If you wanted to get ahead in Iron-Age Central Europe you would use a strategy that still works today -- dress to impress and throw parties with free alcohol.
Pre-Roman Celtic people practiced what archaeologist Bettina Arnold calls "competitive feasting," in which people vying for social and political status tried to outdo one another through power partying.
Artifacts recovered from two 2,600-year-old Celtic burial mounds in southwest Germany, including items for personal adornment and vessels for alcohol, offer a glimpse of how these people lived in a time before written records were kept.
That was the aim of the more than 10-year research project, says Arnold, anthropology professor at the University of Wisconsin-Milwaukee and co-director of a field excavation at the Heuneburg hillfort in German state of Baden-Wurttemberg. The work was partially funded by the National Geographic Society and Arnold collaborated with the State Monuments Office in Tübingen, Germany.
In fact, based on the drinking vessels found in graves near the hillfort settlement and other imported objects, archaeologists have concluded the central European Celts were trading with people from around the Mediterranean.
Braü or mead?
"Beer was the barbarian's beverage, while wine was more for the elite, especially if you lived near a trade route," says Kevin Cullen, an archaeology project associate at Discovery World in Milwaukee and a former graduate student of Arnold's.
Since grapes had not yet been introduced to central Europe, imported grape wine would indicated the most social status. The Celts also made their own honey-based wine, or mead, flavored with herbs and flowers, that would have been more expensive than beer, but less so than grape wine.
They also made a wheat or barley ale without hops that could be mixed with mead or consumed on its own, but that had to be consumed very soon after being made. "Keltenbräu," is an example of such an ale. It would have been a dark, roasted ale with a smoky flavor.
To the upper-class, the quantity of alcohol consumed was as important as the quality. Arnold excavated at least one fully intact cauldron used for serving alcoholic beverages in one of the graves at Heuneburg. But it's hard to top the recovery of nine drinking horns -- including one that held 10 pints -- at a single chieftain's grave in nearby Hochdorf in the 1970s.
Dapper dudes and biker chicks
In addition to their fondness for alcohol, Celtic populations from this period were said by the Greeks and Romans to favor flashy ornament and brightly striped and checked fabrics, says Arnold. The claim has always been difficult to confirm, however, since cloth and leather are perishable.
The Heuneburg mounds yielded evidence of both, even though no bones remain due to acidic soil. But the team of archaeologists were able to reconstruct elements of dress and ornamentation using new technology.
Rather than attempt to excavate fragile metal remains, such as hairpins, jewelry, weapons and clothing fasteners, Arnold and her colleagues encased blocks of earth containing the objects in plaster, then put the sealed bundles through a computerized tomography, or CT, scanner.
"We found fabulous leather belts in some of the high-status women's graves, with thousands of tiny bronze staples attached to the leather that would have taken hours to make," she says. "I call them the Iron-Age Harley-Davidson biker chicks." Images show such fine detail, the archaeologists theorize that some of the items were not just for fashion.
"You could tell whether someone was male, female, a child, married, occupied a certain role in society and much more from what they were wearing."
The pins that secured a veil to a woman's head, for example, also appear to symbolize marital status and perhaps motherhood. Other adornment was gender-specific -- bracelets worn on the left arm were found in men's graves, but bracelets worn on both arms and neck rings were found only in graves of women.
Read more at Science Daily
Mar 20, 2012
Super-Earth Unlikely Able to Transfer Life to Other Planets
While scientists believe conditions suitable for life might exist on the so-called "super-Earth" in the Gliese 581 system, it's unlikely to be transferred to other planets within that solar system.
"One of the big scientific questions is how did life get started and how did it spread through the universe," said Jay Melosh, distinguished professor of earth and atmospheric sciences. "That question used to be limited to just the Earth, but we now know in our solar system there is a lot of exchange that takes place, and it's quite possible life started on Mars and came to Earth. There's also been a great deal of discussion about the possible spread of life in the universe from star to star."
Moon rocks and Mars meteorites have been found on Earth, which led Melosh to previously suggest living microbes could be exchanged among planets in a similar manner.
A Purdue research team has found that, in contrast to our own solar system, the exchange of living microbes between "super-Earth" and planets in that solar system is not likely to occur.
Laci Brock, a student studying interdisciplinary physics and planetary science, and Melosh will present those findings March 20 at the 43rd Lunar and Planetary Science Conference in The Woodlands, Texas.
Brock examined the Gliese 581 planetary system because Planet d, known as super-Earth, falls in a "habitable zone" where liquid water could possibly exist.
"Laci has found the somewhat surprising result that it is very difficult for materials to spread throughout that system in the same way it could take place in our solar system," Melosh said.
All four planets found in Gliese 581 are within close proximity to their central star, which results in large orbital velocities, Brock said. However, the initial velocity of material leaving Planet d is not enough to allow exchanges among planets.
"Planet d would have a very small chance of transferring material to the other planets in the Gliese system and, thus, is far more isolated, biologically, than the inner planets of our own solar system," Brock said. "It really shows us how unique our solar system is."
Melosh said a more extended solar system would be needed for exchange of materials among planets.
"None of the solar systems that have been found so far would have opportunities for exchange of life among the different planets like what our own solar system offers," he said.
The Opik-Arnold method was used to simulate 10,000 particles being ejected from Planet e and super-Earth. The velocity ranges of the particles were scaled from each of the planet's orbital velocities, which is very high by solar system standards due to the close proximity to their central star.
"Ejections from Planet d have a low probability of impact on any other planet than itself, and most ejected particles would enter an initial hyperbolic orbit and be ejected from the planetary system," Brock said.
Several members of Purdue's planetary sciences department are attending the 43rd Lunar and Planetary Science Conference, presenting research on possible biologic contamination of Mars' moon Phobos by microbes from the surface of Mars; the formation of jets on comets; and gravity anomalies around large lunar craters.
Read more at Science Daily
"One of the big scientific questions is how did life get started and how did it spread through the universe," said Jay Melosh, distinguished professor of earth and atmospheric sciences. "That question used to be limited to just the Earth, but we now know in our solar system there is a lot of exchange that takes place, and it's quite possible life started on Mars and came to Earth. There's also been a great deal of discussion about the possible spread of life in the universe from star to star."
Moon rocks and Mars meteorites have been found on Earth, which led Melosh to previously suggest living microbes could be exchanged among planets in a similar manner.
A Purdue research team has found that, in contrast to our own solar system, the exchange of living microbes between "super-Earth" and planets in that solar system is not likely to occur.
Laci Brock, a student studying interdisciplinary physics and planetary science, and Melosh will present those findings March 20 at the 43rd Lunar and Planetary Science Conference in The Woodlands, Texas.
Brock examined the Gliese 581 planetary system because Planet d, known as super-Earth, falls in a "habitable zone" where liquid water could possibly exist.
"Laci has found the somewhat surprising result that it is very difficult for materials to spread throughout that system in the same way it could take place in our solar system," Melosh said.
All four planets found in Gliese 581 are within close proximity to their central star, which results in large orbital velocities, Brock said. However, the initial velocity of material leaving Planet d is not enough to allow exchanges among planets.
"Planet d would have a very small chance of transferring material to the other planets in the Gliese system and, thus, is far more isolated, biologically, than the inner planets of our own solar system," Brock said. "It really shows us how unique our solar system is."
Melosh said a more extended solar system would be needed for exchange of materials among planets.
"None of the solar systems that have been found so far would have opportunities for exchange of life among the different planets like what our own solar system offers," he said.
The Opik-Arnold method was used to simulate 10,000 particles being ejected from Planet e and super-Earth. The velocity ranges of the particles were scaled from each of the planet's orbital velocities, which is very high by solar system standards due to the close proximity to their central star.
"Ejections from Planet d have a low probability of impact on any other planet than itself, and most ejected particles would enter an initial hyperbolic orbit and be ejected from the planetary system," Brock said.
Several members of Purdue's planetary sciences department are attending the 43rd Lunar and Planetary Science Conference, presenting research on possible biologic contamination of Mars' moon Phobos by microbes from the surface of Mars; the formation of jets on comets; and gravity anomalies around large lunar craters.
Read more at Science Daily
Satellite Views Reveal Early Human Settlements
Scientists have unveiled a new technique for mapping early human settlements in Mesopotamia, the so-called "cradle of civilization" comprised of modern-day Iraq, northeast Syria, southeast Turkey and southwest Iran.
A pair of Harvard University anthropologists developed a way to measure mounds of athrosol, a type of soil formed by long-term human activity, in multi-wavelength satellite images.
Anthrosols are finer, lighter-colored, and richer in organic material than surrounding soil.
"Soil discoloration is one of the characteristics of archaeological sites in this part of the world (alongside surface artifact density and mounding)," Harvard University anthropologist Jason Ur wrote in an email to Discovery News.
Scientists have been using anthrosols to locate settlement sites for 10 years, but were limited to ground observations and declassified black-and-white spy satellite imagery.
"Multi-spectral imagery opens up new possibilities for identifying ancient places because now we can look for these distinctive soil discolorations not only in the visible part of the spectrum (what the human eye seems as red, green, and blue) but also beyond the abilities of our eyes (the near-infrared and even larger wavelengths)," Ur said.
"The mounds that we find are entirely artificial creations on an otherwise relatively flat plain," he added.
Until the development of cement, building material was limited to mud bricks, which don't last forever.
Eventually, the structures become unstable and must be leveled and rebuilt.
"If this process continues for centuries or millennia, settlements grow vertically," Ur said, leading to massive buildups of decayed mud brick.
For example, the largest site, Tell Brak in northern Syria, contains about 8 million cubic meters of decayed mud brick and rises about 40 meters (131 feet) above ground.
"The sites are essentially large piles of anthrosols," Ur said.
He and colleague Bjoern Menze, a computer scientist by training, used imagery from a sensor on NASA's Terra satellite to detect the telltale sediments and a global digital terrain map made from radar imagery taken during a 2000 space shuttle mission to model the height and volume of mounded sites.
In all, the scientists mapped more than 14,000 sites, spanning 8,000 years of human settlement in northeast Syria. Some 9,500 of those sites showed significant elevations, a mass accumulation of 700 million cubic meters of collapsed architecture and settlement debris.
Read more at Discovery News
A pair of Harvard University anthropologists developed a way to measure mounds of athrosol, a type of soil formed by long-term human activity, in multi-wavelength satellite images.
Anthrosols are finer, lighter-colored, and richer in organic material than surrounding soil.
"Soil discoloration is one of the characteristics of archaeological sites in this part of the world (alongside surface artifact density and mounding)," Harvard University anthropologist Jason Ur wrote in an email to Discovery News.
Scientists have been using anthrosols to locate settlement sites for 10 years, but were limited to ground observations and declassified black-and-white spy satellite imagery.
"Multi-spectral imagery opens up new possibilities for identifying ancient places because now we can look for these distinctive soil discolorations not only in the visible part of the spectrum (what the human eye seems as red, green, and blue) but also beyond the abilities of our eyes (the near-infrared and even larger wavelengths)," Ur said.
"The mounds that we find are entirely artificial creations on an otherwise relatively flat plain," he added.
Until the development of cement, building material was limited to mud bricks, which don't last forever.
Eventually, the structures become unstable and must be leveled and rebuilt.
"If this process continues for centuries or millennia, settlements grow vertically," Ur said, leading to massive buildups of decayed mud brick.
For example, the largest site, Tell Brak in northern Syria, contains about 8 million cubic meters of decayed mud brick and rises about 40 meters (131 feet) above ground.
"The sites are essentially large piles of anthrosols," Ur said.
He and colleague Bjoern Menze, a computer scientist by training, used imagery from a sensor on NASA's Terra satellite to detect the telltale sediments and a global digital terrain map made from radar imagery taken during a 2000 space shuttle mission to model the height and volume of mounded sites.
In all, the scientists mapped more than 14,000 sites, spanning 8,000 years of human settlement in northeast Syria. Some 9,500 of those sites showed significant elevations, a mass accumulation of 700 million cubic meters of collapsed architecture and settlement debris.
Read more at Discovery News
Wounded Black Bears Sleep It Off
Injured black bears emerge from hibernation with barely a scratch.
Although their body temperatures and heart rates drop dramatically and blood circulation slows, black bears heal while hibernating without infections and little scaring, reported zoologists in the journal Integrative Zoology. What's more, the sleeping bears heal without eating, drinking, or relieving themselves.
But the benefits aren't just for bears. Understanding the healing hibernating bruins could bear fruit for doctors.
“Further research as to the underlying mechanisms of wound healing during hibernation could have applications in human medicine,” said the zoologists in the abstract to the paper.
Humans and most other mammals don't heal well when their body temperatures are even slightly below normal or they have poor circulation.
“Unique approaches may be found to improve healing for malnourished, hypothermic, diabetic and elderly patients or to reduce scarring associated with burns and traumatic injuries,” wrote the zoologists.
To test the healing ability of the bears, the zoologists proved they were willing to risk it all in the name of science. They gave small cuts to the skin of a group of wild bears they were observing just as the bears were preparing for hibernation. Then they backed off and let them hibernate for two to three months. As the bears were reaching the natural time in the season when they wake up, the brave bear researchers checked the wounds.
Not only had every bear healed itself, the skin had sealed up with little visible damage and even started growing new fur.
Read more at Discovery News
Although their body temperatures and heart rates drop dramatically and blood circulation slows, black bears heal while hibernating without infections and little scaring, reported zoologists in the journal Integrative Zoology. What's more, the sleeping bears heal without eating, drinking, or relieving themselves.
But the benefits aren't just for bears. Understanding the healing hibernating bruins could bear fruit for doctors.
“Further research as to the underlying mechanisms of wound healing during hibernation could have applications in human medicine,” said the zoologists in the abstract to the paper.
Humans and most other mammals don't heal well when their body temperatures are even slightly below normal or they have poor circulation.
“Unique approaches may be found to improve healing for malnourished, hypothermic, diabetic and elderly patients or to reduce scarring associated with burns and traumatic injuries,” wrote the zoologists.
To test the healing ability of the bears, the zoologists proved they were willing to risk it all in the name of science. They gave small cuts to the skin of a group of wild bears they were observing just as the bears were preparing for hibernation. Then they backed off and let them hibernate for two to three months. As the bears were reaching the natural time in the season when they wake up, the brave bear researchers checked the wounds.
Not only had every bear healed itself, the skin had sealed up with little visible damage and even started growing new fur.
Read more at Discovery News
Mar 19, 2012
Are Some Brains Better at Learning Languages?
In his spare time, an otherwise ordinary 16-year old boy from New York taught himself Hebrew, Arabic, Russian, Swahili, and a dozen other languages, the New York Times reported last week.
And even though it's not entirely clear how close to fluent Timothy Doner is in any of his studied languages, the high school sophomore -- along with other polyglots like him -- are certainly different from most Americans, who speak one or maybe two languages.
That raises the question: Is there something unique about certain brains, which allows some people to speak and understand so many more languages than the rest of us?
The answer, experts say, seems to be yes, no and it's complicated. For some people, genes may prime the brain to be good at language learning, according to some new research. And studies are just starting to pinpoint a few brain regions that are extra-large or extra-efficient in people who excel at languages.
For others, though, it's more a matter of being determined and motivated enough to put in the hours and hard work necessary to learn new ways of communicating.
"Kids do well in what they like," said Michael Paradis, a neurolinguist at McGill University in Montreal, who compared language learning to piano, sports or anything else that requires discipline. "Kids who love math do well in math. He loves languages and is doing well in languages."
"This is just an extreme case of a general principle," he added. "If you practice and have a great deal of motivation for a particular domain, you're going to be able to improve in that domain beyond normal limits."
Very young children are remarkably good at learning multiple languages simultaneously. They can develop native-sounding accents in each tongue. And into adulthood, all reinforced languages hold their own in the brain without interfering with the others -- unlike later learners who may have trouble remembering a second language when they begin to learn a third.
With age, though, it not only becomes tougher to learn new languages, there may even be developmental stages beyond which certain nuances of language simply become inaccessible. By the age of 9 to 12 months, for example, babies begin to lose the ability to distinguish between sounds that are not used in their native language, said Loraine Obler, a neurolinguist at the CUNY Graduate Center in New York.
After about age 4, most people will never gain a truly deep grasp on a second language's morphology, which refers to the rules that govern how words are formed from linguistic units. After age 7 or so, the brain begins to pay more attention to what it's learning, Paradis said, which affects the type of memory kids use to pick up languages.
And beyond puberty, it becomes unlikely that someone will be able to speak a new language without a foreign accent, though Doner is unique in how impressive his accent sounds, which may reflect a late-to-mature brain. (There seems to be no cut-off point for learning vocabulary).
For more than a century, scientists have known that there are key areas on the exterior cortex of the brain's left hemisphere, known as Broca's area and Wernicke's area, that are critical for learning to speak and understanding speech, Obler said. There are also many other areas throughout the brain that process language.
Genes, neurotransmitters and brain regions involved in long-term memory play roles as well, Paradis said. And a number of different structures probably come into play when people speak a second language compared to when they speak their first.
That would explain why brain damage from Parkinson's, Alzheimer's or other disorders that affect specific areas of the brain can knock out just a native language -- or just a language that was learned later in life, leaving the other one intact. Aging can also bring out an accent that was once unnoticeable.
Read more at Discovery News
And even though it's not entirely clear how close to fluent Timothy Doner is in any of his studied languages, the high school sophomore -- along with other polyglots like him -- are certainly different from most Americans, who speak one or maybe two languages.
That raises the question: Is there something unique about certain brains, which allows some people to speak and understand so many more languages than the rest of us?
The answer, experts say, seems to be yes, no and it's complicated. For some people, genes may prime the brain to be good at language learning, according to some new research. And studies are just starting to pinpoint a few brain regions that are extra-large or extra-efficient in people who excel at languages.
For others, though, it's more a matter of being determined and motivated enough to put in the hours and hard work necessary to learn new ways of communicating.
"Kids do well in what they like," said Michael Paradis, a neurolinguist at McGill University in Montreal, who compared language learning to piano, sports or anything else that requires discipline. "Kids who love math do well in math. He loves languages and is doing well in languages."
"This is just an extreme case of a general principle," he added. "If you practice and have a great deal of motivation for a particular domain, you're going to be able to improve in that domain beyond normal limits."
Very young children are remarkably good at learning multiple languages simultaneously. They can develop native-sounding accents in each tongue. And into adulthood, all reinforced languages hold their own in the brain without interfering with the others -- unlike later learners who may have trouble remembering a second language when they begin to learn a third.
With age, though, it not only becomes tougher to learn new languages, there may even be developmental stages beyond which certain nuances of language simply become inaccessible. By the age of 9 to 12 months, for example, babies begin to lose the ability to distinguish between sounds that are not used in their native language, said Loraine Obler, a neurolinguist at the CUNY Graduate Center in New York.
After about age 4, most people will never gain a truly deep grasp on a second language's morphology, which refers to the rules that govern how words are formed from linguistic units. After age 7 or so, the brain begins to pay more attention to what it's learning, Paradis said, which affects the type of memory kids use to pick up languages.
And beyond puberty, it becomes unlikely that someone will be able to speak a new language without a foreign accent, though Doner is unique in how impressive his accent sounds, which may reflect a late-to-mature brain. (There seems to be no cut-off point for learning vocabulary).
For more than a century, scientists have known that there are key areas on the exterior cortex of the brain's left hemisphere, known as Broca's area and Wernicke's area, that are critical for learning to speak and understanding speech, Obler said. There are also many other areas throughout the brain that process language.
Genes, neurotransmitters and brain regions involved in long-term memory play roles as well, Paradis said. And a number of different structures probably come into play when people speak a second language compared to when they speak their first.
That would explain why brain damage from Parkinson's, Alzheimer's or other disorders that affect specific areas of the brain can knock out just a native language -- or just a language that was learned later in life, leaving the other one intact. Aging can also bring out an accent that was once unnoticeable.
Read more at Discovery News
Success! LHC Sets New Energy Record
Over the weekend, physicists and engineers at the Large Hadron Collider (LHC) nudged proton beam energies to a new record: 4 Tera-electron volts (TeV). This record comes shortly after CERN announced last month they'd be cranking up the juice through 2012.
"Record-breaking 4 TeV beams in the #LHC over the weekend (22h40 CET on Friday to be precise). First collisions at 4 TeV planned for April." -- CERN (Twitter)
Now their goal of 4 TeV has been achieved, CERN aims to collide the first protons at this energy in April. As the LHC collides protons head-on, the counter-circulating protons speeding around the 11-mile ring of supercooled electromagnets under the France-Swiss border will have an effective collision energy of 8 TeV (double the beam energy).
Although these collision energies are impressive, the LHC still isn't operating at its designed maximum. In 2014, after the facility's routine 20-month shutdown, physicists hope that they will be ready to push beam energies to 7 TeV -- culminating in collision energies of 14 TeV.
With larger collision energies comes the promise of uncovering new physics. But first on the list of "Cosmic Mysteries to Solve" is to discover the Higgs boson -- the long-theorized (and much-hyped) subatomic particle believed to endow all matter in the Universe with mass. Tantalizing hints of the Higgs are beginning to show in the huge quantity of data being spewed by the LHC and the vast archive of data from the recently retired U.S. Tevatron particle accelerator.
Read more at Discovery News
"Record-breaking 4 TeV beams in the #LHC over the weekend (22h40 CET on Friday to be precise). First collisions at 4 TeV planned for April." -- CERN (Twitter)
Now their goal of 4 TeV has been achieved, CERN aims to collide the first protons at this energy in April. As the LHC collides protons head-on, the counter-circulating protons speeding around the 11-mile ring of supercooled electromagnets under the France-Swiss border will have an effective collision energy of 8 TeV (double the beam energy).
Although these collision energies are impressive, the LHC still isn't operating at its designed maximum. In 2014, after the facility's routine 20-month shutdown, physicists hope that they will be ready to push beam energies to 7 TeV -- culminating in collision energies of 14 TeV.
With larger collision energies comes the promise of uncovering new physics. But first on the list of "Cosmic Mysteries to Solve" is to discover the Higgs boson -- the long-theorized (and much-hyped) subatomic particle believed to endow all matter in the Universe with mass. Tantalizing hints of the Higgs are beginning to show in the huge quantity of data being spewed by the LHC and the vast archive of data from the recently retired U.S. Tevatron particle accelerator.
Read more at Discovery News
Viking Mice Live On
Fierce Viking raiders spread out from Scandinavia during the late eighth to mid-10th centuries. They spread terror, destruction ... and mice ... wherever they went.
House mice (Mus musculus domesticus) accompanied the Norse in their longships and colonized the same lands. Genetic studies of mice in lands visited by ancient Scandinavians showed that the mice lived on in Iceland along with their Norse hosts but died out on Greenland and Newfoundland, just like the Vikings.
"Human settlement history over the last 1,000 years is reflected in the genetic sequence of mouse mitochondrial DNA. We can match the pattern of human populations to that of the house mice," said one of the scientists involved in the study, Eleanor Jones of the University of York and Uppsala University, in Sweden, in a press release.
DNA samples from nine sites in Iceland, Narsaq in Greenland and four sites near the Viking archaeological site, L'Anse aux Meadows, in Newfoundland, formed the modern set of mouse genetics. Mouse remains from the Eastern and Western settlements in Greenland and four archaeological sites in Iceland provided ancient samples of mouse DNA.
Icelandic mice still contained the genetic fingerprint of their seafaring ancestors, but mice on Greenland had been replaced by Danish mice (Mus musculus musculus), brought over by a more recent wave of European colonizers.
Read more at Discovery News
House mice (Mus musculus domesticus) accompanied the Norse in their longships and colonized the same lands. Genetic studies of mice in lands visited by ancient Scandinavians showed that the mice lived on in Iceland along with their Norse hosts but died out on Greenland and Newfoundland, just like the Vikings.
"Human settlement history over the last 1,000 years is reflected in the genetic sequence of mouse mitochondrial DNA. We can match the pattern of human populations to that of the house mice," said one of the scientists involved in the study, Eleanor Jones of the University of York and Uppsala University, in Sweden, in a press release.
DNA samples from nine sites in Iceland, Narsaq in Greenland and four sites near the Viking archaeological site, L'Anse aux Meadows, in Newfoundland, formed the modern set of mouse genetics. Mouse remains from the Eastern and Western settlements in Greenland and four archaeological sites in Iceland provided ancient samples of mouse DNA.
Icelandic mice still contained the genetic fingerprint of their seafaring ancestors, but mice on Greenland had been replaced by Danish mice (Mus musculus musculus), brought over by a more recent wave of European colonizers.
Read more at Discovery News
Early Earth Hazy One Day, Clear the Next
A new study of ancient South African rocks indicates Earth may have experienced huge swings in the composition of its early atmosphere.
The study in the journal Nature Geoscience indicates Earth's atmosphere transitioned between an oxygen-rich environment and a thick methane hydrocarbon haze similar to what is now seen on the Saturnian moon Titan.
The work by scientists including Dr Aubrey Zerkle from the University of Newcastle in the United Kingdom, analyzed marine sediments deposited in the Campbellrand-Malmani carbonate platform in South Africa's Ghaap Group.
The platform is one of the oldest on Earth with rocks dating back to between 2.65 and 2.5 billion years ago.
The analyses allowed Zerkle and colleagues to reconstruct the ocean and atmospheric chemistry of the period, finding evidence of oxygen production by microbes.
They also found carbon and sulfur isotopes indicating the oxygen was made in a reduced atmosphere that was periodically rich in methane.
Zerkle and colleagues believe the findings are consistent with previous theories of Earth's early atmosphere having a thick organic haze similar to that on Titan.
However their simulations suggests Earth's atmosphere repeatedly transitioned between two main atmospheric states, one haze free, the other thick in hydrocarbons.
Zerkle and colleagues attribute the transitions to changes in the rate of methane production by microbes.
They say the hydrocarbon haze didn't permanently retreat until the oxygenation of the atmosphere some 100 million years later.
Professor Malcolm Walter from the Australian Center for astro-biology at the University of New South Wales says the paper confirms a very large change in the chemistry of the Earth's surface about 2.65 billion years ago.
Read more at Discovery News
The study in the journal Nature Geoscience indicates Earth's atmosphere transitioned between an oxygen-rich environment and a thick methane hydrocarbon haze similar to what is now seen on the Saturnian moon Titan.
The work by scientists including Dr Aubrey Zerkle from the University of Newcastle in the United Kingdom, analyzed marine sediments deposited in the Campbellrand-Malmani carbonate platform in South Africa's Ghaap Group.
The platform is one of the oldest on Earth with rocks dating back to between 2.65 and 2.5 billion years ago.
The analyses allowed Zerkle and colleagues to reconstruct the ocean and atmospheric chemistry of the period, finding evidence of oxygen production by microbes.
They also found carbon and sulfur isotopes indicating the oxygen was made in a reduced atmosphere that was periodically rich in methane.
Zerkle and colleagues believe the findings are consistent with previous theories of Earth's early atmosphere having a thick organic haze similar to that on Titan.
However their simulations suggests Earth's atmosphere repeatedly transitioned between two main atmospheric states, one haze free, the other thick in hydrocarbons.
Zerkle and colleagues attribute the transitions to changes in the rate of methane production by microbes.
They say the hydrocarbon haze didn't permanently retreat until the oxygenation of the atmosphere some 100 million years later.
Professor Malcolm Walter from the Australian Center for astro-biology at the University of New South Wales says the paper confirms a very large change in the chemistry of the Earth's surface about 2.65 billion years ago.
Read more at Discovery News
Mar 18, 2012
Ultracold Experiments Heat Up Quantum Research
University of Chicago physicists have experimentally demonstrated for the first time that atoms chilled to temperatures near absolute zero may behave like seemingly unrelated natural systems of vastly different scales, offering potential insights into links between the atomic realm and deep questions of cosmology.
This ultracold state, called "quantum criticality," hints at similarities between such diverse phenomena as the gravitational dynamics of black holes or the exotic conditions that prevailed at the birth of the universe, said Cheng Chin, associate professor in physics at UChicago. The results could even point to ways of simulating cosmological phenomena of the early universe by studying systems of atoms in states of quantum criticality.
"Quantum criticality is the entry point for us to make connections between our observations and other systems in nature," said Chin, whose team is the first to observe quantum criticality in ultracold atoms in optical lattices, a regular array of cells formed by multiple laser beams that capture and localize individual atoms.
UChicago graduate student Xibo Zhang and two co-authors published their observations online Feb. 16 in Science Express and in the March 2 issue of Science.
Quantum criticality emerges only in the vicinity of a quantum phase transition. In the physics of everyday life, rather mundane phase transitions occur when, for example, water freezes into ice in response to a drop in temperature. The far more elusive and exotic quantum phase transitions occur only at ultracold temperatures under the influence of magnetism, pressure or other factors.
"This is a very important step in having a complete test of the theory of quantum criticality in a system that you can characterize and measure extremely well," said Harvard University physics professor Subir Sachdev about the UChicago study.
Physicists have extensively investigated quantum criticality in crystals, superconductors and magnetic materials, especially as it pertains to the motions of electrons. "Those efforts are impeded by the fact that we can't go in and really look at what every electron is doing and all the various properties at will," Sachdev said.
Sachdev's theoretical work has revealed a deep mathematical connection between how subatomic particles behave near a quantum critical point and the gravitational dynamics of black holes. A few years hence, offshoots of the Chicago experiments could provide a testing ground for such ideas, he said.
There are two types of critical points, which separate one phase from another. The Chicago paper deals with the simpler of the two types, an important milestone to tackling the more complex version, Sachdev said. "I imagine that's going to happen in the next year or two and that's what we're all looking forward to now," he said.
Critical Experiments
Other teams at UChicago and elsewhere have observed quantum criticality under completely different experimental conditions. In 2010, for example, a team led by Thomas Rosenbaum, the John T. Wilson Distinguished Service Professor in Physics at UChicago, observed quantum criticality in a sample of pure chromium when it was subjected to ultrahigh pressures.
Zhang, who will receive his doctorate this month, invested nearly two and a half years of work in the latest findings from Chin's laboratory. Co-authoring the study with Zhang and Chin were Chen-Lung Hung, PhD'11, now a postdoctoral scientist at the California Institute of Technology, and UChicago postdoctoral scientist Shih-Kuang Tung.
In their tabletop experiments, the Chicago scientists use sets of crossed laser beams to trap and cool up to 20,000 cesium atoms in a horizontal plane contained within an eight-inch cylindrical vacuum chamber. The process transforms the atoms from a hot gas to a superfluid, an exotic form of matter that exists only at temperatures hundreds of degrees below zero.
"The whole experiment takes six to seven seconds and we can repeat the experiment again and again," Zhang said.
The experimental apparatus includes a CCD camera sensitive enough to image the distribution of atoms in a state of quantum criticality. The CCD camera records the intensity of laser light as it enters that vacuum chamber containing thousands of specially configured ultracold atoms.
"What we record on the camera is essentially a shadow cast by the atoms," Chin explained.
The UChicago scientists first looked for signs of quantum criticality in experiments performed at ultracold temperatures from 30 to 12 nano-Kelvin, but failed to see convincing evidence. Last year they were able to push the temperatures down to 5.8 nano-Kelvin, just billionths of a degree above absolute zero (minus 459 degrees Fahrenehit). "It turns out that you need to go below 10 nano-Kelvin in order to see this phenomenon in our system," Chin said.
Read more at Science Daily
This ultracold state, called "quantum criticality," hints at similarities between such diverse phenomena as the gravitational dynamics of black holes or the exotic conditions that prevailed at the birth of the universe, said Cheng Chin, associate professor in physics at UChicago. The results could even point to ways of simulating cosmological phenomena of the early universe by studying systems of atoms in states of quantum criticality.
"Quantum criticality is the entry point for us to make connections between our observations and other systems in nature," said Chin, whose team is the first to observe quantum criticality in ultracold atoms in optical lattices, a regular array of cells formed by multiple laser beams that capture and localize individual atoms.
UChicago graduate student Xibo Zhang and two co-authors published their observations online Feb. 16 in Science Express and in the March 2 issue of Science.
Quantum criticality emerges only in the vicinity of a quantum phase transition. In the physics of everyday life, rather mundane phase transitions occur when, for example, water freezes into ice in response to a drop in temperature. The far more elusive and exotic quantum phase transitions occur only at ultracold temperatures under the influence of magnetism, pressure or other factors.
"This is a very important step in having a complete test of the theory of quantum criticality in a system that you can characterize and measure extremely well," said Harvard University physics professor Subir Sachdev about the UChicago study.
Physicists have extensively investigated quantum criticality in crystals, superconductors and magnetic materials, especially as it pertains to the motions of electrons. "Those efforts are impeded by the fact that we can't go in and really look at what every electron is doing and all the various properties at will," Sachdev said.
Sachdev's theoretical work has revealed a deep mathematical connection between how subatomic particles behave near a quantum critical point and the gravitational dynamics of black holes. A few years hence, offshoots of the Chicago experiments could provide a testing ground for such ideas, he said.
There are two types of critical points, which separate one phase from another. The Chicago paper deals with the simpler of the two types, an important milestone to tackling the more complex version, Sachdev said. "I imagine that's going to happen in the next year or two and that's what we're all looking forward to now," he said.
Critical Experiments
Other teams at UChicago and elsewhere have observed quantum criticality under completely different experimental conditions. In 2010, for example, a team led by Thomas Rosenbaum, the John T. Wilson Distinguished Service Professor in Physics at UChicago, observed quantum criticality in a sample of pure chromium when it was subjected to ultrahigh pressures.
Zhang, who will receive his doctorate this month, invested nearly two and a half years of work in the latest findings from Chin's laboratory. Co-authoring the study with Zhang and Chin were Chen-Lung Hung, PhD'11, now a postdoctoral scientist at the California Institute of Technology, and UChicago postdoctoral scientist Shih-Kuang Tung.
In their tabletop experiments, the Chicago scientists use sets of crossed laser beams to trap and cool up to 20,000 cesium atoms in a horizontal plane contained within an eight-inch cylindrical vacuum chamber. The process transforms the atoms from a hot gas to a superfluid, an exotic form of matter that exists only at temperatures hundreds of degrees below zero.
"The whole experiment takes six to seven seconds and we can repeat the experiment again and again," Zhang said.
The experimental apparatus includes a CCD camera sensitive enough to image the distribution of atoms in a state of quantum criticality. The CCD camera records the intensity of laser light as it enters that vacuum chamber containing thousands of specially configured ultracold atoms.
"What we record on the camera is essentially a shadow cast by the atoms," Chin explained.
The UChicago scientists first looked for signs of quantum criticality in experiments performed at ultracold temperatures from 30 to 12 nano-Kelvin, but failed to see convincing evidence. Last year they were able to push the temperatures down to 5.8 nano-Kelvin, just billionths of a degree above absolute zero (minus 459 degrees Fahrenehit). "It turns out that you need to go below 10 nano-Kelvin in order to see this phenomenon in our system," Chin said.
Read more at Science Daily
T. Rex's Killer Smile Revealed
One of the most prominent features of life-size models of Tyrannosaurus rex is its fearsome array of flesh-ripping, bone-crushing teeth.
Until recently, most researchers who studied the carnivore's smile only noted the varying sizes of its teeth. But University of Alberta paleontologist Miriam Reichel discovered that beyond the obvious size difference in each tooth family in T. rex's gaping jaw, there is considerable variation in the serrated edges of the teeth.
"The varying edges, or keels, not only enabled T. rex's very strong teeth to cut through flesh and bone," says Reichel, "the placement and angle of the teeth also directed food into its mouth."
Reichel analyzed the teeth of the entire tyrannosaurid family of meat-eating dinosaurs and found T. rex had the greatest variation in tooth morphology or structure. The dental specialization was a great benefit for a dinosaur whose preoccupation was ripping other dinosaurs apart.
Reichel's research shows that the T. rex's front teeth gripped and pulled, while the teeth along the side of the jaw punctured and tore flesh. The teeth at the back of the mouth did double duty: not only could they slice and dice chunks of prey, they forced food to the back of the throat.
Reichel says her findings add strength to the classification of tyrannosaurids as heterodont animals, which are animals with teeth adapted for different functions depending on their position in the mouth.
One surprising aspect of T. rex teeth, common to all tyrannosaurid's, is that they weren't sharp and dagger-like. "They were fairly dull and wide, almost like bananas," said Reichel. "If the teeth were flat, knife-like and sharp, they could have snapped if the prey struggled violently when T. rex's jaws first clamped down."
Read more at Science Daily
Until recently, most researchers who studied the carnivore's smile only noted the varying sizes of its teeth. But University of Alberta paleontologist Miriam Reichel discovered that beyond the obvious size difference in each tooth family in T. rex's gaping jaw, there is considerable variation in the serrated edges of the teeth.
"The varying edges, or keels, not only enabled T. rex's very strong teeth to cut through flesh and bone," says Reichel, "the placement and angle of the teeth also directed food into its mouth."
Reichel analyzed the teeth of the entire tyrannosaurid family of meat-eating dinosaurs and found T. rex had the greatest variation in tooth morphology or structure. The dental specialization was a great benefit for a dinosaur whose preoccupation was ripping other dinosaurs apart.
Reichel's research shows that the T. rex's front teeth gripped and pulled, while the teeth along the side of the jaw punctured and tore flesh. The teeth at the back of the mouth did double duty: not only could they slice and dice chunks of prey, they forced food to the back of the throat.
Reichel says her findings add strength to the classification of tyrannosaurids as heterodont animals, which are animals with teeth adapted for different functions depending on their position in the mouth.
One surprising aspect of T. rex teeth, common to all tyrannosaurid's, is that they weren't sharp and dagger-like. "They were fairly dull and wide, almost like bananas," said Reichel. "If the teeth were flat, knife-like and sharp, they could have snapped if the prey struggled violently when T. rex's jaws first clamped down."
Read more at Science Daily
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