A new paper by a team of researchers led by Karel Matous, College of Engineering Associate Professor of Computational Mechanics in the Department of Aerospace and Mechanical Engineering at the University of Notre Dame, describes how an accurate statistical description of heterogeneous particulate materials, which is used within statistical micromechanics theories, governs the overall thermo-mechanical properties. This detailed statistical description was computed using a novel adaptive interpolation/integration scheme on the nation's largest parallel supercomputers. Quantifying the morphology of many-body systems has applications in many scientific fields at a variety of length scales from molecular configurations up to structural composites and celestial bodies.
"For centuries, great minds like Kepler, Maxwell and Einstein have investigated the statistical characterization of many-body systems and the implications of small-scale structures on the macroscopic transport and mechanical properties," Matous said. "For the first time, we predicted the properties of granular Platonic solids (crystalline) packs and discovered a significant shape effect in their overall thermo-mechanical behavior. Based on our work, a large class of materials with arbitrary inclusions can now be easily studied."
The research is part of the Matous group's data-driven (image-based) multi-scale modeling strategy, where computations are guided by micro-structural experimental data.
"In my research, I study heterogeneous and multifunctional materials in extreme environments by computational and experimental means," Matous said. "These materials are essential in our daily lives and are utilized in bioengineering, the automotive and aerospace industries, micro-electro-mechanical systems (MEMS) and other applications. Heterogeneous multifunctional materials fill several pivotal roles, including structural support, self-healing capability, power generation and storage, stress mitigation and bio-filtration, just to name a few.
"These seemingly simple and elegant material functions are governed by a plethora of physics, mechanics and chemistry that test our understanding of microstructure-statistics-property relations and our capacity to tune properties at will. Many of these materials can be better understood if higher-order statistical information is retained in their well-resolved multi-scale analysis. My goal is to advance detailed understanding of mechanics and materials science through developing microstructure-statistics-property relations that can aid the development of new materials."
Matous notes that the next step in this line of work is to understand the effect of material interfaces and anisotropy (directionally dependent material behavior).
Read more at Science Daily
Apr 18, 2015
Changes in the functional connections between neurons -- 'synapses' -- contribute to our ability to adapt to environmental changes. However until now, little was known about the signalling underlying such 'synaptic plasticity'. Now, investigations of fruit flies by researchers at the German Center for Neurodegenerative Diseases (DZNE), Tokyo Tech, the National Institute of Genetics in Japan, and the European Neuroscience Institute in Germany reveal details of the mechanisms behind synaptic plasticity.
"The synaptic changes that we have identified might reflect an innate neuronal property that leads to protection from excessive stimuli," explains Dr. Atsushi Sugie, the study's lead author and Postdoc at DZNE. "By enhancing this property, we might be able to protect neurons from degeneration or cell death."
Recent studies have suggested that changes in a region at the presynaptic membrane, described as the active zone, control synapse function. The research teams based in Germany and Japan exposed living fruit flies -- the commonly studied Drosophila -- to different light regimes and then compared the active zones in the photoreceptors.
T-shaped structures at the presynaptic membrane tether synaptic vesicles and control the release of neurotransmitters to the postsynaptic neuron. By tagging proteins that are crucial to these T-shaped structures the researchers revealed a drop in a subset of active zone proteins, while others remained unchanged. Further, they found that corresponding to the loss of structural proteins, the number of T-shaped structures was also reduced.
Read more at Science Daily
Apr 17, 2015
Until this year, scientists hadn't seen the Bouvier's red colobus monkey in the wild since the 1970s. The small primate lives in groups in swampy forests along the Congo River, in the Republic of the Congo. Hunting and logging decimated its population, leading some scientists to suggest the monkey was extinct.
Now, independent explorers have rediscovered the rare monkey. The researchers, Lieven Devreese of Belgium and Gaël Elie Gnondo Gobolo of the Republic of the Congo, set off in February to track down the elusive species. Their expedition was supported by donations collected through the crowdfunding website Indiegogo, and funding from the Wildlife Conservation Society.
"Our photos are the world's first [of the monkey], and confirm that the species is not extinct," Devreese said in a statement.
There are several species of red colobus monkey. Until now, scientists only knew of the Bouvier's red species from a few museum specimens collected more than 100 years ago.
This particular colobus monkey shows little fear of humans — one reason it is so vulnerable to bushmeat hunters. Instead of fleeing hunters or curious scientists, the monkeys gaze at them from the trees. This makes the large groups easy pickings for the bushmeat trade, according to the Wildlife Conservation Society.
"Thankfully, many of these colobus monkeys live in the recently gazetted national park and are protected from threats such as logging, agriculture and roads, all of which can lead to increased hunting," Fiona Maisels, a biologist and expert on Central Africa for the Wildlife Conservation Society, said in the statement.
To find the Bouvier's red colobus monkey, Devreese and Gobolo asked locals to describe local monkeys and their calls. This helped narrow down where remaining colobus groups might live. The researchers started in the town of Owando, and then hired a dugout canoe in Makoua to traverse the Likouala River.
Read more at Discovery News
The grave likely belonged to a wealthy individual, said Keith Fitzpatrick-Matthews, the archaeology and outreach officer for the North Hertfordshire District Council. Once Fitzpatrick-Matthews and his colleagues located the grave, they also found evidence of a nearby building, likely a shrine or temple, attached to a villa.
The man with the metal detector, Phil Kirk, found the grave in a field in Kelshall, a small village located between London and Cambridge. He had once found a Roman coin in the same field, and had a hunch that there were more Roman artifacts nearby, Fitzpatrick-Matthews said.
In October 2014, Kirk hit the jackpot. His metal detector led him to a buried bronze jug that stood roughly 10 inches (25 centimeters) tall. Next, he pulled out a bronze patera (a dish used for pouring wine or blood libations) and two other jugs.
Elated with what he had found, Kirk contacted local experts and told them about the findings. They returned to the spot later that month and in November and found even more artifacts: a bronze pin, an iron lamp, glassware and bottles of different shapes, including octagonal, hexagonal, rectangular and square, Fitzpatrick-Matthews said.
The hexagonal bottle held an unusual and macabre surprise.
"It quickly became apparent that the large hexagonal bottle was stuffed full with cremated bone," said Fitzpatrick-Matthews, who hadn't realized they were digging into a grave. "Suddenly, that explained everything. We were looking at a wealthy burial."
The entire grave measures about 6.2 feet by 5.2 feet (1.9 meters by 1.6 meters), and contains a plethora of Roman artifacts. They found hobnails, which are small iron nails used on the soles of leather sandals. The sandals had straps that people would tie around their legs, but the sandals must have decayed over the ages. Only the hobnails remained.
"The idea of providing footwear in a Roman grave is that the journey to the underworld, taken by the soul after death, is taken on foot to the River Styx, where you're ferried across," Fitzpatrick-Matthews told Live Science. "It's a walking journey, so you need a pair of footwear. Anybody who could afford it was buried with their best sandals."
The archaeologists also found mosaic glass plates, possibly from Egypt or western Europe; a small piece of lava; and the remains of a wooden box containing two glass cups. A silver coin, called a denarius, sat inside the box and likely slowed the wood's decomposition, Fitzpatrick-Matthews said. The coin features Emperor Trajan, who ruled Rome from A.D. 98 to A.D. 117.
A second coin helped them date the grave. The worn bronze coin sat inside the cremation urn. It likely served as payment for Charon, the man thought to ferry people across the River Styx, Fitzpatrick-Matthews said. Emperor Marcus Aurelius issued the coin in the A.D. 170s, he said.
"You never find these things in Roman burials, except in this one," Fitzpatrick-Matthews said. "The fact that it's worn means it was a good 20 to 30 years old by the time it got into the ground, which gives us a really nice date for the burial ground — about 200."
"Everything is absolutely perfect, except for this wretched coin of Trajan," which is about 100 years younger than the other artifacts, he said. "Who knows what it's doing there. It may have been completely accidental, and have fallen into the box without anybody really noticing."
The entire grave was lined with flint, which partly smashed the artifacts under its weight, but also preserved the burial. The farmer who owns the field recalled his family noticing that area, and how the plow was unable to dig into the earth there.
The newly discovered grave fits with other clues of an earlier civilization on the farmer's property. In 1954, the farmer's family found Roman pottery in the field and donated it to a local museum.
In 2013, a circular hole about 23 feet (7 m) deep suddenly appeared in the field. Fitzpatrick-Matthews remembers looking at the hole, about 3.2 feet (1 m) in diameter, and realizing that it was the remains of a Roman well.
Now, having found the grave, the group decided to look for more clues. They found postholes, suggesting the grave neighbored a building, probably a shrine or a temple, which was attached to a villa.
"Whoever had this burial was quite clearly extremely wealthy. They've been buried with the second-century equivalent of bling," Fitzpatrick-Matthews said, referring to the lavish artifacts.
Read more at Discovery News
Because the collection of bacteria, or microbiome, from people living in industrialized countries is about 40 percent less diverse, the scientists suspect that certain aspects of a more urban lifestyle could be reducing the diversity of the trillions of bacteria that live on and in our bodies.
“We have found unprecedented diversity in fecal, skin, and oral samples collected from the Yanomami villagers,” Maria Dominguez-Bello, an associate professor of medicine at NYU Langone Medical Center, said in a press release. She is the senior author of the study, which is published in the latest issue of the journal Science Advances.
The Yanomami are believed to have lived in total seclusion from the outside world until 2009, when they were first contacted by a medical expedition. They are among a rare population of people who are unexposed to modern antibiotics.
Dominguez-Bello continued, “Our results bolster a growing body of data suggesting a link between, on the one hand, decreased bacterial diversity, industrialized diets, and modern antibiotics, and on the other, immunological and metabolic diseases — such as obesity, asthma, allergies, and diabetes, which have dramatically increased since the 1970s.”
She added, “We believe there is something environmental occurring in the past 30 years that is driving these diseases. We think the microbiome could be involved.”
She and her team analyzed bacterial samples collected and preserved from 34 of the known 54 Yanomami villagers. Among the volunteers, 28 gave skin and oral swab samples, while 11 gave fecal samples.
Bacterial DNA from the Yanomami was then compared to samples from populations in the United States, as well as to samples from the Amazonian Guahibo Amerindians in Venezuela and residents of rural Malawian communities in southeast Africa. The latter communities represent tribal populations with more exposure to Western culture than the Yanomami, who have subsisted by hunting and gathering for hundreds of generations.
“There is a gradient of diversity in feces and skin that is inversely proportional to exposure to antibiotics and processed foods,” explained co-author Jose Clemente, who is an assistant professor of genetics and genomics at the Icahn School of Medicine at Mount Sinai. “Even minimal exposure greatly decreases diversity and removes potentially beneficial bacteria from our microbiome.”
Among the Yanomami skin samples, the researchers found no single dominant type of bacteria. This was in contrast to the U.S. skin samples, which showed lower diversity and relatively higher proportions of Staphylococcus, Corynebacterium, Neisseriaceae, and Propionibacterium. While these bacteria are common and usually harmless, they can cause serious infections, such as the well know “staph infections” that can be difficult to treat.
A genetic analysis of gut and oral bacteria also revealed that the Yanomami villagers had bacteria containing genes coding for antibiotic resistance. The bacterial genes conferred resistance not only to natural antibiotics found in the soil, but also to synthetic antibiotics.
“During the 1940s and 1950s, in the heyday of pharmaceutical antibiotic development, most antibiotics were derived from naturally occurring bacteria in the soil,” said co-author Gautam Dantas, who is an associate professor of pathology, immunology, and biomedical engineering at the Washington University School of Medicine.
“So, we would expect that natural resistance to antibiotics would emerge over millions of years of evolution,” he added. “We didn’t expect to find resistance to modern synthetic antibiotics. The silenced antibiotic-resistant genes show that you don’t need exposure to antibiotics to possess antibiotic-resistant genes.”
Read more at Discovery News
|Regular pigs may roll around in mud, but sea pigs eat it. Om nom nom.|
Dive deeper, though, down past 3,000 feet, and you’ll find a variety of sea cucumber that’s living the good life—relatively speaking, that is. These are the little-studied sea pigs, half a dozen species in the genus Scotoplanes that do indeed look a bit like swine, if swine had way too many legs and ate mud instead of rolling around in it. Compared to their shallow-water cousins, sea pigs don’t have nearly as many predators, so they don’t have to bother dropping their guts out the back end. And good on ‘em for that, really.
Now, when you think sea cucumbers, you probably think of a tube of flesh, whereas the sea pig would appear to have limbs. In fact, these are known as tube feet, and while they’re super elongated in the sea pig, they’re found in other sea cucumbers too, plus their echinoderm compatriots, including starfish and sea urchins. These tube feet are connected to a “water vascular system”—that is, echinoderms have a ton of water coursing through them. That water helps give the sea pig its shape, while muscles in the legs allow it to wander around in search of food. Unfortunately, their body wall is also quite delicate: Catch one in a net and it’ll likely disintegrate, and it’s somewhat difficult to study a puddle of goo.
And those antenna-like things on top of the sea pig? Well, those are technically feet too, but they’re not there so the creature can keep walking if it flips over—though, let’s face it, that would be pretty sweet. No, these are thought to be specially adapted to help the sea pig find food in the pitch-blackness. “The animal can sort of smell areas of mud which have higher organic content,” says marine biologist David Pawson of the National Museum of Natural History. “And so you often find them in swarms, in great herds actually concentrated on areas of mud where there’s a high organic content.”
|Unlike regular pigs, sea pigs are translucent. But I guess a pig ghost would be translucent. Doesn’t count though.|
For this they’re equipped with around 10 tentacles—depending on the species—each with smaller structures that function like fingers. Planting these in the mud as they amble along, the sea pigs alternate moving the grub-filled tentacles to the mouth, all while facing against the current to get a whiff of any food “upstream.” The real bonanza, though, is when a whale carcass lands on the seafloor. As it rots into the sediment, hordes of sea pigs will scoot around it, gathering up the nutritious mud.
When they’re not gobbling marine snow or the occasional whale juice, sea pigs are going after all kinds of microbes on the seafloor. Which is just as well, because such microbes are consuming a whole lot of oxygen down there. When the sea pigs pass this microbial mud through their digestive system, they of course absorb all the good nutrients, but also themselves end up adding oxygen back into the muck and pooping it out on the seafloor. “They’re like earthworms,” says Pawson. “They sort of process the deep-sea mud and make it livable for other animals because they’ve increased the amount of available oxygen in it.”
Respiratory Trees, Self-Evisceration, and Other Things Sea Pigs Ain’t Got Time For
When it comes to breathing oxygen, sea pigs again betray their weirdness. Remember those shallow-water species of sea cucumber that have fish climb into their bums? Well, sea cucumbers also breathe through those bums, using a so-called respiratory tree. This is what those parasitic fish swim up, where they get a nice home and a constant supply of water to boot. But even if such fish lived in the depths, the sea pigs wouldn’t have to worry about them. They’re missing the respiratory tree. Instead, they breathe through their exceedingly thin skin, exchanging oxygen with the surrounding water right through their body wall.
Also setting sea pigs apart from other sea cucumbers: They don’t blow their guts out of their backsides when harassed. And that, according to Pawson, is probably because they don’t tend to get harassed that much. Compared to something like a reef, where all manner of predators can make life miserable for sea cucumbers, the deep is relatively safe. And think about just what a traumatic experience eviscerating yourself is (OK maybe don’t). Sure, the sea cucumber grows it all back eventually, but that takes a tremendous amount of energy. And in the deep, where food isn’t exactly plentiful, the sea pig probably wouldn’t have the resources to drive this regeneration.
|Is a herd of sea pigs kinda cute, or is it just me? No? OK, I’ll sit down now.|
Still, for all science knows about the sea pigs (which, all things considered, is a good amount, given that it’s a deep-sea species), there’s much to be learned. How they mate is still a mystery, as is how long they live. “They might live for 10 years, or they might live for 100 years,” says Pawson. They leave tracks, which is a nice little clue, but “in some parts of the world’s oceans the rate of sedimentation, stuff falling from above down to the seafloor, is so slow that the tracks you’re looking at, even though they look fresh, they might be 100 years old.”
Read more at Wired Science
Apr 16, 2015
Ancient sources report that Julius Caesar (100-44 BC) had episodes of vertigo, dizziness and limb weakness.
The dictator of the Roman empire famously suffered falls during his campaigns in Spain and Africa. The first attack occurred in 46 BC in Thapsus, modern Tunisia, and the second in Cordoba, Spain, when he was over 50 years of age.
The Roman historian Suetonius (69-after 122 AD) claimed that “towards the end he was subject to sudden fainting fits and nightmares as well,” and called his disease “morbus comitialis.”
Caesar’s condition was also reported by the Greek historian Plutarch (about 46-120 AD). In his biography of the Roman general, he wrote that Caesar collapsed in Thapsus and was carried to safety to a “neighboring tower where he stayed quietly during the battle.”
Suetonius and Plutarch’s accounts contributed to produce a diagnosis of epilepsy which has prevailed for centuries.
“The theory that Caesar was epileptic appears not to have very solid philological foundations. If carefully re-examined, the facts appear to suggest a simpler and more logical diagnosis of stroke,” Francesco M. Galassi, an MD at Imperial College London, told Discovery News.
Detailing their review in the journal Neurological Sciences, Galassi and colleague Hutan Ashrafian, a surgeon at the college, argue that most studies have focused on the origin of Caesar’s epilepsy, but virtually none has questioned the assumption that he was epileptic.
“Suetonius uses the words ‘morbus comitialis’, a very general definition, not necessarily meaning epilepsy,” Galassi said.
According to Galassi and Ashrafian, the symptoms reported in Caesar’s life — falls, headache, vertigo, giddiness — are consistent with him having multiple mini-strokes.
“Furthermore, Caesar also suffered from other symptoms including depression and personality changes (exampled by emotional lability when listening to a moving oration by Cicero) which may also be consistent with cerebrovascular disease,” Galassi and Ashrafian wrote.
Another attack might have occurred when Caesar failed to stand up as senators honored him. On that occasion, he reported symptoms of headaches, vertigo and later mentioned giddiness and insensibility.
Considered one of the greatest military leaders of all time, Caesar first conquered territory in Britain, Gaul (now France), and Spain. He crossed Italy’s Rubicon River, giving rise to the five-year-long civil war that left him dictator of Rome.
By 45 BC, Caesar controlled a vast territory that later was the Roman Empire. But his rule was cut short when conspirators, who feared he had too much power, stabbed him to death in the Senate building.
Until now, cardiovascular explanations for Caesar condition have been largely ruled out because until his death he was apparently otherwise well in private and state affairs.
“Even if Caesar participated in an active lifestyle and may have benefited from the background of a Mediterranean diet, there is the added possibility of genetic predisposition towards cardiovascular disease,” the researchers wrote.
Indeed, Pliny the Elder reports that both Caesar’s father and another forefather died suddenly without any real explanation while putting on their shoes.
“This has been explained in terms of SUDEP (sudden unexpected death in epilepsy) but it is much more logical and less complicated to think of these deaths in terms of cerebrovascular disease or lethal myocardial infarction,” Galassi said.
Read more at Discovery News
Out of fuel, the robotic Mercury Surface, Space Environment, Geochemistry and Ranging, or MESSENGER, probe on April 30 will succumb to the gravitational pull of this strange world that has been its home since March 2011. The purpose of the mission, originally designed to last one year, is to collect detailed geochemical and other data that will help scientists piece together of how Mercury formed and evolved. Mercury is one of four versions of rocky planets in the solar system, along with cloud-shrouded Venus, life-friendly Earth and dry, cold Mars.
After two mission extensions, scientists got a six-week bonus run after engineers figured out a way to vent helium used to pressurize the spacecraft’s fuel tank as a way to gain some altitude. MESSENGER’s last boost, scheduled for April 24, will hike the probe’s altitude from about six miles to about 12 miles above the planet’s surface, adding another six days -- roughly 40 orbits -- for studies.
"MESSENGER is going to create a new crater on Mercury sometime in the near future ... let's not be sad about that," NASA associate administrator John Grunsfeld said Thursday, kicking off an event to celebrate the mission's science results.
MESSENGER’s last days have been among the mission’s most rewarding, including details on the surprising discovery that Mercury, despite being so close to the sun, has ice inside craters near its poles, regions that are never directly exposed to sunlight.
Analysis of images shows a dark, possibly carbon-rich material overlying ice in one crater, named Fuller after architect Richard Buckminster Fuller. That could have happened when an icy comet or carbon-rich asteroid smashed into Mercury.
MESSENGER also has found bright spots inside some craters, which turned out to be shallow, recently formed depressions known as hallows.
"Hallows are a land form we didn't expect. They are some of the youngest features on the planet, and this speaks to some unstable material whose identity we are still working out," said MESSENGER's lead scientist Sean Solomon, with Columbia University.
Similar features have been found on the water-rich dwarf planet Ceres, which is about to become the focus of detailed studies by NASA’s orbiting Dawn spacecraft.
Read more at Discovery News
Using images from NASA’s Cassini mission, the source of these tendrils have been tracked down and they originate from the icy moon’s famous geysers. But even better than that, scientists have been able to track the specific tendril shapes down to the specific geysers that produce them.
“We’ve been able to show that each unique tendril structure can be reproduced by particular sets of geysers on the moon’s surface,” said Colin Mitchell, a Cassini imaging team associate at the Space Science Institute in Boulder, Colo., and lead author of a paper published int he Astrophysical Journal.
Mitchell’s team combined the high-resolution Cassini data with computer simulations to track the trajectories of the ice grains to individual geysers blasting through giant fissures in Enceladus’ icy crust. Consisting of tiny ice particles, dust and organic molecules, the geysers provide a tantalizing view into the components of the sub-surface ocean that is theorized to exist below the moon’s thick icy crust.
From Enceladus, these huge features reach tens of thousands of miles away into Saturn’s E ring, supplying it with icy particles. The researchers were able to deduce the size of the ice particles in the E-ring and the tendrils, measuring them to “no smaller than about a hundred thousandth of an inch,” according to a NASA news release. This provided a direct link from Enceladus’ geysers to one of Saturn’s outer rings.
Throughout Cassini’s studies of Enceladus’ tendrils, variations in their shape and size have become apparent, probably due to the tidal squeezing regulating the icy output from the moon’s contracting and expanding fissures. Further work is needed to verify this correlation, however.
A cool implication of this work is that understanding the dynamics of Enceladus’ tendrils may provide an accurate measure on how ice is leaving the small moon and how much is making it to the E ring. This, in turn, may help planetary scientists understand the lifetime and evolution of Enceladus’ sub-surface ocean.
“As the supply lanes for Saturn’s E ring, the tendrils give us a way to ascertain how much mass is leaving Enceladus and making its way into Saturn orbit,” said Carolyn Porco, team leader for the imaging experiment and a coauthor on the paper. “So, another important step is to determine how much mass is involved, and thus estimate how much longer the moon’s sub-surface ocean may last.”
Read more at Discovery News
Hubble, a joint project of NASA and the European Space Agency (ESA), blasted off aboard the space shuttle Discovery on April 24, 1990. Spacewalking astronauts fixed a serious problem with the telescope's optics in 1993, and Hubble has been transforming astronomers' understanding of the cosmos — and bringing gorgeous images of the universe into laypeople's lives —ever since.
"It has really allowed people to participate in the excitement of discovery," said Mario Livio, an astrophysicist based at the Space Telescope Science Institute in Baltimore, which operates Hubble's science program.
"Hubble images have become part of our culture," Livio told Space.com. "I regard this as an incredible contribution."
While the venerable Hubble will likely be able to keep studying the heavens for at least five more years, it's now time to start planning out a future space telescope that will tackle the next big frontier in space science, Livio says — the search for signs of life beyond our neck of the cosmic woods.
"Hubble has taught us that to answer the most intriguing questions in astrophysics, we must think big and put scientific ambition ahead of budgetary concerns," he wrote in a commentary piece published online today (April 15) in the journal Nature.
"In my view, the next priority should be the search for life beyond our solar system," Livio added. "A powerful space telescope that can spot biological signatures in the atmospheres of Earth-like exoplanets would be a worthy successor."
Hubble's immediate successor is NASA's $8.8 billion James Webb Space Telescope (JWST), which is due to launch in 2018. The infrared-optimized JWST will be able to study the atmospheres of some nearby planets discovered by the Transiting Exoplanet Survey Satellite, or TESS, which NASA aims to launch in 2017.
The agency is also developing a potential space-telescope mission called WFIRST/AFTA (short for Wide Field Infrared Survey Telescope–Astrophysics Focused Telescope Assets). WFIRST/AFTA, which could launch around 2024 if it gets the final go-ahead, would continue the hunt for biosignatures, among several other major tasks.
But Livio has something more ambitious in mind: A space telescope with a primary mirror at least 39 feet (12 meters) wide, with vision 25 times sharper than that of Hubble. (For comparison, the main mirrors of Hubble, WFIRST/AFTA and JWST are 7.9 feet [2.4 m], 7.9 feet and 21.3 feet [6.5 m] wide, respectively.)
Such a powerful instrument could scan the skies of enough Earthlike exoplanets to place "meaningful statistical constraints" on the abundance or rarity of alien life throughout the Milky Way galaxy, according to Livio.
"A large sample of planets — around 50 — would have to be tested," he wrote in the Nature commentary. "Calculations show, for example, that if no biosignatures are detected in more than about three dozen Earth analogues, the probability of remotely detectable extrasolar life in our galactic neighborhood is less than about 10 percent."
Read more at Discovery News
Apr 15, 2015
NASA’s New Horizons spacecraft is racing toward Pluto and it is expected to make a historic flyby only 7,750 miles (12,500 kilometers) from the dwarf planet’s surface. In the meantime, we’ve been gradually getting a sharper and sharper view of the dwarf planet and its system of moons.
This image was captured on April 9 by New Horizons’ Ralph color imager at a distance of approximately 71 million miles (115 million kilometers). At this distance, no surface features are discernible, although there does appear to be some color variations.
“This is pure exploration; we’re going to turn points of light into a planet and a system of moons before your eyes!” said New Horizons principal investigator Alan Stern, of the Southwest Research Institute (SwRI) in Boulder, Colo. “New Horizons is flying to Pluto — the biggest, brightest and most complex of the dwarf planets in the Kuiper Belt. This 21st century encounter is going to be an exploration bonanza unparalleled in anticipation since the storied missions of Voyager in the 1980s.”
Pluto, Charon and a growing number of smaller moons will offer an unprescedented sceintific opportunity as our first robotic explorer to the Kuiper belt makes its historic flyby. But the mission will be far from over after July 14.
The Hubble Space Telescope has been assisting with a campaign to seek out new and mysterious Kuiper belt objects beyond Pluto that the spacecraft could also visit post-Pluto and several candidates have been found.
From Discovery News
A massive infusion of heat-trapping CO2 from powerful volcanoes — more CO2 than we’re likely to emit in many hundreds of years, to be sure — saved the planet from this so-called Snowball Earth environment. The second report covers an event that happened about 250 million years ago, and this time the effects weren’t so benign. Another set of gigantic eruptions poured enough CO2 into the air not only to warm the planet drastically, but also to acidify the oceans so profoundly that some 90 percent of all ocean species died off, followed by two-thirds of land species. It’s the worst mass extinction, as far as we know, in history.
These monumental episodes of climate change, both linked intimately to levels of CO2 in the atmosphere, are a testament to the dramatic effects this greenhouse gas has on the entire planet. So it’s no surprise that the smaller amounts we’re emitting could have a significant effect as well.
The first of the new papers was published in the Proceedings of the National Academy of Sciences and the second in Science.
During the older episode, continental drift had brought most of the continents near the equator, where CO2, washed out of the atmosphere by rain, reacted chemically with exposed rock and was no longer available to trap heat from the Sun. The global cooling that resulted let sea ice expand until it reached well into what would are now the planet’s temperate zones. At that point, the dazzlingly white surface of the ice would have reflected enough sunlight back into space to accelerate the cooling — just the opposite of the so-called ice-albedo feedback in which diminishing Arctic ice coverage is speeding warming in the region.
Eventually, said Paul Hoffman, an emeritus Harvard geologist who helped develop this concept in the 1990s, “the ice expanding in the Northern and Southern hemispheres would meet at the equator.” The evidence that this actually happened comes largely from glacial deposits, found on several continents, that date back to that time. In the early days, he said, “most geologists were antithetical to this idea. But most now accept it.”
What the new paper adds is a good estimate of where temperatures stood at the time. “Nowadays,” said lead author Daniel Hewartz, a geologist with the University of Göttingen, “you can measure past temperatures by looking at ice cores” — that is, samples of ancient ice drilled from the ice caps in Greenland and Antarctica.
Bubbles trapped in the ice allow scientists to measure past atmospheric levels of CO2, while the ice itself holds clues to temperatures.
Unfortunately, scientists only have ice reaching back about 800,000 years. “For the Snowball Earth period, all the ice is long gone,” Hewartz said. So he and his colleagues looked instead at volcanic rocks from the period that cooled in the presence of water — the same process that’s happening in geysers in Yellowstone National Park and in Iceland today. The rocks incorporated oxygen from that water, which must have come from the ice from the long-vanished glaciers. So by looking at the different weights of oxygen atoms in the rocks, Hewartz and his colleagues teased out where temperature must have stood at the time.
“We suggested this idea back in 2010, 2011, and now they’ve proven what we predicted. This is a very good effort. I wish I had done this analysis myself,” said geologist Ilya Bindeman, of the University of Oregon, who was not involved with the research.
Hoffman was equally enthusiastic. “What’s new here is the ability to quantify surface air temperatures over an ancient ice sheet,” he said. The main drawback is the limited distribution of rocks known to have interacted with glacial meltwater, and uncertainty over their age. “It’s not clear how extensive a geographical picture will emerge,” he said.
One argument against the original Snowball Earth idea is that once the planet froze over, it would be extremely difficult to unfreeze. Clearly, it eventually did, and here again, CO2 almost certainly played a role. The planet has been rocked many times in the past by titanic volcanic eruptions, far more violent and long-lasting than anything humans have ever seen.
Heat-trapping carbon dioxide was among the gases spewed out by these eruptions. Geologists know this because acidification of the oceans is a hallmark of excess CO2 in the atmosphere, and they have evidence that the oceans became strongly acidic at the time snowball phase ended.
With the new paper in Science, they now have evidence that the oceans acidified dramatically about 252 million years ago as well, at just the time that the planet underwent the greatest mass extinction of species known to science. Known as the Permo-Triassic or End-Permian extinction event, it wiped out vast numbers of species, especially in the oceans, and set the evolutionary stage for the rise of the dinosaurs.
“It’s always been thought that a cascade of events happened at this time,” said Rachel Wood, of the University of Edinburgh, a co-author of the Science paper. Scientists know, for example, that the oceans became depleted in oxygen. They know that Earth warmed significantly, in part, perhaps, due to a massive release of the powerful greenhouse gas methane. “Now we’re adding another piece to the jigsaw puzzle, another kill mechanism,” Wood said.
The evidence for acidification comes from ancient limestone, which incorporates the element boron in different ways depending on how acidic conditions were when the rock originally formed. Based on the differences in boron they found in limestone deposits of slightly different ages, Wood and her colleagues scientists posit that the ocean was acidified by carbon dioxide emitted during a known series of eruptions that laid down a vast expanse of lava in what is now Siberia. Acidification during this extinction event, Wood said, “is something that has been long suspected, but never proven until now.”
The acidification took about 10,000 years to play out, the authors write — a period over which carbon emissions per year were probably less than the emissions humans are pumping into the atmosphere today, but which added up over time to help turn the oceans into a toxic acid bath.
Read more at Discovery News
Compared with other human relatives such as Neanderthals, modern Homo sapiens have particularly prominent chins. Some researchers have hypothesized that the modern human chin helps the jaw stand up to the forces generated by chewing, said Nathan Holton, an anthropologist at the University of Iowa.
In a new study, Holton and his colleagues find that the chewing theory doesn't hold water.
"The development of the chin doesn't seem to have anything to do with resistance to bending stresses," Holton told Live Science. "They're just not related."
Instead, he said, the prominence of the chin may simply be a side effect of the rest of the face evolving to be smaller.
To determine whether chin prominence protects the jaw from bending while chewing, Holton and his colleagues examined X-ray images from the Iowa Facial Growth Study, which tracked children's skull development from age 3 into adulthood. Using 292 measurements from 18 females and 19 males, the researchers tracked jaw development and bone distribution associated with protecting against various types of stresses.
Chins become more prominent with age, but the scientists found no consistent links between chin prominence and resistance. In fact, jaws are relatively better at resisting some types of forces at age 3, when chins are not well developed, compared to adulthood, Holton said.
The findings appeared online April 11 in the Journal of Anatomy.
If chins don't confer jaw protection, the reason for the pointy human chin is something of a mystery, Holton said. Overall, the Homo genus (which includes humans, Neanderthals and other ancestors) has experienced an evolution toward smaller faces over time, with Homo sapiens showing the greatest reductions in size. Among features on the modern human's face, the lower jaw stops growing last, making it relatively more prominent compared with the rest of the face.
The prominent chin "is a secondary consequence of faces getting smaller," Holton said.
Read more at Discovery News
The research, which is based on computer models, resolves two long-standing mysteries about Mother Nature's recipe for Earth. The first is why the planet has an abundance of the rare-earth metals samarium (Sm) and neodymium (Nd) compared meteorites, which are believed to be samples of Earth’s building blocks.
The second riddle is how the planet’s metallic core has stayed hot enough over the eons to continue convection, a process that generates Earth’s protective magnetic shield.
Oxford University researchers Anke Wohlers and Bernard Wood got the idea to incorporate a sulfur-rich body like Mercury into Earth-formation computer simulations after making connections between colleagues’ previous studies relating rare earth elements, including samarium and neodymium, to sulfides; the elements’ chemical mismatch between Earth and meteorites; and observations from NASA’s MESSENGER spacecraft that Mercury has high levels of sulfur.
“Then we had to do the experiments to test the idea,” Wood told Discovery News.
The models show the impacting body would have to have been 20 to 40 percent as big as Earth to produce the required chemical mix. The crash could have happened as the building blocks for Earth were melding together, or it could have been the hypothesized Mars-sized impactor, named Theia, that hit Earth and led to the formation of the moon.
With Jupiter on the move, the inner solar system was like a “mixing bowl,” Wood said.
“Under these circumstances, Mercury-like bodies could have been scattered both outwards and inwards. One could envision an early Mercury-like Earth or even a much later collision with a Mercury-like body, such as that which formed the moon,” Wood wrote in an email.
The experiments explored possible chemical pathways the rare earth elements could take as they oxidized from iron metal to iron sulfide and silicates. It also explains how a sulfur-rich core would leave enough radioactive uranium and other elements to drive Earth’s dynamo, the swirl of liquid iron that generates the planet’s magnetic field.
“As with any new idea, there will be a lot of tests that it will need to pass first before it becomes convincing,” geochemist Richard Carlson, with the Carnegie Institution for Science, wrote in an email to Discovery News.
“One of the strengths of modern geochemistry is that we have reasonably precise data for the abundance of almost every element in the periodic table, at least in Earth’s outer layers. If core formation under the reducing conditions explored by the Wohlers and Wood experiments can reproduce the whole pattern of element abundances in the silicate Earth, that would give the model more support,” he said.
Scientists also can look for naturally occurring telltale traces of radioactive uranium and thorium breaking down to measure concentrations inside Earth.
Read more at Discovery News
So what’s going on?
Using the advanced MUSE instrument at the VLT and Hubble, astronomers were able to zoom in on 4 colliding galaxies within the galaxy cluster Abell 3827. This cluster is huge and is often the hunting ground for enigmatic gravitational lenses.
All galaxies are comprised primarily of dark matter. Without this invisible mass, which accounts for 85 percent of the mass of the entire universe, observations of the visible matter within a spinning galaxy wouldn’t make much sense; the stars should fly apart. But with the presence of dark matter, galaxies have the gravitational bulk to retain their structure.
So when observing Abell 3827, astronomers know that dark matter is there through observations of gravitational lenses — starlight from galaxies behind the cluster becomes warped and bent around curved spacetime. If you remove the gravitational influence of the visible galaxies, a huge gravitational component remains, allowing astronomers to accurately measure the quantities and locations of dark matter clouds within the galaxy cluster.
Using this method to map out the distribution of dark matter in 4 colliding galaxies, astronomers have deduced that the dark matter associated with each galaxy is lagging some 5,000 light-years behind the normal matter in those galaxies.
What’s causing this lag? According to the study, published in the journal Monthly Notices of the Royal Astronomical Society on April 15, it is being caused by some kind of interaction between the galactic halos of dark matter within the colliding galaxies. As the galaxies collide, the visible matter interacts as expected, but the dark matter halos appear to have a net drag effect on one another, creating the 5,000 light-year lag.
“We used to think that dark matter just sits around, minding its own business, except for its gravitational pull,” said Richard Massey of Durham University and lead author of this study. “But if dark matter were being slowed down during this collision, it could be the first evidence for rich physics in the dark sector — the hidden Universe all around us.”
This is an exciting discovery, but to understand what kind of mutual dark matter interaction is causing this large-scale effect, we need more observations and refined computer simulations.
Read more at Discovery News
Apr 14, 2015
In footage released to Youtube that's quickly racking up the view totals, the Royal Burgers Zoo resident, perched in a tree in his outdoor enclosure, spies the strange thing in the sky and simply swats it with a stick. Problem solved!
The zoo reports that while the attached camera functioned beyond the takedown, the dazed and confused drone did not survive its injuries.
After the swat-down, be sure to watch the other chimps gather 'round the grounded aircraft to take a closer look.
Unfortunately for said buzzing hardware, while most of the other chimpanzees in the enclosure did not seem to mind being spied upon, it only took one that did to send it to its death.
The dearly departed drone was filming the chimpanzees for a TV program created by the zoo.
The dead whale was found on a remote beach near the town of Exmouth, 1,265 kilometres (784 miles) north of Perth, in the wake of Tropical Cyclone Olwyn which hit the region last month.
Western Australia Environment Minister Albert Jacob said it was the first record and sighting of the species in the state and only the second nationally.
"This find is highly significant for whale scientists in Western Australia and researchers globally because there have not been many recorded sightings of this species so very little is known about it," Jacob said.
"Omura's whale was only described in scientific journals for the first time in 2003 and is apparently restricted to tropical and subtropical waters.
"The knowledge we gain from this whale will help to improve field identification guides to better understand the whale's regional distribution," he added.
"Scientists know a fair bit about many whale species but this exciting discovery shows there is still so much more to learn in our oceans."
According to the International Union for Conservation of Nature, only a handful of specimens have been found before, including in the Sea of Japan and the Solomon Sea.
There is no population estimate, given the scarcity of information about them, with little known of the species' ecology and virtually nothing about its reproductive biology.
Read more at Discovery News
Richard III suffered from a spine curving condition known as adolescent idiopathic scoliosis, which he most likely developed after the age of about 10. The 15h century king was reinterred last month with a solemn ceremony at Leicester Cathedral, 530 years after his death and more than two years after archaeologists discovered his twisted skeleton in a car park.
According to Mary Ann Lund, of the School of English at the University of Leicester, Richard III probably kept any signs of his scoliosis hidden outside of the royal household as part of his "propaganda of power."
"It is highly likely that Richard took care to control his public image," Lund wrote in the Medical Humanities journal.
"Tailoring probably kept the signs of his scoliosis hidden to spectators outside the royal household of attendants, servants and medical staff who dressed, bathed and tended to the monarch's body," she added.
Lund noted that no mention of Richard's anatomical abnormality survives from during his lifetime, perhaps out of respect to a reigning monarch, or perhaps because he hid it so well.
Richard, who reigned from 1483 to 1485, was probably treated by his surgically trained physician with a mixture of painful axial traction and manual manipulation — a therapy which needed specially designed equipment, space and assistants.
"Yet, it may have been only a relatively small group of people in Richard's trusted circle who knew of his condition. The absence of contemporary testimony does not prove this, however," Lund said.
What is certain is that hundreds of witnesses could see Richard’s severely bent spine after his death.
The last king of England to die on the battlefield, Richard was killed in 1485 at Bosworth. His defeat by Henry Tudor, who became King Henry VII, marked the end of the decades-long fight over the throne known as War of the Roses and the end of the Plantagenet dynasty.
Historical sources report Richard was vilified, stripped naked, slung across a horse and paraded through Leicester to let people know he was truly dead.
Read more at Discovery News
The man may have participated in a form of jousting called tourney, in which men rode atop their horses and attacked one another, in large groups, with blunted weapons.
Archaeologists uncovered the man's skeleton, along with about 2,500 others — including a person who had leprosy and a woman with a severed hand — buried at Hereford Cathedral in the United Kingdom. The cathedral was built in the 12th century and served as a place of worship and a burial ground in the following centuries, said Andy Boucher, a regional manager at Headland Archaeology, a commercial archaeology company that works with construction companies in the United Kingdom.
A few years ago, the Heritage Lottery Fund, which is financed by the national lottery in the United Kingdom, awarded money to the cathedral for the landscaping and restoration of its grounds. But first, workers had to relocate the thousands of skeletons, many of which were near the ground's surface.
"By church law, anybody who died in the parish had to be buried in the cathedral burial ground," almost continuously from the time the cathedral was built until the early 19th century, Boucher told Live Science.
From 2009 to 2011, his team respectfully removed the human remains. But one stood out — a 5-foot-8-inch (1.7 meters) man with serious trauma on his right shoulder blade, 10 of his right ribs and left leg.
"He's the most battered corpse on the site," Boucher said. "He had the largest number of broken bones."
The man was about 45 years or older when he died, according to a bone analysis. He was buried in a stone-lined grave, a type of grave that was used between the 12th and 14th centuries, the researchers said.
Four of the man's ribs showed healed fractures that may have occurred simultaneously, suggesting a single instance of trauma, researchers wrote in the pathology report. Another four ribs were in the process of healing, indicating that the man was still recovering from the injuries when he died. The other two damaged ribs also show evidence of trauma, and his left lower leg has an unusual twisting break, one that could have been caused by a direct blow or a rolled ankle, according to the report.
In addition, the man had lost three of his teeth during his lifetime. A chemical analysis of his other teeth that matched different isotopes (a variation of an element) to foods and water samples from different geological locations showed that the man likely grew up in Normandy and moved to Hereford later in life, Boucher said.
It's impossible to know what wounded the man, but his injuries are in line with those that nobility got through tourney, or jousting, the researchers said.
"Tourney, the true form of jousting, is open combat between large groups of people in fields — basically, a mock battle," Boucher said. "They just laid into each other with blunted weapons, which is another reason we think he might be a knight, because none of the wounds to him are caused by sharp weapons. They're all caused by blunt-force trauma."
Perhaps the man injured his leg during a horse ride during one of these tourneys, if the foot had gotten stuck in the stirrup, Boucher said. Moreover, the injuries to his right shoulder and ribs could have happened if he fell from his horse, or was hit with a blunt weapon on the right side of his body, according to the report.
However, the man may have sustained his injuries in other ways. The coroner's files show that men older than age 46 who died of accidental deaths during medieval times were likely to die while traveling or transporting goods, according to the report.
Read more at Discovery News
Our own moon exhibits “Earthshine” when the position of the sun and Earth are just right for us to see the double reflection of sunlight — light is reflected off our planet and then that light reflects off the moon’s surface, often producing a dim glow when much of the lunar disk is otherwise in shadow.
And this is exactly what is happening to Mimas here; sunlight is reflected off Saturn’s upper atmosphere, casting a weak glow across the 250 mile-wide moon.
In a news release, NASA notes that, to better illustrate the effect of Saturnshine, Mimas “has had its brightness enhanced by a factor of 2.5 relative to the rings.”
The result is a beautiful portrait of a little cratered moon, highlighted by the reflected light from its parent planet Saturn.
This observation was made by Cassini on Feb. 16 when the spacecraft was approximately 1.6 million miles from Mimas.
From Discovery News
Apr 13, 2015
Mosasaurs, once thought to be reared from eggs deposited on land, were instead born out in the open ocean, a new study out of Yale University and the University of Toronto suggests.
The family of marine reptiles, which could reach some 50 feet in length, lived during the Late Cretaceous, between 66 and 85 million years ago. The top-drawer predators ate fare such as turtles and birds but weren't averse to taking on bigger prey such as sharks and plesiosaurs. They went extinct along with practically everything else in the Cretaceous-Tertiary extinction of 65 million years ago.
While the creature's later stages of life are well known, little is understood about the initial environment it faced.
"Mosasaurs are among the best-studied groups of Mesozoic vertebrate animals, but evidence regarding how they were born and what baby mosasaur ecology was like has historically been elusive," said Yale doctoral candidate in geology and geophysics, Daniel Field, the study's lead author.
Field and Aaron LeBlanc, a doctoral candidate at the University of Toronto at Mississauga, examined mosasaur specimens from the Yale Peabody Museum of Natural History that had been gathered more than a century ago.
The finds in the collection had been identified as belonging to ancient marine birds, but the two scientists saw something else. They noted jaw and teeth features that were unique to mosasaurs and realized they were studying the youngest mosasaur samples ever found. Too, the finds came from open ocean deposits.
Read more at Discovery News
This finding is based on analysis of oxygen isotopes in rocks bathed in the meltwater of ancient glaciers shows annual mean temperatures of minus-40 degrees Fahrenheit or colder during a planet-wide deep-freeze roughly 2.4 billion years ago.
The new data indicates Earth’s global oceans froze into a blanket of ice and glaciers 1,000 feet thick, challenging theories that open patches of water existed in the equatorial regions during the first of at least two Snowball Earth periods.
“These events are fascinating. We had times where we really had a completely frozen Earth. If you go now to tropical regions and you imagine thick glaciers and all the oceans frozen, it’s crazy I think, but it appears to be that this has happened,” geoscientist Daniel Herwartz, with the University of Gottingen in Germany, told Discovery News.
Scientists have been dividend about whether some of Earth’s oceans remained liquid (or slushy). That research that has been dependent on climate models, not hard data.
The new study changes that paradigm with a technique to ferret out a third oxygen isotope from 700 million-year-old rocks from China and 2.4 billion-year-old rocks from northwestern Russia. Both lands were then located close to the equator.
“These Snowball Earth events also happened when most of the continents were forming a supercontinent, which was located at equatorial regions,” Herwartz said.
The research shows the 700 million-year-old rocks were exposed to water temperatures similar to what southern Greenland experiences today. The 2.4 billion-year-old samples, however, experienced much colder temperatures.
“This low temperature would actually require that the whole Earth was completely frozen in and that we really had most of the oceans under hundreds-of-meter thick ice,” Herwartz said.
The study has implications for understanding what happened to life on Earth during the deep freeze, namely whether it could still exist via photosynthesis or if it retreated into more extreme niches powered by hydrothermal vents, for example.
“Life on Earth originated and spread in shallow, light-filled, ice-free environments. Organisms in these environments evolved over billions of years, so glaciations, as long as they may be, are temporary interruptions to our biosphere, which is powered largely by photosynthesis,” geobiologist Tanja Bosak, with Massachusetts Institute of Technology, told Discovery News.
Read more at Discovery News
But Four Corners has another, more puzzling distinction. As a 2014 study of data from a European satellite by NASA and University of Michigan researchers revealed, a 2,500-square mile area near the intersection produces the nation’s biggest concentration of methane, a greenhouse gas that’s many times more potent than carbon dioxide, and a significant contributor to global warming.
Now, as scientists launch a team effort to figure out the cause for the massive methane plume, another more troubling question arises. Is the hotspot an anomaly, or an indication that previous measurements have underestimated the amount of methane that’s being released into the atmosphere?
If the latter is true, it could have disturbing implications for the struggle against climate change.
Nobody knows yet why Four Corners is giving off so much methane — an amount equivalent to almost 15 million tons of carbon dioxide, or the equivalent of adding 3.1 million cars to the road every year, according to ThinkProgress.
For much of the 2003-2009 period in the satellite study, the area didn’t have a lot of hydraulic fracturing, or fracking, for oil and gas,a process that some are concerned is a source of methane emissions. But Four Corners is a major coal mining area, and a source of coal-bed methane, which supplies about 8 percent of the nation’s natural gas.
The plume discovered over Four Corners, raises the possibility that large amounts of methane are escaping from the mines — a problem that hasn’t been factored into the equation before.
Read more at Discovery News
But now, thanks to a robotic submarine deployed by the National Oceanic and Atmospheric Administration research ship Okeanos Explorer, we’ll all be able to go online and take a peek at some of that unknown territory in the Caribbean Sea and the Atlantic Ocean.
The just-started mission will send the robotic sub on 20 dives, some of them as much as 3.7 miles deep, according to a NOAA press release. Many of those dives will take place in the Puerto Rico Trench, a 500-mile-long stretch of the sea floor that in some places is 5.4 miles deep, making it the deepest part of the Atlantic Ocean basin.
Other areas to be explored include the Muertos Trough, Mona Channel and Virgin Islands Trough.
The robotic sub — in NOAA lingo, a remotely-operated vehicle, or ROV — will continuously capture high-definition video, which the public will be able to view on this website.
While the area to be explored is uncharted, scientists know that it has a lot of tectonic plate activity and is a potential source of earthquakes and tsunamis. They also suspect that it contains geological figures such as seamounts and mud volcanoes.
Okeanos Explorer recently finished mapping 13,600 square miles of seafloor around the U.S. Virgin Islands and Puerto Rico, gathering data that will be used by biologists, geologists, oceanographers and geophysicists.
Live video from a 2013 expedition to deep-sea canyons off the northeast Atlantic coast of the United States garnered more than 875,000 views.
From Discovery News
Apr 12, 2015
Most importantly, the findings hint at the possibility that the acceleration of the expansion of the universe might not be quite as fast as textbooks say.
The team, led by UA astronomer Peter A. Milne, discovered that type Ia supernovae, which have been considered so uniform that cosmologists have used them as cosmic "beacons" to plumb the depths of the universe, actually fall into different populations. The findings are analogous to sampling a selection of 100-watt light bulbs at the hardware store and discovering that they vary in brightness.
"We found that the differences are not random, but lead to separating Ia supernovae into two groups, where the group that is in the minority near us are in the majority at large distances -- and thus when the universe was younger," said Milne, an associate astronomer with the UA's Department of Astronomy and Steward Observatory. "There are different populations out there, and they have not been recognized. The big assumption has been that as you go from near to far, type Ia supernovae are the same. That doesn't appear to be the case."
The discovery casts new light on the currently accepted view of the universe expanding at a faster and faster rate, pulled apart by a poorly understood force called dark energy. This view is based on observations that resulted in the 2011 Nobel Prize for Physics awarded to three scientists, including UA alumnus Brian P. Schmidt.
The Nobel laureates discovered independently that many supernovae appeared fainter than predicted because they had moved farther away from Earth than they should have done if the universe expanded at the same rate. This indicated that the rate at which stars and galaxies move away from each other is increasing; in other words, something has been pushing the universe apart faster and faster.
"The idea behind this reasoning," Milne explained, "is that type Ia supernovae happen to be the same brightness -- they all end up pretty similar when they explode. Once people knew why, they started using them as mileposts for the far side of the universe.
"The faraway supernovae should be like the ones nearby because they look like them, but because they're fainter than expected, it led people to conclude they're farther away than expected, and this in turn has led to the conclusion that the universe is expanding faster than it did in the past."
Milne and his co-authors -- Ryan J. Foley of the University of Illinois at Urbana-Champaign, Peter J. Brown at Texas A&M University and Gautham Narayan of the National Optical Astronomy Observatory, or NOAO, in Tucson -- observed a large sample of type Ia supernovae in ultraviolet and visible light. For their study, they combined observations made by the Hubble Space Telescope with those made by NASA's Swift satellite.
The data collected with Swift were crucial because the differences between the populations -- slight shifts toward the red or the blue spectrum -- are subtle in visible light, which had been used to detect type Ia supernovae previously, but became obvious only through Swift's dedicated follow-up observations in the ultraviolet.
"These are great results," said Neil Gehrels, principal investigator of the Swift satellite, who co-authored the first paper. "I am delighted that Swift has provided such important observations, which have been made toward a science goal that is completely independent of the primary mission. It demonstrates the flexibility of our satellite to respond to new phenomena swiftly."
"The realization that there were two groups of type Ia supernovae started with Swift data," Milne said. "Then we went through other datasets to see if we see the same. And we found the trend to be present in all the other datasets.
"As you're going back in time, we see a change in the supernovae population," he added. "The explosion has something different about it, something that doesn't jump out at you when you look at it in optical light, but we see it in the ultraviolet.
"Since nobody realized that before, all these supernovae were thrown in the same barrel. But if you were to look at 10 of them nearby, those 10 are going to be redder on average than a sample of 10 faraway supernovae."
The authors conclude that some of the reported acceleration of the universe can be explained by color differences between the two groups of supernovae, leaving less acceleration than initially reported. This would, in turn, require less dark energy than currently assumed.
Read more at Science Daily
Now, scientists plan to drill 5,000 feet (1,500 meters) below the surface of the Chicxulub crater in Mexico to bring up a giant core — and delve 10 million to 15 million years into the past. The endeavor would result in the first offshore core taken from near the center of the crater, which is named for a nearby seaside village located on the Yucatán Peninsula.
An international team of scientists met last week in Mérida, Mexico, located within the 125-mile-wide (200 kilometers) Chicxulub crater, to discuss their plans for the drilling project, slated to start in spring 2016.
Why now? “The Chicxulub impact crater has been a remarkable scientific opportunity for the 20 years since it’s been discovered,” said Sean Gulick, of The University of Texas at Austin Institute for Geophysics.
And, for the first time, scientists have subsurface images from the offshore part of the crater, so they can pinpoint a spot for sampling. They chose a spot along the crater’s peak ring — a ring of mountainlike structures around the center of the crater.
By sampling there, the researchers can get a clearer picture of ancient biological and geological processes.
Scientists think that, when a big rock smashes into Earth at high enough velocities, the collision causes the crust temporarily to act sort of like a liquid, first forming a so-called transient crater (like the indentation that forms on a lake surface after a rock is thrown in), and the center rebounds, or splashes, upward and then outward.
“We think the peak ring is the record of the material that rebounded and splashed outward,” Gulick told Live Science.
All of these ideas are based on models and aren’t necessarily what happened. “We’ve never gotten a rock back from a peak ring to know if that’s correct,” Gulick said.
Read more at Discovery News