dollars on it – a fact easily checked on the NIH website — and that the speed of light has decreased since the 1920s, a statement dismissed by best-selling author and physicist Sean Carroll of the Moore Center for Theoretical Cosmology and Physics at Caltech.

The TED editors responded: “While TED does not vet speakers at independent TEDx events, a TEDx talk can be removed from the TEDx archive if the ideas contained in it are wrong to the point of being unscientific, and that includes misrepresenting the scientific process itself. 

Sheldrake is on that line, to some commenters around Twitter and the web.”

Read more at Discovery News

Mar 14, 2013

Birds May Have Flown Like Four-Winged Kittyhawk

The world's first birds all had four wings -- not two -- and flew with a similar construction to the Wright Brothers' Kitty Hawk plane, contends new research led by the renowned dinosaur and early avian hunter Xing Xu.

Xu, a paleontologist at the Chinese Academy of Sciences, and his team suggest this perhaps might be the simplest form of flight, as even the Wright brothers' first experiments with flight were done with a biplane in 1903.

As for how this system in birds evolved, Xu told Discovery News, "The first birds descended from four-winged dinosaurs, which are not necessarily gliders in the strictest sense."

One such dinosaur might have been Microraptor, a non-avian dino that had feathers on both its arms and legs. Paleontologists believe it could fly.

The researchers studied well-preserved fossils of 11 birds from at least four diverse groups dating from about 150 to 100 million years ago. All of the birds were found in the Jehol formation in Liaoning, northeastern China.

The ancient birds were found to have clumps of stiff leg feathers that resemble wings. Xu and his colleagues believe these were, in fact, wings, according to the study, published in the journal Science. He said they "either provided lift, or created drag, or enhanced maneuverability or a combination of all of these functions."

Xu explained that the earliest birds were primarily arboreal, so they would have flown from trees instead of taking off from the ground or water, as today’s birds often do, depending on the species.

This could help to explain why birds lost the extra “wing” leg feathers over time, evolving the two-winged anatomy of today.

Xu said that this loss happened “primarily because of the evolution of two different locomotion systems in birds -- arm wings for flight and legs for walking and running.”

He added that the shift from a tree habitat to ground and water ones would have also favored the loss of the leg feathers.

Sankar Chatterjee, a paleontologist at Texas Tech University, told Michael Balter of Science that the new study makes it clear that "the four-wing form was exhibited not just by Microraptor, but also retained …in successive lineages of early birds."

Kevin Padian, a paleontologist at the University of California at Berkeley, also agrees that the research establishes that leg feathers were widely distributed, but he remains skeptical that the leg feathers were, in fact, used for flight.

Read more at Discovery News

Physicists Hunt Weird Antimatter Within Earth

Scientists have tentatively identified several particles lurking deep inside the Earth's mantle that could reveal how much heat the planet produces and confirm that the Earth formed from materials from the sun.

The wacky particles are called geoneutrinos, or the antimatter partners of neutrinos (exotic fundamental particles that can pass right through Earth), that form deep within the Earth's mantle. Every matter particle has an antimatter partner particle that has an opposite charge, and when the two meet they annihilate each other. The findings were detailed described March 11 in the preprint journal

Geoneutrinos aren't the only particles scientists are hoping to find inside Earth. An experiment using the Earth as a source of electrons recently narrowed down the search for a new force-bearing particle, possibly the so-called unparticle, placing tighter limits on the force it carries.

Giant Engine

When Earth formed, the radioactive elements thorium and uranium were distributed in Earth's interior at different concentrations within the crust (the planet's outer layer) and mantle. As these elements within the mantle radioactively decay, they give off heat and also form subatomic particles known as geoneutrinos, said study co-author Aldo Ianni, a physicist at the Gran Sasso National Laboratory in Italy.

The heat formed from this decay is the engine that drives the motion of the viscous, oozing material that forms the Earth's mantle. That, in turn can shift the tectonic plates, causing earthquakes. Whereas researchers have models to predict how much heat is generated inside the Earth, measuring it has proved tricky.

That's partly because mantle lies miles beneath the Earth's surface, so "if you want to understand how much heat is produced by these radioactive elements, the only way today to understand how much is this so-called radiogenic heat is through the geoneutrinos," Ianni said.

Tiny Particles

To do so, researchers at the Gran Sasso underground laboratory, which is nearly a mile below a mountain in Italy, looked for signals in a vast pool of oil-based liquid that scintillates, or produces flashes of light when particles such as protons pass through it. When geoneutrinos pass through the scintillating liquid they bump into protons and emit a positron and then a neutron, creating a distinctive signal, Ianni told LiveScience.

Many of the particles they initially identified actually came from nuclear reactors from power plants. But by measuring the energy levels of the neutrinos, they could isolate the 30 percent that came from the Earth's mantle, Ianni said.

The geoneutrinos are created from the decay of radioactive thorium and uranium in a reaction that gives off a known amount of heat. As a result, how frequently the researchers find the particles can reveal the quantity of the radioactive elements lurking in Earth's mantle, and in turn how much heat they generate. That can help scientists refine their knowledge of plate tectonics, Ianni said.

Read more at Discovery News

Confirmed! Newfound Particle Is the Higgs

A newfound particle discovered at the world's largest atom smasher last year is, indeed, the Higgs boson, the particle thought to give other matter its mass, scientists reported today (March 14) at the annual Rencontres de Moriond conference in Italy.

Physicists announced on July 4, 2012, that, with more than 99 percent certainty, they had found a new elementary particle weighing about 126 times the mass of the proton that was likely the long-sought Higgs boson. The Higgs is sometimes referred to as the "God particle," to the chagrin of many scientists, who prefer its official name.

But the two experiments, CMS and ATLAS, hadn't collected enough data to say the particle was, for sure, the Higgs boson, the last undiscovered piece of the puzzle predicted by the Standard Model, the reigning theory of particle physics.

Now, after collecting two and a half times more data inside the Large Hadron Collider (LHC) — where protons zip at near light-speed around the 17-mile-long (27 kilometer) underground ring beneath Switzerland and France — physicists say the particle is the Higgs.

"The preliminary results with the full 2012 data set are magnificent and to me it is clear that we are dealing with a Higgs boson though we still have a long way to go to know what kind of Higgs boson it is," said CMS spokesperson Joe Incandela in a statement.

Dave Charlton, ATLAS spokesperson agreed, the new results "point to the new particle having the spin-parity of a Higgs boson as in the Standard Model," referring to a quantum property of elementary particles.

To confirm the particle as the Higgs boson, physicists needed to collect tons of data that would reveal its quantum properties as well as how it interacted with other particles. For instance, a Higgs particle should have no spin and its parity, or the measure of how its mirror image behaves, should be positive, both of which were supported by data from the ATLAS and CMS experiments.

Even so, the scientists are not sure whether this Higgs boson is the one predicted by the Standard Model or perhaps the lightest of several bosons predicted to exist by other theories.

Seeing how this particle decays into other particles could let physicists know whether this Higgs is the "plain vanilla" Standard Model Higgs. Detecting a Higgs boson is rare, with just one observed for every 1 trillion proton-proton collisions. As such, the LHC physicists say they need much more data to understand all of the ways in which the Higgs decays.

From what is known about the particle now, physicists have said the Higgs boson may spell the universe's doom in the very far future. That's because the mass of the Higgs boson is a critical part of a calculation that portends the future of space and time. Its mass of 126 times the mass of the proton is just about what would be needed to create a fundamentally unstable universe that would lead to a cataclysm billions of years from now.

Read more at Discovery News

Life Under a Tiny, Red, Angry Sun

Recent estimates are that 6 percent of red dwarf stars in our galaxy should have Earth-sized worlds. Six percent! That means that our galaxy could potentially be overflowing with terrestrial planets.

Six percent may not sound like a lot, but red dwarfs are astonishingly populous. Approximately 75 percent of all stars are red dwarfs. Assuming that there are around 300 billion stars in the Milky Way, that means there should be over 13.5 billion exo-Earths orbiting the tiny red suns strewn across our galaxy.

Red dwarfs have always been a source of controversy for planet hunters and astrobiologists. They’ve been frequently ignored in exoplanet searches, largely because they’re noisy little beasts that makes finding anything out about them rather taxing. That is, until Courtney Dressing and her colleagues looked at data from Kepler in an attempt to settle the arguments. As it happens, their study found that around 60 percent of red dwarfs should have planets smaller than Neptune, which means — as some astronomers have long suspected — these tiny stars are likely to be good hunting grounds for exoplanets.

So what exactly is the deal with red dwarfs? Are they good homes for life or not?

One Angry Dwarf

Well, a big problem with red dwarfs is that many of them are ill-tempered little things; prone to violent and unpredictable outbursts.

These little stars are fully convective, meaning that material circulates all the way from the core up to their surfaces, unlike the sun that only has convection currents in its exterior layers. This gives rise to immense magnetic fields, which are responsible for Goliath temper tantrums.

Many red dwarfs are flare stars, occasionally increasing significantly in brightness. Flares seen on these little red stars can put the solar flares we see on the sun to shame. They’re also correspondingly more lethal, brightening the star’s electromagnetic output from radio waves all the way up to x rays!

Paradoxically, the same magnetic activity powering these flares also causes dramatic starspot activity — just like sunspots, only much much more so.

Because a red dwarf is so much smaller than the sun, and its magnetic fields are so much stronger, starspots can cause the brightness of these grouchy little stars to drop by up to 40 percent. I hasten to add that not all red dwarfs are quite so volatile. But many of them are.

The other problem with life under a red sun is that red dwarf stars are cool. And I don’t mean cool like Neil deGrasse Tyson, I mean literally cool. The surface temperature of an average red dwarf is around 2000-4000 Kelvin. Compared with the sun’s surface temperature of nearly 6000 Kelvin, that’s only lukewarm. At this lower temperature, most red dwarfs struggle to put out even 1 percent the luminosity of the sun.

This means that habitable planets around red dwarfs have to lie in very tight orbits to stay warm. Practically hugging their tiny red suns for warmth, they’re very much in danger from the titanic flares that these stars can belch out.

Sunny Side Up

This isn’t to say, however, that life isn’t possible under a red sun — but it would have to be very different to what we’re familiar with.

For one thing, the habitable zone around a red dwarf is so close that any of these watery Earth-like worlds would surely be tidally locked. One side would constantly be facing the warmth of their parent star, while the other side would be freezing cold and in constant night.

This may not be as bad as it sounds. Some have hypothesized that the star-facing side of such planets may have a perpetual storm, and the night side would likely be frozen solid. In between the extremes though, such planets may have a belt of warm and potentially life sustaining surface.

Geothermal energy locked in these planets could help to stabilize their temperatures, oceans would certainly help to transport warmth around a planet. A dense Earth-like atmosphere would help too, and even more of that precious red sunlight could be trapped by greenhouse gasses which might accumulate in that atmosphere. Red dwarf stars don’t emit a lot of ultraviolet light.

With less ultraviolet to break molecules apart, potent greenhouse gasses like methane could accumulate and act like planetary blankets. The chemistry of planets around red dwarfs stars is likely to be very different to anything we see in our own solar system.

A Leisurely Life

Red dwarfs have one more trick up their sleeves. They’re very very long lived. So long lived, in fact, that no red dwarf has ever died in our universe, because the universe isn’t old enough yet!

The sun formed roughly 4.6 billion years, and will keep on burning just as it is today for another 5.4 billion years. By contrast, a red dwarf born at the same time would barely be a teenager. For example, Barnard’s star — a friendly neighborhood red dwarf, just under 6 light years away — has a life expectancy of 2.5 trillion years. Over 200 times that of the sun. No one even knows if a planet can support life for that long!

While we know that life evolved here on Earth quite soon after our planet formed, we have no idea how long it would normally take for this to happen. If it’s even remotely possible for the same thing to happen on a red dwarf planet, it would have literally all the time in the universe in which to do so!

Whether or not life exists is still an unanswered question, and one that we won’t be able to answer until our telescopes are powerful enough to actually take a detailed look at planets around red dwarf stars. That said, with 13.5 billion planets to choose from, probability may well be on the side of the astrobiologists!

Read more at Discovery News

Mar 13, 2013

Shape-Shifting Jesus Described in Ancient Egyptian Text

A newly deciphered Egyptian text, dating back almost 1,200 years, tells part of the crucifixion story of Jesus with apocryphal plot twists, some of which have never been seen before.

Written in the Coptic language, the ancient text tells of Pontius Pilate, the judge who authorized Jesus' crucifixion, having dinner with Jesus before his crucifixion and offering to sacrifice his own son in the place of Jesus. It also explains why Judas used a kiss, specifically, to betray Jesus — because Jesus had the ability to change shape, according to the text  — and it puts the day of the arrest of Jesus on Tuesday evening rather than Thursday evening, something that contravenes the Easter timeline.

The discovery of the text doesn't mean these events happened, but rather that some people living at the time appear to have believed in them, said Roelof van den Broek, of Utrecht University in the Netherlands, who published the translation in the book "Pseudo-Cyril of Jerusalem on the Life and the Passion of Christ"(Brill, 2013).

Copies of the text are found in two manuscripts, one in the Morgan Library and Museum in New York City and the other at the Museum of the University of Pennsylvania. Most of the translation comes from the New York text, because the relevant text in the Pennsylvania manuscript is mostly illegible.

Pontius Pilate has dinner with Jesus

While apocryphal stories about Pilate are known from ancient times, van den Broek wrote in an email to LiveScience that he has never seen this one before, with Pilate offering to sacrifice his own son in the place of Jesus.

"Without further ado, Pilate prepared a table and he ate with Jesus on the fifth day of the week. And Jesus blessed Pilate and his whole house," reads part of the text in translation. Pilate later tells Jesus, "well then, behold, the night has come, rise and withdraw, and when the morning comes and they accuse me because of you, I shall give them the only son I have so that they can kill him in your place."

In the text, Jesus comforts him, saying, "Oh Pilate, you have been deemed worthy of a great grace because you have shown a good disposition to me." Jesus also showed Pilate that he can escape if he chose to. "Pilate, then, looked at Jesus and, behold, he became incorporeal: He did not see him for a long time ..." the text read.

Pilate and his wife both have visions that night that show an eagle (representing Jesus) being killed.

In the Coptic and Ethiopian churches, Pilate is regarded as a saint, which explains the sympathetic portrayal in the text, van den Broek writes.

The reason for Judas using a kiss

In the canonical bible the apostle Judas betrays Jesus in exchange for money by using a kiss to identify him leading to Jesus' arrest. This apocryphal tale explains that the reason Judas used a kiss, specifically, is because Jesus had the ability to change shape.

"Then the Jews said to Judas: How shall we arrest him (Jesus), for he does not have a single shape but his appearance changes. Sometimes he is ruddy, sometimes he is white, sometimes he is red, sometimes he is wheat coloured, sometimes he is pallid like ascetics, sometimes he is a youth, sometimes an old man ..." This leads Judas to suggest using a kiss as a means to identify him. If Judas had given the arresters a description of Jesus he could have changed shape. By kissing Jesus Judas tells the people exactly who he is.

This understanding of Judas' kiss goes way back. "This explanation of Judas' kiss is first found in Origen (a theologian who lived A.D. 185-254)," van den Broek writes. In his work, Contra Celsum the ancient writerOrigen, stated that "to those who saw him he did not appear alike to all."

St. Cyril impersonation

The text is written in the name of St. Cyril of Jerusalem who lived during the fourth century. In the story Cyril tells the Easter story as part of a homily (a type of sermon).  A number of texts in ancient times claim to be homilies by St. Cyril and they were probably not given by the saint in real life, van den Broek explained in his book.

Near the beginning of the text, Cyril, or the person writing in his name, claims that a book has been found in Jerusalem showing the writings of the apostles on the life and crucifixion of Jesus. "Listen to me, oh my honored children, and let me tell you something of what we found written in the house of Mary ..." reads part of the text.

Again, it's unlikely that such a book was found in real life. Van den Broek said that a claim like this would have been used by the writer "to enhance the credibility of the peculiar views and uncanonical facts he is about to present by ascribing them to an apostolic source," adding that examples of this plot device can be found "frequently" in Coptic literature.

Arrest on Tuesday

Van den Broek says that he is surprised that the writer of the text moved the date of Jesus' Last Supper, with the apostles, and arrest to Tuesday. In fact, in this text, Jesus' actual Last Supper appears to be with Pontius Pilate. In between his arrest and supper with Pilate, he is brought before Caiaphas and Herod.

In the canonical texts, the last supper and arrest of Jesus happens on Thursday evening and present-day Christians mark this event with Maundy Thursday services. It "remains remarkable that Pseudo-Cyril relates the story of Jesus' arrest on Tuesday evening as if the canonical story about his arrest on Thursday evening (which was commemorated each year in the services of Holy Week) did not exist!" writes van den Broek in the email.

A gift to a monastery ... and then to New York

About 1,200 years ago the New York text was in the library of the Monastery of St. Michael in the Egyptian desert near present-day al-Hamuli in the western part of the Faiyum. The text says, in translation, that it was a gift from "archpriest Father Paul," who, "has provided for this book by his own labors."

The monastery appears to have ceased operations around the early 10th century, and the text was rediscovered in the spring of 1910. In December 1911, it was purchased, along with other texts, by American financier J.P. Morgan. His collections would later be given to the public and are part of the present-day Morgan Library and Museum in New York City. The manuscript is currently displayed as part of the museum's exhibition "Treasures from the Vault" running through May 5.

Read more at Discovery News

Neanderthals Lacked Social Skills

For ages, anthropologists have puzzled over Neanderthal and human brains, since they were the same size. If each species had comparable brainpower, why did humans dominate?

A comparison of Neanderthal and human brains has revealed it was a matter of allocation: Neanderthal brains focused more on vision and movement, leaving less room for cognition related to social networking.

According to the study, published in the journal Proceedings of the Royal Society B, bigger eyed and larger bodied Neanderthals required more brain space devoted to the visual system and basic body functions, leaving less area for what co-author Robin Dunbar called "the smart part."

He explained to Discovery News that this is "the part that is doing the creative thinking."

Dunbar, a professor of evolutionary psychology at the University of Oxford, and colleagues Eiluned Pearce and Chris Stringer compared the skulls of 32 anatomically modern humans and 13 Neanderthals. The skulls date to 27,000 to 75,000 years ago. The researchers noticed that Neanderthals had significantly larger eye sockets.

The researchers next used the known relationship between the height of the eye socket and the size of visual brain areas in living primates to estimate how much of each brain was dedicated to visual processing. Once differences in body and visual system size were taken into account, the researchers could then compare how much of the brain was left over for other types of cognition.

It's clear that environmental differences affected the evolution of each species. The common ancestor of Neanderthals and Homo sapiens was Homo heidelbergensis. It had a bulkier body, as for Neanderthals, but did not possess enlarged eyes.

"The large eyes (of Neanderthals) are purely an adaptation to low light levels, and long dark nights at higher latitudes outside the tropics," Dunbar said.

Neanderthals also tended to be shorter than humans, which again was an adaptation to colder climates since this reduces heat loss through the extremities. Modern Eskimos exhibit some of this adaptation.

Neanderthals in Europe also "developed a very confrontational and dangerous style of hunting, and were very dependent on a heavy meat diet," Dunbar shared. "Modern humans (in Africa) developed the bow and arrow, as well as spear throwers, which allowed hunting at arms’ length and often focused on smaller prey."

As for what happened to the Neanderthals, some researchers believe that they were simply absorbed into the modern human population. There is evidence that, as numerous humans migrated north into Europe, they interbred with Neanderthals.

Another theory, supported by this new study, is that Neanderthals went extinct because they were less capable of forming larger social networks. Pearce theorized that "smaller social groups might have made Neanderthals less able to cope with the difficulties of their harsh Eurasian environments because they would have had fewer friends to help them out in times of need."

She continued, "Overall, differences in brain organization and social cognition may go a long way towards explaining why Neanderthals went extinct whereas modern humans survived."

Dunbar further thinks that new diseases brought in by humans could have hurt Neanderthals. He said, "It was clear that, by the end, they were struggling to maintain a foothold in Ice Age Europe, having been squeezed down into the southern appendages of Europe (in places like Spain and Italy)."

Clive Gamble, an expert on the archaeology of human origins and a professor at Southampton University praised the new work, saying, "This paper cracks a big problem in human evolution. Neanderthals had brains as big as ours, yet did not regularly produce the sorts of cultural stuff- art, ornamentation and complicated tools -- that we take for granted…Brains got bigger, but in different ways."

Read more at Discovery News

What Is Life, Anyway?

NASA officials announced March 12 that ancient Mars could have supported primitive life. But this begs the question: What exactly constitutes life? defines life as "an organismic state characterized by capacity for metabolism, growth, reaction to stimuli and reproduction." But there's no single satisfactory definition of life.

"I think it is a mistake to try to define life, because we have only one example of life, familiar life on Earth, and we have reason to believe that this example may be unrepresentative of life in general," Carol Cleland, a philosopher of science at the University of Colorado, Boulder, told LiveScience in an email.

Defining life

Aristotle made the first attempt at a definition, describing life as something that grows, maintains itself and reproduces. But this definition would exclude mules, which are sterile, while including things like fire.

Calling life something that has a metabolism, the ability to take in energy to grow or move and excrete waste, is no good either; cars do this, for example.

In 1944, the physicist Erwin Schrödinger gave life a definition based on the second law of thermodynamics, which states that the entropy, or disorder, of a closed system increases over time. Schrödinger defined life as something that decreases or maintains its entropy. Yet this definition fails because it includes crystals, which resist entropy by forming highly structured lattices.

Trying to define life by its qualities is the wrong approach, Cleland said. As an example, she cites scientists' early attempts to define water in terms of properties like being wet, transparent and a good solvent. "We didn't 'define' water as H2O, but rather discovered, in the context of molecular theory, that it is a chemical substance composed mostly of H2O molecules," Cleland said.

Life on Earth is typically divided into two main groups: the cellular life forms, which include archaea, bacteria and eukarya (all the plants and animals), and non-cellular life forms, like viruses. Whether viruses, which can replicate only inside the cells of a host organism, count as "life" is debated.

Life in the universe

Finding an airtight definition for life may not be so important, astrobiologist Chris McKay of NASA's Ames Research Center in California wrote in an email to LiveScience. It's "much better to have an idea of what life is built of," McKay said. "Life is built of complex, organic molecules."

Characterizing life is vital for identifying it elsewhere in the universe, a possibility now beyond the realm of science fiction. McKay said that if life exists somewhere else, it would be a material system evolving through reproduction, mutation and natural selection.

Read more at Discovery News

Monster Starbursts Seen by New Radio Telescope

With new instruments coming online, the most distant (and youngest) regions of our universe are finally being explored in depth.

This week, the Atacama Large Millimeter/Submillimeter Array, or ALMA, is being dedicated, and they’re celebrating with an amazing new study of some of the most distant prolifically star-forming galaxies.

The millimeter and submillimeter wave bands can be thought of as very short wavelength radio astronomy, or very long wavelength infrared. For decades, it’s been a hard region of the electromagnetic spectrum to probe since water vapor in our atmosphere causes a lot of absorption and distortion, and the challenges that go into the technology are non-trivial.

But after 30 years of plotting and planning, an international collaboration has succeeded in creating a sensitive instrument at a high dry mountain site that can fully open up this part of the universe.

It turns out, thanks to a lucky coincidence of physics, that the millimeter band is a great place to study distant, star-forming galaxies. You can see galaxies over a wide range of redshifts, or distances, in this band with little bias. That is, you just don’t see the brightest sources from further away; you get the whole history of galaxy formation in one go. Well, theoretically, at least. Previously existing millimeter wave telescopes were not very sensitive, and so only could see a small part of the population.

Now ALMA is coming online, and a study led by Joaquin Vieira using just 16 of the array’s planned 66 antennas have already doubled the number of star-forming galaxies seen at redshifts greater than 4, or from the first 1.5 billion years of the universe’s history. Also, each observation took only 2 minutes to create images that would have taken older telescopes hours to produce, if they even could.

So, technologically, this is pretty mind-blowing and demonstrates the capability of ALMA, even in its earliest stages. Scientifically, this is a boon for astronomers wanting to understand galaxy formation in the early universe, as this is one of the most important research questions of the day.

These galaxies are all gravitationally lensed by some foreground object, such as an elliptical galaxy, and that helps us to see the furthest objects.

In total, 47 galaxies were imaged, and spectra were collected from 26 of these. A spectrum is taken when the light from the object is separated by wavelength, not unlike a prism making a rainbow out of visible light.

ALMA’s scientific prowess stems in part from very fine spectral resolution, allowing for detailed studies of emission lines from molecular clouds. The other part of its strength, the incredible sensitivity, allows astronomers to see much fainter lines than ever before.

The spectra collected from these galaxies highlight an important analysis, the exact determination of redshift, or distance, to distant galaxies.

The most accurate way to determine redshift is to measure several spectra lines and how much they have been shifted to longer wavelengths by the expansion of the universe over great distances. However, astronomers often rely on more indirect techniques for very distant objects when no lines can be seen. Also, optical and infrared telescopes cannot easily survey these star-forming distant galaxies because they are obscured by their own dust. The millimeter and submillimeter regime is the way to go to collect precise redshifts of this population.

Read more at Discovery News

Mar 12, 2013

New Hope for Reversing the Effects of Spinal Cord Injury

Walking is the obvious goal for individuals who have a chronic spinal cord injury, but it is not the only one. Regaining sensation and continence control also are important goals that can positively impact an individual's quality of life. New hope for reversing the effects of spinal cord injury may be found in a combination of stem cell therapy and physical therapy as reported in Cell Transplantation by scientists at the University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School.

"Our phase one/two clinical trial had one goal: to give patients who have no other treatment options some hope," said Hatem E. Sabaawy, MD, PhD, an assistant professor of medicine in the molecular and regenerative medicine program at Robert Wood Johnson Medical School. "Early findings have concluded that we have met our goal and can improve the quality of life for individuals with spinal cord injuries by providing a safe treatment that restores some neurological function."

Dr. Sabaawy led a clinical trial that included 70 patients who had cervical or thoracic spinal cord injuries and were previously treated for at least six months without response. The patients were randomized into two groups, both of which were given physical therapy treatment. One of the groups also received stem cells derived from their own bone marrow injected near the injury site. Using the American Spinal Injury Association Impairment (AIS) Scale, patients received neurological and physical evaluations monthly for 18 months to determine if sensory and motor functions improved.

"Of primary importance, there was a notable absence of side effects in patients treated with stem cells during the course of our investigation," added Dr. Sabaawy, who also is a resident member of The Cancer Institute of New Jersey at Robert Wood Johnson Medical School.

None of the patients in the control group who received only physical therapy showed any improvement in sensory or motor function during the same time frame. Although the scale of injuries differed, all patients who were treated with a combination of bone-marrow derived stem cells and physical therapy responded to tactile and sensory stimuli as early as 4 weeks into the study. After 12 weeks, they experienced improvements in sensation and muscle strength, which was associated with enhanced potency and improved bladder and bowel control that eventually allowed patients to live catheter-free. Patients who showed improvement based on the AIS scale also were able to sit up and turn in their beds.

"Since the emergence of stem cells as a potential therapy for spinal cord injury, scientists have diligently sought the best application for using their regenerating properties to improve a patient's mobility," said Joseph R. Bertino, MD, University Professor of medicine and pharmacology, interim director, Stem Cell Institute of New Jersey and chief scientific officer at The Cancer Institute of New Jersey. "Dr. Sabaawy's discovery that treatment is more successful when stem cell therapy is combined with physical therapy could provide a remarkable, and hopefully sustainable, improvement in the overall quality of life for patients with spinal cord injury."

At the end of 18 months, 23 of the 50 patients who received both physical therapy and stem cell therapy showed a significant improvement of at least 10 points on the AIS scale. Several were able to walk with assistance. In addition, more gains were made in motor skill control by patients with thoracic spinal cord injuries, suggesting that patients with thoracic spinal cord injuries may respond better to the combined treatment.

Dr. Sabaawy however cautioned that more studies are needed with a larger number of patients to test different cell dose levels and intervals at which stem cell therapy should be delivered.

Read more at Science Daily

Earth-Sized Planets in Habitable Zones Are More Common Than Previously Thought

The number of potentially habitable planets is greater than previously thought, according to a new analysis by a Penn State researcher, and some of those planets are likely lurking around nearby stars.

"We now estimate that if we were to look at 10 of the nearest small stars we would find about four potentially habitable planets, give or take," said Ravi Kopparapu, a post-doctoral researcher in geosciences. "That is a conservative estimate," he added. "There could be more."

Kopparapu detailed his findings in a paper accepted for publication in Astrophysical Journal Letters. In it, he recalculated the commonness of Earth-sized planets in the habitable zones of low-mass stars, also known as cool stars or M-dwarfs.

Scientists focus on M-dwarfs for several reasons, he explained. The orbit of planets around M-dwarfs is very short, which allows scientists to gather data on a greater number of orbits in a shorter period of time than can be gathered on Sun-like stars, which have larger habitable zones. M-dwarfs are also more common than stars like Earth's Sun, which means more of them can be observed.

According to his findings, "The average distance to the nearest potentially habitable planet is about seven light years. That is about half the distance of previous estimates," Kopparapu said. "There are about eight cool stars within 10 light-years, so conservatively, we should expect to find about three Earth-size planets in the habitable zones."

The work follows up on a recent study by researchers at the Harvard-Smithsonian Center for Astrophysics which analyzed 3,987 M-dwarf stars to calculate the number of Earth-sized planet candidates in cool stars' habitable zones -- a region around a star where rocky planets are capable of sustaining liquid water and therefore life. That study used habitable zone limits calculated in 1993 by Jim Kasting, now an Evan Pugh Professor in Penn State's Department of Geosciences. Kopparapu noticed that its findings, based on data from NASA's Kepler satellite, didn't reflect the most recent estimates for determining whether planets fall within a habitable zone.

These newer estimates are based on an updated model developed by Kopparapu and collaborators, using information on water and carbon dioxide absorption that was not available in 1993. Kopparapu applied those findings to the Harvard team's study, using the same calculation method, and found that there are additional planets in the newly determined habitable zones.

Read more at Science Daily

'Bubble-Pop' Bird May Be Rarest in U.S.

The Gunnison sage-grouse, a bird with an unusual “bubble pop” mating call and display, could be America’s rarest bird, according to avian experts.

The bird was only discovered 13 years ago, and yet it’s already nearly a goner. Today, fewer than 5,000 of these birds remain in the wild, and they are rapidly dwindling.

“In my view, the Gunnison sage-grouse is the most biologically endangered bird species in all of continental North America,” Cornell Lab of Ornithology director John Fitzpatrick said in a statement sent to the U.S. Fish and Wildlife Service.

The chicken-sized bird has an amazingly unusual mating ritual. To court females, the males strut about while wagging their spiky tails and making a popping-like noise as they inflate yellow air sacs from their white chests.

Fitzpatrick and others are paying attention to this bird now, as it’s a candidate for listing as endangered under the Endangered Species Act. The Gunnison sage-grouse only lives in eastern Utah and Colorado.

“The Gunnison sage-grouse is now in imminent danger of a series of local population collapses, which — when they occur — will result in extinction of the species,” Fitzpatrick explained.

Efforts by public agencies and private landowners to help stabilize the bird’s populations through private land easements, conservation plans and community education have not halted its decline, says Fitzpatrick.

Despite the bird’s precarious status, getting a species endangered classification can be a long, laborious process.

For example the Dakota skipper butterfly, on the candidate’s list since 1975, is now extinct in Indiana and Iowa. The Eastern Massasauga rattlesnake has been a candidate since 1982. And the Kittlitz’s murrelet, a small bird, has been on the candidate’s list for nearly 20 years.

Read more at Discovery News

Cause of Odd Arctic Ozone 'Hole' Found

Cold temperatures, chlorine and a stagnant atmosphere caused a thinning in the ozone layer over the Arctic in 2011, a new NASA study finds.

This ozone loss is not the more famous ozone hole, found seasonally over Antarctica, which has been shrinking since the phase-out of chlorofluorocarbons, or CFCs, that interact with ozone molecules in the atmosphere. These ozone molecules are made of three oxygen atoms bound together. Their high concentration in the stratosphere about 12 miles to 19 miles (20 to 30 kilometers) above the Earth's surface blocks harmful ultraviolet light from the sun.

Arctic ozone depletion is typically not as severe as that in the Antarctic. Over the South Pole, the sun barely or never sets around Christmas, creating a confluence of sunlight and cold in the atmosphere. Under these conditions, chlorine from CFCs eats away at ozone molecules.

Arctic ozone

Up north, however, the sun reappears in the sky in the spring as temperatures start to warm, so the conditions aren't as favorable for ozone depletion. But in 2011, the ozone concentration in the late winter Arctic was about 20 percent lower than average. [North vs. South Pole: 10 Wild Differences]

"You can safely say that 2011 was very atypical: In over 30 years of satellite records, we hadn't seen any time where it was this cold for this long," study researcher Susan Strahan, an atmospheric scientist at NASA Goddard Space Flight Center, said in a statement.

Using atmospheric simulations, Strahan and her colleagues found that a mix of cold temperatures, chlorine and an unusually strong Arctic vortex caused the odd thinning. The Arctic vortex is a region of fast-blowing circular winds that get stronger each fall, creating an eddy of chilled air around the pole.

In 2011, the atmosphere was unusually quiet, allowing the Arctic vortex to remain strong well into the spring, after it usually breaks up. The reappearance of the sun in March while it was still especially cold created the conditions that led to the ozone thinning, the researchers report in the Journal of Geophysical Research - Atmospheres.

"Arctic ozone levels were possibly the lowest ever recorded, but they were still significantly higher than the Antarctic's," Strahan said. "There was about half as much ozone loss as in the Antarctic," and the levels remained above the threshold for calling the ozone loss an actual "hole," Strahan added.

Future outlook

Strahan and her team calculate that two-thirds of the thinning was caused by a combination of chlorine pollution and extreme cold. The remaining third was caused by the oddly quiet atmosphere, which prevented ozone molecules from elsewhere from moving in to fill the gap.

The ozone layer over the Arctic returned to normal in April 2011. It's unlikely that such thinning will become a reoccurring problem, because the meteorological conditions were so odd, Strahan said. Not only that, but CFC levels in the atmosphere are still declining.

Read more at Discovery News

Mar 11, 2013

Closest Star System Found in a Century

A pair of newly discovered stars is the third-closest star system to the Sun, according to a paper that will be published in Astrophysical Journal Letters. The duo is the closest star system discovered since 1916. The discovery was made by Kevin Luhman, an associate professor of astronomy and astrophysics at Penn State University and a researcher in Penn State's Center for Exoplanets and Habitable Worlds.

Both stars in the new binary system are "brown dwarfs," which are stars that are too small in mass to ever become hot enough to ignite hydrogen fusion. As a result, they are very cool and dim, resembling a giant planet like Jupiter more than a bright star like the Sun.

"The distance to this brown dwarf pair is 6.5 light years -- so close that Earth's television transmissions from 2006 are now arriving there," Luhman said. "It will be an excellent hunting ground for planets because it is very close to Earth, which makes it a lot easier to see any planets orbiting either of the brown dwarfs." Since it is the third-closest star system, in the distant future it might be one of the first destinations for manned expeditions outside our solar system, Luhman said.

The star system is named "WISE J104915.57-531906" because it was discovered in a map of the entire sky obtained by the NASA-funded Wide-field Infrared Survey Explorer (WISE) satellite. It is only slightly farther away than the second-closest star, Barnard's star, which was discovered 6.0 light years from the Sun in 1916. The closest star system consists of Alpha Centauri, found to be a neighbor of the Sun in 1839 at 4.4 light years, and the fainter Proxima Centauri, discovered in 1917 at 4.2 light years.

Edward (Ned) Wright, the principal investigator for the WISE satellite, said "One major goal when proposing WISE was to find the closest stars to the Sun. WISE 1049-5319 is by far the closest star found to date using the WISE data, and the close-up views of this binary system we can get with big telescopes like Gemini and the future James Webb Space Telescope will tell us a lot about the low mass stars known as brown dwarfs." Wright is the David Saxon Presidential Chair in Physics and a professor of physics and astronomy at UCLA.

Astronomers have long speculated about the possible presence of a distant, dim object orbiting the Sun, which is sometimes called Nemesis. However, Luhman has concluded, "we can rule out that the new brown dwarf system is such an object because it is moving across the sky much too fast to be in orbit around the Sun."

To discover the new star system, Luhman studied the images of the sky that the WISE satellite had obtained during a 13-month period ending in 2011. During its mission, WISE observed each point in the sky 2 to 3 times. "In these time-lapse images, I was able to tell that this system was moving very quickly across the sky -- which was a big clue that it was probably very close to our solar system," Luhman said.

After noticing its rapid motion in the WISE images, Luhman went hunting for detections of the suspected nearby star in older sky surveys. He found that it indeed was detected in images spanning from 1978 to 1999 from the Digitized Sky Survey, the Two Micron All-Sky Survey, and the Deep Near Infrared Survey of the Southern Sky. "Based on how this star system was moving in the images from the WISE survey, I was able to extrapolate back in time to predict where it should have been located in the older surveys and, sure enough, it was there," Luhman said.

By combining the detections of the star system from the various surveys, Luhman was able to measure its distance via parallax, which is the apparent shift of a star in the sky due to Earth's orbit around the Sun. He then used the Gemini South telescope on Cerro Pachón in Chile to obtain a spectrum of it, which demonstrated that it had a very cool temperature, and hence was a brown dwarf. "As an unexpected bonus, the sharp images from Gemini also revealed that the object actually was not just one but a pair of brown dwarfs orbiting each other," Luhman said.

Read more at Science Daily

Mummy Scans Reveal Clogged Arteries

Scans of mummies from as long ago as 2,000 BC have revealed that ancient people also had clogged arteries, a condition blamed on modern vices like smoking, overeating and inactivity, a study said Monday.

The finding, published in the Lancet medical journal, casts doubt on our understanding of the condition known as atherosclerosis that causes heart attacks and strokes.

"The presence of atherosclerosis in premodern human beings suggests that the disease is an inherent component of human aging and not associated with any specific diet or lifestyle," states the study conclusion.

"A common assumption is that the rise in levels of atherosclerosis is predominantly lifestyle-related, and that if modern humans could emulate pre-industrial or even pre-agricultural lifestyles, that atherosclerosis... would be avoided," cardiologist Randall Thompson, one of the authors of the international study, said in a statement issued by Lancet.

"Our findings seem to cast doubt on that assumption, and at the very least, we think they suggest that our understanding of the causes of atherosclerosis is incomplete, and that it might be somehow inherent to the process of human aging."

This did not mean that lifestyle factors should be discounted, senior author Gregory Thomas, medical director of the Memorial Care Heart and Vascular Institute at Long Beach Memorial Medical Center in California, said.

They have been shown in study after study to contribute to the development of atherosclerosis, though the degree remains unclear.

"Our study demonstrates... that we are all at risk of atherosclerosis," said Thomas.

"We should do the very best we can to avoid these risk factors. We can not expect, however, that avoiding them will prevent atherosclerosis."

Atherosclerosis is a hardening and narrowing of the arteries that transport oxygen-rich blood from the heart, through a buildup of fatty material or cholesterol.

The World Health Organization considers smoking, physical inactivity, a high-salt, high-fat diet and high alcohol use as risk factors.

For this study, the researchers performed full-body computed tomography (CT) scans on 137 mummies from four geographic regions in modern-day Egypt, Peru, southwest America and Alaska.

The mummies were of people who had lived over a 4,000-year period stretching from ancient Egypt in about 2,000 BC to the Unangan hunter-gatherers who lived in the Aleutian Islands of modern-day Alaska as recently as 1930.

The team diagnosed "probable or definite" atherosclerosis in more than a third of the mummies on the basis of calcification of the arteries shown up by the scans.

A similar diagnostic method is used today.

The calcification was found in the same locations as in modern humans, and the appearance was the same.

"Our findings greatly increase the number of ancient people known to have atherosclerosis and show for the first time that the disease was common in several ancient cultures with varying lifestyles, diets and genetics, across a wide geographical distance and over a very long span of human history," the scientists wrote.

"These findings suggest that our understanding of the causative factors of atherosclerosis is incomplete."

The mummies of older people were more likely to show signs of the disease, just as in humans today.

Other research cited in the study has found atherosclerosis to be common in people living today, even ubiquitous in men by age 60 and women by 70.

"We simply don't know enough about the diet and lifestyle of the people studied to say whether behavior or genetics lies at the root" of the disease, the British Heart Foundation said in a comment on the study.

And Grethe Tell, an expert with the European Society of Cardiology, said the findings "do not refute" that an unhealthy lifestyle increased the risk of heart attack and stroke.

"Not everybody who has atherosclerosis (whatever the cause may be) gets clinical disease," she explained.

"Lifestyle factors increase the risk of heart attacks and may therefore be a triggering factor in the chain between atherosclerosis and heart attack."

According to the study, the ancient populations' diets had been varied -- including everything from shellfish and fish, game, domesticated cattle, sheep, pigs and ducks to a wide variety of berries, farmed maize, beans and potato -- even beer and wine in the case of the Egyptians.

Read more at Discovery News

First Evidence of Viking-Like 'Sunstone' Found

Ancient lore has suggested that the Vikings used special crystals to find their way under less-than-sunny skies. Though none of these so-called "sunstones" have ever been found at Viking archaeological sites, a crystal uncovered in a British shipwreck could help prove they did indeed exist.

The crystal was found amongst the wreckage of the Alderney, an Elizabethan warship that sank near the Channel Islands in 1592. The stone was discovered less than 3 feet (1 meter) from a pair of navigation dividers, suggesting it may have been kept with the ship's other navigational tools, according to the research team headed by scientists at the University of Rennes in France.

A chemical analysis confirmed that the stone was Icelandic Spar, or calcite crystal, believed to be the Vikings' mineral of choice for their fabled sunstones, mentioned in the 13th-century Viking saga of Saint Olaf.

Today, the Alderney crystal would be useless for navigation, because it has been abraded by sand and clouded by magnesium salts. But in better days, such a stone would have bent light in a helpful way for seafarers.

Because of the rhombohedral shape of calcite crystals, "they refract or polarize light in such a way to create a double image," Mike Harrison, coordinator of the Alderney Maritime Trust, told LiveScience. This means that if you were to look at someone's face through a clear chunk of Icelandic spar, you would see two faces. But if the crystal is held in just the right position, the double image becomes a single image and you know the crystal is pointing east-west, Harrison said.

These refractive powers remain even in low light when it's foggy or cloudy or when twilight has come. In a previous study, the researchers proved they could use Icelandic spar to orient themselves within a few degrees of the sun, even after the sun had dipped below the horizon.

European seafarers had not fully figured out magnetic compasses for navigation until the end of 16th century. The researchers say the crystal might have been used on board the Elizabethan ship to help correct for errors with a magnetic compass.

"In particular, at twilight when the sun is no longer observable being below the horizon, and the stars still not observable, this optical device could provide the mariners with an absolute reference in such situation," the researchers wrote online this week in the journal Proceedings of the Royal Society A.

No such crystals have been found yet at Viking sites. The team notes that archaeologists are unlikely to find complete crystals as part of a group of grave goods, since the Vikings often cremated their dead.

Read more at Discovery News

Why Humans Get Lost

In 1996, a ranger flying a helicopter over Death Valley, Calif., spotted a minivan in a wash near Anvil Canyon. That was ominous for several reasons: There was no road leading up to the spot, and the area wasn't passable without a four-wheel vehicle.

After investigating the vehicle, park rangers determined that four German tourists — a man, a woman, and their two sons, ages 4 and 11 — had last rented the minivan. But there was no trace of the family itself.

Their remains were not found for about 15 years, until Tom Mahood, a physicist-turned-adventurer, retraced their steps. As he recounts on his website, a series of reasonable mistakes, such as misreading the steepness of a canyon descent and being led astray by culturally confusing map landmarks, likely led to the decisions that ended in them separating, then dying in the scorching desert heat.

The story reveals how easy it is for people to become hopelessly lost in the wilderness. Humans get lost in part because we don't pay attention and have lost ancient ways of reading the environment to navigate. But humans' way-finding abilities are also less precise than the abilities of other animals.

While innate navigational ability differs, "just about everyone can get better," said Daniel Montello, a geographer and psychologist at the University of California Santa Barbara.

Ancient tools

Historically, not getting lost was a matter of life or death. One wrong turn could lead to a hyena's den or a nasty death from thirst. As a result, all indigenous cultures navigate in part by tracking the sun or the stars' positions in the sky relative to the fixed star Polaris, said Tristan Gooley, author of "The Natural Navigator" (The Experiment, 2012) and owner of

Those cues "are as good if not better than a compass in many situations," Gooley told LiveScience.

For instance, Polynesian seafarers track direction using ocean swells, the natural rise and fall of the water caused when a huge storm generates waves deep at sea. Because swells can linger for days, they can reliably be used to fine-tune direction, Gooley said. The Polynesians can track up to eight swells at a time, he said.

Both land and sea bear traces of long- and short-term directional cues. For instance, grass may wave in the direction of the winds on a given day, but a tree may lean toward the direction the winds blow over long periods of time, Gooley said.

Use it or lose it

Human mental-mapping stems in part from a brain region called the hippocampus, and studies suggest it can be strengthened with practice. For instance, one study found cab drivers in London have bigger and thicker hippocampi than the average person, said Colin Ellard, a psychologist at the University of Waterloo in Canada and author of the book "You Are Here" (Doubleday, 2009).

But the sense of direction may also wither with disuse. Small studies have found that using a GPS for just a few hours seems to impair people's navigational skills in the short term, Montello said. Many people get lost because they simply aren't paying attention, he added.

Animal sense

It's also true that the human sense of direction is simply less precise than that of many animals. For instance, migratory birds can use internal magnetic compasses or sonar maps to create incredibly detailed mental maps. And many animals' sense of direction is instinctual and is genetically hard-wired.

In addition, humans have faulty internal senses of direction. For instance, several studies have found that people walk in circles when blindfolded or disoriented (for instance, in an unfamiliar, heavily forested area), Ellard said. African desert ants, by contrast, can march in a straight line for miles. [Album: Stunning Photos of the World's Ants]

"They have this prodigious ability to keep track of where they are with respect to their initial starting point," Ellard told LiveScience. "They have a very accurate internal odometer."

But while animals' sense of direction is more precise, we have a much more flexible way-finding ability, Montello said. For instance, migrating animals travel thousands of miles but usually go to specific, pre-determined locations. But humans use landmarks, directional cues, a sense of how far they've traveled, as well as myriad other cues to go vastly more places, often with no prior knowledge.

Read more at Discovery News

Mar 10, 2013

Amplified Greenhouse Effect Shaping North Into South

An international team of 21 authors from 17 institutions in seven countries has just published a study in the journal Natural Climate Change showing that, as the cover of snow and ice in the northern latitudes has diminished in recent years, the temperature over the northern land mass has increased at different rates during the four seasons, causing a reduction in temperature and vegetation seasonality in this area. In other words, the temperature and vegetation at northern latitudes increasingly resembles those found several degrees of latitude farther south as recently as 30 years ago.

The NASA-funded study, based on newly improved ground and satellite data sets, examines critically the relationship between changes in temperature and vegetation productivity in northern latitudes.

On the amplified greenhouse effect, Prof. Ranga Myneni, Department of Earth and Environment, Boston University and lead co-author says "A greenhouse effect initiated by increased atmospheric concentration of heat-trapping gasses -- such as water vapor, carbon dioxide and methane -- causes the Earth's surface and nearby air to warm. The warming reduces the extent of polar sea ice and snow cover on the large land mass that surrounds the Arctic ocean, thereby increasing the amount of solar energy absorbed by the no longer energy-reflecting surface. This sets in motion a cycle of positive reinforcement between warming and loss of sea ice and snow cover, thus amplifying the base greenhouse effect."

"The amplified warming in the circumpolar area roughly above the Canada-USA border is reducing temperature seasonality over time because the colder seasons are warming more rapidly than the summer," says Liang Xu, a Boston University doctoral student and lead co-author of the study.

"As a result of the enhanced warming over a longer ground-thaw season, the total amount of heat available for plant growth in these northern latitudes is increasing. This created during the past 30 years large patches of vigorously productive vegetation, totaling more than a third of the northern landscape -- over 9 million km2, which is roughly about the area of the USA -- resembling the vegetation that occurs further to the south," says Dr. Compton Tucker, Senior Scientist, NASA's Goddard Space Flight Center, Greenbelt, Maryland.

The authors measured seasonality changes using latitude as a yardstick. They first defined reference latitudinal profiles for the quantities being observed and then quantified changes in them over time as shifts along these profiles.

"Arctic plant growth during the early-1980s reference period equaled that of lands north of 64 degrees north. Today, just 30 years later, it equals that of lands above 57 degrees north -- a reduction in vegetation seasonality of about seven degrees south in latitude," says co-author Prof. Terry Chapin, Professor Emeritus, University of Alaska, Fairbanks. "This manner of analyses suggested a decline in temperature and vegetation seasonality of about four to seven degrees of latitude during the past 30 years," says co-author Eugenie Euskirchen, Research Professor, University of Alaska, Fairbanks.

"The reduction of vegetation seasonality, resulting in increased greenness in the Arctic, is visible on the ground as an increasing abundance of tall shrubs and tree incursions in several locations all over the circumpolar Arctic," says co-author Terry Callaghan, Professor, Royal Swedish Academy of Sciences and the University of Sheffield, UK. He notes that the greening in the adjacent Boreal areas is much less conspicuous in North America than in Eurasia.

A key finding of this study is an accelerating greening rate in the Arctic and a decelerating rate in the boreal region, despite a nearly constant rate of temperature seasonality diminishment in these regions over the past 30 years. "This may portend a decoupling between growing season warmth and vegetation productivity in some parts of the North as the ramifications of amplified greenhouse effect -- including permafrost thawing, frequent forest fires, outbreak of pest infestations, and summertime droughts -- come in to play," says co-author Hans Tømmervik, Senior Researcher, Norwegian Institute for Nature Research, Tromsø, Norway.

According to the authors, the future does indeed look troubling: Based on analysis of 17 state-of-the-art climate model simulations, diminishment of temperature seasonality in these regions could be more than 20 degrees in latitude by the end of this century relative to the 1951-1980 reference period. The projected temperature seasonality decline by these models for the 2001-2010 decade is actually less than the observed decline. "Since we don't know the actual trajectory of atmospheric concentration of various agents capable of forcing a change in climate, long-term projections should be interpreted cautiously," says co-author Bruce Anderson, Professor of Earth and Environment at Boston University.

"These changes will affect local residents through changes in provisioning ecosystem services such as timber and traditional foods," says Research Professor Bruce Forbes, University of Lapland, Rovaniemi, Finland. They will also impact the global community through changes in regulatory ecosystem services relating to emissions of greenhouse gases. "The soils in the northern land mass potentially can release significant amounts of greenhouse gases which are currently locked up in the permanently frozen ground. Any large-scale deep-thawing of these soils has the potential to further amplify the greenhouse effect," says co-author Philippe Ciais, Associate Director, Laboratory of Climate and Environmental Science, Paris, France.

Read more at Science Daily

Bronze-Age Donkey Sacrifice Found in Israel

Archaeologists in southern Israel say they've uncovered a young donkey that was carefully laid to rest on its side more than 3,500 years ago, complete with a copper bridle bit in its mouth and saddle bags on its back.

Its accessories -- and the lack of butchery marks on its bones -- lead researchers to believe the venerated pack animal was sacrificed and buried as part of a Bronze Age ritual.

Donkeys were valuable beasts of burden in the ancient Near East. Donkey caravans helped open up vast trade networks across the Levant and Anatolia in the 18th and 17th centuries B.C., according to archives from Amorite settlements like Mari in modern-day Syria. Ancient Egyptian inscriptions from around the same time show that hundreds of pack donkeys were used in large-scale expeditions to mining sites in the eastern desert and southern Sinai, researchers say.

The animals have even been associated with royalty. In 2003, paleoscientists discovered the skeletons of 10 donkeys nestled in three mud graves dating back 5,000 years ago when Egypt was just forming a state. The donkey skeletons were lying on their sides in graves at a burial complex of one of the first pharaohs at Abydos, Egypt.

The donkey found in Israel seems to have been symbolically important, too, though this particular animal likely was never made to do hard labor before its death, said a team headed by archaeologist Guy Bar-Oz, of Israel's University of Haifa.

The grave was found in a temple courtyard, in the heart of the sacred precinct of Tel Haror, a Middle Bronze Age city near Gaza that was fortified by massive ramparts and a deep moat and dates back from around 1700 B.C. to 1550 B.C.

The donkey, estimated to be about 4 years old, was laid on its left side with its limbs neatly bent, the researchers say, and a copper bridle bit, a mouthpiece used to help steer animals, was found in its mouth. Some parts of the bit were extensively worn and it likely wasn't functional at the time of the burial. But an examination of the donkey's teeth suggests it was never meant to be practical.

"The absence of any sign of bit wear on the lower premolars indicates that the animal was not ridden or driven with a bit for prolonged periods of time," the researchers write in a paper published online this week in the journal PLOS ONE. "Moreover, the young donkey was still in the process of shedding its teeth and permanent teeth were just erupting. Based on its age, the Haror donkey would probably have been too young to be a trained draught animal."

Read more at Discovery News