viernes, 31 de enero de 2014

Hundreds of Dead Animals Found at South Africa Airport

Animal-rights group says shipping containers were headed for U.S.' exotic pet trade

Miona Janeke, HO, NSPCA / AP
This photo released by National Society for the Prevention of Cruelty to Animals. (NSPCA), shows dead reptiles and amphibians on top of a metal table at the Johannesburg Zoo, South Africa, Wednesday, Jan. 29, 2014.

Hundreds of endangered animals were found dead in crates at a South African airport, animal inspectors said on Friday, after not receiving food or water for several days.

South Africa’s National Society for the Prevention of Cruelty to Animals was called to O.R. Tambo International Airport after an inspector noticed a “bad smell” during a typical cargo search on Jan. 29 at the Johannesburg’s main airport. Taking a closer look, inspectors opened two crates to find more than 1,600 reptiles and amphibians—including many endangered species of chameleons, lizards, geckos, toads and frogs—but not all of them were alive.

About one-fourth of the animals had died by the time they were discovered. “Many animals could not move or turn around in their containers. None had been provided with water which caused extreme dehydration in the surviving animals,” the NSPCA said in a statement.
The group believes they were traveling from Madagascar and destined for the United States’ exotic pet market. The surviving animals were taken to the Johannesburg Zoo, where they are receiving care.

A substantial number have stabilized, eating and drinking. There are about over 1,200 that have survived—others with irreparable damage,Brett Gardener, the zoo’s veterinarian, told the BBC. ”The boxes arrived on Tuesday morning and were scheduled to connect on a flight that evening. The flight was delayed indefinitely due to bad weather and attempts to put them in another flight failed.

The incident will be further investigated by the NSPCA and Department of Agriculture, Forestry and Fisheries.

Jan. 31, 2014

Watch: Jazz band serenades cows

An American jazz band entertains a group of moosic-loving cows in France.

BEEF SERENADE: This herd of cattle liked what it heard. (Photo: YouTube)

First it was mariachi for marine mammals, and now this — Dixieland for dairy cows.

The video below features U.S. jazz band the New Hot 5 performing "When the Saints Go Marching In" for an intrigued herd of cattle in Autrans, France. It started with just one band member blaring out a few notes, but quickly escalated as more and more cows stopped grazing and marched over to get a front-row seat.

Or maybe they just thought the song needed more cowbell. 

Via BuzzFeed 
Mon, Sep 12, 2011M

Biodiesel: The afterlife of oil

How could you dispose of your cooking oil when you're done cooking? The easiest thing to do might be to pour it down your drain -- but if you save it up and send it to a processing plant, it can gain useful new life as biodiesel, a biodegradable energy source which can run in diesel engines instead of refined petroleum. Natascia Radice describes the process of turning goop into good.

ORIGINAL: Science Dump
by Jur on Thu,

18 strange and beautiful hummingbird species

All photos: David Hemmings

Birds, bats, bees and other insects are all important pollinators, but hummingbirds seem to do the job with the most flare. They have that vibrant coloration, their rapier-like bills perfectly adapted to each species' flowery food source, their adorably tiny size, and of course their jaw-dropping flying abilities.

Wildlife photographer David Hemmings captures a diversity of species in his travels, but he is particularly good at capturing these tiny flying jewels, and has many incredibly beautiful species in his portfolio. For instance, there's the sword-billed hummingbird pictured above. This is the only species of bird with a beak longer than its body. And no wonder — wielding that beak can't be an easy task. The creature actually has to hold its bill pointed up in the air when perched to keep from tipping over. But the oddity also has a purpose. This hummingbird feeds on flowers with long corollas, so it has to reach deep to get to nectar. Even when you count that impressive beak, the hummingbird still averages less than 10 inches in length.

There are well more than 300 species of hummingbirds, 51 of which are considered threatened or endangered. There are so many, it's hard to pick favorites. But we gave it a try anyway. Here are 17 more examples of the diversity and wonder of hummingbirds:

Rufous breasted hummingbird: This species (pictured below) is a very picky eater. It will only eat from flowers that have a corolla (the whorl of petals that lead down into the nectaries) length and curvature exactly match that of its bill. Interestingly, the males and females have differently shaped bills, an evolutionary trait that researchers think cuts down on competition with each other for food sources.

Long-tailed sylph: The males of this species sport an amazingly long tail — so long that it hampers their flight and a male has to be a particularly strong and skilled flier to survive to breeding age. Females choose to mate with males with the longest tail feathers, since the length proves the male's level of strength and fitness.

Rufous-crested coquette: Coquettes are some of the smallest species of hummingbird, and the rufous-crested coquette measures only a little more than 2.5 inches in length and weight just under 3 grams. Now that's a featherweight!

Ruby topaz hummingbird: This species may look small and dainty but don't let their size fool you. Males will perch in conspicuous places, and aggressively defend their territories from competitors.

Anna's hummingbird: Those of us living along the western coast of North America will likely recognize the species below. This is the most common hummingbird along the Pacific Coast. And they have a fascinating courtship dance. Males will fly up to 130 feet in the sky and swoop down to Earth with alarming speed, making a chirp sound with their tail feathers before swooping back up to the sky again. You can see a video of the behavior here.

Booted racket-tail hummingbird: The male of this species has a pair of impressive tail feathers. The feathers extend well past his body and end in two iridescent racket-like flares. Many native flowering plants rely on this hummingbird species for pollination, since they can reach into the long tubular flowers that exclude bees or butterflies from access.
Many native and cultivated plants on whose flowers these birds feed heavily rely on them for pollination. The mostly tubular-shaped flowers actually exclude most bees and butterflies from feeding on them and, subsequently, from pollinating the plants. -
See more at:

Many native and cultivated plants on whose flowers these birds feed heavily rely on them for pollination. The mostly tubular-shaped flowers actually exclude most bees and butterflies from feeding on them and, subsequently, from pollinating the plants. -
See more at:

Many native and cultivated plants on whose flowers these birds feed heavily rely on them for pollination. The mostly tubular-shaped flowers actually exclude most bees and butterflies from feeding on them and, subsequently, from pollinating the plants. -
See more at:

Cinnamon hummingbird: This long-winged lovely gets its name from its light brown coloring on the underside of its body. Found in western Mexico down to northwestern Costa Rica, they thrive in dry forests, and are sometimes spotted as far north as Texas and the southwest U.S.

Green hermit hummingbird: This is one of the larger hummingbird species, measuring about 5.3 inches in body length. In this species, the males have shorter tails than the females, but they still proudly wiggle these white-tipped feathers during competitive displays with other males as they vie for female mates.

Rufous-tailed hummingbird: This is a common bird of riverbanks and woodlands, living everywhere from open country to the edges of forests, and even coffee plantations (yes, your morning coffee might have been pollinated by a rufous-tailed hummingbird!). Not only your coffee, but perhaps also the banana you're snacking on, since they also love visiting the flowers of banana trees. Highly aggressive about defending their feeding territory, they're usually the top hummingbird in an area.

Brown violetear hummingbird: Don't let the relatively drab coloring of this species fool you. They do sport some wonderfully colored iridescent feathers under their throats and of course, they have that speck of violet over their ears, hence their name. They can flare these purple feathers out in a beautiful display. They can be found in the canopy of rain forests, in tall second growth forests, and they also visit coffee plantations like the rufous-tailed hummingbird. Plantations that use shade growing methods help birds (and other native pollinators) thrive by providing both a food source and the shrubby habitat needed for shelter and breeding.

Green crowned brilliant hummingbird: This emerald bird is one of the larger hummingbird species and is found in highlands from Costa Rica to western Ecuador. Instead of hovering at flowers like most hummingbird species, the green crowned brilliant hummingbird actually perches while feeding.

Chestnut-breasted coronet: This hummingbird is admired for the striking contrast between its rufous-colored underbody and its bright green head and back. It also has a characteristic trait of holding its wings upright over its back for a few moments after landing on a new perch. It can be found on the eastern slopes of the Andes mountain range.
The Chestnut-breasted Coronet (Boissonneaua matthewsii) is a South American hummingbird that occurs naturally in the humid montane Andean forests in extreme southeastern Colombia, Ecuador and Peru (on the western slope south to Cajamarca, on eastern slope south to Cuzco. - See more at:

Snow capped hummingbird: We'll give you one guess as to how this species got its name. Despite its stand-out markings, it is a very difficult hummingbird species to find as they are extremely localized and do not visit feeders. Plus, they are only 2.5 inches long and weigh less than a penny — so looking for them is like looking for a moving flower among other flowers!

Snowcaps occur naturally in Honduras, Nicaragua, Costa Rica, as well as central and western Panama; but they are extremely localized and difficult to find.
They inhabit the Central American cloud forests; where they feed in humid montane evergreen forests. They are typically found high up in the canopy and along the edges of wet forest, as well as adjacent woodland.
The highest concentration occurs on the Caribbean mountain slopes, where they breed at heights of ~1,000 - 2,600 ft (300–800 m). After the breeding season, most will move down to the adjacent lowlands. However, some may move up to higher elevations to about 4,500 ft (1,400 m).
- See more at:

Ecuadorian hillstar: This species's name is apt, given that they live at high altitudes in the Andes, feeding along the slopes right up to the snowline. Because they live in such cold areas year-round, they save energy by taking shelter in protected roosts and going into torpor (lowered metabolic rate, heart rate, oxygen intake and body temperature) at night.

White-necked Jacobin hummingbird: It's hard to miss this species of hummingbird, with the bright white belly and tail of the males, and of course that dark blue head. Like many hummingbird species, the Jacobin feeds not only on nectar but also gets protein from small insects, which it catches by "hawking" or snatching in mid-air.

Velvet purple coronet: This incredibly beautiful bird may appear all black at first, but just wait until the light catches those iridescent feathers and you'll see flashes of vivid purple, blue and green. The underparts of its wings are also a contrasting chestnut color. No wonder it is called a flying jewel!

Green-throated mango hummingbird: This species loves mangrove and swamp forests, and can be found along a narrow strip of the Atlantic Coast along the north and south of the Amazon river outlet. Though not much is known about this species, it is known that the population occurring in Trinidad is now rare due to the loss of its preferred swamp and mangrove habitat.

ORIGINAL: Mother Nature Network
By Jaymi Heimbuch
Jan 14, 2014

The genetic contribution Neanderthal man made to modern humanity is clearer

Kissing cousins

HOW Neanderthal are you? That question sounds vaguely insulting. But unless you are African, or of recent African ancestry, the answer is likely to be 1-3%.

Though Homo sapiens is the only type of human around at the moment, that was not true until recently. Sixty thousand years ago, when modern humans first left Africa, they encountered other species of humanity, such as Neanderthals (imagined above, in an artist’s interpretation), in Europe and Asia. In some cases, they interbred with them. The genetic traces of those encounters remain in modern human genomes. And two studies, one just published in Nature, and one in Science, have now looked in detail at this miscegenation, and tried to understand its consequences.

The Nature study, conducted by Sriram Sankararaman of Harvard Medical School and his colleagues, looked at the genomes of 1,004 living people of European and Asian descent and compared them with Neanderthal DNA from a 50,000-year-old toe bone found in a Siberian cave, and also with the genomes of 176 west Africans. This latter group, Dr Sankararaman assumed, could have little Neanderthal DNA in them because Neanderthals, as far as can be determined from the fossil record, lived only in Europe and western Asia.

Dr Sankararaman and his colleagues certainly did find plenty of DNA which seems to have come from Neanderthals in their Eurasians. Tellingly, it was not sprinkled evenly throughout the modern human genome. That let them make educated guesses about the effects it is having on those who carry it. For instance, genes affecting the production of keratin—an important component of hair and skin—showed more Neanderthal influence than most. Neanderthals, whose homeland was much colder then than it is now because of the ice age, were hairier (and thus better insulated) than Homo sapiens. Retaining Neanderthal traits of this sort, in an African species that was trying to make good in sub-Arctic conditions, would thus be encouraged by natural selection.

More surprisingly, Dr Sankararaman also found Neanderthal DNA in genes associated with diabetes, Crohn’s disease, lupus and even the propensity to smoke. This does not necessarily mean such DNA was bad for those who inherited it. A gene which increases the risk of diabetes in modern circumstances of abundant food might, for example, have had benefits in a more austere environment.

Indeed, truly deleterious DNA would be expected to be noticeable by its absence, because natural selection would have worked to eliminate it in the 30,000 years since Neanderthals died out. And Dr Sankararaman found evidence for exactly that, as well.

There is, for example, little Neanderthal DNA on the X chromosome (which, along with the Y chromosome, determines an individual’s sex). Nor is there much in genes that are expressed in the testicles. Studies from other hybrid animals, which are frequently sterile, suggest genes which reduce male fertility are often found on the X chromosome. Since few things are a bigger evolutionary no-no than being unable to produce children, tremendous selective pressure would have existed to remove the offending DNA from the hybrid descendants of Neanderthals and Homo sapiens.

The study published in Science, by Benjamin Vernot and Joshua Akey of the University of Washington, in Seattle, reaches similar conclusions to Dr Sankararaman’s. Dr Vernot and Dr Akey hunted down Neanderthal DNA in the genomes of 665 Europeans and East Asians. They, too, found evidence of its having inserted itself into genes associated with the skin, and that not all of the newly arrived genetic material is helpful to its current bearers.

They made other discoveries, too. With the help of computer models, they concluded that there were probably several pulses of interbreeding over the millennia, rather than a steady stream of it. Both they and Dr Sankararaman also found that, on average, East Asians have more Neanderthal DNA than Europeans do—which is odd, because Neanderthals are not known to have lived in East Asia.

The ghost in the machine
Dr Vernot and Dr Akey also used their data to try to improve understanding of the Neanderthal genome itself, by combining the bits and bobs scattered among modern humans. Though both their study and Dr Sankararaman’s depended on being able to identify what was Neanderthal by comparing modern human genomes with fossil DNA, the fossil material available is imperfect. Looking at the exact sequence of DNA “letters” (the chemical bases which carry the genetic message) in areas identified as Neanderthal in modern genomes can therefore improve understanding of the Neanderthal original.

Crucially, though the amount of Neanderthal DNA in any individual is small, the exact bits vary a lot from person to person. Look at enough people, then, and it becomes possible to rebuild quite large swathes of the Neanderthal genome. Dr Vernot and Dr Akey reckon that from their sample of 665 they have recovered around 20% of it.

This is an impressive figure for an extinct species. It shows just how much the concept of a “species” is a construct of human thinking rather than a truly natural category. Technically, Neanderthals may be gone. But their DNA ghosts linger on.

From the print edition: Science and technology

ORIGINAL: The Economist
Feb 1st 2014

Influx of Snowy Owls Thrills and Baffles Birders

Launch media viewer Norman Smith, who runs the Snowy Owl Project for Mass Audubon, released a female snowy owl on a beach in Duxbury, Mass. Gretchen Ertl for The New York Times

DUXBURY, Mass. — The snowy owl seemed almost complacent, showing the confidence of a top predator whose bright yellow eyes suggested she might be sizing you up as a weaker combatant — or perhaps a large snack.

She had been where no bird should safely be — Logan International Airport in Boston — and now, regal and imposing even in brief captivity, she represented the latest of her kind to arrive in a remarkable and growing winter’s wandering to the Lower 48.

Not only is the Boston area seeing the largest number of snowy owls ever recorded, they are popping up in territory far from their usual habitat near the Arctic Circle. Ecstatic bird watchers have spotted them perched atop the Chesapeake Bay Bridge and in Washington (where one made headlines for being struck by a bus) , in Little Rock, Ark., and northern Florida — even in Bermuda.

This year’s been bizarre,” said Dan Haas, a birder in Maryland. “The numbers have been unprecedented. Historic.
 Related Coverage

The Lede: Tracking the Snowy Owl Migration in Real TimeDEC. 19, 2013

No one is sure why so many snowies are showing up in so many places — whether it can be attributed to more food in their Arctic habitats than usual, or climate change at the top of the world. Think about the canary in the coal mine,” said Henry Tepper, the president of Mass Audubon, “you think about the snowy owl in the Arctic.
Launch media viewer Patrick Castleberry, left, took photos of a snowy owl at Little Talbot Island State Park in Jacksonville, Fla. The very rare sighting of the owl in the area drew birders from miles around. Will Dickey/Florida Times-Union, via Associated Press

The big birds known as Bubo scandiacus reach a height of 20 to 27 inches and have a wingspan of 54 to 66 inches
. They can live more than 30 years in captivity, and have feathers that can range from mottled brown and white to pure white. They have their own movie star – Harry Potter’s Hedwig — and Internet meme, the image of a snowy asking the impertinent question “O RLY?” as in “Oh, really?”

It’s such a charismatic bird,” said David Sibley, the author and illustrator of a series of birding guides.

Sighting one, especially in an unexpected place, can be thrilling for birders. Georgeta Pourchot was apparently the first person to identify the Florida owl. She and her husband, Eric, were driving in late December from their home in Virginia through Florida on their Christmas vacation when she suggested they pull off at Little Talbot Island, near Jacksonville, to look for unusual birds: snow buntings, she thought, or a long-billed curlew.

Ms. Pourchot said as birders, she and her husband are “just beginners.” They scanned two beaches without seeing anything interesting. They encountered a park ranger, who suggested they look a little farther: “When you get to the other side of that ‘Do Not Enter’ sign, there’s a good view over there.

So they drove past the sign and parked. And as she got out of the car, Ms. Pourchot told her husband, “Babe, I think we have a snowy owl here!”

You’re kidding,” he replied, but acknowledged that while they might have been looking for the avian equivalent of a zebra, they had happened on a unicorn.

On Dec. 27, she posted her report to ebird, an online tracking system created by Cornell University’s department of ornithology and the National Audubon Society. The next day, members of the local Audubon chapter were doing their annual Christmas bird count when word spread, said Kevin E. Dailey, the leader of one team. The news was so exciting that volunteers left their assigned zones in search of the truly rare bird. “That’s kind of heresy to leave your count circle area,” he said.

Some people are less happy to encounter snowy owls — particularly, the managers of airports that the birds are drawn to. With wide open spaces and short grass, “the airports, to them, look more like the Arctic tundra than anything else,” said Norman Smith, who runs the Snowy Owl Project for Mass Audubon. The Port Authority of New York and New Jersey took heated criticism in December when it shot three snowy owls. Since then, the authority has tried trapping the birds, with limited success, and harassing them away from the airport by shooting off fireworks, said Ron Marsico, a spokesman for the Port Authority.

Mr. Smith had trapped the female owl at Logan one recent morning and had driven her here to the beach at Duxbury, about 40 miles southeast, for release into the wild, with hopes that she would continue heading south, away from the airport. In most years, Mr. Smith makes a trip from Logan to Duxbury or other release sites a half-dozen times. This year, however, the number has climbed above 75. “And the season is only half over,” he said.

When he released his grip on the owl’s legs, the bird flapped her broad wings and headed to the southwest, toward a small cluster of homes. Suddenly, another snowy owl sailed down from the houses and met the newcomer in midair, their talons locking. An aerial territorial skirmish followed as the two wheeled overhead, with the newcomer finally heading off to the west.

Ornithologists and bird watchers are not sure why the birds have come so far and in such great numbers this year. In decades of study, Mr. Smith said, “what I’ve learned is we know very little about this bird.” He suggests that the large population is the result of a bonanza of lemmings and other small rodents that snowy owls feed on, perhaps a consequence of the milder Arctic weather. That led to larger population of hatchlings that must spread farther and farther out to find territory of their own.

The lemming hypothesis does not satisfy Kevin J. McGowan, an ornithologist at Cornell. He noted that tiny transmitters placed on the owls have shown some of the birds do a surprising thing in winter: Instead of flying to the more temperate south, they fly farther north and scout the Arctic ice pack for pools of open water populated by sea ducks and other waterfowl.

Climate change
, which has been thawing Arctic ice so actively that new shipping routes are opening in the far north, could have disrupted the habitat,
Professor McGowan speculated. “That has to be one of the most vulnerable ecosystems on the planet. That’s going to be one of the first places that falls apart when there is warming in the atmosphere,” he said. This may have driven more of them south instead of north. A big shift in bird movement one year might just be a freak event, he said, or potentially “it’s the beginning of a pattern.

Whatever the reason for their abundance, the snowy visitors have brought attention beyond the usual core group of birders, said Mr. Sibley, the guide author. Mr. Sibley, who has released a print of one of his snowy owl illustrations to raise money for research, said that while it is good to see such excitement, “it would be great if that kind of attention could extend to less flashy birds, like the red cockaded woodpecker or the Henslow’s sparrow.

JAN. 31, 2014

This tree branch is actually a camouflaged bird standing really still

What are you looking at? Some trees, some leaves, a few branches and... a bird. You see, on top of that broken tree branch actually stands a completely still bird, the common potoo. It's hiding in plain sight and will stay that way even if predators are deathly close to them.

The common potoo stands so incredibly still it's hard to believe the bird is even alive. But the one you see above is well and is actually protecting her little chick hidden in the tree branch (you can see the little baby bird practicing its posture too). When it detects a predator nearby, it shoots its beak high up, squints its striking yellow eyes and stays completely straight. It's awesome to see. Jonny Tropics, the guy who posted this video, explains:

Potoos squint their eyes in order to not expose their bright yellow irises and give the game away while keeping track of potential predators. Fortunately for them, potoos have an amazing, subtle adaptation — slight notches in the eyelids, which are presumed to enable them to see even when their eyes are apparently closed.

It's hard to tell where the bird ends and where the broken branch begins.

Casey Chan on Sploid

jueves, 30 de enero de 2014

Scientists in US and Japan achieve possible breakthrough on stem cells

A lab treatment can turn a mouse's ordinary cells into stem cells, a surprising study has found. The research hints at a possible new way to grow tissue for treating illnesses such as diabetes and Parkinson's disease.

Scientists reported in this week's Nature journal that they had found a way to reprogram mature mouse cells into an embryonic-like state that allows them to generate many types of tissue. The research suggests that scientists could in the future similarly reprogram human cells, offering a simpler way to replace damaged cells or grow new organs for sick and injured people. The experiments, reported in two papers in the journal Nature on Wednesday, involved scientists from the RIKEN Center for Developmental Biology in Japan and Brigham and Women's Hospital and Harvard Medical School in the United States.

"It's very simple to do," said Dr. Charles Vacanti of Brigham and Women's Hospital in Boston. "I think you could do this actually in a college lab."

Vacanti acknowledged that the technique could conceivably provide a new potential route towards cloning people - a subject that remains highly controversial. He has no interest in doing that, he said, but "it is a concern."

'A wide range'

Researchers wrote that they allowed mature adult cells from the mice to multiply and then subjected them to stress "almost to the point of death" by exposing them to various events, including trauma, low oxygen levels and acidic environments. Within days, the scientists found that the cells had survived and recovered from the stressful stimulus by naturally reverting to a state similar to that of embryonic stem cells. The cells created by exposure to stresses - dubbed STAP cells by the researchers - then differentiated and matured into different types of cells and tissue depending on their environments.

Haruko Obokata, a scientist at the RIKEN Center for Developmental Biology in Kobe, Japan, and one of the study's co-authors, said that researchers had begun studying whether the technique might work with humans. By making stem cells from the patients themselves, doctors could get around the problem of transplant rejection.

"If we can work out the mechanisms by which differentiation states are maintained and lost, it could open up a wide range of possibilities for new research and applications using living cells," said Obokata, who led the work at RIKEN.

Many possible uses

Stem cells, the body's master cells, can develop into all other types of bodily cells. Scientists believe that, by helping to regenerate tissue, they could offer ways of tackling diseases for which only limited treatments currently exist - such as strokes, heart disease and Parkinson's. Two primary types of stem cells exist:
  • those harvested from embryos and 
  • adult or iPS cells, which scientists take from skin or blood and then reprogram back into stem cells.
Chris Mason, chair of regenerative medicine bioprocessing at University College London, called the study's approach "the most simple, lowest-cost and quickest method" to generate "pluripotent" cells - those able to develop into many different types - from mature cells.

"If it works in man, this could be the game changer that ultimately makes a wide range of cell therapies available using the patient's own cells as starting material," Mason said. "The age of personalized medicine would have finally arrived."

Earlier this year, German scientists reported their own research breakthough when looking at how to treat leukemia with stem cells.

mkg/msh (Reuters, AFP, AP)


miércoles, 29 de enero de 2014

Natural 3D Counterpart to Graphene Discovered in Arcane Form of Quantum Matter

The discovery of what is essentially a 3D version of graphene -- the 2D sheets of carbon through which electrons race at many times the speed at which they move through silicon -- promises exciting new things to come for the high-tech industry, including much faster transistors and far more compact hard drives. A collaboration of researchers at DOE's Berkeley Lab has discovered that sodium bismuthate can exist as a form of quantum matter called a three-dimensional topological Dirac semi-metal (3DTDS). This is the first experimental confirmation of 3D Dirac fermions in the interior or bulk of a material, a novel state that was only recently proposed by theorists.

Related Articles

Robust 3D Graphene Structures Curiously Created With Ancient Technique, Enabling Super-Capacitors

"A 3DTDS is a natural three-dimensional counterpart to graphene with similar or even better electron mobility and velocity," says Yulin Chen, a physicist with Berkeley Lab's Advanced Light Source (ALS) when he initiated the study that led to this discovery, and now with the University of Oxford.

"Because of its 3D Dirac fermions in the bulk, a 3DTDS also features intriguing non-saturating linear magnetoresistance that can be orders of magnitude higher than the materials now used in hard drives, and it opens the door to more efficient optical sensors." Chen is the corresponding author of a paper in Science reporting the discovery.

Two of the most exciting new materials in the world of high technology today are graphene and topological insulators, crystalline materials that are electrically insulating in the bulk but conducting on the surface. Both feature 2D Dirac fermions (fermions that aren't their own antiparticle), which give rise to extraordinary and highly coveted physical properties. Topological insulators also possess a unique electronic structure, in which bulk electrons behave like those in an insulator while surface electrons behave like those in graphene. 

(Photo : Roy Kaltschmidt)Beamline 10.0.1 at Berkeley Lab’s Advanced Light Source is optimized for the study of for electron structures and correlated electron systems.

"The swift development of graphene and topological insulators has raised questions as to whether there are 3D counterparts and other materials with unusual topology in their electronic structure," says Chen. "Our discovery answers both questions. In the sodium bismuthate we studied, the bulk conduction and valence bands touch only at discrete points and disperse linearly along all three momentum directions to form bulk 3D Dirac fermions. Furthermore, the topology of a 3DTSD electronic structure is also as unique as those of topological insulators."

The discovery was made at the Advanced Light Source (ALS), a DOE (U.S. Department of Energy) national user facility housed at Lawrence Berkeley National Laboratory, using beamline 10.0.1, which is optimized for electron structure studies. The collaborating research team first developed a special procedure to properly synthesize and transport the sodium bismuthate, a semi-metal compound identified as a strong 3DTDS candidate by co-authors Fang and Dai, theorists with the Chinese Academy of Sciences.

At ALS beamline 10.0.1, the collaborators determined the electronic structure of their material using Angle-Resolved Photoemission Spectroscopy (ARPES), in which x-rays striking a material surface or interface cause the photoemission of electrons at angles and kinetic energies that can be measured to obtain a detailed electronic spectrum.

Sodium bismuthate is too unstable to be used in devices without proper packaging, but it triggers the exploration for the development of other 3DTDS materials more suitable for everyday devices, a search that is already underway. Sodium bismuthate can also be used to demonstrate potential applications of 3DTDS systems, which offer some distinct advantages over graphene.

"A 3DTDS system could provide a significant improvement in efficiency in many applications over graphene because of its 3D volume," Chen says. "Also, preparing large-size atomically thin single domain graphene films is still a challenge. It could be easier to fabricate graphene-type devices for a wider range of applications from 3DTDS systems."

In addition, Chen says, a 3DTDS system also opens the door to other novel physical properties, such as giant diamagnetism that diverges when energy approaches the 3D Dirac point, quantum magnetoresistance in the bulk, unique Landau level structures under strong magnetic fields, and oscillating quantum spin Hall effects. All of these novel properties can be a boon for future electronic technologies. Future 3DTDS systems can also serve as an ideal platform for applications in spintronics. -- Source: Lawrence Berkeley Laboratory

Z. K. Liu, B. Zhou, Y. Zhang, Z. J. Wang, H. M. Weng, D. Prabhakaran, S.-K. Mo, Z. X. Shen, Z. Fang, X. Dai, Z. Hussain, Y. L. Chen. Discovery of a Three-Dimensional Topological Dirac Semimetal, Na3Bi. Science, 2014 DOI: 10.1126/science.124508

ORIGINAL:Science World Report
Jan 19, 2014

martes, 28 de enero de 2014

How to Change Education - from the ground up

World-renowned educationalist Sir Ken Robinson delivers the long-awaited follow-up to his now legendary Changing Education Paradigms talk.

He addresses the fundamental economic, cultural, social and personal purposes of education, and argues that education should be personalised to every student's talent, passion, and learning styles, and that creativity should be embedded in the culture of every single school.

Chair: Matthew Taylor, RSA chief executive.

Supported by Samsung Mobile

01 Jul 2013