With the discovery of antibiotics, medicine acquired power on a scale never before possible to protect health, save lives, and reduce suffering caused by certain bacteria. But the power of antibiotics is now under siege because some virulent infections no longer respond to antibiotic drugs.
This antibiotic resistance is an urgent public health threat that a team of researchers from Sabanci University in Istanbul, Turkey, and Harvard Medical School and Harvard University in Cambridge, Mass., aim to stop. Their approach is based on an automated device they created that yields a new understanding of how antibiotic resistance evolves at the genetic level. The team will present its work at the 57th Annual Meeting of the Biophysical Society (BPS), held Feb. 2-6, 2013, in Philadelphia, Pa.
Called the "morbidostat," the device grows bacteria in various concentrations of antibiotic. This enabled researchers to identify the concentrations at which the antibiotics stopped working and the bacteria became resistant to therapy. Next, they targeted key genes involved in creating the drug-resistant states. Their approach documented real-time changes in genes that gave bacteria an advantage in evolving to "outwit" antibiotics.
Knowledge at the gene level can be applied to the molecular design of the next generation of bacteria-killing antibiotics.
"Morbidostat is designed to evolve bacteria in conditions comparable with clinical settings," explains Erdal Toprak of Sabanci University. "Combined with next generation genome sequencing technologies, it is possible to follow the evolution of resistance in real time and identify resistance-conferring genetic changes that accumulate in the bacterial genome."
Data show an unusual survival profile of the common bacteria they used, Escherichia coli. "We identified striking features in the evolution of resistance to the antibiotic trimethoprim," Toprak says. It was these unusual features that helped them isolate the gene involved in conferring antibiotic resistance through multiple mutations.
Read more at Science Daily
Feb 2, 2013
What If Earth Became Tidally Locked?
Why does tidal locking happen? And more importantly, why hasn't Earth become a tidally locked planet? And are we doomed to go that way eventually?
When the planet Zarmina was first reported as having been discovered, people got all excited about the idea of a planet existing in its star's habitable zone — only to have their excitement fade a little when they learned that Zarmina was tidally locked to its star. This reduced the chances of life, in any complex form, existing on the surface. Tidal locking does a number on a planet, and not just its surface temperature. Everything from water composition to geography changes as one side starts getting all the sunlight, and the other slowly freezes.
How Tidal Locking Happens
When a planet orbits a star, it is being pulled by the gravity of that star. The different sides of the planet are pulled to different degrees, with the side closest to the star receiving a small but noticeably larger pull. This bends the planet out of shape, from a ball into an ellipse. No water is necessary for this to happen. Even solid rock stretched out — the surfaces of both the Earth and the Moon stretch toward each other. This stretching doesn't happen immediately, though. It takes time for the planet to stretch its solid mass towards the sun and to settle back, and while it is stretching and settling, it is moving.
At first, it is moving in two different ways. It is rotating on its axis, the way the Earth does to produce night and day. It is also orbiting the star, as the Earth does to produce a year. Those two movements rarely sync up. For example, sometimes the rotation speeds past the orbit. In that case, instead of the bulges in the ellipse "pointing" directly at and away from the star, they turn past it.
The problem is, the near bulge is closer to the star than the rest of the planet, and it feels a gravitational pull dragging it backwards — so it's once again aligned with the center of the star. It doesn't necessarily get pulled all the way back, but it gets shifted a little bit. That shift happens every time the planet rotates. If the rotation is too slow and the orbit is fast, the bulge lags behind as the planet orbits forward, and the gravitational pull of the star drags it forward. No matter what, the planet gets a tug until its rotation is exactly the same period of time as its orbit. When that happens, it's tidally locked. It shows one face to the sun at all times.
Life on a Tidally Locked Planet
The immediate disadvantage of a tidally locked planet is obvious. One side of the planet cooks while the other freezes. Water on one side is vapor, and on the other side is ice. If there is any appreciable amount of life on the surface of the planet, it has to be in the twilight strip of land between the two halves.
But it's not as simple as getting the temperature right. If our atmosphere permanently lost the heat of the sun, it would first turn into a denser gas, then condense into a liquid, and then further condense into solid ice. Meanwhile, air that is constantly exposed to light — or that is heated by a ground that is constantly exposed to light — will heat up and expand.
Although it's doubtful that the atmosphere on the dark side of the planet would get to solid form, it would certainly keep condensing and leaving a vacuum to suck in the expanding hot air from the other side. This might make for circulation of atmosphere that would make the planet livable, but it would also lead to hellish storms, as the atmosphere from the light and dark side of the planet essentially switched sides continually.
And those winds may bring some very, very nasty things with them. Even geologists foresee major problems with tidally locked planets. Rock and soil erodes differently when it's exposed to different levels of light. The cool side of the planet is preserved fairly well, but the lit side of the planet is stripped of its oceans and made to face burning sun and scrubbing wind every day. It will erode faster, and rocks that might have turned to terrestrial sand in a climate with night and day may be vaporized, picked up by the wind, or dissolved in water vapor to go airborne. Life, if it manages to struggle along on such a planet, will either be underground or very, very hardy.
So will Earth become tidally locked?
So why are some planets and moons tidally locked while others are not? All planets bulge towards their stars, and all of them have their orbit slightly out of sync with their rotation. The mechanics of how it happens are the same in every case — but whether tidal locking actually happens depends on things like orbit distance, the mass of both bodies, and the malleability of the orbiting object.
Generally, closer objects are more likely to experience tidal locking. Far-away objects are less likely to experience dramatic differences in gravity between their two sides, resulting in smaller bulges, and the bulges themselves will feel less of a pull. For many stars, the habitable zone — the ring of space within which planets are able to sustain life — overlaps partially with a zone that makes planets likely to be tidally locked to their star, making them significantly less habitable.
Nervous scientists have speculated that the Earth might eventually be a tidally locked planet, but it appears that such a fate is not in store for us. At least not with the sun. The Moon, which we've already ensnared, might turn the tables on us. The Earth's rotation actually gets slowed down by the Moon a little bit each year.
Read more at Discovery News
Feb 1, 2013
How Owls Spin Their Heads Around
But how do they do it without severing their arteries or preventing blood from reaching the brain? An illustrator and a physician at the Johns Hopkins University School of Medicine teamed up to find out.
"Until now, brain imaging specialists like me who deal with human injuries caused by trauma to arteries in the head and neck have always been puzzled as to why rapid, twisting head movements did not leave thousands of owls lying dead on the forest floor from stroke," said study author Dr. Philippe Gailloud, in a statement from the university.
If humans tried to rotate our heads so rapidly or far, we'd tear the lining of our arteries, which would cause clots to form and lead to a stroke (besides also breaking our necks), he added. "The carotid and vertebral arteries in the neck of most animals — including owls and humans — are very fragile and highly susceptible to even minor tears of the vessel lining."
Looking inside owls
To get a glimpse of the owl's blood vessels when their necks were turning, the duo injected dye into the blood vessels of a dozen dead owls and used a CT scan to visualize the shimmering fluid spreading throughout the birds' arteries like blood, said Fabian de Kok-Mercado, who performed the work while getting a master's in medical illustration at Johns Hopkins. (He is now an illustrator at the Howard Hughes Medical Institute in Chevy Chase, Md.) The researchers then twisted the dead owls' heads to see what happened.
After creating the CT scan images, the researchers injected a plastic-like substance into the veins of dead snowy, barred and great horned owls and dissected the animals, drawing the routes and locations of the vessels.
They found a number of previously undiscovered and unique traits, de Kok-Mercado told OurAmazingPlanet. For one, the owls' neck bones, or vertebrae, contain holes that are much larger than those found in other birds or humans. In humans, the hole in the vertebra is about the same size as the artery, but in owls the hole is about 10 times larger than the artery, according to the study, published today (Jan. 31) in the journal Science. These holes, or canals, likely hold air sacks meant to cushion the twisting motion of the head, de Kok-Mercado said.
Read more at Discovery News
Is Scientific Genius Extinct?
Dean Keith Simonton of the University of California, Davis, says that just like the ill-fated dodo, scientific geniuses like these men have gone extinct.
"Future advances are likely to build on what is already known rather than alter the foundations of knowledge," Simonton writes in a commentary published in today’s (Jan. 31) issue of the journal Nature.
An End to Momentous Leaps Forward?
For the past century, no truly original disciplines have been created; instead new arrivals are hybrids of existing ones, such as astrophysics or biochemistry. It has also become much more difficult for an individual to make groundbreaking contributions, since cutting-edge work is often done by large, well-funded teams, he argues.
What's more, almost none of the natural sciences appear ripe for a revolution.
"The core disciplines have accumulated not so much anomalies as mere loose ends that will be tidied up one way or another," he writes.
Only theoretical physics shows signs of a "crisis," or accumulation of findings that cannot be explained, that leaves it open for a major paradigm shift, he writes.
Read more at Discovery News
Anti-Wi-Fi Activism 'Fear Mongering'
From their report:
Many activists blame Wi-Fi networks’ low level radio signals for a broad variety of medical problems, from mild headaches and fatigue to chest pain and heart palpitations, claiming those who suffer from them have ‘Electromagnetic-Hypersensitivity,’ or EHS. These claims are not substantiated by the scientific literature and have little acceptance from medical professionals and the scientific community. This activism therefore amounts to nothing more than fear-mongering by misguided special interest groups who are attempting to have these networks removed… As a result many school boards, libraries, and town councils across Canada have been called on by concerned citizens to limit or remove Wi-Fi networks.
Jamie Williams, Executive Director of Bad Science Watch, noted that “Some of the most prominent anti-WiFi scaremongers are tied to the sale and promotion of bogus products to ‘block’ Wi-Fi.”
Indeed, there is a burgeoning market for so-called “EMF shields” that can be inserted into cell phones that allegedly block harmful electromagnetic waves (though consumer groups say there’s no evidence they are effective).
The report notes that the fear mongering surrounding Wi-Fi is not just an academic matter but has real consequences for the public: “Those who stand to suffer from these efforts the most are students (especially from low-income families) who rely on wireless networks for access to the Internet and education resources, and taxpayers who will have to pay for the expensive reversion to wired networks. In addition, families are being been misled into believing that their children are suffering from EHS and may miss an opportunity for early diagnosis of real and serious health problems in their children.”
Last year an Albuquerque, New Mexico, anti-WiFi activist named Arthur Firstenberg sued his neighbor claiming that her use of wireless devices including her cell phone and computer caused health problems including hip pain and heart damage. According to an Albuquerque Journal story, District Judge Sarah Singleton ruled that scientific evidence does not support electromagnetic sensitivity.
In her ruling, the judge stated, “Studies have failed to provide clear support for a causal relationship between electromagnetic fields and complaints of EMS.”
Singleton relied extensively on the position of the World Health Organization, which concluded that “well controlled and conducted double-blind studies have shown that symptoms do not seem to be correlated with EMF exposure… these symptoms may be due to pre-existing psychiatric conditions as well as stress reactions as a result of worrying about believed EMF health effects, rather than EMF exposure.”
Determining whether or not Wi-Fi and EMFs have an immediate effect on health — as Firstenberg claimed — should be very simple using a blinded scientific testing protocol: the Wi-Fi would be randomly turned on or off (unbeknownst to Firstenberg), and he would state whether or not he had hip pain; either the pain appears when the WiFi is on, or it does not.
Unfortunately for Firstenberg the judge found that he could not reliably tell when the Wi-Fi was on and “cannot discern or discriminate the effects of anxiety caused by a testing situation or the presence of electromagnetic stimulus.” The case was dismissed.
Concern over the effects of EMFs (via power lines) have been around since the 1970s, and resurfaced in the past 10 years as cell phones have become ubiquitous. Though there’s little evidence that they pose a health threat, many people remain concerned. However that fear has done little to stem the popularity of those products.
Read more at Discovery News
Orion: The Hunter Becomes the Hunted
Straddling the celestial equator, it is well placed for observations this time of year and, unlike many other constellations, it actually looks like its mythological symbol.
The stars outlining the shape of The Hunter are bright and easy to spot and can be used as signposts to other constellations -- but look within its boundaries to find some real treasures.
Perhaps the most famous star marking the north eastern shoulder -- or, more accurately, the armpit -- of the giant hunter is Betelgeuse, a red supergiant star. At magnitude 0.4 it's the second brightest star in Orion and to the naked eye looks distinctly red in color. As a red supergiant, it is nearing the end of its life and in the near future (possibly within the next 100,000 years) it will explode as a supernova, an explosion so great that it will be visible in the daytime sky.
To the opposite corner of Betelgeuse is the blue white star Rigel. To the naked eye this bright supergiant looks like a single star, but telescopic observations reveal a companion star 500 times fainter. Further studies of the light from Rigel's companion star have revealed that it too is a very special binary star called a "spectroscopic binary" meaning its companion is only visible when the spectrum of its light is studied.
Lying directly between the two stars is Orion's famous three star belt. The star at the eastern end of the belt is called Alnitak and is located 817 light-years away. This distance is comparable to the star at the western end called Mintaka, at 916 light-years. The central star, Alnilam, is a distant 1342 light-years away. It's interesting to note that the stars look as if they are at the same distance from Earth as their different brightness compensate for their variation I light-years.
Just to the south of the belt's central star is the jewel of Orion -- the stunning Great Orion Nebula. Looking at that region of the sky with the naked eye will reveal a number of faint stars depicting the hunter's sword and in the middle of them, a faint fuzzy blob. It's a rather mundane description of a beautiful object, but take a look at it through binoculars and you start to see some of the wispy nebulosity. The word nebula is Latin for "cloud" and that's exactly what it is; a vast cloud of gas and dust out of which a new generation of stars are forming.
Read more at Discovery News
Jan 31, 2013
Tapeworm Eggs Found in Fossilized Shark Poop
Tapeworms cling to the inner walls of the intestines of vertebrates -- creatures with backbones such as fish, pigs, cows and humans. When these parasites reach adulthood, they unleash their eggs on the world via the feces of their hosts.
Investigating the early history of such parasites of vertebrates is tricky because fossils of these parasites dating back to the age of dinosaurs or before are rare. One way researchers might unearth such fossils is by analyzing coprolites, or fossilized dung.
Scientists now reveal they found a spiral-shaped coprolite from a shark that holds a cluster of 93 oval tapeworm eggs. One of them even contains a probable developing larva, which held a cluster of fiber-like objects that may have been the beginnings of hooklets used to attach to a host's intestines as adults.
The fossils, unearthed in southern Brazil, date to the Paleozoic era (251 million to 542 million years ago), before dinosaurs roamed the Earth. This predates other known examples of intestinal parasites in vertebrates by 140 million years.
The eggs are each only about 150 microns long, or about one-and-a-half times the average width of a human hair. The researchers discovered the eggs by cutting coprolites into thin slices.
"Luckily in one of them, we found the eggs," researcher Paula Dentzien-Dias, a paleontologist at the Federal University of the Rio Grande in Brazil, told LiveScience. "The eggs were found in only one thin section."
This coprolite was found with more than 500 others at one site. The researchers suggest the area was once a freshwater pond where many fish got trapped together during a dry spell.
The mineral pyrite, also known as fool's gold, was found in the coprolite. This suggests its environment was depleted of oxygen, conditions that probably helped preserve the fossils for millions of years.
There is no way of knowing for certain what specific type of shark left this fossil behind, since all sharks have similar intestines (and thus poop). It is unlikely the tapeworm infestation killed the shark that left this coprolite, unless the infestation was huge, Dentzien-Dias said.
Read more at Discovery News
Priceless Timbuktu Manuscripts Escape Burning
After French-led forces on Sunday recaptured Timbuktu, the northern city of Mali on the edge of the Sahara desert, the city’s mayor Hallé Ousmane Cissé made a shocking announcement. He reported that fleeing Islamic militants had set on fire several buildings, reducing thousands of priceless manuscripts kept inside the structures to a pile of ashes.
“For these Islamists, these Jihadis, there is only the Koran, everything else is worthless,” local historian and archaeologist Abdullahi Cisse told reporters.
Yet the world’s cultural community took a sigh of relief today as experts confirmed that about 300,000 texts existing in Timbuktu remained unharmed.
Although up to 2,000 manuscripts may have been destroyed in the fire of the Ahmed Baba Institute, a government-funded research centre for the study and conservation of the scripts, the vast majority of the city’s volumes appear to have escaped destruction.
“They were put in a very safe place. I can guarantee you. The manuscripts are in total security,” Mahmoud Zouber told TIME. Before the 10-month occupation by the Islamist radicals, Zouber was Mali’s presidential aide on Islamic affairs.
Just as Afghanistans saved the Bactrian treasure from the Taliban destruction by hiding the most valuable items in a vault deep beneath Kabul’s presidential palace, Malian preservationists moved thousands of manuscripts out of the Ahmed Baba Institute to safe and hidden locations.
“There were a few items in the Ahmed Baba library, but the rest were kept away,” Shamil Jeppie, director of the Timbuktu Manuscripts Project at the University of Cape Town, told TIME.
Begun shortly after the sharia-observing militants seized control of Timbuktu, the large rescue operation involved hiding the manuscripts everywhere in the city and its surroundings.
“The people here have long memories. They are used to hiding their manuscripts. They go into the desert and bury them until it is safe,” Sidi Ahmed, a reporter who fled to Bamako during Timbuktu occupation, told National Geographic News.
Indeed, this is not the first time that manuscripts faced dramatic threats.
Hidden in trunks or buried in the mud walls of mosques, they survived the Moroccans invasion of Timbuktu in 1591. In their efforts to take control of the city’s trans-Saharan gold trade, which gained Timbuktu a wealth unparalleled with anything seen in Africa, the Moroccans killed or deported most scholars and banned their texts.
Dating back to the late 12th century, the beginning of a 300-year golden age in which intellectual activity flourished, the ancient texts showcase an unknown aspect of Africa, depicting a country rich in kingdoms, literature, science and history.
Thousands of delicate pages, written in a variety of calligraphic styles and beautifully illustrated, incorporate the most varied subjects, such as architecture, astronomy, economics, geography, mathematics, poetry, music and even women’s rights.
Most of the manuscripts were written in Arabic, but African languages, such as Songhai, Tamashek and Bambara, were also used. The oldest script dates from 1204.
Read more at Discovery News
Buried Antarctic Lake Yields Hints of Life
Water retrieved from subglacial Lake Whillans contains tiny cells, and they respond to DNA-sensitive dye, Discover magazine reported. This initial test is a good sign the lake may harbor life. Further experiments in Antarctica, and with samples shipped back to the United States, will reveal whether the microscopic cells are truly alive.
Working out of shipping containers stationed above the lake, a U.S. team pulled its first samples of mud and water Monday, making the Whillans Ice Stream Subglacial Access Research Drilling mission a success, the researchers said on the WISSARD project's website.
"This effort marks the first successful retrieval of clean whole samples from an Antarctic subglacial lake," the researchers wrote.
Lake Whillans is 2,625 feet (800 meters) below the West Antarctic Ice Sheet.
The U.S. effort was one of three attempts during this southern summer to drill into buried lakes in Antarctica. The others were at Lake Ellsworth and Lake Vostok. Of the three lakes, Whillans was closest to the surface, by more than a mile (2 kilometers).
Great Britain's Ellsworth mission was called off when technical difficulties prevented the drillers from reaching the water. A Russian-led Vostok effort found organic material last year, but it was determined to have come from the drill fluid. Results from this year's Vostok expedition have not yet been announced.
Read more at Discovery News
Ancient Mound Built in Record Time
“We’re talking about an area of northern Louisiana that now tends to receive a great deal of rainfall,” study co-author Tristam Kidder, anthropology chair at Washington University in St. Louis, said in a press release. “Even in a very dry year, it would seem very unlikely that this location could go more than 90 days without experiencing some significant level of rainfall. Yet, the soil in these mounds shows no sign of erosion taking place during the construction period. There is no evidence from the region of an epic drought at this time, either.”
Piling the estimated 238,500 cubic meters of soil in the mound would require 3,000 laborers working full time, according to the anthropologists’ recent estimate published in the journal Geoarcheology. Modern 10-wheel dump truck would need 31,217 loads to equal that amount, Kidder estimated.
“The Poverty Point mounds were built by people who had no access to domesticated draft animals, no wheelbarrows, no sophisticated tools for moving earth,” Kidder said. “It’s likely that these mounds were built using a simple ‘bucket brigade’ system, with thousands of people passing soil along from one to another using some form of crude container, such as a woven basket, a hide sack or a wooden platter.”
Modern hunter-gather societies are generally not large, rarely comprising more than a few dozen people. However, the rapid construction of the mounds suggests that ancient hunter-gathers were capable of sophisticated organization of large groups.
Read more at Discovery News
Jan 30, 2013
Prehistoric Humans Not Wiped out by Comet, Says Researchers
Researchers from Royal Holloway university, together with Sandia National Laboratories and 13 other universities across the United States and Europe, have found evidence which rebuts the belief that a large impact or airburst caused a significant and abrupt change to Earth's climate and terminated the Clovis culture. They argue that other explanations must be found for the apparent disappearance.
Clovis is the name archaeologists have given to the earliest well-established human culture in the North American continent. It is named after the town in New Mexico, where distinct stone tools were found in the 1920s and 1930s.
Researchers argue that no appropriately sized impact craters from that time period have been discovered, and no shocked material or any other features of impact have been found in sediments. They also found that samples presented in support of the impact hypothesis were contaminated with modern material and that no physics model can support the theory.
"The theory has reached zombie status," said Professor Andrew Scott from the Department of Earth Sciences at Royal Holloway. "Whenever we are able to show flaws and think it is dead, it reappears with new, equally unsatisfactory, arguments.
Read more at Science Daily
Previously Unknown Mechanism of Memory Formation Discovered
It takes a lot to make a memory. New proteins have to be synthesized, neuron structures altered. While some of these memory-building mechanisms are known, many are not. Some recent studies have indicated that a unique group of molecules called microRNAs, known to control production of proteins in cells, may play a far more important role in memory formation than previously thought.
Now, a new study by scientists on the Florida campus of The Scripps Research Institute has for the first time confirmed a critical role for microRNAs in the development of memory in the part of the brain called the amygdala, which is involved in emotional memory. The new study found that a specific microRNA -- miR-182 -- was deeply involved in memory formation within this brain structure.
"No one had looked at the role of microRNAs in amygdala memory," said Courtney Miller, a TSRI assistant professor who led the study. "And it looks as though miR-182 may be promoting local protein synthesis, helping to support the synapse-specificity of memories."
In the new study, published in the Journal of Neuroscience, the scientists measured the levels of all known microRNAs following an animal model of learning. A microarray analysis, which enables rapid genetic testing on a large scale, showed that more than half of all known microRNAs are expressed in the amygdala. Seven of those microRNAs increased and 32 decreased when learning occurred.
The study found that, of the microRNAs expressed in the brain, miR-182 had one of the lowest levels and these decreased further with learning. Despite these very low levels, its overexpression prevented the formation of memory and led to a decrease in proteins that regulate neuronal plasticity (neurons' ability to adapt) through changes in structure.
These findings suggest that learning-induced suppression of miR-182 is a main supporting factor in the formation of long-term memory in the amagdala, as well as an underappreciated mechanism for regulating protein synthesis during memory consolidation, Miller said.
Further analysis identified miR-182 as a repressor of proteins that control actin -- a major component of the cytoskeleton, the scaffolding that holds cells together.
"We know that memory formation requires changes in dendritic spines on the neurons through regulation of the actin cytoskeleton," Miller said. "When miR-182 is suppressed through learning it halts, at least in part, repression of actin-regulating proteins, so there's a good chance that miR-182 exerts important control over the actin cytoskeleton."
Read more at Science Daily
Now, a new study by scientists on the Florida campus of The Scripps Research Institute has for the first time confirmed a critical role for microRNAs in the development of memory in the part of the brain called the amygdala, which is involved in emotional memory. The new study found that a specific microRNA -- miR-182 -- was deeply involved in memory formation within this brain structure.
"No one had looked at the role of microRNAs in amygdala memory," said Courtney Miller, a TSRI assistant professor who led the study. "And it looks as though miR-182 may be promoting local protein synthesis, helping to support the synapse-specificity of memories."
In the new study, published in the Journal of Neuroscience, the scientists measured the levels of all known microRNAs following an animal model of learning. A microarray analysis, which enables rapid genetic testing on a large scale, showed that more than half of all known microRNAs are expressed in the amygdala. Seven of those microRNAs increased and 32 decreased when learning occurred.
The study found that, of the microRNAs expressed in the brain, miR-182 had one of the lowest levels and these decreased further with learning. Despite these very low levels, its overexpression prevented the formation of memory and led to a decrease in proteins that regulate neuronal plasticity (neurons' ability to adapt) through changes in structure.
These findings suggest that learning-induced suppression of miR-182 is a main supporting factor in the formation of long-term memory in the amagdala, as well as an underappreciated mechanism for regulating protein synthesis during memory consolidation, Miller said.
Further analysis identified miR-182 as a repressor of proteins that control actin -- a major component of the cytoskeleton, the scaffolding that holds cells together.
"We know that memory formation requires changes in dendritic spines on the neurons through regulation of the actin cytoskeleton," Miller said. "When miR-182 is suppressed through learning it halts, at least in part, repression of actin-regulating proteins, so there's a good chance that miR-182 exerts important control over the actin cytoskeleton."
Read more at Science Daily
'Zombie Planet' Resurrected: Fomalhaut b is Real
The past year has seen announcements of some of the most Earth-like planets yet discovered, and even a small planet around one of the two stars in Alpha Centauri, our nearest neighboring star system. But in all of this, there’s been one thing in the back of our minds that has been sitting slightly uncomfortably: 25 light-years away lies Fomalhaut b, a planet that has been the cause of an astronomical altercation.
If you’ve been reading the right news feeds, you’ll probably know by now that Fomalhaut b has officially been confirmed as a planet. And it’s an interesting one, too. Orbiting the star Fomalhaut, an A-type star somewhat more massive and hotter than the sun, this planet has a wildly eccentric orbit. As befitting a larger star, Fomalhaut b’s orbit is huge compared to our solar system.
Even at the closest point in its orbit, the orbits of every planet in our own solar system could fit between it and Fomalhaut (as shown in this, now outdated, image). At the furthest point in its orbit, it reaches nearly 10 times the distance between Neptune and the sun, ploughing through a thick disk of dusty material held in Fomalhaut’s gravitational grip.
So what was the controversy over this planet? As it happens, it’s quite an interesting story, and an excellent example of the way good science works.
You see, Fomalhaut b was, for a long time, the poster child of exoplanet discovery. Its presence was inferred from some Hubble observations taken in 2005. A debris disk like the one encircling Fomalhaut, still quite a young star, is not unusual in itself. The strange thing about this disk is that it has a sharp inner boundary, as if some massive object had cleared away all of the dust from the inner part of the disk.
It wouldn’t be until 2008 that two astronomers at UC Berkeley, James Graham and Paul Kalas, were re-examining Hubble images taken in 2004 and 2006. With a rush of excitement, they realized that a small cluster of pixels in the image had moved, and the only explanation was that they were looking at the first ever direct image of a planet orbiting another star.
Kalas and Graham’s images showed the planet in scattered starlight at 600 nm, and thermal emission at 800 nm. However, Fomalhaut b was destined to cause some controversy amongst the exoplanet community. As any good scientist should, others set out to try and detect the planet for themselves. Unfortunately, that caused some problems — despite looking carefully, no trace of any planet was found where they were expecting to see it.
In particular, attempts to take infrared images of it were met with failure. Puzzling, because any sizable planet should shine brightly, and obviously, in infrared light. Coupled with the fact that, from the previous work, it seemed that this object must be moving too fast to have the predicted effect on Fomalhaut’s debris disk, some began to doubt that what they were seeing was a planet at all.
In 2011, researchers at the Atacama Large Millimetre Array (ALMA) devised a hypothesis under which Fomalhaut b wasn’t actually needed to explain the star’s debris disk. With some convincing evidence, many had to agree that things didn’t look good for the would-be planet.
So it would remain, until last year, when Thayne Currie at the University of Toronto finally made an independent confirmation of the planet, presenting new observations, re-examining old observations, and giving a brand new detection at a new and much bluer wavelength of 400 nm. After showing that Fomalhaut b was actually quite unlikely to be observed in infrared, and recalculating some details about it, Fomalhaut b was once again starting to win people over.
Finally, a third group of researchers, Raphael Galicher and Christian Marois, independently detected and confirmed it. This was indeed a real planet we were all looking at.
Galicher and Marois could tell, this was a rather unusual planet they were looking at. Its spectrum of light suggests that it lies shrouded in dust, perhaps a huge ring system or the aftermath of a recent collision between two dwarf planets. The latter idea would nicely explain a narrow and suspiciously new outer disk seen around Fomalhaut.
If current calculations are proven to be correct, Fomalhaut b is due to dive back into that debris disk around 2032, at which point astronomers will start watching very carefully to see if they can spot any collisions with further objects. If the planet orbits in the same plane as the debris disk, such collisions are entirely possible.
Read more at Discovery News
Could Nearby Star Host a Baby Solar System?
However, TW Hydrae’s protoplanetary disk has been too small to image directly and its size can only be inferred through spectroscopic analysis (i.e. astronomers analyze the light from the system, deducing what material it contains). Now, with the help of Europe’s Herschel Space Observatory and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, a team of astronomers have made a lucky discovery. Not only have they gained a more precise estimate of the mass of the protoplanetary disk, they’ve also found that it may produce a system of worlds of comparable mass to the solar system.
Yes, TW Hydrae may look like the solar system did over 4 billion years ago.
Previous mass estimates came from model assumptions of the star’s protoplanetary material — creating huge margins for error — but Herschel’s sensitivity to a certain wavelength of radiation from TW Hydrae was a game changer.
Contained within the protoplanetary disk are hydrogen molecules, but some contain deuterium (a hydrogen atom with an additional neutron in its nucleus). These “hydrogen deuteride” molecules emit a very specific radiation and because Herschel has such a fine-tuned resolution to this specific wavelength, astronomers were able to use this radiation as a guide. ALMA provided key information about the temperature of the protoplanetary disk by detecting the temperature of carbon monoxide. By combining these data, a precise ratio of hydrogen deuteride to hydrogen could be made — a mass estimate could therefore be attained.
It turns out that the baby TW Hydrae system is more massive than other estimates predicted. Rather than ranging anything from 0.5 to 63 Jupiter masses, the material contained within the protoplanetary disk has a lower limit of 52 Jupiter masses — this is more material than what formed our solar system during its formative years. Perhaps TW Hydrae will eventually host a similar system of planets as our sun did.
“This project started in casual conversation … We realized that Herschel was our only chance to observe hydrogen deuteride in this disk — way too good an opportunity to pass up. But we also realized we would be taking a risk. At least one model predicted that we shouldn’t have seen anything! Instead, the results were much better than we had dared to hope,” said Thomas Henning, of the Max Planck Institute for Astronomy in Heidelberg.
“If there’s no chance your project can fail, you’re probably not doing very interesting science. TW Hydrae is a good example of how a calculated scientific gamble can pay off.”
Interestingly, although TW Hydrae is a “young” star in cosmic terms, it is also a star that would normally be considered too mature to host a protoplanetary disk.
“We did not expect to find so much gas around this 10-million-year-old star,” said lead researcher Edwin Bergin of the University of Michigan.
Read more at Discovery News
Jan 29, 2013
Antarctic Lake Beneath the Ice Sheet Tested
Scientists and drillers with the interdisciplinary Whillans Ice Stream Subglacial Access Research Drilling project (WISSARD) announced Jan. 28 local time (U.S. stations in Antarctica keep New Zealand time) that they had used a customized clean hot-water drill to directly obtain samples from the waters and sediments of subglacial Lake Whillans.
The samples may contain microscopic life that has evolved uniquely to survive in conditions of extreme cold and lack of light and nutrients. Studying the samples may help scientists understand not only how life can survive in other extreme ecosystems on Earth, but also on other icy worlds in our solar system.
The WISSARD teams' accomplishment, the researchers said, "hails a new era in polar science, opening a window for future interdisciplinary science in one of Earth's last unexplored frontiers."
A massive ice sheet, almost two miles thick in places, covers more than 95 percent of the Antarctic continent. Only in recent decades have airborne and satellite radar and other mapping technologies revealed that a vast, subglacial system of rivers and lakes exists under the ice sheet. Lakes vary in size, with the largest being Vostok Subglacial Lake in the Antarctic interior that is comparable in size to Lake Ontario.
WISSARD targeted a smaller lake (1.2 square miles in area), where several lakes appear linked to each other and may drain to the ocean, as the first project to obtain clean, intact samples of water and sediments from a subglacial lake.
The achievement is the culmination of more than a decade of international and national planning and 3 1/2 years of project preparation by the WISSARD consortium of U.S. universities and two international contributors. There are 13 WISSARD principal investigators representing eight different U.S. institutions.
NSF, which manages the United States Antarctic Program, provided over $10 million in grants as part of NSF's International Polar Year portfolio to support the WISSARD science and development of related technologies.
The National Aeronautics and Space Administration's (NASA) Cryospheric Sciences Program, the National Oceanic and Atmospheric Administration (NOAA), and the private Gordon and Betty Moore Foundation also provided support for the project.
The interdisciplinary research team includes groups of experts in the following areas of science: life in icy environments, led by John Priscu, of Montana State University; glacial geology, led by Ross Powell, of Northern Illinois University; and glacial hydrology, led by Slawek Tulaczyk, of the University of California, Santa Cruz.
Sharing of expertise by the groups of disciplinary experts will allow the data collected to be cast in a systemic, global context.
The WISSARD team will now process the water and sediment samples they have collected in hopes of answering seminal questions related to the structure and function of subglacial microbial life, climate history and contemporary ice-sheet dynamics.
Video surveys of the lake floor and measurements of selected physical and chemical properties of the waters and sediments will allow the team to further characterize the lake and its environs.
The approach to drilling was guided by recommendations in the 2007 National Research Council-sponsored report, "Exploration of Antarctic Subglacial Aquatic Environments: Environmental and Scientific Stewardship," aimed to protect these unique environments from contamination.
A team of engineers and technicians directed by Frank Rack, of the University of Nebraska-Lincoln, designed, developed and fabricated the specialized hot-water drill that was fitted with a filtration and germicidal UV system to prevent contamination of the subglacial environment and to recover clean samples for microbial analyses. In addition, the numerous customized scientific samplers and instruments used for this project were also carefully cleaned before being lowered into the borehole through the ice and into the lake.
Read more at Science Daily
Identity of Famous 19th-Century Brain Discovered
The new finding, detailed in the January issue of the Journal of the History of the Neurosciences, identifies the famous patient as Monsieur Louis Leborgne, a French craftsman who battled epilepsy his entire life.
Wordless Patient
In 1840, a wordless patient was admitted to the Bicêtre Hospital outside Paris for aphasia, or an inability to speak. He was essentially just kept there, slowly deteriorating. It wasn't until 1861 that the man, who came to be known as Monsieur Leborgne, or "Tan," for his only spoken word, came to the famous physician Paul Broca's ward at the hospital.
Shortly after the meeting, Leborgne died, and Broca performed his autopsy. During the autopsy, Broca found a lesion in a region of the brain tucked back and up behind the eyes.
Paradigm Shift
After doing a detailed examination, Broca concluded that Tan's aphasia was caused by damage to this region, and that the particular brain region controlled speech. That region of the brain was later renamed Broca's area in honor of the doctor.
At the time, scientists were debating whether specific areas of the brain performed specific functions, or whether it was an undifferentiated lump that did one task, like the liver, said Marjorie Lorch, a neurolinguist at Birkbeck, University of London, who was not involved in the study.
"Tan was the first patient whose case proved that damage to a specific part of the brain causes specific speech disorders," said study author Cezary Domanski, a medical historian at the Maria Curie-Sklodowska University in Poland.
Life Reconstructed
Yet Tan's identity remained shrouded in mystery. Most historians believed he was a poor, illiterate laborer, while others said he had gone mad from syphilis and that madness could explain his inability to speak. To discover just who he was, Domanski began to retrace the man's history.
Read more at Discovery News
'Horizontal Falls': New Australian National Park
The new park is situated in the Kimberley region, the northernmost part of the state of Western Australia. The region is bordered on the west by the Indian Ocean, on the north by the Timor Sea, on the east by the Northern Territory and on the south by the Great Sandy and Tanami Deserts.
Despite its name, the Horizontal Falls are a coastal feature that isn't a waterfall at all — it is a set of parallel gorges with narrow openings through which seawater rushes with the ebb and flow of the tide, in a waterfall-like effect. They are located within Talbot Bay on the Buccaneer Peninsula.
"The extraordinary Horizontal Falls are an internationally renowned tourist attraction and it is imperative we maintain the pristine environment that surrounds them," said Western Australia Premier Colin Barnett in a statement.
Both the national park and marine park will be designated Class A by the government, which gives them the highest level of protection, according to the Western Australia government statement.
While the final borders of the parks have yet to be determined, the marine park would cover about 1,160 square miles (3,000 square kilometers) and would protect coral reefs, dolphins and mangrove forests, the statement said. The new marine park will expand the Great Kimberley Marine Park to 10,000 square miles (26,000 square km).
"Protecting the Kimberley coast and its marine and bird life provides a balance to the rapid spread of mining and other industrial development," John Carey, the Pew Environment Group's Kimberley Conservation Project director, told the Australian Associated Press.
The marine park would be multiple-use, with fishing and tourism opportunities. Existing pearling leases will also be maintained, the government statement said.
Read more at Discovery News
See the Andromeda Galaxy in a Cool New Light
Now, with a little help from Europe's infrared space observatory Herschel, astronomers have been given the most intricate view yet of Andromeda's beautiful spiraling lanes of cool dust.
In two new observations released Tuesday, warm interstellar dust can be seen collecting around Andromeda's galactic core. Star formation is underway in these regions.
Further out, away from the galactic nucleus, extremely cold dust -- some of it only a few tens of degrees warmer than absolute zero -- dominates. Star formation continues further away from the core, but at a much slower rate, highlighted by dusty knots embedded within the larger-scale rings.
One of the new observations (shown here) is a mosaic of a combination of the space telescope's instruments. Data from Herschel's Photodetecting Array Camera and Spectrometer (PACS) and spectral and photometric imaging receiver (SPIRE) highlight the most intense star-forming region (blue/white hues) whereas the darker reds and orange exhibit the coolest regions.
Read more at Discovery News
Jan 28, 2013
Mysteries of Spider Silk Strength Unraveled
"Spider silk has a unique combination of mechanical strength and elasticity that make it one of the toughest materials we know," said Professor Jeffery Yarger of ASU's Department of Chemistry and Biochemistry, and lead researcher of the study. "This work represents the most complete understanding we have of the underlying mechanical properties of spider silks."
Spider silk is an exceptional biological polymer, related to collagen (the stuff of skin and bones) but much more complex in its structure. The ASU team of chemists is studying its molecular structure in an effort to produce materials ranging from bulletproof vests to artificial tendons.
The extensive array of elastic and mechanical properties of spider silks in situ, obtained by the ASU team, is the first of its kind and will greatly facilitate future modeling efforts aimed at understanding the interplay of the mechanical properties and the molecular structure of silk used to produce spider webs.
The team published their results in a recent issue of Nature materials and their paper is titled "Non-invasive determination of the complete elastic moduli of spider silks."
"This information should help provide a blueprint for structural engineering of an abundant array of bio-inspired materials, such as precise materials engineering of synthetic fibers to create stronger, stretchier, and more elastic materials," explained Yarger.
Other members of Yarger's team, in ASU's College of Liberal Arts and Sciences, included Kristie Koski, at the time a postdoctoral researcher and currently a postdoctoral fellow at Stanford University, and ASU undergraduate students Paul Akhenblit and Keri McKiernan.
The Brillouin light scattering technique used an extremely low power laser, less than 3.5 milliwatts, which is significantly less than the average laser pointer. Recording what happened to this laser beam as it passed through the intact spider webs enabled the researchers to spatially map the elastic stiffnesses of each web without deforming or disrupting it. This non-invasive, non-contact measurement produced findings showing variations among discrete fibers, junctions and glue spots.
Four different types of spider's webs were studied. They included Nephila clavipes (pictured), A. aurantia ("gilded silver face"-common to the contiguous United States), L. Hesperus the western black widow and P. viridans the green lynx spider, the only spider included that does not build a web for catching prey but has major silk elastic properties similar to those of the other species studied.
The group also investigated one of the most studied aspects of orb-weaving dragline spider silk, namely supercontraction, a property unique to silk. Spider silk takes up water when exposed to high humidity. Absorbed water leads to shrinkage in an unrestrained fiber up to 50 percent shrinkage with 100 percent humidity in N. clavipes silk.
Their results are consistent with the hypothesis that supercontraction helps the spider tailor the properties of the silk during spinning. This type of behavior, specifically adjusting mechanical properties by simply adjusting water content, is inspirational from a bio-inspired mechanical structure perspective.
Read more at Science Daily
Tiny Feathered Dinosaur Found
Remains of the tiny beast, dubbed Eosinopteryx brevipenna, found in northeastern China suggest it was slightly less than a foot long (30 centimeters) and had a short snout and a short tail. Based on the dinosaur's small wingspan and bone structure, researchers believe it would have been able to run around quite easily, but likely couldn't whip up enough of a wing-beat to fly. The dinosaur also sported toes that would have been suitable for walking along the ground, the researchers added.
This birdlike dinosaur's plumage was much more reduced compared with the feathers on some of its contemporaries, which suggests that feathering was already diversified by the Late Jurassic, adapted to different ecological niches and purposes, the researchers said. (The Jurassic period lasted from about 199.6 million to 145.5 million years ago.)
"This discovery sheds further doubt on the theory that the famous fossil Archaeopteryx — or 'first bird' as it is sometimes referred to — was pivotal in the evolution of modern birds," researcher Gareth Dyke, a senior lecturer in paleontology at the U.K.'s University of Southampton, said in a statement.
"Our findings suggest that the origin of flight was much more complex than previously thought."
Archaeopteryx was long thought by many to have been the earliest bird. Discovered in 1860 in Germany, it is sometimes referred to as Urvogel, the German word for "original bird" or "first bird." But recent findings suggest late-stage Jurassic Archaeopteryx was actually just a relative of the lineage that ultimately gave rise to birds.
Read more at Discovery News
Einstein Also Studied An Obscure Geological Law
We know about Einstein's paper on Special Relativity, and we know about his paper on General Relativity. Many of us even know about his paper about chemistry and Brownian Motion. What's less well know is his brief stop over in geology. In 1926, he published a paper that examined Baer's Law. Ever heard of that? You probably haven't - for two different reasons. It doesn't have any practical effect on the world, and Karl Ernst von Baer was such a talented researcher in some areas that, like Einstein, his other achievements overshadowed his work in geology.
Von Baer made a lifelong study of embryology, uncovering the development of everything from birds to humans. He showed that, at different stages of development, embryos from different organisms can look very similar. Basically, he kick-started the field of embryology. But he spent some time studying geology as well, and came up with a theory about the erosion of rivers. Baer's Law is the river equivalent of the Coriolis Effect - which shows that objects moving over long distances are affected by the rotation of the Earth.
Imagine standing on the north pole and being able to throw a ball to the equator. A target is set out for you. But you are standing, basically still, while the target is zooming by so fast that it travels the entire circumference of the Earth in a day. It's zooming, from your perspective, to the left, so your ball seems to curve to the right. The trick of the Coriolis Effect is, when you trundle down to the equator, retrieve your ball, and throw it back up, it will still seem to zoom to the right. How can that be? As you look up towards the north pole from the equator, you are constantly in line with it. But technically you're not. You're being pulled to your right as a high rate of speed. The pole is sitting relatively still, like the center of a merry-go-round. The ball is being pulled, along with you, to the right at a high rate of speed, and as it goes towards the north pole, the ground slows down under it, making it seem to pull to the right, again. In the southern hemisphere, the same thing happens but in reverse. Flying objects are pulled to the left.
Baer—and Einstein—reasoned that this didn't just happen with things like air and thrown balls. It happened in the water, too. Rivers experienced this pull, or at least the water in rivers did. Plant your feet to either side of a river in the northern hemisphere, and look downstream, and the water will wash against the right bank more. In the southern hemisphere, it will wash against the left bank. This wear and tear will erode away the sediment on the banks, so in the southern hemisphere the left bank will get more wear, and in the northern hemisphere the right bank will. This was Baer's Law, but people didn't understand the mechanics of it.
Einstein's paper argued that, as water rushed toward a river bank and was pushed away, it experiences an inward push to match the outward push of the water. This establishes a pressure gradient along the banks of the river. Along the bottom of rivers, the water experiences friction, which slows it down and lessens the outward push. The pressure gradient then sweeps the sediment from the sides to the bottom of the river. This, Einstein thought, was the mechanism that ate away at the side of the river, and built up the bottom.
Read more at Discovery News
Anti-Science Bills Weighed in Four States
Bills like these pop up a lot, says evolutionary biologist Josh Rosenau, who works on policy issues for the National Center for Science Education (NCSE). But in recent years the language of the bills has been converging, suggesting that it is essentially the same bill being re-introduced around the country, rather than something original to each state.
"It is almost identical language in all of the bills," said Rosenau. "It's a package of bills that we've been tracking since the 2004 'Academic Freedom' bill." That bill, which was passed into law, was based on language generated by the Discovery Institute, which has long pushed for the inclusion of biblical creationism and pseudo-scientific "intelligent design" into science classes in public schools.
The academic freedom approach sounds good because it seems to protect students and teachers from being expelled if they want to argue about creationism, deny climate science, or refer to stem cell research in the classroom. The only catch, said Rosenau, is that it's a solution in search of a problem.
"No one has been expelled," said Rosenau.
On the other hand the bills would create problems for administrators and teachers, said Eric Feaver, president of the Montana Education Association and the Montana Federation of Teachers.
“It affects the supervisors of the schools,” said Feaver, because they would not be able to stop the teaching of religion disguised as science. “Teachers who teach creationism would be immune to punishment.” That basically undermines school supervisors, he said.
In Montana, HB 183 reflects the same "academic freedom" approach, and was introduced by newly sworn-in legislator Clayton Fiscus, a realtor and high school graduate.
Read more at Discovery News
Jan 27, 2013
Accelerating Neutral Atoms On a Table Top
In a simple picture, charged particles like electrons and protons are accelerated between two end plates across which an electrical voltage is applied. High energies need high voltages (millions and billions of volts) and long acceleration paths in giant sized machines -- for instance the trillion volt machine called the 'large hadron collider' (LHC) which discovered the Higgs boson, circles over 27 km underground in Geneva! A new concept for a compact accelerator was discovered in the last decade using high powered, short pulses of laser light.
Alternating large electric fields of the light can be transformed in plasmas to create quasi static fields that can produce hundreds of millions volt accelerating voltages just over millimeter lengths on a table top!
How do we accelerate neutral particles -- i.e. particles that cannot be energized by electrical voltages? And do it over millimeters rather than hundreds of meters and moreover using lasers? Research at Ultra Short Pulse High Intensity Lab in TIFR has now found a novel scheme that can do precisely this. The concept uses the ability of powerful lasers to strip nearly 8 electrons per atom in a nano sized, cooled aggregate of argon atoms- a nano piece of ice. A 40,000 atom cluster of argon is charged to 320,000 by a laser that lasts only a 100 billionth of a millionth of a second. Such a super highly charged ice piece explodes soon after, accelerating the charged atoms (Ions) to a million electron volts of energy. The TIFR research now found that all the expelled electrons can be put back into the charged ion that has been accelerated so that it now reverts to being a neutral atom but at high energies. To top it all, this process is nearly 100% efficient at neutralizing the speeding ions and converting them to fast atoms.
Accelerated neutral atoms are very important for many applications. Unaffected by electric or magnetic fields, they penetrate deeper in solids than electrons/ions and thereby create high finesse microstructures for novel electronics and optical devices. Fast atoms are used both as diagnostics and heating sources in Tokomak machines like the ITER (International Thermonuclear Experimental Reactor) in France, that are being developed to create sustained thermo-nuclear fusion. The TIFR scheme can produce a point source of fast neutral atoms close to the location of an intended application.
Read more at Science Daily
Cities Affect Temperatures for Thousands of Miles
In a new study that shows the extent to which human activities are influencing the atmosphere, scientists have concluded that the heat generated by everyday activities in metropolitan areas alters the character of the jet stream and other major atmospheric systems. This affects temperatures across thousands of miles, significantly warming some areas and cooling others, according to the study this week in Nature Climate Change.
The extra "waste heat" generated from buildings, cars, and other sources in major Northern Hemisphere urban areas causes winter warming across large areas of northern North America and northern Asia. Temperatures in some remote areas increase by as much as 1 degree Celsius (1.8 degrees Fahrenheit), according to the research by scientists at the Scripps Institution of Oceanography; University of California, San Diego; Florida State University; and the National Center for Atmospheric Research.
At the same time, the changes to atmospheric circulation caused by the waste heat cool areas of Europe by as much as 1 degree C (1.8 degrees F), with much of the temperature decrease occurring in the fall.
The net effect on global mean temperatures is nearly negligible -- an average increase worldwide of just 0.01 degrees C (about 0.02 degrees F). This is because the total human-produced waste heat is only about 0.3 percent of the heat transported across higher latitudes by atmospheric and oceanic circulations.
However, the noticeable impact on regional temperatures may explain why some regions are experiencing more winter warming than projected by climate computer models, the researchers conclude. They suggest that models be adjusted to take the influence of waste heat into account.
"The burning of fossil fuel not only emits greenhouse gases but also directly affects temperatures because of heat that escapes from sources like buildings and cars," says NCAR scientist Aixue Hu, a co-author of the study. "Although much of this waste heat is concentrated in large cities, it can change atmospheric patterns in a way that raises or lowers temperatures across considerable distances."
Distinct from urban heat island effect
The researchers stressed that the effect of waste heat is distinct from the so-called urban heat island effect. Such islands are mainly a function of the heat collected and re-radiated by pavement, buildings, and other urban features, whereas the new study examines the heat produced directly through transportation, heating and cooling units, and other activities.
The study, "Energy consumption and the unexplained winter warming over northern Asia and North America," appeared online January 27. It was funded by the National Science Foundation, NCAR's sponsor, as well as the Department of Energy and the National Oceanic and Atmospheric Administration.
Hu, along with lead author Guang Zhang of Scripps and Ming Cai of Florida State University, analyzed the energy consumption -- from heating buildings to powering vehicles -- that generates waste heat release. The world's total energy consumption in 2006 was equivalent to a constant-use rate of 16 terawatts (1 terawatt, or TW, equals 1 trillion watts). Of that, an average rate of 6.7 TW was consumed in 86 metropolitan areas in the Northern Hemisphere.
Using a computer model of the atmosphere, the authors found that the influence of this waste heat can widen the jet stream.
"What we found is that energy use from multiple urban areas collectively can warm the atmosphere remotely, thousands of miles away from the energy consumption regions," Zhang says. "This is accomplished through atmospheric circulation change."
The release of waste heat is different from energy that is naturally distributed in the atmosphere, the researchers noted. The largest source of heat, solar energy, warms Earth's surface and atmospheric circulations redistribute that energy from one region to another. Human energy consumption distributes energy that had lain dormant and sequestered for millions of years, mostly in the form of oil or coal.
Read more at Science Daily
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