Rare Borneo Bay Cat Captured in Stunning Photo

An extremely elusive creature called a bay cat has been photographed in stunning detail in its native Borneo in Southeast Asia.

The new image, which was captured by a photographer working with the wildcat conservation organization Panthera, is one of the first high-resolution images taken of the enigmatic species. Previously, grainy camera-trap images were the main evidence of the cat's existence.

The bay cat, or Pardofelis badia, is a mysterious little wildcat that lives only on the island of Borneo, which includes the countries of Malaysia, Brunei and Indonesia. The diminutive hunters are smaller than the average house cat and have either ruddy chestnut or grayish coats. Their nocturnal nature and secretive demeanors, combined with a low population density, make sightings of the cats incredibly rare. Almost nothing is known about what they eat or how they reproduce.

Logging has threatened some of these cats' tropical forest habitats, and the creature is now listed as endangered by the International Union for Conservation of Nature. In the past, the elusive cats were only documented in poor-resolution camera-trap images first captured in 1998. In November 2013, another research team captured several camera-trap images of the cats, along with Sunda clouded leopards and marbled cats.

To find out more about the species, photographer Sebastian Kennerknecht and Andrew Hearn, a researcher at Oxford University's Wildlife Conservation Research Unit, went out into the rainforests of Borneo on the hunt for the bay cat. The team took two trips but managed to get just one photo of the cat.

"During the first trip, we were able to get pictures of a marbled cat and Sunda clouded leopards, but the bay cat proved elusive," Kennerknecht said in an email. "Only on the second trip did we get this single picture. It is of a grey phased male that Andrew has gotten on camera before."

Read more at Discovery News

Frog's Love Call Beckons Predators, Too

A frog's evening serenade beckons his would-be suitors but also summons competition from rivals and attracts predators, making dating a dangerous endeavor, international researchers said Thursday.

The tiny brown tungara frog, found in Central and South America, seeks out females by perching in a shallow pond and making a unique mating call that comes out as a series of whines and "chuck" sounds. A large vocal sac under his mouth inflates and deflates as he calls, causing ripples in the water.

Researchers from the United States, the Netherlands and Panama decided to study how these ripples affected competition among frogs and predation by local bats that eat frogs. They found that mating calls accompanied by ripples tended to arouse more competitive calls from nearby male frogs than calls that were sent out without making waves.

They also discovered that bats were using their own biological sonar abilities to find frogs in the dark via the pond ripples. Although the frogs have learned to stop calling if they glimpse a bat overhead, the tactic usually comes too late.

"Unfortunately for the frog, the water ripples created by his call do not also stop immediately," said lead author Wouter Halfwerk, a postdoctoral researcher at University of Texas at Austin.

"The ripples continue to emanate out for several seconds, creating a watery bull's-eye on the frog. Bats use the ripples, thereby beating the anti-predator strategy."

Read more at Discovery News

Prehistoric Inbred Dog Spread Cancer Worldwide

An inbred dog that lived about 11,000 years ago was ground zero for a form of canine cancer that spread via mating and is afflicting dogs around the world to this day, according to new research in the journal Science.

The cancer-canine transmissible venereal tumor (CTVT) is one of only two known transmissible cancers. The other is found among afflicted Tasmanian Devils. CTVT causes genital tumors and can be fatal, particularly in older dogs or those suffering from an immune system deficiency.

The cancer spread, in part, because it wasn’t always fatal. If afflicted dogs died before mating, the disease wouldn’t spread across generations.

To track down the cancer’s source, Elizabeth Murchison, from the Wellcome Trust Sanger Institute and the University of Cambridge, and her colleagues sequenced the genome for CTVT. It is now believed to be the world’s oldest continuously surviving cancer.

“The genome of this remarkable long-lived cancer has demonstrated that, given the right conditions, cancers can continue to survive for more than 10,000 years despite the accumulation of millions of mutations,” Murchison said in a press release.

Remarkably, the genome of the cancer carries at least 2 million mutations. This is many more than in most human cancers. (Most of those have anywhere from 1,000 to 5,000 mutations.) For the study, the researchers used one type of mutation, known to accumulate steadily over time as a “molecular clock,” to estimate that the cancer first arose 11,000 years ago.

The genome also contains clues about what the prehistoric, ground-zero dog looked like. The researchers think it resembled an Alaskan malamute or husky. It likely had a short, straight coat that was grey/born or black.

The genetic sequence could not determine if the dog was male or female, but the scientists could determine that this dog was inbred. That might have led to the cancer arising in the first place, but the first appearance of the disease is still a mystery at this point.

“We do not know why this particular individual gave rise to a transmissible cancer,” said Dr Murchison. “But it is fascinating to look back in time and reconstruct the identity of this ancient dog whose genome is still alive today in the cells of the cancer that it spawned.”

She thinks the cancer first existed in an isolated population, before rapidly spreading around the world in recent centuries.

“It spread around the world within the last 500 years,” she explained, “possibly carried by dogs accompanying seafarers on their global explorations during the dawn of the age of exploration.”

Read more at Discovery News

Bones Found in Scotland Linked to 19th-Century Serial Killers

Evidence linked to one of Edinburgh's most nefarious trade has emerged from the rear garden of a house in the Haymarket district, according to archaeologists who have linked humans remains unearthed more than a year ago to the body snatching era made infamous by Irish killers Burke and Hare.

Belonging to four adults and at least one child, the disarticulated remains -- about 60 bones -- feature small holes used to re-articulate the skeletons with wire. This suggests they were used for anatomical display, said experts at consultants GUARD Archaeology.

"The forensic archaeologist at GUARD also identified that some of the bones had very smooth shinny patches, suggesting that they had been handled many times," John Lawson, from the City of Edinburgh Council Archaeology Service, told Discovery News.

Indeed the remains date back to the early 19th century, when the Scottish capital was a world leader in the study of anatomy.

"Edinburgh's medical schools acquired human remains legally from hangings, unclaimed poor or, in fact, from illegally dug graves," Lawson said.

It was at that time, when demand for fresh bodies far outweighed supply, when Irish immigrants William Burke and William Hare began their grisly trade.

From 1827 until 1828 the infamous duo delivered at least 16 bodies to Dr Robert Knox, an anatomy lecturer who was meticulously and obsessively devoted to getting the very best bodies to illustrate specific aspects of human anatomy for his students.

Only the first of the bodies they sold to Knox died naturally. All the rest were murdered.

The pair lured poor people into Hare's lodging house, plying them with whiskey and beer. Then they killed the drunken, insensible victims by compressing their chest and covering their nose and mouth.

Later known as "burking," this method of suffocation left no suspicious homicide marks and provided the anatomy students with fresh, undamaged bodies.

Finally caught in 1828, the two men had different fates. Burke was hanged in front of a crowd estimated at 30,000 people, while Hare got immunity from prosecution in return for his testimony against his accomplice. No charges were ever brought against Knox.

Ironically, Burke's remains were handed over to the University of Edinburgh's medical school where he sold his victims. There, he was publicly dissected and anatomized in the name of science.

Although they are regarded as important relics of this period in Scottish history, the mysterious remains unearthed in the Edinburgh garden may have not passed at all through Burke and Hare’s hands.

"There were so many clandestine dissections and articulated skeletons in early 19th century Edinburgh that there really is no reason at all to trace every single cadaver back to Burke and Hare," Lisa Rosner, author of "The Anatomy Murders" and distinguished professor of history at Stockton College in New Jersey, told Discovery News.

Moreover, the crimes of the infamous duo were so well known that all their victims are believed to have been accounted for.

"The bodies they supplied weren't just any bodies. They were fresh, well-preserved cadavers, and it is extremely unlikely they ended up as articulated skeletons," Rosner said.

Considered as high-quality -- and high priced -- medical commodities, Burke and Hare's victims were given special treatment.

"We know from the documentary evidence that they were preserved in alcohol, or divided into sections and handed over to select students. No practical-minded anatomy lecturer would waste them to create an articulated skeleton," Rosner said.

Indeed, preparing a skeleton for anatomical display was a laborious process which involved soaking the corpse in a closed tub for about two months until all the skin and muscle fell off.

"Then, the preparer had to carefully dig out all the bones from the ‘putrid matter,’ and place them in a basin of pure water," Rosner said.

Once clean, the bones were left to dry for quite a long time during Scotland's summer months. Finally holes were drilled in so that brass or iron wires could hold the bones together.

Most likely, the Haymarket bones underwent the soaking in water treatment.

"That was the fate of second rate, often emaciated cadavers, or those whose soft parts were damaged by injury or disease," Rosner said.

Read more at Discovery News

Symbol of Jesus Graced Ancient Church Mosaic in Israel

Archaeologists in Israel have uncovered intricate mosaics on the floor of a 1,500-year-old Byzantine church, including one that bears a Christogram surrounded by birds.

The ruins were discovered during a salvage excavation ahead of a construction project in Aluma, a village about 30 miles (50 kilometers) south of Tel Aviv, the Israel Antiquities Authority (IAA) announced Wednesday (Jan. 22). Excavator Davida Eisenberg Degen said the team used an industrial digger to probe a mound at the site, and through a 10-foot (3 meters) hole, they could see the white tiles of an ancient mosaic.

Much of the church was revealed during excavations over the past month. The basilica was part of a local Byzantine settlement, but the archaeologists suspect it also served as a center of Christian worship for neighboring communities because it was next to the main road running between the ancient seaport city of Ashkelon in the west and Beit Guvrin and Jerusalem in the east.

"Usually a Byzantine village had a church, but the size of this church and its placement on the road makes it more important," Degen told LiveScience.

Remarkable finds

The excavators plan to keep working on the site for another week, but one of the most remarkable finds so far was a mosaic containing a Christogram, or a "type of monogram of the name of Jesus," Degen said.

At the time, Byzantine Christians wouldn't have put crosses on their mosaic floors so as to not step on the symbol of Christ, Degen explained.

The Christogram in the mosaic may look like a cross, but it's actually more like a "chi rho" symbol, which puts together the first two captial letters in the Greek word for Christ, and often looks like an X superimposed on a P.

There is an alpha and omega (the first and last letters of the Greek alphabet) on either side of the chi rho, which is another Christian symbol, as Christ was often described as the ""the beginning and the end."

Four birds also decorate the mosaic, and two of them are holding up a wreath to the top of the chi rho.

Inside the 72-by-39-foot (22-by-12-meter) basilica, archaeologists also found marble pillars and an open courtyard paved with a white mosaic floor, said Daniel Varga, director of the IAA's excavations.

Just off the courtyard, in the church's narthex, or lobby area, there is "a fine mosaic floor decorated with colored geometric designs" as well as a "twelve-row dedicatory inscription in Greek containing the names 'Mary' and 'Jesus', and the name of the person who funded the mosaic's construction," Varga said in a statement.

The mosaics in the main hall, or nave, meanwhile, are decorated with vine tendrils in the shape of 40 medallions, one of which contains the Christogram. Many of the other medallions contain botanical designs and animals such as a zebras, peacocks, leopards and wild boars, the excavators said. Three contain inscriptions commemorating two heads of the local regional church named Demetrios and Herakles.

Other discoveries

The archaeologists found traces of later occupation on top of the church, including early Islamic walls and Ottoman garbage pits. (Aluma is located near the Ottoman and later Palestinian village of Hatta.)

The excavations also revealed Byzantine glass vessels and a pottery workshop for making amphoras, cooking pots, kraters, bowls and oil lamps, IAA officials said.

To avoid building over ancient sites, archaeologists are often brought in for salvage digs ahead of construction projects like this one, sometimes yielding stunning discoveries. For instance, a "cultic" temple and traces of a 10,000-year-old house were discovered at Eshtaol west of Jerusalem in preparation for the widening of a road.

Read more at Discovery News

Ruins Near Pyramids Reveal Leopard Teeth, Calf Bones

The remains of a mansion that likely held high-ranking officials some 4,500 years ago have been discovered near Egypt's Giza Pyramids. Bones from young cattle and teeth from leopards suggest its residents ate and dressed like royalty.

Archaeologists excavating a city just 400 meters (1,312 feet) south of the Sphinx uncovered the house and nearby mound containing the hind limbs of young cattle, the seals of high-ranking officials, which were inscribed with titles like "the scribe of the royal box" and "the scribe of the royal school," and leopard teeth (but no leopard).

The house, containing at least 21 rooms, is part of a city that dates mainly to the time when the pyramid of Menkaure (the last of the Giza Pyramids) was being built.

"The other thing that is just amazing is almost all the cattle are under 10 months of age … they are eating veal," said Richard Redding, the chief research officer of Ancient Egypt Research Associates, at a recent symposium held here by the Society for the Study of Egyptian Antiquities.

From his sample of 100,000 bones from the nearby mound, Redding said he couldn't find a cow bone that was older than 18 months and found few examples of sheep and goat bones.

"We have very, very, high status individuals," said Redding, also a research scientist at the Kelsey Museum of Archaeology at the University of Michigan.

Leopard teeth

Besides cattle bones, the archaeologists found two leopard teeth in the house and another two in the nearby mound. They, however, found no leopard bones, leaving them with a puzzle.

Redding consulted ancient drawings that date to the Old Kingdom (the age when pyramid building was at its height), between 2649 and 2150 B.C. He found that some high-ranking individuals, including members of the royal family, wore leopard skin that still had the head attached. This would explain why they found teeth — which could have fallen out of the head — but no leopard bones.

High-ranking clergy known as "sem" priests were allowed to wear these leopard skins, and they could have been members of the royal house, noted Mark Lehner, the director of Ancient Egypt Research Associates, in an email to LiveScience.

Redding was also puzzled that many cattle hind bones, yet few forelimbs, were found. For some reason the people of the house avoided eating the forelimbs of the cattle. Again Redding turned to ancient drawings. There, he found numerous examples of scenes where people presented forelimbs as offerings to deities, but almost no examples of hind limbs being offered. As such, the people of this house were likely eating the remains of offerings.

Clues to a priestly complex

This discovery may help the archaeologists identify offering places and dwellings of ancient priests. Since the elite house is full of hind limbs (the remains of offerings), Redding suspects that bone deposits that contain mainly forelimbs would be located in places where the offerings were being made.

In 2011 Redding and his colleagues discovered what might be just such a place. Archaeologists call it the "silo building complex," and it is located near a monument dedicated to Queen Khentkawes, possibly a daughter of the pharaoh Menkaure.

"My analysis of the bones from the small excavations at (the building complex) in 2012, showed a strong bias towards forelimb elements — as to be expected in priestly garbage," Redding wrote in an email to LiveScience. "We will get larger samples this February, but right now my operating hypothesis is that the (complex) was occupied by royal cult priests."

Read more at Discovery News

Milk Drinking Still a Mystery

The mutation for milk-drinking evolved independently in different parts of the world over the last 10,000 years as a result of strong natural selection, but why was it so advantageous?

Among the more momentous developments in human evolution was the ability to digest milk beyond early childhood.

Mutations that enabled lifelong milk drinking appeared independently in several parts of the world over the last 7,500 years, according to growing evidence. And those genes spread rapidly. Today, about a third of adults around the world can drink milk without stomach problems, a trait known as lactase persistence.

But why was milk drinking so advantageous to humankind?

A new study debunks one leading theory: that milk provided a valuable source of vitamin D, which would’ve helped people absorb its calcium.

Newly analyzed human skeletons from an ancient site in Spain show that the milk-drinking gene spread just as rapidly in that sun-drenched climate as it did in other places, suggesting that milk must have been beneficial there for some reason other than its vitamin D content.

“Throughout the years, I have heard so many evolutionary hypotheses about lactase persistence because they are so fun to coin,” said Oddný Sverrisdóttir, an evolutionary biologist at the University of Uppsala in Sweden. “For decades now, people have hypothesized that it was because of lack of sunlight in the north of Europe that people would have had to supplement the lack of calcium and vitamin D by drinking milk.”

“Now, looking at this picture from Spain,” she said, “the calcium-assimilation hypothesis either didn’t affect the evolution of lactase persistence at all, or other forces were there as well.”

Sverrisdóttir has long been interested in how and why Europe’s early farmers began drinking milk, so she was excited when she got her hands on well-preserved samples of skeletal remains from eight people who lived in northeastern Spain about 5,000 years ago. That was well after the milk-drinking mutation had appeared in northern Europe, and she was eager to find out if those ancient Spaniards were drinking milk, too. So the first thing she did was test their DNA for lactase persistence.

“I thought at least one would have the mutation,” since so many of today’s Spanish adults can drink milk without health consequences, Sverrisdóttir said. “None did.”

To figure out whether the recent and rapid spread of lactase persistence in Spain was a fluke or if natural selection was at play, Sverrisdóttir and colleagues compared the mitochondrial DNA of modern Spaniards with the ancient samples. Mitochondrial DNA changes very slowly, making it ideal for tracing family trees over time.

And, the researchers report today in the journal Molecular Biology and Evolution, analyses showed that the ancient cave dwellers were indeed ancestors of people who live and frequently drink milk in Spain today.

Then, the team used computer simulations to see what kind of genetic shifts were necessary to get from a population where no one could digest milk past childhood to one where about a third of adults could drink it over the course of just 5,000 years.

Those simulations ruled out the possibility that the mutation reached its current level just by chance and instead showed that there was strong selection for it: Something gave people who had the milk-drinking gene a big advantage over people who didn’t.

But if it wasn’t the vitamin D that made milk so beneficial in sunny Spain, then what was it?

The new findings can’t answer that question, but Sverrisdóttir has a favorite theory. Early farmers were eating cheese and yogurt long before they could drink milk because fermented dairy products are easier to digest. But in times of famine, when crops failed and all of the processed dairy foods had been consumed, people would have turned to milk out of desperation.

Those who happened to have a lurking mutation that helped them digest it would’ve thrived while those who were lactose intolerant would’ve ended up with life-threatening diarrhea.

“During normal times, if you were well-fed and you had diarrhea for days, it wouldn’t matter much,” Sverrisdóttir said. “But if you were already starving, this would mean the difference between life and death. People would have not lived long enough to get their genes into the next generation. This was the new super-food for people who could tolerate it.”

Read more at Discovery News

Supernova Erupts in Nearby Galaxy M82

This morning I woke up with a jolt as I saw on Twitter that a supernova had been discovered in the relatively nearby galaxy M82. This is one of the best chances to observe a supernova for professional and amateur astronomers in the Northern Hemisphere in recent history!

Things in the night sky are fairly static thanks to the long, long timescales of most astrophysical phenomena. So a supernova, the death knoll of a star blowing itself apart, is jarring and exciting when it happens so close by.

11.4 million light-years away might not seem close-by, but by cosmological standards, that’s right next door. M82 is the nearest “starburst galaxy,” meaning that it is undergoing a high rate of star formation. Such sites are typically home to core-collapse supernovae, or the event where a massive star runs out of nuclear fuel and explodes. This supernova, however, is not that type.

The spectrum shows this to be a Type 1a supernova, or a white-dwarf supernova. These can happen anywhere there are old stars, since white dwarfs are the remnants of smaller stars that have run out of fuel and finished their main life cycles.

Type 1a supernovae have distinguished themselves in astronomy as “standard candles.” That is, their peak brightness is predictable based on observations of the light curve, or how the brightness changes with time. These white dwarfs probably detonate when they collect too much mass, getting closer and closer to the Chandrasekhar limit where they can’t support themselves anymore.

This predictability in brightness means that they can be used to accurately measure the distance to very distant galaxies. They are an important rung in the “cosmological distance ladder,” or the way we measure distances in astronomy, and were famously used in the discovery that our Universe’s expansion was accelerating due to dark energy.

Are all Type 1a supernovae really alike, though? There is evidence that the amount of heavy elements in the progenitor white dwarf can affect the brightness, introducing an uncertainty in distance calculations. These uncertainties haven’t been enough to overthrow indirect observations of dark energy, especially in light of other lines of evidence, but astronomers are always after more accuracy.

There is also some debate about the exact nature of a white dwarf supernova explosion. In one case, it may be a white dwarf collecting material from a nearby massive star, such as a red giant. However, it could also be the result of the in-spiral and collision of two white dwarfs. Having such a nearby explosion means we’ll get a much better look at the details in the way that Supernova 1987A is still giving us an amazing view of core-collapse supernovae.

Read more at Discovery News

Water Plume 'Unequivocally' Detected at Dwarf Planet Ceres

Astronomers analyzing data from the now defunct Herschel infrared space observatory have made a huge discovery deep inside the asteroid belt. Dwarf planet Ceres, the largest body in the region, is generating plumes of water vapor.

This exciting discovery by the European mission proves that the small world possesses significant quantities of water ice on its surface (or, indeed, below its surface) that gets heated by solar energy, causing it to erupt into space as a vapor. Ceres now joins a fascinating group of little worlds in the solar system that not only hold onto vast quantities of water ice, but also blasts water vapor into space. For example, water vapor plumes have recently been discovered around Jupiter’s moon Europa and Saturn’s moon Enceladus is famous for its water geysers.

“This is the first time water vapor has been unequivocally detected on Ceres or any other object in the asteroid belt and provides proof that Ceres has an icy surface and an atmosphere,” said Michael Küppers of the European Space Agency in Spain and lead author of a paper published today (Jan. 22) in the journal Nature.

Ceres has long fascinated astronomers since its discovery in 1801 by Italian priest, mathematician and astronomer Giuseppe Piazzi, and has been the target of various ground and space telescope campaigns.

Although a general idea as to the little world’s surface features and composition are known through fuzzy imagery, this is the first conclusive evidence of water vapor being emitted from Ceres. As the most massive asteroid in the asteroid belt that lies between Mars and Jupiter, the 590 mile (950 kilometer) wide object was promoted to dwarf planet status (the smallest dwarf planet in the solar system and closest dwarf planet to Earth) by the International Astronomical Union (IAU) in 2006. At the same time, Pluto was also reclassified — often considered a demotion — to a dwarf planet.

Famous to astronomers it may be, but you can’t beat actually sending a probe to get a closeup look of Ceres before we fully understand its true nature. And it just so happens that we’re in luck.

“We’ve got a spacecraft on the way to Ceres, so we don’t have to wait long before getting more context on this intriguing result, right from the source itself,” said Carol Raymond, deputy principal investigator for NASA’s Dawn spacecraft at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “Dawn will map the geology and chemistry of the surface in high-resolution, revealing the processes that drive the outgassing activity.”

Dawn will arrive in Ceres orbit in February 2015, the second massive asteroid on its tour of the inner solar system. Dawn left the orbit of protoplanet Vesta in September 2012 after orbiting that 525 kilometer (326 mile) wide object for a little over a year. And with this new historic discovery of water plumes around Ceres, Dawn has an exciting time ahead of it, observing not a static and barren world, but a dynamic and rich planetary body.

But before we can get up close and personal, do we know how Ceres is generating this water vapor?

Interestingly, of the four occasions that Herschel studied Ceres, one of those times the signature of water was not detected. This suggests that there may be some seasonal effect influencing the plume’s presence. Astronomers think that as Ceres reaches the closest part in its orbit to the sun, the more intense sunlight causes its icy surface to sublimate (i.e. turn straight from ice to vapor without transitioning through a liquid phase) at a rate of around 6 kilograms (13 pounds) per second. As the dwarf planet drifts further away, little vapor is generated due to a reduction in solar energy.

Herschel also noticed a short term variation in the water plume signal. As Ceres rotates, the water signal rotates with it, suggesting there are discrete regions on the world’s surface generating the plumes. In fact, the astronomers have been able to link the water plumes with two darker regions on the surface that were first observed by Hubble. The regions, which are 5 percent darker than the Ceres average, could be absorbing more sunlight, causing the ice to heat up faster and generating the water vapor plumes more readily.

Another idea proposed by planetary scientists is that the vapor could be produced by cryovolcanoes or geysers from cracks int he surface, liberating reserves of water ice from below the surface. Fortunately, we just have to wait for a year until we find out from Dawn.

This discovery has a far-reaching impact. For starters, scientists are finding that the definition of a comet and an asteroid is becoming more and more blurred with the discoveries of “hybrid” objects that possess qualities of both. Perhaps Ceres, a huge asteroid, also has an aptitude for presenting comet-like features. But above all, this finding adds another fascinating twist to our understanding of the prevalence of water throughout our solar system, possibly shedding more light on how Earth acquired so much of the wet stuff.

Read more at Discovery News

Seeing Things: A New Transparent Display System Could Provide Heads-Up Data

Transparent displays have a variety of potential applications -- such as the ability to see navigation or dashboard information while looking through the windshield of a car or plane, or to project video onto a window or a pair of eyeglasses. A number of technologies have been developed for such displays, but all have limitations.

Now, researchers at MIT have come up with a new approach that can have significant advantages over existing systems, at least for certain kinds of applications: a wide viewing angle, simplicity of manufacture, and potentially low cost and scalability.

The innovative system is described in a paper published this week in the journal Nature Communications, co-authored by MIT professors Marin Soljačić and John Joannopoulos, graduate student Chia Wei Hsu, and four others.

Many current "heads-up" display systems use a mirror or beam-splitter to project an image directly into the user's eyes, making it appear that the display is hovering in space somewhere in front of him. But such systems are extremely limited in their angle of view: The eyes must be in exactly the right position in order to see the image at all. With the new system, the image appears on the glass itself, and can be seen from a wide array of angles.

Other transparent displays use electronics directly integrated into the glass: organic light-emitting diodes for the display, and transparent electronics to control them. But such systems are complex and expensive, and their transparency is limited.

The secret to the new system: Nanoparticles are embedded in the transparent material. These tiny particles can be tuned to scatter only certain wavelengths, or colors, or light, while letting all the rest pass right through. That means the glass remains transparent enough to see colors and shapes clearly through it, while a single-color display is clearly visible on the glass.

To demonstrate the system, the team projected a blue image in front of a scene containing cups of several colors, all of which can clearly be seen through the projected image.

While the team's demonstration used silver nanoparticles -- each about 60 nanometers across -- that produce a blue image, they say it should be possible to create full-color display images using the same technique. Three colors (red, green, and blue) are enough to produce what we perceive as full-color, and each of the three colors would still show only a very narrow spectral band, allowing all other hues to pass through freely.

"The glass will look almost perfectly transparent," Soljačić says, "because most light is not of that precise wavelength" that the nanoparticles are designed to scatter. That scattering allows the projected image to be seen in much the same way that smoke in the air can reveal the presence of a laser beam passing through it.

Such displays might be used, for example, to project images onto store windows while still allowing passersby to see clearly the merchandise on display inside, or to provide heads-up windshield displays for drivers or pilots, regardless of viewing angle.

Soljačić says that his group's demonstration is just a proof-of-concept, and that much work remains to optimize the performance of the system. Silver nanoparticles, which are commercially available, were selected for the initial testing because it was "something we could do very simply and cheaply," Soljačić says. The team's promising results, even without any attempt to optimize the materials, "gives us encouragement that you could make this work better," he says.

The particles could be incorporated in a thin, inexpensive plastic coating applied to the glass, much as tinting is applied to car windows. This would work with commercially available laser projectors or conventional projectors that produce the specified color.

Read more at Science Daily