Mar 3, 2012
Principal investigator Carlos Badenes, assistant professor of physics and astronomy in Pitt's Kenneth P. Dietrich School of Arts and Sciences, detailed the ways in which his team used the Sloan Digital Sky Survey -- a collection of multicolor images and more than a million spectra covering more than a quarter of the sky -- to determine what kinds of starts produce Type Ia supernovae explosions.
"We knew that two stars had to be involved in such an explosion, and that one of them had to be a white dwarf," says Dan Maoz, professor of physics and astronomy at Tel-Aviv University in Israel and coauthor of this soon-to-be-published paper on the discovery. "But there were two possibilities for what the second star is, which is what we sought to discover."
According to Badenes, there were two potential outcomes for the star's type. It could be a "normal star," like the sun, or it could be another white dwarf, which is a smaller, more dense faint star composed of electron-degenerate matter. The team suspected the latter, as two white dwarfs within the same star system would revolve around one another at half a million miles an hour, speeding up and getting closer and closer until one day they merge, most likely producing the fireworks of Type Ia supernovae.
"There were obvious reasons to suspect that Type Ia supernovae come from the merging of a double white dwarf," says Maoz. "But our biggest question was whether there were enough double white dwarfs out there to produce the number of supernovae that we see."
Because white dwarfs are extremely small and faint, there is no hope of seeing them in distant galaxies. Therefore, Badenes and Maoz turned to the only place where they could be seen: the part of the Milky Way Galaxy within about a thousand light years of the sun. To find the star's companion, the team needed two spectra to measure the velocity between the two. However, SDSS only took one spectrum of most objects. The team decided to make use of a little-known feature in the SDSS spectra to separate each one into three or more subspectra. Although the reprocessing of the data was challenging, said Badenes, the team was able to compile a list of more than 4,000 white dwarfs within a year, each of which had two or more high-quality subspectra.
"We found 15 double white dwarfs in the local neighborhood and then used computer simulations to calculate the rate at which double white dwarfs would merge," says Badenes. "We then compared the number of merging white dwarfs here to the number of Type Ia supernovae seen in distant galaxies that resemble the Milky Way."
The result was that, on average, one double white dwarf merger event occurs in the Milky Way about once a century.
"That number is remarkably close to the rate of Type Ia supernovae we observe in galaxies like our own," says Badenes. "This suggests that the merger of a double white dwarf system is a plausible explanation for Type Ia supernovae."
In addition to providing a key clue about the nature of these important events, the team's discovery shows the potential of giant astronomical surveys like the SDSS.
Read more at Science Daily
Dione -- discovered in 1684 by astronomer Giovanni Cassini (after whom the spacecraft was named) -- orbits Saturn at roughly the same distance as our own moon orbits Earth. The tiny moon is a mere 700 miles wide and appears to be a thick, pockmarked layer of water ice surrounding a smaller rock core. As it orbits Saturn every 2.7 days, Dione is bombarded by charged particles (ions) emanating from Saturn's very strong magnetosphere. These ions slam into the surface of Dione, displacing molecular oxygen ions into Dione's thin atmosphere through a process called sputtering.
Molecular oxygen ions are then stripped from Dione's exosphere by Saturn's strong magnetosphere.
A sensor aboard the Cassini spacecraft called the Cassini Plasma Spectrometer (CAPS) detected the oxygen ions in Dione's wake during a flyby of the moon in 2010. Los Alamos researchers Robert Tokar and Michelle Thomsen noted the presence of the oxygen ions.
"The concentration of oxygen in Dione's atmosphere is roughly similar to what you would find in Earth's atmosphere at an altitude of about 300 miles," Tokar said. "It's not enough to sustain life, but -- together with similar observations of other moons around Saturn and Jupiter -- these are definitive examples of a process by which a lot of oxygen can be produced in icy celestial bodies that are bombarded by charged particles or photons from the Sun or whatever light source happens to be nearby."
Perhaps even more exciting is the possibility that on a moon with subsurface water, such as Jupiter's moon Europa, molecular oxygen could combine with carbon in subsurface lakes to form the building blocks of life. Future missions to Europa could help unravel questions about that moon's habitability.
Read more at Science Daily
According to University of Wisconsin-Parkside paleontologist Chris Noto, one of the researchers who has been carefully picking over the site, this place “was probably very similar in overall appearance to the Florida Everglades.” But the Cretaceous fauna was significantly different. While turtles and crocodyliforms were familiar players, dinosaurs, lungfish, sharks, stingrays, and other animals called this prehistoric swamp home. All endured the harsh fluctuations between the wet and dry seasons. “Preservered in the sediment is the story of a seasonal climate,” Noto said, “one which was punctuated by intense storms that may have felled the large trees” and may have sparked wildfires. “Life there was certainly not easy.”
Turtles may have had an especially difficult time. As explained by Noto and collaborators Derek Main and Stephanie Drumheller in the latest issue of PALAIOS, the Cretaceous turtles shared their habitat with a large, powerful crocodyliform capable of crushing through the defenses of the shelled reptiles. And the aquatic ambush predator didn’t just specialize on turtles — the crocodyliform was formidable enough to dismember dinosaurs, too.
As yet, the crocodyliform does not have a name. A formal description of the animal is still in the works. But Noto suggests that this predator would have reached approximately 20 feet in length. “I think in many ways it resembles salt water crocodiles,” he said, although the prehistoric species differed from modern ones in some significant ways. In addition to a “robust A-shaped skull” set with “a pair of large, prominent teeth (pseudocanines) in the upper and lower jaws,” the croc’s bony armor — known as scutes — “were large and rectangular, as opposed to the smaller, rounded scutes seen on living forms,” Noto explained.
This sharp-toothed archosaur left behind a telltale pattern of damage on turtle and dinosaur bones. Out of a sample of two hundred dinosaur bones and 29 turtle shell pieces, Noto and colleagues found tooth marks attributable to the crocodyliform on two dinosaur limb bones and 17 pieces of turtle shell. The pits, punctures, and scores along these bones are permanent signs of prehistoric interactions and might provide paleontologists with clues about how the ancient croc fed.
Turtles seemed to be the crocodyliform’s specialty. About 60 percent of the turtle shell fragments found so far have tooth marks on them. And those bite marks indicate that the croc was a Cretaceous nutcracker. “The marks suggest that the croc flipped turtles on their sides in its mouth using inertial motions of the jaws and head,” Noto said, “then crushed the shell about its long axis.” What is missing from the turtle shells is an additional clue. “We are completely lacking fragments from the central portions of the shell”, Noto explained — the crocodyliform’s bite obliterated this part of the turtle shell. “We believe that this is the first documented evidence in the fossil record of this specific ‘nutcracking’ behavior of turtle shells by crocodyliforms,” Noto said.
Read more at Wired
The investigation, carried out at the University of Modena and Reggio and the Uffizi Gallery in Florence, where the statue has been on display since 1677, indicates that the life-sized naked and sensual Venus originally had red lips and hair laminated with gold.
These features were meant to represent the Venus "in a very realistic way," Fabrizio Paolucci, head of the Uffizi's classical antiquities department, said.
To strenghten the effect, the naked statue also wore precious earrings, as newly discovered earlobe holes suggest.
One of the most copied statues of all time, the Medici Venus -- itself a 1st century BC copy of a Greek bronze statue -- is the oldest sculpture in the Uffizi Gallery.
How and where the statue was discovered is unkown. First recorded in 1638 in the Villa Medici in Rome, it was sent to Florence in 1677 and became the icon of the Grand Tour, the cultural journey of Europe undertaken in the 18th century by young, upper-class men.
On display at the Uffizi scarlet-walled, octagonal "Tribune," the Venus triumphed as the archetype of ideal feminine beauty.
Indeed, the gesture basically drew attention to those parts she hoped to cover.
The Venus was the emotional climax for the Grand Tourist, as Johann Zoffany's 1772 painting The Tribuna of the Uffizi testifies. There, five British connoisseurs are clustered behind the celebrated statue, peering at her bottom - one even scrutinizes the sculpture with a spyglass.
Read more at Discovery News
Mar 2, 2012
"Fiji is a hotspot for biodiversity. Most of the species that occur in Fiji aren't found anywhere else in the world," he said.
"My project looks at how island species in these ancient groups of trees originated."
Dr Prentis will use $150,000 DNA sequencer technology, called an Ion Torrent, to pinpoint genes in three pairs of tree species: Cynometra falcata (critically endangered) and C. insularis; Degeneria vitiense (vulnerable) and D. Roseiflora; and Podocarpus affinis (vulnerable) and P. neriifolius.
Dr Prentis said researchers would compare the vulnerable or endangered tree species with ones more commonly found in Fiji.
"We'll analyse each of the species pairs to find genes that have been important in the process of becoming unique. We're interested in how these rare species evolve," he said.
Dr Prentis said the research could predict how the trees will adapt to climate change.
"We need to understand how biodiversity is created in the first place to understand how to best conserve it in the future," Dr Prentis said.
"With climate change these species are going to have to respond to increasingly changing environmental conditions and an increase in extreme events, such as cyclones.
"We don't know if these living fossil trees have the potential to adjust to these future environments."
The new Ion Torrent technology will accelerate research at QUT, enabling scientists to analyse tens of thousands of genes at the same time, compared to studying a handful of genes simultaneously with a standard DNA sequencer.
"What we can do in a couple of hours on the Ion Torrent is the equivalent of six months' work on a standard DNA sequencer," Dr Prentis said.
The Ion Torrent, which can sequence whole microbial genomes and specific genes in species such as humans, insects and plants, will be used for health, agriculture and evolutionary research.
Dr Prentis' research, being conducted with Dr Gunnar Keppel from Curtin University in Western Australia, received $40,000 of funding from the Australian Pacific Sciences Foundation.
Read more at Science Daily
The circles varied in diameter up to a few millionths of a meter, and in the center of each was a perfect square. The mysterious patterns were reminiscent of nothing so much as so‑called "alien" crop circles.
Until recently the cause of these strange formations remained a mystery. Now theoretical insights have explained what's happening, and the results have been published online by Physical Review Letters.
Eagerly melting alloys
When two solids are combined in just the right proportions, changes in chemical bonding may produce an alloy that melts at a temperature far lower than either can melt by itself. Such an alloy is called eutectic, Greek for "good melting." The eutectic alloy of gold and silicon -- 81 percent gold and 19 percent silicon -- is especially useful in processing nanoscale semiconductors such as nanowires, as well as for device interconnections in integrated circuits; it liquefies at a modest 363˚ Celsius, far lower than the melting point of either pure gold, 1064°C, or pure silicon, 1414°C.
"Gold-silicon eutectic liquid can safely solder chip layers together or form microscopic conducting wires, by flowing into channels in the substrate without burning up the surroundings," says Berkeley Lab's Junqiao Wu. "It's particularly interesting for processing nanoscale materials and devices." Wu cites the example of silicon nanowires, which can be grown from beads of eutectic liquid that form from droplets of gold. The beads catalyze the deposition of silicon from a chemical vapor and ride atop continually lengthening nanowire whiskers.
Understanding just how and why this happens has been a challenge. Although eutectic alloys are well studied as solids, the liquid state presents more obstacles, which are particularly formidable at the nanoscale because of greatly increased surface tension -- the same surface forces that make it difficult to form ultra-thin films of water, for example, because they pull the water into droplets. At smaller scales the ratio of surface area to bulk increases markedly, and nanoscale structures have been described as virtually "all surface."
These are the conditions that the team led by Wu, who is a faculty scientist in Berkeley Lab's Materials Sciences Division and a professor in the Department of Materials Science and Engineering at the University of California at Berkeley, set out to examine, by creating the thinnest possible films of gold-silicon eutectic alloys. The researchers did so by starting with a substrate of pure silicon, on whose flat surface an extremely thin barrier layer (two nanometers thick) of silicon dioxide had formed. On this surface they laid layers of pure gold, varying the thickness from one trial to the next between just a few nanometers to a hefty 300 nanometers. The silicon dioxide barrier prevented the pure silicon from mixing with the gold.
The next step was to heat the layered sample to 600 °C for several minutes -- not hot enough to melt the gold or silicon but hot enough to cause naturally existing pinholes in the thin silicon dioxide layer to enlarge into small weak spots, through which pure silicon could come in contact with the overlying gold. At the high temperature, silicon atoms quickly diffused out of the substrate and into the gold, forming a layer of eutectic gold-silicon alloy nearly the same thickness as the original gold and spreading in a virtually perfect circle from the central pinhole.
When the circular disk of eutectic alloy got large enough it suddenly broke up, disrupted by the high surface energy of the gold-silicon eutectic liquid. The debris was literally pulled to the edges of the disk, piling up around it to leave a central denuded zone of bare silicon dioxide.
In the center of the denuded zone, a perfect square of gold and silicon remained.
Read more at Science Daily
Dr. Brian Redmond, curator of archaeology at The Cleveland Museum of Natural History, was lead author on research published in the Feb. 22, 2012 online issue of the journal World Archaeology.
Redmond and researchers analyzed 10 animal bones found in 1998 in the collections of the Firelands Historical Society Museum in Norwalk, Ohio. Found by society member and co-author Matthew Burr, the bones were from a Jefferson's Ground Sloth. This large plant-eating animal became extinct at the end of the Ice Age around 10,000 years ago.
"This research provides the first scientific evidence for hunting or scavenging of Ice Age sloth in North America," said Redmond. "The significant age of the remains makes them the oldest evidence of prehistoric human activity in Ohio, occurring in the Late Pleistocene period."
A series of 41 incisions appear on the animal's left femur. Radiocarbon dating of the femur bone estimates its age to be between 13,435 to 13,738 years old. Microscopic analyses of the cut marks revealed that stone tools made the marks. The pattern and location of the distinct incisions indicate the filleting of leg muscles. No traces of the use of modern, metal cutting tools were found, so the marks are not the result of damage incurred during their unearthing. Instead, the morphology of the marks reveals that they were made by sharp-edged stone flakes or blades.
The "Firelands Ground Sloth," as the specimen is named, is one of only three specimens of Megalonyx jeffersonii known from Ohio. Based on measurements of the femur, tibia and other bones, it is one of the largest individuals of this species on record. It had an estimated body mass of 1,295 kilograms (2,855 pounds).
The sloth bones were first described in a 1915 scientific paper by geologist Oliver Hay. The collection was made known to Hay by Roe Niver, a University of Illinois student who lived in Huron County and died in July 1915. The bones were donated to the Firelands Museum before 1915. The only documentation with the remains indicates they were found in a swamp in Norwich Township. The exact locality where the bones were first discovered is uncertain.
Read more at Science Daily
A new paper in Science examines the geologic record for context relating to ocean acidification, a lowering of the pH driven by the increased concentration of carbon dioxide in the atmosphere. The research group (twenty-one scientists from nearly as many different universities) reviewed the evidence from past known or suspected intervals of ocean acidification. The work provides perspective on the current trend as well as the potential consequences. They find that the current rate of ocean acidification puts us on a track that, if continued, would likely be unprecedented in last 300 million years.
There are several ways acidification events leave their signature in the rock record. The isotopic composition of carbon changes with shifts in the carbon cycle, such as the movement of greenhouse gases like methane and carbon dioxide in the atmosphere. Isotopes of boron present in marine shells track ocean water pH. The ratios of other trace elements in marine shells (such as uranium or zinc) to calcium indicate the availability of carbonate ions. (Ocean acidification is not just about pH, but the reduction of carbonate mineral saturation that makes it more difficult for calcifiers to build their shells.) In addition to all this, the fossil record records the extinctions and morphological changes in marine species that occur around catastrophic events in Earth history.
Reconstructing the past
The paper covers the last 300 million years. That’s not just a round number—it’s about as far back as we can confidently go. Because plate tectonics drives oceanic plates back down into the mantle at subduction zones, there is no oceanic crust or sediment older than 180 million years for us to examine.
To look back farther than that, you’ve got to rely on the limited supply of marine rocks that shifted onto continental plates. That makes it harder to construct a global picture, as some regions become over-represented. Also, as these records extend deeper and deeper into the past, uncertainty in ages and calcifier physiology reduces confidence in the results of these analyses. Beyond 300 million years ago, the unknowns for some of these measures are just too large.
The first period the researchers looked at was the end of the last ice age, starting around 18,000 years ago. Over a period of about 6,000 years, atmospheric CO2 levels increased by 30 percent, a change of roughly 75 ppm. (For reference, atmospheric CO2 has gone up by about the same amount over the past 50 years.) Over that 6,000 year time period, surface ocean pH dropped by approximately 0.15 units. That comes out to about 0.002 units per century. Our current rate is over 0.1 units per century—two orders of magnitude greater, which lines up well with a model estimate we covered recently.
The last deglaciation did not trigger a mass extinction, but it did cause changes in some species. The shells of planktic foraminfera decreased by 40-50 percent, while those of coccolithophores went down 25 percent.
During the Pliocene warm period, about 3 million years ago, atmospheric CO2 was about the same as today, but pH was only 0.06 to 0.11 units lower than preindustrial conditions. This is because the event played out over 320,000 years or so. We see species migration in the fossil record in response to the warming planet, but not ill effects on calcifiers. This is because ocean acidification depends primarily on the rate of atmospheric CO2 increases, not the absolute concentration.
Next, the researchers turned their focus to the Paleocene-Eocene Thermal Maximum (or PETM), which occurred 56 million years ago. Global temperature increased about 6°C over 20,000 years due to an abrupt release of carbon to the atmosphere (though this was not as abrupt as current emissions). The PETM saw the largest extinction of deep-sea foraminifera of the last 75 million years, and was one of the four biggest coral reef disasters of the last 300 million years.
We don’t have good records of pH over this period, so it’s difficult to tell how much of the extinctions were caused by ocean acidification as opposed to the temperature change or decrease in dissolved oxygen that results from warming ocean water.
The group also examined the several mass extinctions that defined the Mesozoic—the age of dinosaurs. The boundary between the Triassic and Jurassic included a large increase in atmospheric CO2 (adding as much as 1,300 to 2,400 ppm) over a relatively short period of time, perhaps just 20,000 years. The authors write, “A calcification crisis amongst hypercalcifying taxa is inferred for this period, with reefs and scleractinian corals experiencing a near-total collapse.” Again, though, it’s unclear how much of the catastrophe can be blamed on acidification rather than warming.
Finally, we come the big one—The Great Dying. The Permian-Triassic mass extinction (about 252 million years ago) wiped out around 96 percent of marine species. Still, the rate of CO2 released to the atmosphere that drove the dangerous climate change was 10-100 times slower than current emissions.
Read more at Wired Science
Mar 1, 2012
Then, when the jar has been forgotten, soft beating against its glass walls calls attention to a new wonder: the jar now holds a fragile-winged butterfly or dusky moth with fringed antennae.
These transformations are so startling that a child's awe seems a more appropriate response than an adult's calm acceptance.
How is it, after all, that an insect can remake itself so completely that it appears to be a different creature altogether, not just once, but several times in its lifetime?
Working with fruit flies rather than butterflies, a team led by Ian and Dianne Duncan of Washington University in St. Louis provides part of the answer in the latest issue of PNAS. Ian Duncan, PhD, is professor of biology in Arts & Sciences; Dianne Duncan is a research associate and director of the Biology Imaging Facility.
The puzzling question
Fruit flies go through three main life phases: the larva, the pupa, and the adult.
Earlier work had shown that the larval and adult forms are patterned by the same "signaling systems," or chains of biochemicals that transfer a signal from receptors on the surface of cells to target genes within cell nuclei.
What scientists didn't understand was how the same signaling systems could orchestrate the formation of a larva in one case and the adult fly in the other.
The Duncans, working with collaborator Eric Baehrecke, PhD, of the University of Massachusetts Medical School and graduate student Xiaochun (Joanna) Mou were able to show that a gene expressed only in the pupal stage redirects signaling systems so that they activate a different set of target genes than in earlier stages.
This gene is itself controlled by a steroid hormone that turns on many other genes as well. So insect metamorphosis, triggered by a hormone, resembles puberty, the human analog of metamorphosis, which is also triggered by hormones.
A wholesale change
In 2011, Michael Akam and Anastasios Pavlopoulos, scientists at the University of Cambridge, published a paper in PNAS that described what happened when they artificially turned on a regulatory gene at different stages of a fly's metamorphosis.
Using microarrays that detected the products of gene activity, they found that at every stage of metamorphosis, the regulatory gene subtly increased or decreased the expression of hundreds of downstream genes. But the kicker was that at different stages of metamorphosis, different downstream genes were turned on.
"They found 870-some target genes," Ian Duncan says, "and among those 870, roughly 200 were induced in the larva, more than 400 were induced in the prepupa, and 350 were induced in the pupa, but the thing is, the genes controlled at each stage were almost completely different. So they realized there were global changes of rules from one stage to the next."
"It's as if two teams were playing soccer," Dianne Duncan says, "and at halftime the referee comes out and hands out a new set of rules. Now you've got the same players, the same field, the same goals, but the teams are playing hockey not soccer. The rules are different, so the game is different."
Akam and Pavlopoulos ended their article in PNAS by saying that more research was needed to understand how this repurposing of signaling pathways happens. The Duncans, in reply, are publishing their paper in the same journal.
Throwing two switches
The Duncans focused on a gene called E93 that is turned on by steroid pulses, but only at the pupal stage. "It is required for all patterning and production of new structures in the pupa, but it doesn't play any role in making the larva," Ian Duncan says.
To understand in detail what E93 was doing in the fly, the Duncans chose a simple and well understood patterning process: the activation of a target gene called Distal-less that makes dark spots near the fly's leg bristles called bracts.
The target gene is activated by a well-studied signaling pathway -- the epidermal growth factor receptor (EGFR) pathway. "The EGFR signal pathway is used all over the place in the fly," Ian Duncan says. "It's used for different things at different times."
To demonstrate that E93 had to be activated before the EGFR pathway could turn on the target gene, the Duncans looked at flies with mutated E93 genes.
"In the mutant that doesn't have this gene, cells don't respond to the signaling pathway, and bracts fail to form," Ian Duncan says.
Further experiments showed that E93 and EGFR signaling are both needed to turn on the target gene Distal-less. E93 tells Distal-less when to turn on and EGFR signaling tells it where to turn on. Having to throw two switches ensures that the target gene is activated at only the right time and place.
Read more at Science Daily
Named Guidraco venator, which is Chinese and Latin for “ghost dragon hunter,” the meat-eating pterosaur had a wingspan of between 13 and 16 feet. The basket of pointy teeth at the end of its foot-long skull probably helped it catch fish, and a round sail on its head may have stabilized flight.
“This is really an amazing fossil, but the funny thing to me is that it was found in Asia. It looks very similar but not identical to pterosaurs found in Brazil,” said Eberhard “Dino” Frey, a paleontologist at the State Museum of Natural History in Karlsruhe. Frey was not involved in the work, published online Feb. 22 in Naturwissenschaften.
The closest relative to G. venator may be a fossil Frey and his colleagues recovered in 2003, called Ludodactylus sibbicki, adding further evidence that now 40 known species of pterosaurs were more globally distributed than previously thought. “The longer we search, the more of these animals turn up,” Frey said.
Pterosaurs were highly successful reptiles (not dinosaurs, as they’re commonly mislabeled) that lived between 210 and 65 million years ago. Although insects took to air first, pterosaurs are recognized as the first flying vertebrates.
Most of their fossils are found in formerly arid plains or river valleys, suggesting the animals primarily dwelled inland. All pterosaurs are thought to have eaten meat, and two crucial features suggest G. venator ate fish: Its 2-inch-long teeth appear suited to trapping fish from water, and pieces of fossilized poop found near its head are full of fish vertebrae.
Whether pterosaurs scavenged, hunted or pursued both strategies, however, is an ongoing debate for many species, including giant pterosaurs known as Quetzalcoatlus. The new G. venator is no exception.
The new study’s authors – paleontologist Alexander Kellner of the Federal University of Rio de Janeiro and Xiaolin Wang, Ahunxing Jiang and Xin Cheng of the Chinese Academy of Sciences — could not be reached for comment, but wrote in the study that G. venator likely hunted actively for fish.
Frey politely disagreed. “Just imagine yourself as this creature. How would you catch living fish with such needles? You have no fingers, no fork, nothing to remove a fish if it gets stuck,” he said. “They might have randomly collected what was there and probed it with a spaghetti-like tongue. If edible, they’d eat it. If not, they’d bump it out.”
Such behavior would mirror that of L. sibbicki, its closest relative. The only fossil L. sibbicki recovered in Brazil suggests the animal died by getting a plant leaf wedged in its mouth while filter-feeding. “It may have mistaken the leaf for a dead fish and accidentally it got stuck. It couldn’t remove it,” Frey said.
Most pterosaur fossils have turned up in silty and fine-grained sediments in what is now Brazil, but the new find, from the Jiufotang Formation in northeast China, adds an interesting twist to the evolutionary histories of pterosaurs.
“[I]ts similarities to some Brazilian pterosaurs show that these animals were probably distributed globally,” paleontologist David Martill of the University of Portsmouth, another pterosaur researcher who wasn’t involved in the study, wrote to Wired.
“We can [now] hope to find them anywhere in the world where early Cretaceous strata crop out. We have found some tantalising fragments in England, some dating back to discoveries made in the 19th century, that indicate similar animals.”
Read more at Wired Science
These ancient bloodsuckers are the oldest fleas ever found, and the oldest example of bloodsucking parasites in the fossil record, study researcher André Nel of the Muséum National d’Histoire Naturelle in Paris told LiveScience.
These early fleas lacked the strong hindlegs of modern fleas, Nel said.
"Their biology and behavior was certainly different, more like that of a louse creeping among the fur and feathers of the hosts," said Nel, who, along with his colleagues, analyzed nine fossil specimens of the fleas discovered in outcrops in China.
The fleas lived in the Mesozoic era, a chunk of geologic time extending from 250 million years ago to 65 million years ago and includes the Jurassic period. They were giant compared with today's fleas, with one female specimen's body longer than 0.8 inches (2 cm), said study researcher Diying Huang, a researcher at the Chinese Academy of Science in Nanjing, China. Modern fleas don't get much larger than 0.1 inches, or 3 mm, in length.
The fleas' size and tough mouthparts would have made it easy for them to feast on large hosts — even dinosaurs.
"Their long siphonate dentate mouthparts may easily penetrate dinosaur skin," Huang told LiveScience.
The fossils, which reside in the collections of the Nanjing Institute of Geology and Palaeontology, fill in some of the gaps of flea evolution, Nel said. The first fleas evolved from ancestors that fed on plant fluids. Some then evolved from plants to animals, becoming bloodsuckers. These parasites lost their wings and developed grasping legs to cling to fur and feathers.
Read more at Discovery News
The forest, which stood in what is now Gilboa, N.Y., was first unearthed in a quarry in the 1920s. But now, a new construction project has revealed for the first time the forest floor as it stood 380 million years ago in the Devonian period.
"For the first time, we actually have a map of about 1,200 square meters (12,900 square feet) of a Devonian forest," said study researcher Chris Berry, a scientist at Cardiff University in the United Kingdom. "We know which plants were growing where in this forest, and how they were interacting."
The fossilized forest floor contained three types of enormous plants. The first, known as the Gilboa tree or Eospermatopteris, was once thought to be the only type of tree in the forest; quarry workers have been carting specimens out of the area since the fossil plants were first discovered. This tree was tall and looked like today's palm trees, with a crown of branches at the very top.
But an even stranger specimen lurked in this ancient forest. Amid the towering Gilboa trees were woody creeping plants with branches about 6 inches (15 centimeters) in diameter. These giant plants, known as progymnosperms, seemed to lean against the Gilboa trees for support, perhaps even climbing into them occasionally, Berry said.
"Those trees were covered in little branches which sprung out in all directions and made a sort of thicket on the floor of the forest," Berry said. "That was a big surprise."
The researchers also found a fragment of a third type of tree, lycopsids, which would later dominate the Carboniferous period from about 360 million to about 300 million years ago. They reported their findings Wednesday (Feb. 29) in the journal Nature.
Understanding an ecosystem
The new view of the ancient forest is changing paleontologists' understanding of what the landscape looked like. The earliest researchers thought the forest was in a swamp, but Berry and his colleagues, including study leader William Stein of Binghamton University in New York, now believe the forest stood in a flat coastal plain near an ancient shoreline. It was probably buried and preserved when a river channel shifted, bringing in loads of sand to cover the forest floor.
Before the forest's death, it was probably chock full of millipedes and insects, Berry said. As they grew, the Gilboa trees shed branches, which would have littered the forest floor and created a perfect habitat for creepy-crawlies.
"I've spent 20 years trying to imagine what these plants were like as individuals, and yet I really had no conception of them as an ecosystem," Berry said. "Going to Gilboa and sitting in the middle of the forest floor, you could almost see them growing out of the ground. … The fossil forest came to life in front of my eyes in a way that has never happened before."
Read more at Discovery News
Feb 29, 2012
The helmet dates back around 2,600 years and likely belonged to a wealthy Greek mercenary who took part in a series of wars, immortalized in the Bible, which ravaged the region at that time. Archaeologists believe that he likely fought for an Egyptian pharaoh named Necho II.
The helmet was discovered accidentally in 2007 during commercial dredging operations in the harbor. After it was discovered, conservators with the Israel Antiquities Authority went to work cleaning it and archaeologists began to analyze it.
They discovered that it is very similar to another helmet found in the 1950s near the Italian island of Giglio, about 1,500 miles (2,300 kilometers) away. That helmet has been dated to around 2,600 years ago, something which helped the researchers arrive at a date for the Haifa Bay helmet.
"The gilding and figural ornaments make this one of the most ornate pieces of early Greek armor discovered," writes Jacob Sharvit, director of the Marine Archaeology Unit with the Israel Antiquities Authority, and John Hale, a professor at the University of Louisville, in a summary of their research being presented at the meeting.
This Greek warrior likely would have been a very wealthy individual, as few soldiers could afford such an ornate helmet. The researchers aren't sure where the helmet was made, though they suspect the warrior could be from one of the Greek colonies in Ionia, on the west coast of modern-day Turkey.
Greek warrior loses helmet
At the time the helmet was made, circa 600 B.C., Greek colonies dotted the Mediterranean coast, stretching from the Black Sea to southern France. Even so, there is no evidence of Greek colonies in Israel, indicating the warrior who ventured into Haifa Bay was likely the leader of a group of Greek mercenaries.
This warrior was likely one of Egyptian pharaoh Necho II's troops, which he sent through Israel accompanied by a fleet of ancient ships. The pharaoh was heavily involved in military campaigns in the region for nearly a decade, operations in which this warrior and his group likely were involved.
"They were not fighting for the Greeks, they were fighting for Egypt," Sharvit told LiveScience in an interview.
The series of wars engulfed Egypt, Judah (a Jewish kingdom), Assyria and Babylon, with Necho II of Egypt intervening on the side of Assyria.
The end result of these conflicts was the conquest of Judah and the rise of a resurgent Babylon led by King Nebuchadnezzar II. These events would be immortalized in the Torah (the Christian Old Testament).
At some point, amidst all this history, the elite Greek warrior's helmet ended up at the bottom of Haifa Bay.
Read more at Discovery News
As part of work on the Iceman's genome — his complete genetic blueprint — scientists found genetic material from the bacterium responsible for the disease, which is spread by ticks and causes a rash and flu-like symptoms and can lead to joint, heart and nervous system problems.
The new analysis also indicates the Iceman was lactose intolerant, predisposed to cardiovascular disease, and most likely had brown eyes and blood type O.
To sequence the Iceman's genome, researchers took a sample from his hip bone. In it, they looked for not only human DNA — the chemical code that makes up genes — but also for that of other organisms. While they found evidence of other microbes, the Lyme disease bacterium, called Borrelia burgdorferi, was the only one known to cause disease, said Albert Zink, a study researcher and head of the European Institute for Mummies and the Iceman at the European Academy of Bozen/Bolzano (EURAC) in Italy.
"Our data point to the earliest documented case of a B. burgdorferi infection in mankind. To our knowledge, no other case report about borreliosis [Lyme disease] is available for ancient or historic specimens," Zink and colleagues write in an article published on Tuesday (Feb. 28) in the journal Nature Communications.
Discovering evidence of Borrelia is an "intriguing investigative lead," said Dr. Steven Schutzer, an immunologist at the University of Medicine and Dentistry of New Jersey-New Jersey Medical School.
Schutzer is a lead investigator on a National Institutes of Health-funded project that has sequenced at least 17 strains of the modern bacterium, and has published 13 of those so far.
The discovery of the traces of Borrelia within the sample taken from the Iceman still needs to be confirmed, he said. "Now we know what we want to look for, now that we know there is a possibility of that being here, we can do a very targeted approach that looks for Borrelia," Schutzer said.
Lyme disease is transmitted by ticks in North America and Eurasia. It was first found in the United States in Connecticut in the mid-1970s; a similar disorder had been identified in Europe earlier in the 20th century.
Schutzer said he is discussing follow-up studies with Zink.
Previous work had examined genetic material within the Iceman's mitochondria -- the energy-producing centers in cells. His mitochondrial DNA,which is inherited through the maternal line, did not reveal any living relatives.
In this new project, researchers decoded the DNA found within the nuclei of the Iceman's cells, which is inherited from both parents. They found the Iceman belonged to a lineage that is now rare,but still present in some places.
Read more at Discovery News
The prime evidence comes from an ossuary, a box or chest built to contain human remains that was examined in the tomb in Jerusalem by a robotic arm and a “snake camera.” It has a four-line Greek inscription that refers to God “raising up” someone. A carved image found on an adjacent ossuary shows what appears to be a large fish with a human stick figure in its mouth -- interpreted by the excavation team to be an image evoking the biblical story of Jonah.
"If anyone had claimed to find either a statement about resurrection or a Jonah image in a Jewish tomb of this period I would have said impossible -- until now," said James D. Tabor, professor and chair of religious studies at the University of North Carolina at Charlotte. "Our team was in a kind of ecstatic disbelief, but the evidence was clearly before our eyes, causing us to revise our prior assumptions."
Tabor collaborated with filmmaker/professor Simcha Jacobovici to study the tomb, which lies in close proximity to the Jesus family tomb, the subject of a wildly popular and highly controversial Discovery Channel documentary of the same name.
The new findings will be detailed online at www.bibleinterp.com on Feb. 28, 2012.
They will also be published in a book by Simon & Schuster entitled "The Jesus Discovery: The New Archaeological Find That Reveals the Birth of Christianity" and detailed in a fresh documentary to be aired by the Discovery Channel in spring 2012.
The findings and their interpretation are likely to be controversial, since most scholars are skeptical of any Christian archaeological remains from so early a period.
"Context is everything in archaeology," Tabor pointed out. "These two tombs, less than 200 feet apart, were part of an ancient estate, likely related to a rich family of the time. We chose to investigate this tomb because of its proximity to the so-called 'Jesus tomb,' not knowing if it would yield anything unusual."
An ossuary expert debunked the 2007 documentary, telling the Associated Press at the time that the documentary fudged some of the facts.
"James Cameron is a great guru of science fiction, and he's taking it to a new level with Simcha Jacobovici. You take a little bit of science, spin a good yarn out of it and you get another 'Terminator' or 'Life of Brian,'" said Stephen Pfann, a textual scholar and paleographer at the University of the Holy Land in Jerusalem who briefly appeared as an ossuary expert in that documentary.
The tomb containing the new discoveries is a modest sized, carefully carved rock cut cave tomb typical of Jerusalem in the period from 20 BCE until 70 CE.
It was exposed in 1981 by builders and is currently several meters under the basement level of a modern condominium building in East Talpiot, a neighborhood of Jerusalem less than two miles south of the Old City.
Archaeologists entered the tomb at the time, were able to briefly examine it and its ossuaries, take preliminary photographs, and remove one pot and an ossuary, before they were forced to leave by Orthodox religious groups who oppose excavation of Jewish tombs.
In 2009 and 2010, Tabor and Rami Arav, professor of archaeology at the University of Nebraska at Omaha, working together with Jacobovici, obtained a license to excavate the current tomb from the Israel Antiquities Authority under the academic sponsorship of the University of North Carolina at Charlotte, excavations funded by the Discovery Channel.
Among the approximately 2000 ossuaries that have been recovered by the Israel Antiquities Authority, only 650 have any inscriptions on them, and none have inscriptions comparable to those on ossuaries 5 and 6.
Read more at Discovery News
The force of T. rex's bite was comparable to having an elephant sit on the victim with each crunch, according to a paper in the latest issue of Biology Letters. The carnivorous dinosaur’s biting force was between 35,000 to 57,000 Newtons at a single tooth.
In comparison, human biting force is usually documented as being less than 1000 Newtons, suggesting that T. rex could have bitten through thick bone and probably whatever else it wanted to attack.
“I have no idea what the bite would do to an animal beyond hurt a lot,” co-author Karl Bates told Discovery News. “The force is obviously much higher than alligators and lions (some of the most forceful living animals) and you wouldn’t want to be bitten by either of those.”
Bates, a researcher in the University of Liverpool’s Department of Musculoskeletal Biology, and colleague Peter Falkingham of the University of Manchester artificially scaled up the skulls of a human, an alligator, a juvenile T. rex, and Allosaurus to the size of an adult T. rex. In each case, the bite forces increases as expected, but they did not increase to the level of the adult T. rex, suggesting that this formidable predator had the most powerful bite of any land animal.
Perhaps the only contender would be Gigantosaurus, another huge carnivorous dinosaur, but its bite force hasn't been measured yet.
Alligators hold the record for highest bite force of a living terrestrial animal, but Falkingham said he’s not sure how they would compare to great white sharks. Larger crocodilians, such as Nile crocs, have not been measured, but they would still not exceed the biting force of T. rex.
Previous studies estimated that T. rex bit at a force between 8,000 to 13,400 Newtons, but this latest study tested a range of muscle powers, as it is not precisely known what the muscles of dinosaurs were like since this tissue has not survived. The researchers believe their new numbers better match the size and body structure of T. rex a dinosaur thought to weigh more than 13,228 pounds.
“We speculate in our paper that the high bite force of adult T. rex may be indicative of it being a ‘large prey specialist,’” Falkingham told Discovery News. He and Bates explained that the carnivore preyed upon various plant-eating dinosaurs, as evidenced by T. rex tooth marks found on bones for some of these large beasts.
The scientists further determined that juvenile T. rexhad a relatively weaker bite than the adult T. rex, even when size differences and uncertainties about muscle size were taken into account. This indicates the species underwent a change of feeding behavior as it grew.
“It certainly makes sense from a ‘survival of the fittest’ point of view for members of the same species to avoid competition with themselves,” Bates said.
John Hutchinson, a professor of evolutionary biomechanics at the University of London’s Royal Veterinary College, told Discovery News “there’s no question that T. rex had a remarkably strong bite -- that’s old news -- but this study suggests it had an even stronger bite than previously thought.”
Read more at Discovery News
The space rock, which is called 2011 AG5, is about 460 feet (140 meters) wide. It may come close enough to Earth in 2040 that some researchers are calling for a discussion about how to deflect it.
Talk about the asteroid was on the agenda during the 49th session of the Scientific and Technical Subcommittee of the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS), held earlier this month in Vienna.
A UN Action Team on near-Earth objects (NEOs) noted the asteroid's repeat approaches to Earth and the possibility -- however remote -- that 2011 AG5 might smack into our planet 28 years from now.
The object was discovered in January 2011 by Mount Lemmon Survey observers in Tucson, Ariz. While scientists have a good bead on the space rock's size, its mass and compositional makeup are unknown at present.
An Asteroid Desktop Exercise
"2011 AG5 is the object which currently has the highest chance of impacting the Earth ... in 2040. However, we have only observed it for about half an orbit, thus the confidence in these calculations is still not very high," said Detlef Koschny of the European Space Agency's Solar System Missions Division in Noordwijk, The Netherlands.
"In our Action Team 14 discussions, we thus concluded that it not necessarily can be called a 'real' threat. To do that, ideally, we should have at least one, if not two, full orbits observed," Koschny told SPACE.com.
Koschny added that the Action Team did recommend to the NEO Working Group of COPUOS to use 2011 AG5 as a "desktop exercise" and link ongoing studies to the asteroid.
"We are currently also in the process of making institutions like the European Southern Observatory aware of this object," Koschny said. "We hope to make the point that this object deserves the allocation of some special telescope time."
Non-Zero Impact Probability
The near-Earth asteroid 2011 AG5 currently has an impact probability of 1 in 625 for Feb. 5, 2040, said Donald Yeomans, head of the Near-Earth Object Observations Program at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
This impact probability isn't set in stone, however. So far, researchers have been able to watch the asteroid for just a short time -- the first nine months of 2011 -- and the numbers may change after further observation, Yeomans told SPACE.com.
"Fortunately, this object will be observable from the ground in the 2013-2016 interval," Yeomans said. In the very unlikely scenario that its impact probability does not significantly decrease after processing these additional observations, "there would be time to mount a deflection mission to alter its course before the 2023 keyhole," he added.
Keyholes are small regions in space near Earth through which a passing NEO's orbit may be perturbed due to gravitational effects, possibly placing it onto a path that would impact Earth.
Prudent Course of Action
2011 AG5 may zip through such a keyhole on its close approach to Earth in February 2023, which will bring the asteroid within 0.02 astronomical units (1.86 million miles, or 2.99 million kilometers) of Earth.
One astronomical unit is the average distance between Earth and sun, which is approximately 93 million miles (150 million km).
Read more at Discovery News
The questionable integrity of this company's scientific research, which Leslie Kaufman detailed last week in The New York Times, has fueled a much broader debate over what levels of selenium pollution should be allowed in U.S. watersheds. Federal agencies, environmental groups and one of the nation’s largest private companies are at odds, and Kaufman’s portrayal of the details is both intriguing and disturbing.
“In my research, I have seen lots of malformed baby fish, but never one with two heads,” David Janz, an aquatic toxicology professor at the University of Saskatchewan, told Kaufman. “Selenium is emerging as a pollutant of global concern,” he said. “We need to be careful here.”
As is the case with many essential nutrients, the dose makes the poison: Too much selenium can trigger hair and fingernail loss in people, as well as and numbness in fingers and toes (which is why it has been regulated in drinking water since the 1970s). It is even more dangerous for aquatic, egg-laying animals. Kaufman cites an incident in California in the early 1980s when excessive selenium in agricultural runoff plagued waterfowl with grotesque birth defects, including missing eyes and protruding brains.
So, how much is too much? The mining company at the center of the current controversy, J.R. Simplot Company, has asked the Environmental Protection Agency for special permission to allow selenium in creeks near its Smoky Canyon Phosphate Mine to remain at current levels, even though the concentration of that element in at least one local waterway is 70 parts per billion: 14 times higher than the federal limit. (And that’s apparently after a $3.5-million clean-up effort.)
Read more at Discovery News
Feb 28, 2012
It's called the Magneto-Ionosphere Coupling in the Alfven Resonator mission, with the aim of studying so-called "space weather" -- arising from the stream of charged particles from the sun that mess with the magnetosphere, sometimes interfering with our electronic systems -- like the Global Positioning System (GPS) satellites. We would like our GPS to keep on working, and not be knocked out by a solar storm.
The rocket's instruments collected tons of real-time data as it shot through the display before coming back down to Earth a good 200 miles away. And the scientists got some pretty stunning photographs to boot.
Scientists are interested in studying auroral processes because they could shed light on how energy from the solar wind ends up coupling with Earth's magnetic field (the magnetosphere), before being summarily dumped into the upper atmosphere. Out of the solar wind's heartbreak comes our space weather.
There are two types of aurora: diffuse and discrete. With the former, you'll get a faint flow that might not even be visible at night; with the latter, you'll see that gorgeous, sharply defined band of colorful light most of us associate with the Northern Lights,or Aurora Borealis.
The MICA mission is especially interested in the discrete aurora, particularly one of the possible underlying mechanisms: Alfven waves, created by something in the ionosphere called the Alfven resonator.
It's a long narrow channel in space and the same beam of charged particles from the sun that creates the aurora, also boosts the electrical conductivity in the resonator. And this produces Alfven waves. That's the hypothesis, anyway; MICA's measurements should help validate it.
Marc Lessard of the Univeristy of New Hampshire's Institute for the Study of Earth, Oceans and Space, provided a wonderfully poetic analogy for how this works in the UNH press release, comparing the Alfven resonator to a giant guitar string stretching through space:
"The ionosphere... is one end of the guitar string and there's another structure over a thousand miles up in space that is the other end of the string. When it gets plucked by incoming energy, we get a fundamental frequency and other 'harmonies' along the background magnetic field sitting above the ionosphere."
Read more at Discovery News
The penguin, Kairuku grebneffi lived in what is now New Zealand and likely speared fish and squid with its curved beak. In comparison, today's largest penguin is the Emperor penguin, which measures just over 3 feet tall and weighs approximately 85 pounds.
Yet another new big fossil penguin, Kairuku waitaki, was also recently discovered. It lived alongside K. grebneffi. The finds by an international team of researchers was described in the latest Journal of Vertebrate Paleontology.
"The Kairuku penguins were the last generation of so-called "giant penguins," the term indicating any fossil penguins that were much larger than the living largest Emperor penguin," co-author Tatsuro Ando of the Ashoro Museum of Paleontology in Japan told Discovery News.
Ando explained that these big flightless birds emerged around 50 million years ago and thrived for about 25 million years before dying out. It remains a mystery as to why they disappeared, "but probably the drastic change in paleoenvironment was the cause of their demise," he said.
The researchers, led by Daniel Ksepka of North Carolina State University, analyzed the near-complete fossils for the penguins, which were unearthed at New Zealand's Waitaki Region. This area was known as Zealandia during prehistoric times, and it was a veritable penguin paradise.
"For much of its history, New Zealand has been sitting in the middle of the Southern Ocean, the sea that circles Antarctica," co-author Ewan Fordyce of Otago University told Discovery News. "For millions of years, it has provided suitable land for rookeries (breeding grounds) and access to rich food resources in nearby seas."
To this day, New Zealand is a center of diversity for penguins. Out of the 17 existing species of penguin, six live and breed in New Zealand.
The two new fossil species, from a distance, would have looked like modern penguins, Fordyce said.
"Up close, however, it is clear that both species had relatively longer bills and a more slender body than in living species," he explained. "The wing was probably able to flex a little more."
Their long beaks would have enabled these penguins to spear prey, such as fish and squid. Sharks and shark-toothed dolphins, a type of prehistoric super strong dolphin with heavily toothed jaws, probably hunted the enormous penguins, which could have snapped back with their beaks.
The research team, which also included Craig Jones, mentioned that the oldest known penguin so far is Waimanu from New Zealand.
"It lived 55-60+ million years ago, not long after the extinction of dinosaurs," Fordyce said.
Ksepka said one theory holds that penguins lost their ability to fly after the Cretaceous mass extinction. DNA evidence indicates that the closest living relatives of penguins are tubenose seabirds, such as albatrosses and petrels. Since the latter can dive to significant depths, the scientists suspect that the first penguins could both fly and dive underwater.
Read more at Discovery News
"Bacteria have never been given observatory access, to study the cosmos for themselves," Keats told Wired (for which he is an occasional columnist) back in January. "Their experience of the universe has always been at the scale of microns."
Keats aims to rectify that appalling oversight, in hopes that his little cyanobacteria will succeed where humanity's greatest minds have failed: devising a viable theory of everything "reconciling cosmic and quantum observations... in their own bacterial way."
Keats' project is part of a larger exhibit called "Vast and Undetectable," at the San Francisco Arts Commission Gallery, designed to "explore space that is either so large or so small we cannot conceive of it with our known processes of sight and comprehension."
The exhibit runs through April 14, and also includes installations centered on slime molds (video footage, not the actual slime molds, because gross!), embossed prints of star clusters stripped of colorization and presented in their raw form, and deconstructed color-coded maps from the Hubble Space Telescope's deep-field images.
Keats has made a bit of a name for himself over the years as the agent provacateur behind various wacky exercises in multimedia performance art -- or, as the New Yorker prefers to think of him, a "poet of ideas."
* He copyrighted his own mind in 2003, claiming it was a sculpture he had created, neuron by neuron, by thinking; he even created a conceptual futures market based on his copyright.
* In 2004, he collaborated with scientists at University of California, Berkeley, to genetically engineer god (they failed, but they garnered a lot of press).
* In 2005, he produced a series of paintings based on signals detected by the radio telescope at the Arecibo Observatory in Puerto Rico.
* His most controversial project? Establishing The Atheon, the first temple devoted to the worship of science, that annoyed scientists and believers alike.
* And then there was the time he attempting to forge a brave new economy based on antimatter. No, really. You could even purchase your own anti-money by sending a check to The First Bank of Antimatter.
I think you get the idea. His celestial observatory for cyanobacteria is very much in the same vein.
There is no question that cyanobacteria deserve our respect, if only because they are the oldest known fossils -- dating back some 3.5 billion years -- and yet still flourish today. They get their name from their blue-green tinge that comes from a pigment, phycocyanin, which helps the bacteria capture sunlight to fuel their photosynthesis.
It's that photosynthetic ability that Keats is exploiting in his installation, figuring the cyanobacteria should be able to detect starlight much like we see light with our eyes -- or how telescopes gather light from distant stars.
His "celestial observatory" is actually terrestrial: rows of petri dishes teeming with cyanobacteria, thanks to brackish water, set on top of a flat screen monitor laid horizontally. Images from the Hubble Space Telescope are fed into the monitor, and the glow from those images should -- in theory -- be "detected" by the plucky little cyanobacteria. Then they'll be released into their natural habitat, and new batch of cyanobacteria will take their place.
Read more at Discovery News
To see the sun, which reliably shone day after day, disappear from view as though devoured by some great monster or at the hands of a disgruntled deity would have sent any observer into panic.
Fortunately, today we understand what's happening when the sun disappears from view and thankfully don't resort to human sacrifice to bring it back!
A solar eclipse has to be one of the most amazing natural displays and they happen just a few times each year. Because of the conditions that cause the eclipse you need to be in very specific locations on Earth to see them, unlike the lunar eclipses that are visible over half the Earth at a time.
These quite surreal events occur due to very specific alignments of the Earth, moon and sun. If the Earth lies between the sun and moon then it will block sunlight from reaching the moon and we see a lunar eclipse or "eclipse of the moon." If, on the other hand, the moon is between the Earth and sun, then sunlight is blocked from a very small patch of the Earth -- this is a solar eclipse or "eclipse of the sun."
Parts of the US (Nevada, California, Utah, Arizona, Colarado, New Mexico and Texas), Japan and China are treated to a solar eclipse on May 20 this year, although it's not going to be a total solar eclipse; it's going to be something a little special between 22:06 and 01:39 UTC (5:06 p.m. and 8:39 p.m. EST).
The moon's orbit around the Earth isn't perfectly circular, instead its shaped like an ellipse. This means the distance between the Earth and moon varies and with that, the apparent size of the moon in the sky varies a little.
When the moon's disk appears the same size or larger than the sun, we see a total solar eclipse where the bright photosphere of the sun is blocked from view, revealing the intricate glory of the outer atmosphere of the sun -- the corona. On occasions, though, the moon's disk is slightly smaller than the sun as it appears in the sky leading to the strange spectacle of an annular solar eclipse.
Annular solar eclipses differ visually from total eclipses as the moon isn't large enough to block the entire photosphere from view, leaving the moon surrounded by a ring of bright sunlight (as seen in the photo, top). It's for this reason that annular eclipses must be observed with filters or using projection techniques. At no point of the eclipse on May 20th will it be safe to look directly at the eclipsed sun with the naked eye or with optical aid.
Read more at Discovery News
Feb 27, 2012
The results have been published in Nature Physics.
The "quantum microphone" is based on a single electron transistor, that is, a transistor where the current passes one electron at a time. The acoustic waves studied by the research team propagate over the surface of a crystalline microchip, and resemble the ripples formed on a pond when a pebble is thrown into it. The wavelength of the sound is a mere 3 micrometers, but the detector is even smaller, and capable of rapidly sensing the acoustic waves as they pass by.
On the chip surface, the researchers have fabricated a three-millimeter-long echo chamber, and even though the speed of sound on the crystal is ten times higher than in air, the detector shows how sound pulses reflect back and forth between the walls of the chamber, thereby verifying the acoustic nature of the wave.
The detector is sensitive to waves with peak heights of a few percent of a proton diameter, levels so quiet that sound can be governed by quantum law rather than classical mechanics, much in the same way as light.
"The experiment is done on classical acoustic waves, but it shows that we have everything in place to begin studies of proper quantum-acoustics, and nobody has attempted that before," says Martin Gustafsson, PhD student and first author of the article.
Read more at Science Daily
Their work is published online by the Proceedings of the National Academy of Sciences in the week of February 27-March 2.
It is widely accepted that chloroplasts originated from photosynthetic, single-celled bacteria called cyanobacteria, which were engulfed by a more complex, non-photosynthetic cell more than 1.5 billion years ago. While the relationship between the two organisms was originally symbiotic, over evolutionary time the cyanobacterium transferred most of its genetic information to the nucleus of the host organism, transforming the original cyanobacterium into a chloroplast that is no longer able to survive without its host. A similar process resulted in the creation of mitochondria.
To sustain the function of the organelle, proteins encoded by the transferred genes are synthesized in the cytoplasm, or cell's interior, and then imported back into the organelle. In most systems that have been studied, the transport of proteins into the chloroplast occurs through a multi-protein import complex that enables the proteins to pass through the envelope membranes that surround the chloroplast.
Clearly the events that gave rise to chloroplasts and mitochondria changed the world forever. But it is difficult to research the process by which this happened because it took place so long ago. One strategy used to elucidate the way in which this process evolved has relied on identifying organisms for which the events that resulted in the conversion of a bacterium into a host-dependent organelle occurred more recently.
Nowack and Grossman focused their research on a type of amoeba called Paulinella chromatophora, which contains two photosynthetic compartments that also originated from an endosymbiotic cyanobacterium, but that represent an earlier stage in the formation of a fully evolved organelle.
These compartments, called chromatophores, transferred more than 30 of the original cyanobacterial genes to the nucleus of the host organism. While gene transfer has been observed for other bacterial endosymbionts, the function of the transferred genes has been unclear, since it does not appear that the endosymbionts (in contrast to organelles) are equipped to recapture those proteins, because they do not have appropriate protein import machineries.
The Carnegie team honed in on three of the P. chromatophora transferred genes, which encode proteins involved in photosynthesis, a process localized to the chromatophore. They set out to determine whether these proteins are synthesized in the cytoplasm of the amoeba and whether the mature proteins became localized to the chromatophore.
Using an advanced array of research techniques, they were able to determine that these three proteins are synthesized in the cytoplasm and then transported into chromatophores, where they assemble together with other, internally encoded proteins into working protein complexes that are part of the photosynthetic process.
Interestingly, the process by which these proteins are transported into chromatophores may also be novel and involve transit through an organelle called the Golgi apparatus, prior to becoming localized to the chromatophore. This suggests the occurrence of an initial, rudimentary process for proteins to cross the envelope membrane of the nascent chloroplast. This process ultimately evolved into one that is potentially more sophisticated and that uses specific protein complexes for efficient transport.
"This work demonstrates that P. chromatophora is a potentially powerful model for studying evolutionary processes by which organelles developed," Nowack said. "Obtaining a comprehensive list of proteins imported into chromatophores, including their functions and origins, as well as understanding the pathway by which these proteins are imported, could provide insight into the mechanism that eukaryotic cells use to 'enslave' bacteria and turn them into organelles such as chloroplasts and mitochondria."
This research was supported by Michael Melkonian, Deutsche Forschungsgemeinschaft, and the National Science Foundation.
Read more at Science Daily
In 1987, astronomers spotted one of the brightest supernovae seen in 400 years, dubbed 1987A. Seventeen years later, the Hubble Space Telescope snapped the above image showcasing a new kind of light display from 1987A: a cosmic "ring of pearls" made up of several bright spots strewn along a ring of gas.
Those glowing pearls were the result of the original supersonic shock wave from the explosion colliding into the gassy ring at high speeds. The ring itself likely formed from ejected material before the original star exploded -- probably a by-product of it consuming another smaller star.
I bring it up because (a) it's such a pretty image, and (b) it's still possible for supernovae to surprise us. We have a lot to learn about stellar explosions, like, just what is the underlying mechanism that causes them to explode in the first place?
Yes, we understand the basics: It starts when the iron core of a massive star collapses and then stops collapsing abruptly, forming a neutron star. That sudden stop sends a giant shock wave ricocheting out into space.
But to get the explosions astrophysicists observe, something needs to re-energize that shock wave suddenly for it push through the star and separate the outer layers. We just don't know what that "something" might be.
And we don't understand why neutron stars rotate extremely rapidly right after their birth. Sure, it's because angular momentum is conserved: the slower rotation of the parent star starts to speed up as it collapses into the smaller, denser neutron progeny -- just like an ice skater will pull in his or her arms close to the body to achieve a faster spin. But what gives it that initial "kick"?
Enter French physicist Thierry Foglizzo, who worked with colleagues at CEA-Saclay to create an experimental analog of what might be going on in these stellar explosions using something a bit closer to home: shallow water.
He is not the first to notice some striking similarities in the behavior of hydrodynamical systems with supernova shock waves. There have been several large-scale numerical simulations modeling those processes.
For instance, it's now known that the shock wave itself is unstable. Tiny ripples or perturbations gradually become amplified so that you get a "sloshing" effect, similar to how water behaves when it's perturbed and starts sloshing against the sides of a container.
The hypothesis is that this underlying instability -- called a standing accretion shock instability (SASI) -- is the critical factor in stellar explosions, possibly even that "kick" that sets the neutron star's spin in motion.
But a simulation is still an abstract model. Foglizzo et al. came up with an ingenious way to test that hypothesis, in a set up they call the shallow water analog of a shock instability (SWASI). In true physicist fashion, they simplified matters, recreating just the primary components of a SASI: an infalling flow, and something akin to advective and sound waves. (Advective flow is what happens when water's motion carries silt or pollutants downstream.)
Surface gravity waves behave a lot like sound waves, while a good analog for shocks could be hydraulic jumps. The latter are common in river rafting or kayaking, for example, arising when a fast-flowing liquid, like water, slows suddenly and piles up on top of itself -- pretty much how a shock wave forms.
Read more at Discovery News
The electrons responsible for the auroras -- also known as the northern and southern lights -- are likely accelerated to incredible speeds in an active region of Earth's magnetosphere, according to a new study. This region is 1,000 times larger than scientists had thought possible, providing enough volume to generate lots of the fast-moving electrons.
"People have been thinking this region is tiny," lead author Jan Egedal, of the Massachusetts Institute of Technology, said in a statement. But now, he added, "we've shown it can be very large, and can accelerate many electrons."
Egedal and his colleagues analyzed data gathered by various spacecraft, including the European Space Agency's four Cluster probes. They also performed simulations using a supercomputer called Kraken at the United States Department of Energy's Oak Ridge National Laboratory in Tennessee.
Kraken has 112,000 processors working in parallel. The team used 25,000 of these processors for 11 days, following the motions of 180 billion simulated particles in space to map out how aurora-generating electrons move.
The researchers determined that these electrons are likely being rocketed to their tremendous speeds in the magnetotail, a portion of Earth's protective magnetosphere that has been pushed far into space by the solar wind.
As the solar wind -- the million-mph stream of charged particles coming from the sun -- stretches Earth's magnetic-field lines, the field stores energy like a rubber band being stretched, Egedal said. When the normally parallel field lines reconnect, that energy is released like a rubber band being snapped, and electrons are propelled back toward our planet at fantastic speeds.
When these fast-moving electrons hit molecules in Earth's upper atmosphere, the impact generates the phenomenon that we know as the northern and southern lights.
Some physicists had viewed this origin story for the aurora-causing electrons as improbable, because they didn't think the active magnetotail region was big enough to generate the huge numbers of electrons that slam into Earth's atmosphere.
Read more at Discovery News
Feb 26, 2012
Professor Holger Hermanns, who holds the chair of Dependable Systems and Software, and who developed the wireless bicycle brake together with his group, explains: "Wireless networks are never a fail-safe method. That's a fact that's based on a technological background." Nonetheless, the trend is to set up wireless systems that, like a simple bicycle brake, have to function all the time. "In the field of the future European Train Service, for example, concrete plans already exist," Hermanns reports. Furthermore, he says that train and airplane experiments are far too sophisticated, and could even endanger the life of human beings in case of malfunction.
Therefore, the Saarland computer scientist's mathematical methods should now verify the correct function and interaction of the components automatically. "The wireless bicycle brake gives us the necessary playground to optimize these methods for operation in much more complex systems," Hermanns adds. Therefore, his research group examines the brake prototype with algorithms that normally are used in control systems for aircraft or chemical factories. As a result, they found out that the brake works with 99.9999999999997 percent reliability. "This implies that out of a trillion braking attempts, we have three failures," Hermanns explains and concludes: "That is not perfect, but acceptable."
To brake with the wireless brake, a cyclist needs only clench the rubber grip on the right handle. The more tightly the grip is clenched, the harder the disk brake on the front wheel works. It seems as if a ghost hand is in play, but a combination of several electronic components enables the braking. Integrated in the rubber grip is a pressure sensor, which activates a sender if a specified pressure threshold is crossed. The sender is integrated in a blue plastic box which is the size of a cigarette packet and is attached to the handlebar. Its radio signals are sent to a receiver attached at the end of the bicycle's fork. The receiver forwards the signal to an actuator, transforming the radio signal into the mechanical power by which the disk brake is activated. The electrical energy is supplied by a battery, which is also attached to the bicycle's fork. To enhance reliability, there are additional senders attached to the bicycle. These repeatedly send the same signal.
Read more at Science Daily
Even though typical dance-floor activity might suggest otherwise, humans generally demonstrate a remarkable capacity to synchronize their body movements in response to auditory stimuli. But is this ability to move in time to musical rhythm a uniquely human trait?
Some animals are capable of vocal learning, changing the sounds they make in response to those they hear from other members of their species. Scientists have hypothesized that such behavior may be associated with the capacity for so-called 'rhythmic synchronization'. "Motor control of vocal organs is naturally important in vocal learning," says Yoshimasa Seki of the RIKEN Brain Science Institute in Wako. "Once auditory-motor coordination in the vocal control system has been established, a similar auditory-motor transformation system for other body parts might be derived from that."
Studies in vocal-learning species have largely focused on case studies of individual animals, but Seki and colleagues conducted larger-scale experiments and found that budgerigars (Fig. 1) may have an inherent capacity for rhythmic synchronization. The researchers tested their hypothesis by training eight budgerigars to peck a button in response to the rhythm of an external metronome, which could be adjusted to present the birds with audio-visual stimuli at varying intervals.
In all 46 experiments, the birds were able to consistently respond to rhythmic beats within a certain time-frame, demonstrating successful entrainment. However, the accuracy of their timing was dependent on the tempo. Only one out of seven birds was successfully able to match the onset of each beat when the stimuli were generated at 450 millisecond intervals, while all animals achieved this feat when that interval was lengthened to 1,500 or 1,800 milliseconds.
To confirm that actual synchronization was taking place, the researchers used computer simulations of other bird behavior scenarios, such as random pecking or responding directly to individual stimuli rather than the rhythm itself. However, none of these alternative models was sufficient to explain the observed activity. "Our results showed that budgerigars can show rhythmic movements synchronized with external stimuli, which means they potentially have this capability of auditory-motor entrainment as a species," says Seki.
Read more at Science Daily