This is a Simulation of a gravitationally unstable circumstellar disk by
means of hydrodynamic calculations. Protoplanetary 'embryo' form in the
disc thanks to gravitational fragmentation. The three small pictures
show the successive 'disappearance' of the lump by the star.
Stars are born inside a rotating cloud of interstellar gas and dust, which contracts to stellar densities thanks to its own gravity. Before finding itself on the star, however, most of the cloud lands onto a circumstellar disk forming around the star owing to conservation of angular momentum. The manner in which the material is transported through the disk onto the star, causing the star to grow in mass, has recently become a major research topic in astrophysics.
It turned out that stars may not accumulate their final mass steadily, as was previously thought, but in a series of violent events manifesting themselves as sharp stellar brightening. The young FU Orionis star in the constellation of Orion is the prototype example, which showed an increase in brightness by a factor of 250 over a time period of just one year, staying in this high-luminosity state now for almost a century.
One possible mechanism that can explain these brightening events was put forward 10 years ago by Eduard Vorobyov, now working at the Astrophysical Department of the Vienna University, in collaboration with Shantanu Basu from the University of Western Ontario, Canada.
According to their theory, stellar brightening can be caused by fragmentation due to gravitational instabilities in massive gaseous disks surrounding young stars, followed by migration of dense gaseous clumps onto the star. Like the process of throwing logs into a fireplace, these episodes of clump consumption release excess energy which causes the young star to brighten by a factor of hundreds to thousands. During each episode, the star is consuming the equivalent of one Earth mass every ten days. After this, it may take another several thousand years before another event occurs.
Eduard Vorobyov describes the process of clump formation in circumstellar disks followed by their migration onto the star as "cannibalism on astronomical scales." These clumps could have matured into giant planets such as Jupiter, but instead they were swallowed by the parental star. This invokes an interesting analogy with the Greek mythology, wherein Cronus, the leader of the first generation of Titans, ate up his newborn children (though failing to gobble up Zeus, who finally brought death upon his father).
With the advent of advanced observational instruments, such as SUBARU 8.2 meter optical-infrared telescope installed in Mauna Kea (Hawaii), it has become possible for the first time to test the model predictions. Using high-resolution, adaptive optics observations in the polarized light, an international group of astronomers led by Hauyu Liu from European Space Observatory (Garching, Germany) has verified the presence of the key features associated with the disk fragmentation model -- large-scale arms and arcs surrounding four young stars undergoing luminous outbursts, including the prototype FU Orionis star itself. The results of this study were accepted for publication in Science Advances -- a peer-review, open-access journal belonging to the Science publishing group.
US astronaut Edgar Mitchell, one of just 12 people to have walked on the moon, has died aged 85, his family and NASA said Friday, calling him a "pioneer."
NASA paid glowing tribute to Mitchell, who died in Florida after a brief illness late Thursday, the eve of the 45th anniversary of his lunar landing.
The late astronaut was a member of the 1971 Apollo 14 mission along with Alan Shepard Jr. and Stuart Roosa.
Mitchell was the last Apollo 14 survivor: Roosa died in 1994 and Shepard in 1998.
Speaking in a 1997 interview for NASA's oral history program, Mitchell said that he was drawn to spaceflight after president John F. Kennedy's call to send astronauts to the Moon.
"That's what I wanted because it was the bear going over the mountain to see what he could see, and what could you learn, and I've been devoted to that, to exploration, education and discovery since my earliest years, and that's what kept me going," Mitchell said.
NASA Administrator Charles Bolden recalled Mitchell marveling at the stunning view of Earth from space.
"Edgar spoke poetically about seeing our home planet from the Moon saying, 'Suddenly, from behind the rim of the Moon, in long, slow-motion moments of immense majesty, there emerges a sparkling blue and white jewel, a light, delicate sky-blue sphere laced with slowly swirling veils of white, rising gradually like a small pearl in a thick sea of black mystery.
"'It takes more than a moment to fully realize this is Earth... home.’"
Bolden added: "He is one of the pioneers in space exploration on whose shoulders we now stand."
Buzz Aldrin, the second person on the Moon, echoed that on Twitter, calling Mitchell a "lunar pioneer."
The Apollo 14 mission -- Mitchell's only spaceflight -- began when the trio blasted off from Cape Canaveral, Florida, on January 31, 1971.
Mitchell was in charge of piloting the Antares lunar module, which landed in the Fra Mauro region of the Moon.
It was the third manned mission to the Moon and Mitchell became the sixth human to walk on the lunar surface.
During the mission the astronauts collected 100 pounds (40 kilos) of lunar rock samples and carried out a series of experiments.
The mission ended when the astronauts, traveling aboard a space capsule, splashed down in the Pacific Ocean on February 9, 1971.
DNA evidence lifted from the ancient bones and teeth of people who lived in Europe from the Late Pleistocene to the early Holocene -- spanning almost 30,000 years of European prehistory -- has offered some surprises, according to researchers who report their findings in the Cell Press journal Current Biology on Feb. 4, 2016. Perhaps most notably, the evidence shows a major shift in the population around 14,500 years ago, during a period of severe climatic instability.
"We uncovered a completely unknown chapter of human history: a major population turnover in Europe at the end of the last Ice Age," says leading author Johannes Krause of the Max Planck Institute for the Science of Human History in Germany.
The researchers pieced this missing history together by reconstructing the mitochondrial genomes of 35 hunter-gatherer individuals who lived in Italy, Germany, Belgium, France, the Czech Republic, and Romania from 35,000 to 7,000 years ago. Mitochondria are organelles within cells that carry their own DNA and can be used to infer patterns of maternal ancestry.
"There has been a real lack of genetic data from this time period, so consequently we knew very little about the population structure or dynamics of the first modern humans in Europe," Krause says.
The new data show that the mitochondrial DNA of three individuals who lived in present-day Belgium and France before the coldest period in the last Ice Age -- the Last Glacial Maximum -- belonged to haplogroup M. This is remarkable because the M haplogroup is effectively absent in modern Europeans but is extremely common in modern Asian, Australasian, and Native American populations.
The absence of the M haplogroup and its presence in other parts of the world had previously led to the argument that non-African people dispersed on multiple occasions to spread across Eurasia and Australasia. The researchers say the discovery of this maternal lineage in Europe in the ancient past now suggests instead that all non-Africans dispersed rapidly from a single population, at a time they place around 50,000 years ago. Then, at some later stage, the M haplogroup was apparently lost from Europe.
"When the Last Glacial Maximum began around 25,000 years ago, hunter-gatherer populations retreated south to a number of putative refugia, and the consequent genetic bottleneck probably resulted in the loss of this haplogroup," explains first author of the study Cosimo Posth of Germany's University of Tübingen.
The researchers say their biggest surprise, however, was evidence of a major turnover of the population in Europe around 14,500 years ago, as the climate began to warm. "Our model suggests that during this period of climatic upheaval, the descendants of the hunter-gatherers who survived through the Last Glacial Maximum were largely replaced by a population from another source," says Adam Powell, another senior author at the Max Planck Institute for the Science of Human History.
Fourteen new species of tarantula have just been discovered in the southwestern U.S., including one named after the popular late singer-songwriter Johnny Cash.
The newfound spiders double the number of known tarantula species from the region, according to a study published in the journal ZooKeys.
“We often hear about how new species are being discovered from remote corners of the earth, but what is remarkable is that these spiders are in our own backyard,” Chris Hamilton, lead author of the study, said in a press release. “With the earth in the midst of a sixth mass extinction, it is astonishing how little we know about our planet’s biodiversity, even for charismatic groups such as tarantulas.”
Hamilton, a researcher at the Florida Museum of Natural History, and his team spent more than a decade searching for tarantulas throughout scorching deserts, frigid mountains, and other locations in the American Southwest, sometimes literally in the backyards of homeowners. The scientists also looked at specimens in museums.
Overall, the researchers studied nearly 3,000 specimens, undertaking what they say is the most comprehensive taxonomic study ever performed on a group of tarantulas.
Many of the leggy spiders look alike, so the researchers had to employ a combination of anatomical, behavioral, distributional, and genetic data to tell the different species apart from one another.
The results indicate there are 29 tarantula species in the United States, 14 of which are new to science. All belong to the genus Aphonopelma, but sizes can widely vary. Some reach 6 inches or more in leg span, while others are about the size of a quarter.
Johnny Cash the tarantula (Aphonopelma johnnycashi) was found near Folsom Prison, the subject of singer Cash’s song “Folsom Prison Blues.” The music star’s nickname, based on his distinctive dressing style, was the “man in black,” which led to another connection with his namesake spider. Mature males of the species are generally solid black in coloration.
Most of the newly discovered species are abundant and have relatively large distributions, but others have highly restricted distributions and could require conservation efforts to save them.
“Two of the new species are confined to single mountain ranges in southeastern Arizona, one of the United States’ biodiversity hotspots,” explained co-author Brent Hendrixson. “These fragile habitats are threatened by increased urbanization, recreation, and climate change. There is also some concern that these spiders will become popular in the pet trade due to their rarity, so we need to consider the impact that collectors may have on populations as well.”
The Internet loves conspiracy theories. Last December, silly claims that archaeologists in Austria unearthed a clay tablet with a cuneiform writing perfectly resembling a modern-day mobile phone went viral.
Now it’s time for another crazy theory.
Reports this week have resurrected a 2014 video from the YouTube channel “Still Speaking Out” which maintains that a modern-day laptop, complete with USB ports, is depicted on an ancient Greek grave marker.
Paranormal fans and conspiracy theorists went nuts: this is could be proof of time travel. The laptop would link in with none other than the Oracle of Delphi, they claimed.
“When I look at the sculpture I can’t help but think about the Oracle of Delphi, which was supposed to allow the priests to connect with the gods to retrieve advanced information and various aspects,” StillSpeakingOut said in the video.
Currently on display at the J. Paul Getty Museum in Malibu, Calif., the marble carving is titled “Grave Naiskos of an Enthroned Woman with an Attendant” and dates to about 100 B.C.
The relief, which is a little over 37 inches tall, depicts a woman sitting on a cushioned throne while a servant girl holds open a small box.
According to the museum, the rectangular object held by the servant is “the lid of a shallow chest.”
“The depiction of the deceased reaching out for an item held by a servant has a long history in Greek funerary art and probably alludes to the hope of continuing earthly pleasures in the afterlife,” the museum stated.
The dead woman must have come from a wealthy family, as revealed by the snake-bracelets on her upper and lower arms and the elaborate chair showing a leg decorated with lions’ paws and an eagle arm-support.
As for the young attendant, her clothes and hairstyle indicate she was a slave.
But according to StillSpeakingOut the earthly pleasures the deceased woman hoped to continue in the afterlife included the laptop she appears to reach toward, her eyes focused on the screen.
He noted that another picture taken by a random tourist from a better angle reveals the object is wide with a structure too narrow to be a jewel box.
“The claim is ridiculous as it is clearly a box,” classical archaeologist Dorothy Lobel King told Discovery News.
According to Janet Burnett Grossman, author of “Greek Funerary Sculpture: Catalogue of the Collections at the Getty Villa,” the relief was formerly in the collection of British statesman Sir William Fitzmaurice Petty, second Earl of Shelburne and first Marquess of Lansdowne, and most likely came from the Greek island of Delos.
Burnett Grossman described the woman in the relief as reaching out to touch “the lid of an open flat box or mirror held by a girl standing in front of her.”
You’re a mammal, so pat yourself on the back—no, not you, lizard people from outer space posing as high-ranking members of the US government. Mammals have got it made: Fur to keep you warm, milk to nourish your young, relatively big brains to keep you not dumb.
What you don’t have, though, is a venomous bite … unless you are in fact a lizard person from outer space. Or, better yet, a mysterious mammal called the solenodon. They’re one of just a handful of mammals with venom glands that deliver a powerful toxin. But wait, there’s more: The solenodon’s nose has a ball-and-socket joint like the human hip, making it crazy flexible. And a lady solenodon’s teats are … oddly placed. Let’s just leave it at that for now.
If you find yourself in the forests of Cuba or Hispaniola, take a deep breath. It might smell kind of like a goat: musky, earthy, maybe a bit like wet dog, definitely pungent. Now look at your feet. You might find strange conical holes in the dirt, with scratch marks ringing the edges.
Chances are you’re not far behind the aromatic wonder that is the solenodon. Foraging typically at night, it jams its long, highly mobile ball-and-socket schnoz into the soil to root around for invertebrates, things like worms and insects. Its many sensitive whiskers help it feel around the dirt, which is just as well because the solenodon ain’t got much going on in the eyesight department.
“They’ve got tiny little eyes and they don’t seem to have particularly good vision, although they’re really sensitive to light,” says ecologist Joe Nunez-Mino. While not many solenodons live in captivity, the ones Nunez-Mino has come across run like hell if you switch a light on. Clearly, this is an animal most comfortable dancing in the dark.
But should you be lucky enough to bump into a solenodon in the wild, you’re in for a treat. Mildly put, this is a singular mammal. It’s about as big as a large rat with a tail to match. (Looks kind of like a Rodent of Unusual Size, don’t it?) It’s got long, sharp nails and ambles with a wobbly, I’m-just-coming-off-anesthesia gait. Females with their young are particularly awkward. “The teats are sort of in the armpit of the rear legs, and sometimes the females will kind of run around dragging the babies,” Nunez-Mino says.
An adult solenodon at right with a juvenile at left. Between them are rocks of indeterminate age.
All laughing at the expense of the solenodon aside, please no touchy this animal if you happen to find one. Not just because solenodon is endangered, but because it has a venomous bite, an extreme rarity for a mammal. (Shrews have a venomous bite too, and male platypuses have venomous spurs on their hind legs, though the males only use these to fight each other.) Sitting underneath the solenodon’s lower incisors are salivary glands that send venom along grooves in its teeth. All the solenodon has to do is break the victim’s skin—or cuticle, in the case of insects—for the venom to get in there and work its magic.
From the few reports of human envenomations, it sounds like the experience is no picnic. Symptoms are similar to a snake bite, including localized swelling and severe pain, perhaps lasting several days. (Ask your doctor if solenodon venom is right for you!)
If you’re lucky, though, you’ll get what’s known as a dry bite—that is, the critter will nip you without producing venom. And that makes good sense from an energy perspective. Snakes know what’s up here: “Snakes quite often will bite and not inject venom because using venom is actually quite wasteful unless you really have to,” says Nunez-Mino.
Check out the solenodon’s tiny eyes. It’s pretty much the Howard Moon of the forest.
Even if you do get a dose of solenodon venom, you’re getting off easy. The venom incapacitates other victims like lizards, and in laboratory tests, scientists dosed mice with the venom and recorded breathing problems, convulsions, and paralysis. And the solenodon doesn’t stop at prey smaller than it. “There’s one report of a solenodon kept in captivity in London that ate an entire chicken,” says molecular biologist Rodrigo Ligabue Braun of Brazil’s Federal University of Rio Grande do Sul. “He bit a chicken and then ate all the parts he wanted.”
If the also-venomous shrews are any indication, the solenodon may not always be killing and consuming its prey outright. Shrews will often bite and incapacitate their victims, then drag them to their dens and come back later and gnaw on the comatose things. The solenodon may well do the same. (Oh relax—it’s not that bad in the grand scheme of things. The tarantula hawk is a wasp that stings, well, tarantulas, then drags them back to a den for its larva to devour it alive over the course of several weeks.)
Now the why. Why would the solenodon evolve venomousness while pretty much every mammal on Earth gets along fine without it? Well, it may not be the case of the solenodon evolving venomousness, as much as other mammals losing it.
Mammals have it made right now. But for tens of millions of years, puny little mammals spent the bulk of their time running away from dinosaurs. Many ancient mammals may have enlisted venom so they could better defend themselves.
But the game changed big time when the dinosaurs died out. “From an evolutionary point of view,” says Braun, “you’d be expending too much of your resources producing venom in an environment that did not have the same kind of prey or predators that it had before.” So it might have made sense for mammal lineages to evolve away from venomousness.
For whatever reason, though, solenodon held onto it. Indeed, solenodon is a truly ancient mammal, having diverged some 76 million years ago—not long (in evolutionary time, that is) before the dinos met their match in the form of an asteroid punching Earth right in the face. (Braun notes, though, that debate still swirls around the evolution of venom in mammals. It may be that venomousness was rare in early mammals, as it is today, and solenodon has just always been an oddity.)
While venom can land solenodon a meal and protect it from its natural enemies, it won’t do a lick of good against humans. Habitat destruction on Cuba and Hispaniola has hit the solenodon hard. Add to that the invasive species that humans have brought along and you’ve got a massacre.
Dogs in particular are a problem on Hispaniola, “although we’ve also recorded or heard of cases where the solenodon has bitten a dog and the dog has died from presumably the venom,” Nunez-Mino says. Feral cats, too, aren’t just a potential executioner, but competition: The felines target the lizards and large insects and such that the solenodon relies on to survive.
Scientists have discovered an insect that went extinct for more than 120 million years and featured many of the traits associated with modern butterflies including markings on the wing called eye spots.
Known as Kalligrammatid lacewings, paleobotanists for the past century have known they lived in Eurasia during the Mesozoic. But it’s taken recent discoveries of well-preserved fossils from two sites in northeastern China to demonstrate how similar they were to modern butterflies. Thanks to extensive lakes that limited oxygen exposure in these areas during mid-Jurassic through early Cretaceous time, paleontologists have been able to recover exquisitely preserved fossils that retain much of their original structure.
“Poor preservation of lacewing fossils had always stymied attempts to conduct a detailed morphological and ecological examination of the kalligrammatid,” Indiana University’s David Dilcher, who was part of the team that made the discovery published in the journal Proceedings of the Royal Society B, said in a statement. “Upon examining these new fossils, however, we’ve unraveled a surprisingly wide array of physical and ecological similarities between the fossil species and modern butterflies, which shared a common ancestor 320 million years ago.”
Dilcher, who also discovered the first flower last year, found that this insect from the Jurassic period survived in a manner similar their modern sister insects by visiting plants with “flower-like” reproductive organs producing nectar and pollen. They probably used their long tongues to probe nectar deep within the plant and also possessed hairy legs that allowed for carrying pollen from the male flower-like reproductive organs of one plant to the flower-like female reproductive organs of another.
Eventually, this system of pollination by long-tongued lacewings traveling between plants with exposed reproductive parts - called gymnosperms – gave way to more familiar system of insect pollinators and modern flowers, or angiosperms, in which the reproductive parts of the plants are contained with a protective seed.
This butterfly-like behavior is striking considering that modern butterflies didn’t appear on Earth for another 50 million years.
It is an example of what scientists call convergent evolution where two distantly related animals develop similar characteristics independently. In this case, the butterfly-like insect is an extinct “lacewing” of the genus kalligrammatid called Oregramma illecebrosa. Another genus of this insect – of the order Neuroptera – live on today and are commonly known as fishflies, owlflies or snakeflies.
“Here, we’ve got coevolution of plants with these animals due to their feeding behavior, and we’ve got coevolution of the lacewings and their predators,” Dilcher said. It’s building a web of life that is more and more complex.”
The researchers, which also included Conrad Labandeira, a curator at the Smithsonian Institution’s National Museum of Natural History, and Dong Ren of Capital Normal University in Beijing, China, where the fossils are housed, found that the Kalligrammatid lacewings probably were important pollinators during mid-Mesozoic times.
“Various features of the mouthparts all indicate that these things were sucking fluids from the reproductive structures of gymnosperm plants,” Labandeira said in a statement, of a finding that was confirmed by an analysis of material lingering within the food tube of one fossil, which was found to contain only carbon. Had the insect been feeding on blood, its final meal would have left traces of iron.
Researchers were also able to find the presence of scales on wings and mouthparts, which, like the scales on modern butterflies, likely contained pigments that gave the insects vibrant colors. Based on similarities between Kalligrammatid wing patterns and those found on modern nymphalid butterflies (a group that includes red admirals and painted ladies), Labandeira said Kalligrammatids might have been decorated with red or orange hues.
From there, researchers did a chemical composition of various regions of the Kalligrammatid’s patterned wings including the eyespots. In modern butterflies with eyespots such as the modern owl butterfly, the dark center of the mark is formed by a concentration of the pigment melanin. It seems the Kalligrammatids, too, had melanin at the center of their eyespots.
Four new species of deep-sea flatwormlike animals that look like deflated whoopee cushions and lack complex organs have helped solve a complicated puzzle about their group’s placement on the tree of life, scientists found.
The new study, representing 12 years of specimen collection and analysis, adds the new species to a group previously known by only a single species, and in doing so, provides a clearer picture of the evolutionary position these animals hold.
When describing the physical characteristics of these baggy marine creatures, “simple” doesn’t begin to do justice to how simple they are, as animals go. They have no recognizable face or limbs. Their bodies are blobs that look more like empty socks than animals, and are wrinkled by muscular folds and propelled by cilia. A mouth opening at one end leads to a gut sack, but there is no anal opening in the back end. They have no digestive system, no excretory system, no reproductive organs, but they probably don’t worry about that too much because they don’t have brains, either — just a neural network.
Surface appearances aside, this genus — Xenoturbella — has proved surprisingly difficult to position on the tree of life, ever since the first species, Xenoturbella bocki, was discovered in 1950, according to the study researchers. Scientists first classified it as a flatworm, and then, in the 1990s, suggested that it was a type of mollusk that had “degenerated,” losing its more developed features over time to reach a simpler form. This explanation placed Xenoturbella closer to vertebrates andechinoderms — the group of marine life that includes starfish and sea urchins — rather than in an earlier evolutionary location on a more distant branch from these more complex animals.
But new genetic data, with more than 1,000 genes sequenced from just one of the new species, disproves that Xenoturbellawas once complex, according to study lead author Greg Rouse, a marine biologist with the Scripps Institution of Oceanography, at the University of California at San Diego. “Our new analysis and that of another paper in the same issue of Nature using much more data overturns this idea, and supports the idea that Xenoturbella is simple,” Rouse told Live Science in an email. “Sequencing more than 1,000 genes of one of the species gave a large amount of data that could be directly compared with other animals,” he said.
The new species — X. hollanduram, X. monstrosa, X. profunda, and X. churro (named after the fried-dough dessert)—were found in diverse and remote deep-sea locations off the coasts of California and Mexico, the deepest of which, where X. produnda hugged the seafloor, was a hydrothermal vent 12,139 feet (3,700 meters) below the surface of the Gulf of California. The biggest species, X. monstrosa, measured 8 inches (20 centimeters) long, while tiny X. hollandorum was a mere 1 inch (2.5 centimeters) in length.
A prehistoric animal similar in appearance to a modern wildebeest had a "trumpet-like nasal passage" that enabled it to produce a unique array of calls, a new study has found.
The animal’s internal trumpet nasal passage has only been seen once before, in another beast that would seem to have little in common with this now-extinct hoofed mammal, Rusingoryx atopocranion.
"The nasal dome is a completely new structure for mammals — it doesn’t look like anything you could see in an animal that’s alive today," co-author Haley O’Brien of Ohio University, Athens, said in a press release. "The closest example would be hadrosaur dinosaurs with half-circle shaped crests that enclose the nasal passages themselves."
For the study, O’Brien, co-author Tyler Faith of the University of Queensland and colleagues analyzed the remains of Rusingoryx. The fossils were unearthed on Kenya’s Rusinga Island and date to the Late Pleistocene.
Faith explained that their curiosity was piqued in 2009, after they were told about a site called Bovid Hill. The hill had been so named because of an abundance of fossil Bovidae, the group including antelopes and buffaloes, eroding from its surface.
"After several years of collecting fossils from Bovid Hill, it became very clear that most of the fossils belonged to the poorly known species Rusingoryx atopocranion, described from the same site in 1983, and that we may be dealing with an entire herd that was somehow wiped out and buried at the site," Faith said.
The researchers also uncovered stone tools and butchered bone, strongly raising the possibility that early modern humans were responsible for the concentration of Rusingoryx skeletons. In 2011, study co-author Kirsten Jenkins of the University of Minnesota took charge of excavations, hoping to find more complete fossils and to establish why so many skeletons had ended up in that spot. Along the way, she found several intact skulls.
"I was astonished to see that [the skulls] looked unlike any antelope that I had ever seen–the only thing more surprising would have been fossil zebras with horns growing from their heads!" Faith said. "The anatomy was clearly remarkable."
Faith and O'Brien CT-scanned the remains, which revealed their inner structures. They immediately noticed the similarity to hadrosaur anatomy around the nose area.
The little-known hoofed mammals turned out to have a very unusual, trumpet-like nasal passage similar only to the nasal crests of lambeosaurine hadrosaur dinosaurs. These were duck-billed dinos that sported such prominent crests.
At first the scientists thought the hollow nasal dome might have had something to do with thermoregulation. After anatomical investigations and acoustical modeling, however, they now think the trumpet-like nasal tube may have allowed Rusingoryx to deepen its normal vocal calls.
Their calculations even suggest that the animals might have been able to call at levels very close to infrasound, such that other animals may not have been able to hear individuals in the herd calling back and forth to each other.
A rarely seen volcanic eruption on a sub-Antarctic island has been captured by a team of scientists sailing near the remote area.
Heard Island, about 2,500 miles (4,000 kilometers) southwest of Australia and just 600 miles (1,000 kilometers) north of the coast of Antarctica, is about 25 miles (40 kilometers) long and is dominated by an active volcano known as Big Ben. Volcanic activity at the spot has been known since 1881, and satellites recorded eruptions there in the 1990s and 2000s. However, because the island is remote and rarely visited, eye-witness accounts of such eruptions are few and far between.
Researchers and crew on board the Commonwealth Science and Industrial Research Organisation (CSIRO) ship Investigator witnessed the eruption during a University of Tasmania-led expedition to investigate whether iron from underwater volcanoes in the region exerts control on the dynamics of phytoplankton blooms and fertilization of the Southern Ocean.
“We saw vapor being emitted from the top of the volcano and we saw lava flows coming down the flank of Big Ben,” Professor Mike Coffin of the University of Tasmania’s Institute of Marine and Antarctic Studies, the voyage’s chief scientist, said. “This was a very exciting observation. There are very few ships that come to this part of the world and in fact the last geological expedition that landed on Heard Island was in 1987.”
If a material is thicker, it should be less transparent, right? It turns out that in Saturn’s rings, that’s not always the case. A new examination of the B ring shows that even though it’s the most opaque of Saturn’s rings, it’s not the densest one.
The puzzling result is not just isolated to this ring, either. Scientists have found similar results in other studies when looking at the gas giant’s other rings, NASA said. This latest research comes from using the Cassini spacecraft, which is slowly wrapping up investigations at Saturn since arriving there in 2004.
“Appearances can be deceiving,” said research co-author and Cassini co-investigator Phil Nicholson, at Cornell University in New York, in a NASA statement. “A good analogy is how a foggy meadow is much more opaque than a swimming pool, even though the pool is denser and contains a lot more water.”
The research team looked at the ring’s mass density by studying spiral density waves. These features appear when ring particles move under the influence of gravity — gravity from Saturn’s moons as well as the huge gas giant planet itself. Each wave’s structure depends on how dense it is, and the effect of gravity. Scientists now know that the B ring is less dense than it appears, but the full reason is still a mystery.
“It could be something associated with the size or density of individual particles, or it could have something to do with the structure of the rings,” stated Matthew Hedman, the study’s lead author and a Cassini participating scientist at the University of Idaho.
While Saturn’s rings are arguably the most spectacular in the solar system, it’s not the only planet with rings. Jupiter, Uranus and Neptune also have faint ring systems of their own. Maybe this implies different origin stories, but more study will be needed to figure this out for sure. NASA says Saturn’s rings — made up of billions of particles and pieces — are likely fragments of broken-up moons, comets or asteroids that were pulled apart under Saturn’s gravity.
The major features in Saturn’s rings are labelled in this image, which is cropped from a panoramic view of the planet.
Saturn’s B ring was studied before using Cassini’s composite infrared spectrometer, but this study took a bit of a different approach. Using visible and infrared light, the team looked at a bright star in between the rings. They also combined the results of multiple observations, making it possible to see even more subtle ring waves than before.
By looking at how dense the rings are, this could help scientists pin down the age of Saturn’s rings, which are considered relatively young compared with the more than 4.5 billion years the solar system has been around.
“A less massive ring would evolve faster than a ring containing more material, becoming darkened by dust from meteorites and other cosmic sources more quickly,” NASA wrote in the same statement. “Thus, the less massive the B ring is, the younger it might be — perhaps a few hundred million years instead of a few billion.”
Slavery is widespread among certain ants in the United States and has even altered the genetic and chemical diversity of enslaved ant victims, a new study finds.
Some bees, wasps, beetles, crickets and other creatures also either enslave or trick others to do their work, showing the behavior persists in nature. As for slave-making Polyergus breviceps ants, they have been benefiting from the arrangement for years.
Co-author Neil Tsutsui explained to Discovery News that these ants "are successful. They produce more ants who do this and the behavior spreads. Evolution proceeds in basically the same way as for any other trait."
"It's no more cruel than consuming other organisms as food, competing with another organism for resources, or the myriad other ways that organisms come into conflict in the natural world," added Tsutsui, who is a professor in the Department of Environmental Science, Policy & Management at the University of California, Berkeley.
He and co-author Candice Torres compared the chemical, genetic, and behavioral characteristics of enslaved and free-living colonies of the Formica altipetens ant, which is the target of Polyergus' slave-making.
They found the slaves were less aggressive toward non-nest mate ants than were their free-living counterparts. The findings, published in the journal PLOS ONE, suggest that slavery can dramatically change both the chemical and genetic context in which the kidnapped victims develop.
During the summer, Polyergus conducts raids on Formica colonies, explains Tsutsui. During the raids, workers from the slave-making species leave the colony as a group and attempt to steal Formica pupae. The attacked adults do their best to defend themselves and the ant babies.
"There are cases of enslaved ants putting up a vigorous fight to try and repel the slave-makers when their colonies are being raided," he said.
Once stolen, the victim babies are brought back to the Polyergus colony. The attackers then continue to raid different Formica colonies, creating a highly diverse group of victims. As they grow older, the victim ants perform nest maintenance, brood care and foraging for their slaveholders, not even realizing their predicament.
"The way that ants normally develop a sense of colony identity makes them vulnerable to this type of slave-making behavior," Tsutsui said. "Normally, young ants emerge from pupation and imprint on the odors around them. They then use the memory of these odors to figure out who is a member of their colony versus who is an ant from a different colony."
The victim ants have no idea that they are enslaved. They appear to believe that they are in their home colony.
The scientists suspect the system in ants first evolved many years ago, after an ancestor of Polyergus might have occasionally raided other ant colonies, retrieving the larvae and pupae for food. This could have led to some of the raided pupae emerging as adult worker ants that, believing nothing was amiss, toiled away for the attackers. This would have then enhanced the survival and reproduction of Polyergus ants that practiced the raiding, making the behavior more common over time.
There seems to be no benefit for the enslaved ants, but the slave-makers do experience some risks. Some are killed during the raids.
Michelangelo defied the painful arthritis that riddled his hands in the last 15 years of his life by carrying on working until his last days, a new study suggests.
The study relied on analysis of portraits of Michelangelo as well as on historic documents.
"There are no spectroscopic or X-ray images available, and for this reason, the careful observation of the portraits is the only method available today to interpret hand deformities," an international team of researchers wrote in the Journal of the Royal Society of Medicine.
The team included Davide Lazzeri and Manuel Francisco Castello, both specialists in plastic reconstructive and aesthetic surgery at the Villa Salaria Clinic, Rome, Donatella Lippi, director of the department of History of Medicine at Florence University, Marco Matucci-Cerinic, director of the division of rheumatology at Florence University, and George M.Weisz at the University of New South Wales, Sydney, Australia.
In particular, three paintings, which depict the artist between the ages of 60 and 65 show his left hand bearing signs of osteoarthritis, a painful joint disorder which today affects 9.6 per cent of men and 18 per cent of women aged over 60.
"A study of Michelangelo's biography and letters indeed supported the diagnosis of a degenerative osteoarthritis, possibly ruling out other possible diseases," lead author Lazzeri told Discovery News.
Several organic, psychological and behavioral disorders, ranging from lead intoxication to Asperger's disease, have been attributed to Michelangelo.
A large correspondence with Lionardo di Buonarroto Simoni, Michelangelo's nephew, reveals that the artist suffered from "gout," a general term of the period which included all arthritic conditions.
But according to the researchers, no signs of inflammation and no evidence of tophi, the small lumps of uric acid crystals that form under the skin of people with gout, could be detected in the artist's hands.
Lazzeri and colleagues estimate that Michelangelo (1475-1564) likely began experiencing the first symptoms of the disease between 1547 and 1553, when he worked on the Deposition, or Florentine Pietà. The extensive hammering and chiseling carried out during Michelangelo's younger years was likely responsible for the deformed hands in later life.
The disease progressed until his final, and unfinished work, the Rondanini Pietà.
By that time, the hands that carved David, designed St Peter's basilica and painted The Last Judgment in the Sistine Chapel, were twisted into deformed protrusions. Michelangelo was unable to write, and could only sign his letters.
Nevertheless, the master was seen hammering up to six days before his death on Feb. 18, 1564, three weeks before his 89th birthday.
According to the researchers, osteoarthritis affecting the small joints of Michelangelo's left hand can be first detected in a portrait by Florentine Mannerist painter Jacopino del Conte (1510–1598).
Dated 1535, the painting depicts Michelangelo when he was over 60. He looks tired and older than his age. His left hand is shown hanging, with apparent signs of a non-inflammatory articular disease.
The second painting by Daniele Ricciarelli, better known as da Volterra, is dated 1544 and is probably a copy of del Conte's work.
The third portrait, by Pompeo Caccini, was painted in 1595, 36 years after Michelangelo's death, and shows the artist's left hand in a claw-like posture.
Interpreted by contemporary historians as suggesting the artist's left-handedness, all three paintings "show Michelangelo's hand to be affected by degenerative arthritis," the researchers concluded.
"Michelangelo's difficulties with tasks such as writing may have resulted from stiffness of the thumb and the loss of the ability to abduct, flex and adduct it," Lazzeri and colleagues wrote.
They noted that the swellings at the base of the thumb and the swellings of the smaller joints of the thumb and index are not gouty in origin and can be interpreted as osteoarthritic nodules.
"The diagnosis of osteoarthritis offers one plausible explanation for Michelangelo's loss of dexterity in old age and emphasises his triumph over infirmity as he persisted in his work until his last days," Lazzeri said.
"Indeed, the continuous and intense work could have helped Michelangelo to keep the use of his hands for as long as possible," he added.
According to Francesco Galassi, a researcher at the Institute of Evolutionary Medicine at Zurich University who has long worked in the field of pathography, the study is "somehow interesting" but caution is needed.
The remains of 14 women believed to be of high status and importance have been found at Stonehenge, the iconic prehistoric monument in Wiltshire, England.
The discovery, along with other finds, supports the theory that Stonehenge functioned, at least for part of its long history, as a cremation cemetery for leaders and other noteworthy individuals, according to a report published in the latest issue of British Archaeology.
During the recent excavation, more women than men were found buried at Stonehenge, a fact that could change its present image.
"In almost every depiction of Stonehenge by artists and TV re-enactors we see lots of men, a man in charge, and few or no women," archaeologist Mike Pitts, who is the editor of British Archaeology and the author of the book "Hengeworld," told Discovery News.
"The archaeology now shows that as far as the burials go, women were as prominent there as men. This contrasts with the earlier burial mounds, where men seem to be more prominent."
Pitts added, "By definition -- cemeteries are rare, Stonehenge exceptional -- anyone buried at Stonehenge is likely to have been special in some way: high status families, possessors of special skills or knowledge, ritual or political leaders."
The recent excavation focused on what is known as Aubrey Hole 7, one of 56 chalk pits dug just outside of the stone circle and dating to the earliest phases of Stonehenge in the late fourth and early third millennium B.C.
Christie Willis of the University College London Institute of Archaeology worked on the project and confirmed that the remains of at least 14 females and nine males -- all young adults or older -- were found at the site. A barrage of high tech analysis techniques, such as CT scanning, was needed to study the remains, given that the individuals had been cremated.
Radiocarbon dating and other analysis of all known burials at Stonehenge reveal that they took place in several episodes from about 3100 B.C. to at least 2140 B.C. Long bone pins, thought to be hair pins, as well as a mace head made out of gneiss -- a striped stone associated with transformation -- have also been excavated at Stonehenge.
As for why no children’s remains were found during this latest excavation, both Willis and Pitts believe that such corpses must have been treated differently. Pitts suspects that infants and children were also cremated, but that their ashes were scattered in the nearby river Avon.
"There is a common association between late Neolithic religious centers and the sources or upper reaches of significant rivers," he explained.
Stonehenge’s location is also important because prior U.K. burial sites, which were often large mounds containing stone and timber chambers, tended to be erected on hilltops or other high ground, far away from where people lived.
The wind is so strong in Scotland that water is getting blown back up waterfalls, seemingly against the laws of gravity.
Footage shared by a cottage rental firm based in Mull, Scotland shows 90 mile per hour winds stopping a waterfall on the Isle of Mull dead in its tracks earlier this week.
The extraordinary winds are a product of Storm Henry, the latest windstorm of the season, which has prompted severe weather warnings and caused thousands of power outages this week.
While Henry’s waterfall-stopping powers were certainly impressive, the strongest recorded wind of the UK/Ireland windstorm season so far occurred on Jan. 29, when Storm Gertrude produced a blustery gust that reached speeds of 105 miles per hour.
Astronomers have found a protoplanetary disk surrounding a young star with a rather chilly secret: the planetary building blocks it contains are cold, so cold in fact that it doesn’t jive with current planetary formation models.
The star, called 2MASS J16281370-2431391, is located some 400 light-years from Earth in the Rho Ophiuchi star formation region. It is a stellar baby, sporting a stunning protoplanetary disk edge-on to us. The result is a glowing halo with a dark band in the middle and it’s this dark band that has surprised astronomers.
Its appearance looks like something out of a retro sci-fi comic book, earning 2MASS J16281370-2431391′s protoplanetary disk the far more palatable moniker “Flying Saucer.” When studying the Flying Saucer with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile and the IRAM 30-meter telescope in Spain, researchers detected something weird about the dust in the edge-on protoplanetary disk.
“This disc is not observed against a black and empty night sky. Instead it’s seen in silhouette in front of the glow of the Rho Ophiuchi Nebula. This diffuse glow is too extended to be detected by ALMA, but the disc absorbs it,” said Stephane Guilloteau, of the Laboratoire d’Astrophysique de Bordeaux, France, and study lead. “The resulting negative signal means that parts of the disc are colder than the background. The Earth is quite literally in the shadow of the Flying Saucer!”
Guilloteau’s team carried out the first ever direct measurements of the relatively large grains of dust in the Flying Saucer (measuring approximately one millimeter across), located around 15 billion kilometers (9 billion miles) from the star and found they had settled to a low temperature of -266 degrees Celsius — that’s only 7 degrees above absolute zero. These grains will eventually go on to form planets as the system matures, but current theoretical models predict this dust should be at least 10 to 15 degrees (−258 to −253 degrees Celsius) above absolute zero. Although still cold, in the field of planetary formation models, this discrepancy is huge.
“To work out the impact of this discovery on disc structure, we have to find what plausible dust properties can result in such low temperatures,” said co-author Emmanuel di Folco, also of Laboratoire d’Astrophysique de Bordeaux. “We have a few ideas — for example the temperature may depend on grain size, with the bigger grains cooler than the smaller ones. But it is too early to be sure.”
This may sound like a minor complication in the field of planetary science, but the temperature of the dust in protoplanetary disks can greatly impact the size and developmental characteristics of the planets that eventually form. Cooler dust, for example, could allow larger planets to coalesce closer to their parent star in compact protoplanetary disks.
A male daddy longlegs spider’s amorous moment some 99 million years ago in modern-day Burma was captured forever in amber, according to a new study reported in National Geographic.
Researchers from the Berlin Museum for Natural History conducted the study and say the find is the first to show an erect penis frozen in amber.
The ancient spider specimen (Halitherses grimaldii) is a harvestman, which differs from other arachnids in that it has a penis. Fossils of its kind have been found dating back about 400 million years, and today there are more than 6,000 species of the creature.
Researchers can never know exactly how the spider came to be stuck in resin on a tree in its state of excitement. And, missing is the object of the spider’s affection. Perhaps the spider trapped in amber and its lady friend became separated, the female making it out alive, the researchers speculate.
Or, study lead Jason Dunlop told National Geographic: “It might be the case that the animal was struggling as it was trapped in the tree resin, and that this caused the blood pressure to shoot up and the penis to become squeezed out accidentally.”
The study by Dunlop and his colleagues has been published in The Science of Nature.
Ravens can imagine being spied upon by a hidden competitor, showing a capacity for abstraction once thought to be exclusively human, according to a study released Tuesday.
In a clever set of experiments, scientists showed that the famously intelligent birds take extra care to hide food if they suspect their movements are being monitored by another raven, even when the second bird is not really there.
The findings, published in the journal Nature Communications, suggest that ravens — without recourse to direct observation — are able to understand what might be going on in the mind of another individual.
“This shows that traits that we consider ‘uniquely human’ may be found in animals too,” said lead author Thomas Bugnyar, a professor at the University of Vienna and a leading expert on social cognition in animals.
Over a six-month period scientists studied 10 ravens that had been raised in captivity.
The birds were placed in adjoining rooms divided by a window, that was initially left uncovered so one raven could watch while the other was given food to hide.
Researchers then covered the window, but left a peephole in it that the birds were taught they could see and be seen through.
Once this basic training was in place, the scientists played a recording of raven sounds while a bird was in the process of storing its food.
Only when the peephole was open, however, did the raven take extra care to hide its goodies. If the peephole remained closed, the bird — even when raven noises were audible — somehow concluded that it could not be spied upon.
Previous research, mainly with chimpanzees, has shown that non-human animals can understand what others are seeing.
But it was assumed that they did so by monitoring an individual’s head or eye movements, what scientists call “gaze cues.”
“It was still an open question whether any non-human animal can attribute the concept of ‘seeing’ without relying on behavioural cues,” the study noted.
Even without those cues, however, the ravens showed that they understood they were perhaps being watched, and changed their behaviour accordingly.
A unique ancient funerary boat has been unearthed near the Abusir pyramids, Egypt’s Antiquities Minister said in a statement.
The vessel dates to about 2550 B.C. and was discovered by archaeologists excavating a large mastaba, or ancient tomb, in a cemetery of the Old Kingdom officials in Abusir, south of the Giza plateau.
The 59-foot-long boat was found in the area south of the mud-brick tomb by a team of the Czech Institute of Archaeology at Charles University in Prague, led by excavation director Miroslav Bárta.
Covered with the wind-blown sand, the 4,500-year-old remains of the wooden vessel were lying on a bed of stone with ropes and wooden components still in their original position.
The wooden planks, joined with wooden pegs, were found intact. The desert sand preserved the plant fibers that covered the planking seams, while some of the ropes that bound the boat together were also found in their original position with all their details intact.
“It is by all means a remarkable discovery. The careful excavation and recording of the Abusir boat will make a considerable contribution to our understanding of ancient Egyptian watercraft and their place in funerary cult. And where there is one boat, there very well may be more,” Bárta said.
The exact meaning of ancient Egyptian funerary boats is not certain. According to some scholars they were intended as solar barques, used during the journey of the owner through the underworld. Others argue they were simply funerary offerings to be used by the deceased in the afterlife.
The Old Kingdom kings often had several boats buried within their pyramid complexes, but most of the pits have been found empty of any timber, or with little more than patterns of brown dust.
The only exception were the two boats of Khufu, the pharaoh who built the Great Pyramid at Giza. Found in a dismantled state, they are in the process of reconstruction.
The Abusir boat is the first vessel of significant dimensions from the Old Kingdom that has been found in a non-royal context, the archaeologists said.
“This is a highly unusual discovery since boats of such a size and construction were, during this period, reserved solely for top members of the society, who usually belonged to the royal family,” Bárta said.
Although the boat is located almost 40 feet south of the mastaba, its orientation, length, and the pottery collected from its interior, make a clear connection between the structure and the vessel.
A stone bowl discovered in one of the mastaba underground chambers bore the name of king Huni, the last pharaoh of the Third dynasty, thus dating the tomb to that time.
When the moon is high overhead at night, its gravity actually can reduce the amount of rainfall very slightly, new research reveals.
In an article for Geophysical Research Letters, University of Washington scientists Tsubasa Kohyama and John M. Wallace report that the moon causes the Earth’s atmosphere to bulge toward it. That causes the pressure, or weight of the atmosphere, on that side of the planet to go up, which in turn increases the temperature of air below.
Since warmer air can hold more moisture, the same parcels of air are now farther from their maximum moisture capacity, resulting in a slight dip in rainfall.
The researchers studied 15 years of data collected by NASA and the Japan Aerospace Exploration Agency’s Tropical Rainfall Measuring Mission satellite from 1998 to 2012. It proved that the rain is reduced by an amount that is measurable, though imperceptible to humans — a change of about 1 percent in the total rainfall variation.
“As far as I know, this is the first study to convincingly connect the tidal force of the moon with rainfall,” said Tsubasa Kohyama, a doctoral student in atmospheric sciences.
While the effect isn’t going to affect agriculture or alter weather forecasts, the knowledge is potentially beneficial to climate researchers, who can use it to test the physics behind their climate models.
The effect of the moon’s position on air pressure on Earth was first detected back in 1847, and researchers showed in 1932 that the moon could affect air temperature as well. A 2014 study by the same University of Washington researchers confirmed that air pressure on Earth varies with the position of the moon.
Wallace plans to conduct future studies to see whether certain types of rain storms, such as heavy downpours, are more susceptible to the moon’s position, and whether the moon has any effect on the frequency of storms.
Pluto's largest moon, Charon, is cloaked in darkness, with just a tiny sliver lit up by the distant sun, in a newly released photo.
NASA's New Horizons spacecraft captured the image on July 17, 2015, three days after the probe's historic flyby of Pluto. That close encounter brought New Horizons within just 7,800 miles (12,550 kilometers) of Pluto's surface; the night-side view of Charon, on the other hand, was taken from a distance of 1.9 million miles (3.1 million km), NASA officials said.
"Charon's nighttime landscapes are still faintly visible by light softly reflected off Pluto, just as 'Earthshine' lights up a new moon each month," agency officials wrote in a description of the image, which was released Friday (Jan. 22).
"Scientists on the New Horizons team are using this and similar images to map portions of Charon otherwise not visible during the flyby," the officials added. "This includes Charon's south pole — toward the top of this image — which entered polar night in 1989 and will not see sunlight again until 2107. Charon's polar temperatures drop to near absolute zero during this long winter."
At 753 miles (1,207 km) in diameter, Charon is more than half as wide as Pluto itself. The dwarf planet's other four moons — Nix, Hydra, Kerberos and Styx — are all tiny by comparison. For example, Nix and Hydra measure just 33 miles (54 km) and 27 miles (43 km), respectively, in their longest directions, while Styx and Kerberos are even smaller.
The $720 million New Horizons mission launched a decade ago, in January 2006. The probe is currently zooming toward a potential January 2019 flyby of a small object called 2014 MU69, which lies about 1 billion miles (1.6 billion km) beyond Pluto.
New Horizons will study 2014 MU69 up close, if NASA approves and funds a proposed extended mission. The spacecraft is also still beaming home the data and images it collected during the July 2015 flyby; this relay work should be done by this coming autumn, mission team members have said.
The quantity of data exchanged via communications networks around the globe is growing at a breathtaking rate. The volume of data for wired and mobile communications is currently increasing by 23% and 57% respectively every year. It is impossible to predict when this growth will end. This also means that all network components must constantly be made more efficient.
These components include so-called modulators, which convert the information that is originally available in electrical form into optical signals. Modulators are therefore nothing more than fast electrical switches that turn a laser signal on or off at the frequency of the incoming electrical signals. Modulators are installed in data centres in their thousands. However, they all have the disadvantage of being quite large. Measuring a few centimetres across, they take up a great deal of space when used in large numbers.
From micromodulators to nanomodulators
Six months ago, a working group led by Jürg Leuthold, Professor of Photonics and Communications already succeeded in proving that the technology could be made smaller and more energy-efficient. As part of that work, the researchers presented a micromodulator measuring just 10 micrometres across -- or 10,000 times smaller than modulators in commercial use.
Leuthold and his colleagues have now taken this to the next level by developing the world's smallest optical modulator. And this is probably as small as it can get: the component operates at the level of individual atoms. The footprint has therefore been further reduced by a factor of 1,000 if you include the switch together with the light guides. However, the switch itself is even smaller, with a size measured on the atomic scale. The team's latest development was recently presented in the journal Nano Letters.
In fact, the modulator is significantly smaller than the wavelength of light used in the system. In telecommunications, optical signals are transmitted using laser light with a wavelength of 1.55 micrometres. Normally, an optical device can not be smaller than the wavelength it should process. "Until recently, even I thought it was impossible for us to undercut this limit," stresses Leuthold.
New structure
But his senior scientist Alexandros Emboras proved the laws of optics wrong by successfully reconfiguring the construction of a modulator. This construction made it possible to penetrate the order of magnitude of individual atoms, even though the researchers were using light with a "standard wavelength."
Emboras's modulator consists of two tiny pads, one made of silver and the other of platinum, on top of an optical waveguide made of silicon. The two pads are arranged alongside each other at a distance of just a few nanometres, with a small bulge on the silver pad protruding into the gap and almost touching the platinum pad. Short circuit thanks to a silver atom
And here's how the modulator works: light entering from an optical fibre is guided to the entrance of the gap by the optical waveguide. Above the metallic surface, the light turns into a surface plasmon. A plasmon occurs when light transfers energy to electrons in the outermost atomic layer of the metal surface, causing the electrons to oscillate at the frequency of the incident light. These electron oscillations have a far smaller diameter than the ray of light itself. This allows them to enter the gap and pass through the bottleneck. On the other side of the gap, the electron oscillations can be converted back into optical signals.
If a voltage is now applied to the silver pad, a single silver atom or, at most, a few silver atoms move towards the tip of the point and position themselves at the end of it. This creates a short circuit between the silver and platinum pads, so that electrical current flows between them. This closes the loophole for the plasmon; the switch flips and the state changes from "on" to "off" or vice versa. As soon as the voltage falls below a certain threshold again, a silver atom moves back. The gap opens, the plasmon flows, and the switch is "on" again. This process can be repeated millions of times.
ETH Professor Mathieu Luisier, who participated in this study, simulated the system using a high-performance computer at the CSCS in Lugano. This allowed him to confirm that the short circuit at the tip of the silver point is brought about by a single atom. A truly digital signal
As the plasmon has no other options than to pass through the bottleneck either completely or not at all, this produces a truly digital signal -- a one or a zero. "This allows us to create a digital switch, as with a transistor. We have been looking for a solution like this for a long time," summarises Leuthold.
As yet, the modulator is not ready for series production. Although it has the advantage of operating at room temperature, unlike other devices that work using quantum effects at this order of magnitude, it still remains very slow for a modulator: so far, it only works for switching frequencies in the megahertz range or below. The ETH researchers want to fine-tune it for frequencies in the gigahertz to terahertz range.
The origin of matter in the universe has puzzled physicists for generations. Today, we know that matter only accounts for 5% of our universe; another 25% is constituted of dark matter. And the remaining 70% is made up of dark energy. Dark matter itself represents an unsolved riddle.
Physicists believe that such dark matter is composed of (as yet undefined) elementary particles that stick together thanks to gravitational force. In a study recently published in EPJ C, scientists from the CRESST-II research project use the so-called phonon-light technique to detect dark matter. They are the first to use a detection probe that operates with such a low trigger threshold, which yields suitable sensitivity levels to uncover the as-yet elusive particles responsible for dark matter.
Until quite recently, the so-called WIMP -- Weakly Interacting Massive Particle -- was the preferred candidate for a new elementary particle to explain dark matter. However, the asymmetric dark matter particle models have attracted more and more interest in the past few years. The experimental detection is no different from the scattering of two billiard balls, as the particle scatters on an atomic nucleus. The detection method is based on the fact that the scattering would heat up a calcium tungstate (CaWO4) crystal.
The challenge: the lighter the dark matter particle is, the smaller the energy deposited in the crystal is. Currently, no other direct dark matter search method has a threshold for nuclear recoils as low as 0.3 kiloelectronVolt (keV). As such, the CRESST-II team are the first to ever probe dark matter particle masses at such low mass scale (below one GeV/c^2-as far as 0.5GeV/c^2). The next-generation CRESST-III detector is currently being upgraded and promises to reach thresholds of 100 electronVolts (eV), following successful tests of prototypes.
Scientometrics research is the science of evaluating scientific performance. Physics methods designed to predict growth based on a scale-free network have rarely been applied to this field. Now, scientists in Poland have developed an analytical method using a previously developed agent-based model to predict the h-index, probably the most popular citation-based scientific measurement, using bibliometric data. They are the very first to succeed in developing an exact formula to calculate the number of external citations and self-citations for each paper written by an author. These findings have just been published in EPJ B by Barbara Zogala-Siudem from the Systems Research Institute, Polish Academy of Sciences, Warsaw, and colleagues. It opens the door to applying this growth analysis to social network users or citations from different scientific fields.
Knowing an author's overall number of papers and total number of citations helps compute an approximated value of their h-index, which was named after the American physicist J.E. Hirsch in 2005 and measures the overall number of a scientist's publications as well as their quality and number of citations.
In this study, the authors relied on rate equations, a complex systems physics tool. To establish the equations governing the growth of citation networks, they incorporated a rule called the preferential attachment rule. Although this rule has been known for over 50 years, it remained unclear until now how and why such rules matter to the growth of the h-index. The explanation came from incorporating the rule into agent-based models representing citation networks, otherwise known as the Ionescu-Chopard (IC) model.
This led to exact h-index predictions- just like with the IC model alone -- and enabled the authors to explain some underlying bibliometric phenomena. For example, they showed that the h-index can be further investigated using the aggregation theory. Lastly, they verified their results with data from real authors as well as numerical simulations.
Tiny pieces of plastic may endanger Pacific oysters by adversely affecting their reproduction, according to a new study. They may have similar effects on other marine bivalves, raising questions about their impacts on marine ecosystems more broadly.
The plastic pieces are known as microplastics are, which are defined as being anywhere from 5 mm in size to just 1 nanometer (0.000001 mm). Scientists refer to primary microplastics and secondary microplastics: the former are intentionally manufactured super-small, primarily used in cosmetics and personal care products, industrial scrubbers used for abrasive blast cleaning, microfibers used in textiles, and pellets used in plastic manufacturing processes; the latter are the result of larger pieces of plastic disintegrating over time.
Imagery of plastic pollution in the ocean often focuses on more visible impacts, such as trash that has become entangled around the neck of a marine mammal, or the appalling sight of vast amounts of plastic in the stomachs of seabirds on Midway Atoll. It is of course far harder to demonstrate the impacts of pollution that can not be seen, but those impacts are very real.
One of the great problems with microplastics is their ubiquity: It has been estimated that the ocean contains 5 trillion particles, totaling 250,000 tons, while a study last yearconcluded that 100,000 microbeads entered the ocean with each use of a personal cosmetic product that contained them. (The United States recently banned the production of personal care products containing microbeads from July 2017.) Just one cubic meter of ocean water may contain as many as 100,000 particles.
This is a problem particularly for filter feeding organisms such as mussels, sea cucumbers and some zooplankton, which may unintentionally consume large amounts of microplastics, which are often approximately the same size as their phytoplankton prey. Studies have shown that this can have adverse effects on those species’ energetics — unsurprisingly, as eating food-sized plastic is no substitute for eating actual food — as well as, in some cases, having immunological and neurological impacts. An additional concern is the leaching of chemical additives and pollutants from the microplastics.
The latest study, published today in the Proceedings of the National Academy of Sciences, examined the effects of microplastic exposure on reproductively active Pacific oysters — a species the study’s authors chose “because of its worldwide production, economic importance as seafood, and important role in estuarine and coastal habitats.”
The authors established a number of tanks of oysters, which they fed phytoplankton, and in half of the tanks also introduced microplastics. Oysters that were exposed to microplastics readily ingested particles that were similar in size to the phytoplankton and, after two months of exposure, produced fewer and smaller oocytes (cells from which ova grow) and slower sperm, compared with those that weren’t.
Furthermore, exposed oysters produced 41 percent fewer larvae, and those larvae grew at a slower rate and ultimately reached a size 18 percent smaller than larvae from the unexposed tanks.
The deep folds that give the adult human brain its wrinkled walnut appearance were Nature's solution to fitting a large, powerful processor into a small skull.
Like a piece of flat, square paper crumpled together to fit into a small, round hole, folding allows more neurons to be packed closer together, with shorter, faster connections between them.
While scientists have long understood why there are folds in the brain's outer layer, called the cerebral cortex or grey matter, the how has remained a mystery.
Do the creases develop as a result of genetic, biological or chemical signals? Or are they caused by physical forces?
On Monday, a team of researchers from the United States and Europe said the folds can be explained by physics -- a discovery that may have important implications for understanding certain brain disorders.
Folds in the cortex develop through buckling in weak spots which develop as the foetal brain grows, they said.
The brains of human foetuses are smooth for about the first 20 weeks, when folding begins and continues until the child is about 18 months old.
The surface area covered by the folded cortex is almost three times that of a smooth brain the size of our head, study co-author Lakshminarayanan Mahadevan from Harvard University in Massachusetts told AFP.
"The number, size, shape and position of neuronal cells during brain growth all lead to the expansion of the gray matter, known as the cortex, relative to the underlying white matter," he said by email.
"This puts the cortex under compression, leading to a mechanical instability that causes it to crease locally. This simple evolutionary innovation... allows for the thin but expansive cortex to be packed into a small volume, and is the dominant cause behind brain folding."
Mahadevan and a team used MRI scans of smooth foetus brains to build a three-dimensional gel model. They coated the surface with a thin layer of elastomer gel to represent the cortex.
To mimic brain growth, they immersed the gel brain in a solvent that was absorbed by the outer layer, causing it to swell relative to the deeper region.
Within minutes, folds started to appear that were remarkably similar in size and shape to the real thing, showing that the same process happened even though the model did not contain any living tissue.
"It looks like a real brain," said Mahadevan's colleague and fellow author Jun Young Chung.
A few other animals also have brain folds -- including chimpanzees, dolphins, elephants and pigs -- but the human brain is the wrinkliest of them all.
The physical explanation for brain folds was first proposed by Harvard scientists 40 years ago.
Now proven by Mahadevan's team, it was considered a controversial challenge at the time to the conventional wisdom that brain folds were created by purely biological, not physical, processes.
"While we are indeed moving forward in time, there is also always some
movement backwards, a kind of jiggling effect," Professor Vaccaro said.
New research from Griffith University's Centre for Quantum Dynamics is broadening perspectives on time and space.
In a paper published in the journal Proceedings of the Royal Society A, Associate Professor Joan Vaccaro challenges the long-held presumption that time evolution -- the incessant unfolding of the universe over time -- is an elemental part of Nature.
In the paper, entitled "Quantum asymmetry between time and space," she suggests there may be a deeper origin due to a difference between the two directions of time: to the future and to the past.
"If you want to know where the universe came from and where it's going, you need to know about time," says Associate Professor Vaccaro.
"Experiments on subatomic particles over the past 50 years ago show that Nature doesn't treat both directions of time equally.
"In particular, subatomic particles called K and B mesons behave slightly differently depending on the direction of time.
"When this subtle behaviour is included in a model of the universe, what we see is the universe changing from being fixed at one moment in time to continuously evolving.
"In other words, the subtle behaviour appears to be responsible for making the universe move forwards in time.
"Understanding how time evolution comes about in this way opens up a whole new view on the fundamental nature of time itself.
"It may even help us to better understand bizarre ideas such as travelling back in time."
According to the paper, an asymmetry exists between time and space in the sense that physical systems inevitably evolve over time whereas there is no corresponding ubiquitous translation over space.
This asymmetry, long presumed to be elemental, is represented by equations of motion and conservation laws that operate differently over time and space.
However, Associate Professor Vaccaro used a "sum-over-paths formalism" to demonstrate the possibility of a time and space symmetry, meaning the conventional view of time evolution would need to be revisited.
"In the connection between time and space, space is easier to understand because it's simply there. But time is forever forcing us towards the future," says Associate Professor Vaccaro.
Northwestern University researchers have developed a new hybrid polymer
with removable supramolecular compartments, shown in this molecular
model.
Imagine a polymer with removable parts that can deliver something to the environment and then be chemically regenerated to function again. Or a polymer that can lift weights, contracting and expanding the way muscles do.
These functions require polymers with both rigid and soft nano-sized compartments with extremely different properties that are organized in specific ways. A completely new hybrid polymer of this type has been developed by Northwestern University researchers that might one day be used in artificial muscles or other life-like materials; for delivery of drugs, biomolecules or other chemicals; in materials with self-repair capability; and for replaceable energy sources.
"We have created a surprising new polymer with nano-sized compartments that can be removed and chemically regenerated multiple times," said materials scientist Samuel I. Stupp, the senior author of the study.
"Some of the nanoscale compartments contain rigid conventional polymers, but others contain the so-called supramolecular polymers, which can respond rapidly to stimuli, be delivered to the environment and then be easily regenerated again in the same locations. The supramolecular soft compartments could be animated to generate polymers with the functions we see in living things," he said.
Stupp is director of Northwestern's Simpson Querrey Institute for BioNanotechnology. He is a leader in the fields of nanoscience and supramolecular self-assembly, the strategy used by biology to create highly functional ordered structures.
The hybrid polymer cleverly combines the two types of known polymers: those formed with strong covalent bonds and those formed with weak non-covalent bonds, well known as "supramolecular polymers." The integrated polymer offers two distinct "compartments" with which chemists and materials scientists can work to provide useful features.
The study will be published in the Jan. 29 issue of Science.
"Our discovery could transform the world of polymers and start a third chapter in their history: that of the 'hybrid polymer,'" Stupp said. "This would follow the first chapter of broadly useful covalent polymers, then the more recent emerging class of supramolecular polymers.
"We can create active or responsive materials not known previously by taking advantage of the compartments with weak non-covalent bonds, which should be highly dynamic like living things. Some forms of these polymers now under development in my laboratory behave like artificial muscles," he said.
Polymers get their power and features from their structure at the nanoscale. The covalent rigid skeleton of Stupp's first hybrid polymer has a cross-section shaped like a ninja star -- a hard core with arms spiraling out. In between the arms is the softer "life force" material. This is the area that can be animated, refreshed and recharged, features that could be useful in a range of valuable applications.
"The fascinating chemistry of the hybrid polymers is that growing the two types of polymers simultaneously generates a structure that is completely different from the two grown alone," Stupp said. "I can envision this new material being a super-smart patch for drug delivery, where you load the patch with different medications, and then reload it in the exact same compartments when the medicine is gone."
Stupp also is the Board of Trustees Professor of Materials Science and Engineering, Chemistry, Medicine and Biomedical Engineering and holds appointments in Northwestern University Feinberg School of Medicine, the McCormick School of Engineering and Applied Science and the Weinberg College of Arts and Sciences.
Stupp and his research team also discovered that the covalent polymerization that forms the rigid compartment is "catalyzed" by the supramolecular polymerization, thus yielding much higher molecular weight polymers.
The strongly bonded covalent compartment provides the skeleton, and the weakly bonded supramolecular compartment can wear away or be used up, depending on its function, and then be regenerated by adding small molecules. After the simultaneous polymerizations of covalent and non-covalent bonds, the two compartments end up bonded to each other, yielding a very long, perfectly shaped cylindrical filament.
To better understand the hybrid's underlying chemistry, Stupp and his team worked with George C. Schatz, a world-renowned theoretician and a Charles E. and Emma H. Morrison Professor of Chemistry at Northwestern. Schatz's computer simulations showed the two types of compartments are nicely integrated with hydrogen bonds, which are bonds that can be broken. Schatz is a co-author of the study.
