QuoteReplyTopic: Science and Nature News Redux Posted: 23-Mar-2012 at 05:02
Neuroscience: Making connections
Is a project to map the brain’s full communications network worth the money?
The nerve fibres of the author's brain were traced by diffusion spectrum imaging, and coloured to represent their direction.
A building that once housed a Second World War torpedo factory seems an unlikely location for a project aiming to map the human brain. But the Martinos Center for Biomedical Imaging — an outpost of the Massachusetts General Hospital in an industrialized stretch of Boston's riverfront — is home to an impressive collection of magnetic resonance imaging machines. In January, I slid into the newest of these, head first. The operator ran a few test sequences to see whether I experienced any side effects from the unusually rapid changes in this machine's magnetic field. And, when I didn't — no involuntary muscle twitches or illusory flashes of light in my peripheral vision — we began. The machine hummed, then started to vibrate. For 90 minutes, I held still as it scanned my brain.
That scan would be one of the first carried out by the Human Connectome Project (HCP), a five-year, US$40-million initiative funded by the National Institutes of Health (NIH) in Bethesda, Maryland, to map the brain's long-distance communications network. The network, dubbed the 'connectome', is a web of nerve-fibre bundles that criss-cross the brain in their thousands and form the bulk of the brain's white matter. It relays signals between specialized regions devoted to functions such as sight, hearing, motion and memory, and ties them together into a system that perceives, decides and acts as a unified whole.
The connectome is bewilderingly complex and poorly understood. The HCP proposes to resolve this by using new-generation magnetic resonance imaging (MRI) machines, like that used to scan my brain, to trace the connectomes of more than 1,000 individuals. The hope is that this survey will establish a baseline for what is normal, shed light on what the variations might mean for qualities such as intelligence or sociability, and possibly reveal what happens if the network goes awry. “We increasingly believe that brain disorders — from schizophrenia to depression to post-traumatic stress disorder — are disorders of connectivity,” says Thomas Insel, director of the National Institute of Mental Health (NIMH) in Bethesda and a strong supporter of the HCP. “So it is of vital importance that we have ways of detecting and quantifying these connections.”
Yet many wonder whether the NIH is making a mistake. Researchers have yet to prove that MRI techniques can produce a reliable picture of normal connectivity, never mind the types of abnormal connection likely to be found in brain disorders, and some researchers argue that the techniques have not been adequately validated. “I would do the basic neuroscience before I started running lots of people through MRI scanners,” says David Kleinfeld, a physics and neurobiology researcher at the University of California, San Diego.
The grand challenge
Proponents counter that the HCP is a calculated risk. “No one thinks this is going to produce a wiring diagram like you might have for the electricity in your house,” says Insel. But so little is known about the connectome, he says, that even crude maps would represent a major scientific advance.
The decision to take that risk was made by the NIH's Blueprint for Neuroscience Research, set up in 2004 as a collaboration among the 15 NIH institutes, centres and offices with an interest in nervous-system research. In 2009, after five years of funding smaller projects, the group asked officials from across the NIH to submit ideas for 'grand challenges' in neuroscience: large-scale programmes that, Insel says, “would be both extremely high-impact, and virtually impossible with traditional grant mechanisms”.
The Blueprint group received a dozen submissions, including one from Michael Huerta, then a programme officer at the NIMH and a member of a Blueprint subcommittee. Huerta, now at the NIH's National Library of Medicine, began his research career studying the organization of mammalian brains using old-school anatomical and neural-tracing techniques, which typically require the injection of a tracer compound that migrates along nerve fibres and reveals their routes. So he was all too familiar with the barriers to such studies in humans. For ethical reasons, tracers can only be used post-mortem — when they don't migrate far enough to trace a fibre's full length. “The studies just never panned out,” says Huerta..........
"...ScienceDaily (Mar. 14, 2012) — The origin of
the exquisitely complex vertebrate brain is somewhat mysterious. "In
terms of evolution, it basically pops up out of nowhere. You don't see
anything anatomically like it in other animals," says Ariel Pani, an
investigator at the Marine Biological Laboratory (MBL) in Woods Hole and
a graduate student at the University of Chicago. ScienceDaily (Mar. 14, 2012) — The origin of
the exquisitely complex vertebrate brain is somewhat mysterious. "In
terms of evolution, it basically pops up out of nowhere. You don't see
anything anatomically like it in other animals," says Ariel Pani, an
investigator at the Marine Biological Laboratory (MBL) in Woods Hole and
a graduate student at the University of Chicago....
.."What this means is the last (common) ancestor of the hemichordates and
the vertebrates, even though it presumably did not have a
vertebrate-like nervous system, had some very complex and
vertebrate-like mechanisms for establishing its body plan," Pani says.
"And one of the broad implications is that weird, squishy marine animals
can be very informative in terms of understanding the evolution of
vertebrate development and genetics in a way that you wouldn't expect."... http://www.sciencedaily.com/releases/2012/03/120314142843.htm.
World’s Most Powerful Laser Fires Most Powerful Laser Blast in History
Published March 21, 2012-FoxNews.com
The largest laser in the world was turned on for a fraction of a second last week -- and it unleashed the most powerful laser blast in history.
The National Ignition Facility (NIF) -- a laser test facility at Lawrence Livermore National Laboratory in Livermore, Calif. -- turned on its 192 laser beams for a brief instant on March 15, unleashing a record-setting 1.875-megajoule blast into a target chamber. The lasers were combined, gathered and focused through a series of lens into a 2.03-megajoule shot, said Ed Moses, NIF director -- a record for the facility. That pulse of energy lasted for just 23 billionths of a second, yet it generated 411 trillion watts of power, NIF said -- 1,000 times more than the entire United States consumes at any given instant.
Written By Brian Jacobsmeyer-Published March 22, 2012-Inside Science News Service
Jupiter might be having a change of heart. Literally.
New simulations suggest that Jupiter's rocky core has been liquefying, melting, and mixing with the rest of the planet's innards. With this new data, astronomers hope to better explain a recent puzzling discovery of a strange planet outside of our solar system.
"It's a really important piece of the puzzle of trying to figure out what's going on inside giant planets," said Jonathan Fortney, a planetary scientist at the University of California Santa Cruz who was not affiliated with the research.
Conventional planetary formation theory has modeled Jupiter as a set of neat layers with a gassy outer envelope surrounding a rocky core consisting of heavier elements. But increasing evidence has indicated that the insides of gas giants like Jupiter are a messy mixture of elements without strictly defined borders.
Written By Jennifer Welsh-Published March 21, 2012-LiveScience
Captive chimpanzees learn from their mothers to call out to humans, new research suggests. Those chimps raised by their moms were also most likely to use similar calls, from lip-smacking to blowing kisses.
This teaching from mother to child is an example of "social learning," which played an important role in the development of human culture and language.
While social learning of tool use has been seen in chimps before, "it has never really been shown for communication before," study researcher Jared Taglialatela, an assistant professor at Kennesaw State University in Georgia, told LiveScience. Before this study, he said, "social learning of communication signals was seen as unique to human language."
The study suggested a gene variation could contribute to the weight of a newborn child
Scientists say a gene variation could contribute up to 155g (5.5oz) to a child's birthweight.
The gene studied is believed to act as a growth suppressor, reducing birthweight.
But the UK-based researchers found a particular variant passed down from the mother can add 93g (3.3oz) to the birthweight, or 155g if passed down from the maternal grandmother.
Details are published in the American Journal of Human Genetics.
Professor Gudrun Moore of University College London and colleagues looked at a gene called PHLDA2 in nearly 9,500 DNA samples taken from mothers and their babies, collected in three separate studies.
They found a gene variant called RS1 appeared to change the way in which the gene functioned, leading to higher birthweights.
"The gene is already known to have a profound effect on birthweight by acting as a growth suppressor," Prof Moore told BBC News.
"We have found a genetic variant of PHLDA2 that when inherited from the mother, causes the baby to be 93g bigger on average, or even 155g bigger on average, if inherited successively from the mother's mother."
The RS1 variation was found in around 13% of the individuals studied, with 87% possessing the RS2 variation.
"We suggest that the more common RS2 gene variation, which is only found in humans, has evolved to produce a smaller baby as a protective effect to enhance the mother's survival during childbirth," said Prof Moore.
"Dad's lack of involvement in evolutionary terms may stem from his own survival not being at stake and he can continue to reproduce with other females."
Gene 'silenced'
The PHLDA2 gene is unusual in that only the copy inherited from the mother is active, while the copy inherited from the father is "silenced". This silencing of the paternal gene results from molecular processes around the DNA known as epigenetics.
Scientists do not know why, but have speculated that it is to ensure birthweight is reduced to ensure the mother survives childbirth.
Dr Caroline Relton of Newcastle University said: "Although this study looks only at birthweight as an outcome, it is possible that this genetic variant may have longer-term health consequences.
"Indeed the long-term health consequences associated with extremes of birthweight might be due in part to this and other contributory genetic factors."
The water flowing through Venice's famous canals laps at buildings a little higher every year -- and not only because of a rising sea level. Although previous studies had found that Venice has stabilized, new measurements indicate that the historic city continues to slowly sink, and even to tilt slightly to the east.
"Venice appears to be continuing to subside, at a rate of about 2 millimeters (.07 inches) a year," said Yehuda Bock, a research geodesist with Scripps Institution of Oceanography at UC San Diego, and the lead author of the new research paper on the city's downward drift. "It's a small effect, but it's important," he added. Given that sea level is rising in the Venetian lagoon, also at 2 millimeters per year, the slight subsidence doubles the rate at which the heights of surrounding waters are increasing relative to the elevation of the city, he noted. In the next 20 years, if Venice and its immediate surroundings subsided steadily at the current rate, researchers would expect the land to sink up to 80 millimeters (3.2 inches) in that period of time, relative to the sea.
Bock worked with colleagues from the University of Miami in Florida and Italy's Tele-Rilevamento Europa, a company that measures ground deformation, to analyze data collected by GPS and space-borne radar (InSAR) instruments regarding Venice and its lagoon. The GPS measurements provide absolute elevations, while the InSAR data are used to calculate elevations relative to other points. By combining the two datasets from the decade between 2000 and 2010, Bock and his colleagues found that the city of Venice was subsiding on average of 1 to 2 millimeters a year (0.04 to 0.08 inches per year). The patches of land in Venice's lagoon (117 islands in all) are also sinking, they found, with northern sections of the lagoon dropping at a rate of 2 to 3 millimeters (0.08 to 0.12 inches) per year, and the southern lagoon subsiding at 3 to 4 millimeters (0.12 to 0.16 inches) per year.
The findings will be published March 28 in Geochemistry, Geophysics, Geosystems, a journal of the American Geophysical Union.
"Our combined GPS and InSAR analysis clearly captured the movements over the last decade that neither GPS nor InSAR could sense alone" said Shimon Wdowinski, associate research professor of Marine Geology and Geophysics at the University of Miami.
In the new study, using the GPS instruments, Bock and his colleagues were able to take absolute readings of the city and its surrounding lagoons. And not only did they find the sinking, but they found that the area was tilting a bit, about a millimeter or two eastward per year. That means the western part -- where the city of Venice is -- is higher than the eastern sections. Prior satellite analyses didn't pick up on the tilt, Bock said, possibly because the scientists had been taking measurements using InSAR, which only provided the change elevation relative to other sites........
Dawn Sees New Surface Features On Giant Asteroid Vesta
Bright Rays from Canuleia Crater: In this image from NASA's Dawn spacecraft, bright material extends out from the crater Canuleia on Vesta.
NASA's Dawn spacecraft has revealed unexpected details on the surface of the giant asteroid Vesta. New images and data highlight the diversity of Vesta's surface and reveal unusual geologic features, some of which were never previously seen on asteroids.
These results were discussed March 21, 2012 at the Lunar and Planetary Science Conference at The Woodlands, Texas.
Vesta is one of the brightest objects in the solar system and the only asteroid in the so-called main belt between Mars and Jupiter visible to the naked eye from Earth. Dawn has found that some areas on Vesta can be nearly twice as bright as others, revealing clues about the asteroid's history.
"Our analysis finds this bright material originates from Vesta and has undergone little change since the formation of Vesta over 4 billion years ago," said Jian-Yang Li, a Dawn participating scientist at the University of Maryland, College Park. "We're eager to learn more about what minerals make up this material and how the present Vesta surface came to be."
Bright areas appear everywhere on Vesta but are most predominant in and around craters. The areas vary from several hundred feet to around 10 miles (16 kilometers) across. Rocks crashing into the surface of Vesta seem to have exposed and spread this bright material. This impact process may have mixed the bright material with darker surface material.
While scientists had seen some brightness variations in previous images of Vesta from NASA's Hubble Space Telescope, Dawn scientists also did not expect such a wide variety of distinct dark deposits across its surface. The dark materials on Vesta can appear dark gray, brown and red. They sometimes appear as small, well-defined deposits around impact craters. They also can appear as larger regional deposits, like those surrounding the impact craters scientists have nicknamed the "snowman."
"One of the surprises was the dark material is not randomly distributed," said David Williams, a Dawn participating scientist at Arizona State University, Tempe. "This suggests underlying geology determines where it occurs."......
Runner's High Motivated the Evolution of Exercise, Research Suggests
Runners. Researchers say that endocannabinoids motivated the evolution of exercise.
In the last century something unexpected happened: humans became sedentary. We traded in our active lifestyles for a more immobile existence. But these were not the conditions under which we evolved. David Raichlen from the University of Arizona, USA, explains that our hunter-gatherer predecessors were long-distance endurance athletes. 'Aerobic activity has played a role in the evolution of lots of different systems in the human body, which may explain why aerobic exercise seems to be so good for us', says Raichlen. However, he points out that testing the hypothesis that we evolved for high-endurance performance is problematic, because most other mammalian endurance athletes are quadrupedal.
'So we got interested in the brain as a way to look at whether evolution generated exercise behaviours in humans through motivation pathways', says Raichlen.
Explaining that most human athletes experience the infamous 'runner's high' after exertion, which is caused by endocanabinoid signalling in the so-called 'reward centres' of the brain, Raichlen adds little was known about the role of endocanabinoids in the other aerobically active mammals. So, he teamed up with Gregory Gerdeman and other colleagues to find out how exercise influences the endocanabinoid levels of two mammalian natural athletes – humans and dogs – and a low activity species – ferrets. The team publish their discovery that animals that evolved for endurance exercise benefit from endocanabinoids while animals that did not don't experience the pleasures, leading them to propose that natural selection used the endocanabinoid system to motivate endurance exercise in humans. The team publishes their discovery in The Journal of Experimental Biology.
Recruiting recreational runners and pet dogs from the local community, Raichlen and Adam Foster trained the participants to run and walk on a treadmill and collected blood samples from the participants before and after the exercise. Unfortunately, the ferrets were less cooperative, so the team collected the ferrets' blood samples after exercise and during rest.
Next, Andrea Giuffrida and Alexandre Seillier analysed the endocanabinoid levels in the blood samples and found that the concentration of one endocanabinoid – anandamide – rocketed in the blood of the dogs and humans after a brisk run. And when the team tested the human runners' state of mind, they found that they athletes were much happier after the exercise. However, when the team analysed the ferrets' blood samples, the animal's anandamide levels did not increase during exercise. They did not produce endocanabinoids in response to high-intensity exercise......
New Technique Lets Scientists Peer Within Nanoparticles, See Atomic Structure in 3-D
Inside a gold nanoparticle. Jianwei Miao and colleagues have developed an electron tomography method to image the 3-D structure of a gold nanoparticle at a resolution of 2.4 angstroms. Individual atoms are observed in some regions of the particle and several grains are identified in three dimensions. In the figure, the four three-dimensional grains (green and gold; blue and red) form two pairs of twin boundaries inside the nanoparticle.
UCLA researchers are now able to peer deep within the world's tiniest structures to create three-dimensional images of individual atoms and their positions. Their research, published March 22 in the journal Nature, presents a new method for directly measuring the atomic structure of nanomaterials.
"This is the first experiment where we can directly see local structures in three dimensions at atomic-scale resolution -- that's never been done before," said Jianwei (John) Miao, a professor of physics and astronomy and a researcher with the California NanoSystems Institute (CNSI) at UCLA.
Miao and his colleagues used a scanning transmission electron microscope to sweep a narrow beam of high-energy electrons over a tiny gold particle only 10 nanometers in diameter (almost 1,000 times smaller than a red blood cell). The nanoparticle contained tens of thousands of individual gold atoms, each about a million times smaller than the width of a human hair. These atoms interact with the electrons passing through the sample, casting shadows that hold information about the nanoparticle's interior structure onto a detector below the microscope.
Miao's team discovered that by taking measurements at 69 different angles, they could combine the data gleaned from each individual shadow into a 3-D reconstruction of the interior of the nanoparticle. Using this method, which is known as electron tomography, Miao's team was able to directly see individual atoms and how they were positioned inside the specific gold nanoparticle.
Presently, X-ray crystallography is the primary method for visualizing 3-D molecular structures at atomic resolutions. However, this method involves measuring many nearly identical samples and averaging the results. X-ray crystallography typically takes an average across trillions of molecules, which causes some information to get lost in the process, Miao said.
"It is like averaging together everyone on Earth to get an idea of what a human being looks like -- you completely miss the unique characteristics of each individual," he said.
X-ray crystallography is a powerful technique for revealing the structure of perfect crystals, which are materials with an unbroken honeycomb of perfectly spaced atoms lined up as neatly as books on a shelf. Yet most structures existing in nature are non-crystalline, with structures far less ordered than their crystalline counterparts -- picture a rock concert mosh pit rather than soldiers on parade.......
Quantum Plasmons Demonstrated in Atomic-Scale Nanoparticles
A series of electron micrographs of silver nanospheres of between two and ten nanometers in diameter. Individual atoms are visible within the particles.
Addressing a half-decade-old debate, engineers at Stanford have positively identified the presence of plasmons, the collective oscillations of electrons, in individual metal particles as small as one nanometer in diameter. The discovery could impact nanotechnology.
The physical phenomenon of plasmon resonances in small metal particles has been apparent for centuries. They are visible in the vibrant hues of the great stained-glass windows of the world. More recently, plasmon resonances have been used by engineers to develop new, light-activated cancer treatments and to enhance light absorption in photovoltaics and photocatalysis.
"The stained-glass windows of Notre Dame Cathedral and Stanford Chapel derive their color from metal nanoparticles embedded in the glass. When the windows are illuminated, the nanoparticles scatter specific colors depending on the particle's size and geometry " said Jennifer Dionne, an assistant professor of materials science and engineering at Stanford and the senior author of a new paper on plasmon resonances to be published in the journal Nature.
In the study, the team of engineers report the direct observation of plasmon resonances in individual metal particles measuring down to one nanometer in diameter, just a few atoms across.
"Plasmon resonances at these scales are poorly understood," said Jonathan Scholl, a doctoral candidate in Dionne's lab and first author of the paper. "So, this class of quantum-sized metal nanoparticles has gone largely under-utilized. Exploring their size-dependent nature could open up some interesting applications at the nanoscale."
The research could lead to novel electronic or photonic devices based on excitation and detection of plasmons in these extremely small particles, the engineers said.
"Alternatively, there could be opportunities in catalysis, quantum optics, and bio-imaging and therapeutics," added Dionne.......
How the Alphabet of Data Processing Is Growing: Flying 'Qubits' Generated
Electron one-way street. In this dual channel, electrons (blue) move on defined, parallel paths. Only one single electron fits through at a time. By means of tunnel coupling, the electron can switch back and forth between the channels, thus occupying two different states, which are denoted by “arrow up” and “arrow down”. The electron virtually flies in both tracks at the same time, its two states overlap.
The alphabet of data processing could include more elements than the "0" and "1" in future. An international research team has achieved a new kind of bit with single electrons, called quantum bits, or qubits. With them, considerably more than two states can be defined. So far, quantum bits have only existed in relatively large vacuum chambers. The team has now generated them in semiconductors. They have put an effect in practice, which the RUB physicist Prof. Dr. Andreas Wieck had already theoretically predicted 22 years ago. This represents another step along the path to quantum computing.
Together with colleagues from Grenoble and Tokyo, Wieck from the Chair of Applied Solid State Physics reports on the results in the journalNature Nanotechnology.
Conventional bits
The basic units of today's data processing are the bit states "0" and "1," which differ in their electrical voltage. To encode these states, only the charge of the electrons is crucial. "Electrons also have other properties though" says Wieck, and these are exactly what you need for quantum bits. "The extension from bits to quantum bits can dramatically increase the computational power of computers" says the physicist.
The new bit generation
A quantum bit corresponds to a single electron in a particular state. Together with his colleagues, Wieck used the trajectories of an electron through two closely spaced channels for encoding. In principle, two different states are possible: the electron either moves in the upper channel or in the lower channel -- which would then only form a binary system again. According to quantum theory, however, a particle can be in several states simultaneously, that is, it can quasi fly through both channels at the same time. These overlapping states can form an extensive alphabet of data processing.
A recipe for qubits
In order to generate quantum bits with different states, the researchers allowed individual electrons to interfere with each other. This works with the so-called Aharonov-Bohm effect: powered by an external voltage, the electrons fly through a semiconducting solid. Within this solid, their trajectory is first forked and then reunited. Thus, each electron flies simultaneously on both possible paths. When the two paths come together again, there is interference, i.e., the two electron waves overlap and quantum bits with different overlapping states are generated.
Controlling electrons on defined paths
Normally, an electron wave moves through a solid body on many different paths at the same time. Due to impurities in the material, it loses its phase information and thus its ability to encode a particular state. To maintain the phase information, the researchers at the RUB grew a high-purity gallium arsenide crystal and used a dual channel proposed by Wieck more than 20 years ago.......
In this artist’s conception, a runaway planet zooms through interstellar space. New research suggests that the supermassive black hole at our galaxy’s center can fling planets outward at relativistic speeds. Eventually, such worlds will escape the Milky Way and travel through the lonely intergalactic void. In this illustration, a glowing volcano on the planet’s surface hints at active plate tectonics that may keep the planet warm.
Seven years ago, astronomers boggled when they found the first runaway star flying out of our galaxy at a speed of 1.5 million miles per hour. The discovery intrigued theorists, who wondered: If a star can get tossed outward at such an extreme velocity, could the same thing happen to planets?
New research shows that the answer is yes. Not only do runaway planets exist, but some of them zoom through space at a few percent of the speed of light -- up to 30 million miles per hour.
"These warp-speed planets would be some of the fastest objects in our galaxy. If you lived on one of them, you'd be in for a wild ride from the center of the galaxy to the Universe at large," said astrophysicist Avi Loeb of the Harvard-Smithsonian Center for Astrophysics.
"Other than subatomic particles, I don't know of anything leaving our galaxy as fast as these runaway planets," added lead author Idan Ginsburg of Dartmouth College.
Such speedy worlds, called hypervelocity planets, are produced in the same way as hypervelocity stars. A double-star system wanders too close to the supermassive black hole at the galactic center. Strong gravitational forces rip the stars from each other, sending one away at high speed while the other is captured into orbit around the black hole.
For this study, the researchers simulated what would happen if each star had a planet or two orbiting nearby. They found that the star ejected outward could carry its planets along for the ride. The second star, as it's captured by the black hole, could have its planets torn away and flung into the icy blackness of interstellar space at tremendous speeds.
A typical hypervelocity planet would slingshot outward at 7 to 10 million miles per hour. However, a small fraction of them could gain much higher speeds under ideal conditions.
Current instruments can't detect a lone hypervelocity planet since they are dim, distant, and very rare. However, astronomers could spot a planet orbiting a hypervelocity star by watching for the star to dim slightly when the planet crosses its face in a transit.
For a hypervelocity star to carry a planet with it, that planet would have to be in a tight orbit. Therefore, the chances of seeing a transit would be relatively high, around 50 percent.
"With one-in-two odds of seeing a transit, if a hypervelocity star had a planet, it makes a lot of sense to watch for them," said Ginsburg......
Geologists Discover New Class of Landform -- On Mars
Images from the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter show exposed rock strata in periodic bedrock ridges on the floor of the West Candor Chasma on Mars.
An odd, previously unseen landform could provide a window into the geological history of Mars, according to new research by University of Washington geologists.
They call the structures periodic bedrock ridges. The ridges look like sand dunes but, rather than being made from material piled up by the wind, the scientists say the ridges actually form from wind erosion of bedrock.
"These bedforms look for all the world like sand dunes but they are carved into hard rock by wind," said David Montgomery, a UW professor of Earth and space sciences. It is something there are not many analogs for on Earth."
He believes the ridges, while still bedrock, are composed of a softer, more erodible material than typical bedrock and were formed by an unusual form of wind erosion that occurs perpendicular to the prevailing wind rather than in the same direction.
He contrasts the ridges with another bedrock form called a yardang, which has been carved over time by headwinds. A yardang has a wide, blunt leading edge in the face of the wind, and its sides are tapered so that it resembles a teardrop.
In the case of periodic bedrock ridges, Montgomery believes high surface winds on Mars are deflected into the air by a land formation, and they erode the bedrock in the area where they settle back to the surface.
Spacing between ridges depends on how long it takes for the winds to come back to the surface, and that is determined by the strength of the wind, the size of the deflection and the density of the atmosphere, he said......
Cylinder Hides Contents and Makes Them Invisible to Magnetic Fields
Experimental set-up
Universitat Autonoma de Barcelona researchers, in collaboration with an experimental group from the Academy of Sciences of Slovakia, have created a cylinder which hides contents and makes them invisible to magnetic fields. The device was built using superconductor and ferromagnetic materials available on the market.
The cylinder is built using high temperature superconductor material, easily refrigerated with liquid nitrogen and covered in a layer of iron, nickel and chrome. This simple and accessible formula has been used to create a true invisibility cloak.
The cylinder is invisible to magnetic fields and represents a step towards the invisibility of light -- an electromagnetic wave. Never before had a device been created with such simplicity or exactness in theoretical calculations.
The invention is published this week in the journal Science.
Researchers at UAB, led by Àlvar Sánchez, lecturer of the Department of Physics, came up with the mathematical formula to design the device. Using an extraordinarily simple equation scientists described a cylinder which in theory is absolutely undetectable to magnetic fields from the outside, and maintains everything in its interior completely isolated from these fields as well.
Equation in hand and with the aim of building the device, UAB researchers contacted the laboratory specializing in the precise measurement of magnetic fields at the Institute of Electrical Engineering of the Slovak Academy of Sciences in Bratislava. Only a few months later the experimental results were clear. The cylinder was completely invisible to magnetic fields, made invisible whatever content was found in its interior and fully isolated it from external fields.
The superconductor layer of the cylinder prevents the magnetic field from reaching the interior, but distorts the external field and thus makes it detectable. To avoid detection, the ferromagnetic outer layer made of iron, nickel and chrome, produce the opposite effect. It attracts the magnetic field lines and compensates the distortion created by the superconductor, but without allowing the field to reach the interior. The global effect is a completely non-existent magnetic field inside the cylinder and absolutely no distortions in the magnetic field outside......
Mouse. Scripps Research Institute scientists and their colleagues have successfully harnessed neurons in mouse brains, allowing them to at least partially control a specific memory.
Scripps Research Institute scientists and their colleagues have successfully harnessed neurons in mouse brains, allowing them to at least partially control a specific memory. Though just an initial step, the researchers hope such work will eventually lead to better understanding of how memories form in the brain, and possibly even to ways to weaken harmful thoughts for those with conditions such as schizophrenia and post traumatic stress disorder.
The results are reported in the March 23, 2012 issue of the journal Science.
Researchers have known for decades that stimulating various regions of the brain can trigger behaviors and even memories. But understanding the way these brain functions develop and occur normally -- effectively how we become who we are -- has been a much more complex goal.
"The question we're ultimately interested in is: How does the activity of the brain represent the world?" said Scripps Research neuroscientist Mark Mayford, who led the new study. "Understanding all this will help us understand what goes wrong in situations where you have inappropriate perceptions. It can also tell us where the brain changes with learning."
On-Off Switches and a Hybrid Memory
As a first step toward that end, the team set out to manipulate specific memories by inserting two genes into mice. One gene produces receptors that researchers can chemically trigger to activate a neuron. They tied this gene to a natural gene that turns on only in active neurons, such as those involved in a particular memory as it forms, or as the memory is recalled. In other words, this technique allows the researchers to install on-off switches on only the neurons involved in the formation of specific memories.
For the study's main experiment, the team triggered the "on" switch in neurons active as mice were learning about a new environment, Box A, with distinct colors, smells and textures.
Next the team placed the mice in a second distinct environment -- Box B -- after giving them the chemical that would turn on the neurons associated with the memory for Box A. The researchers found the mice behaved as if they were forming a sort of hybrid memory that was part Box A and part Box B. The chemical switch needed to be turned on while the mice were in Box B for them to demonstrate signs of recognition. Alone neither being in Box B nor the chemical switch was effective in producing memory recall.
"We know from studies in both animals and humans that memories are not formed in isolation but are built up over years incorporating previously learned information," Mayford said. "This study suggests that one way the brain performs this feat is to use the activity pattern of nerve cells from old memories and merge this with the activity produced during a new learning session."......
Somatic Stem Cells Obtained from Skin Cells; Pluripotency 'Detour' Skipped
Immunofluorescence microscopy image of the induced neural stem cells using antibodies against two neural stem cell markers SSEA1 (red colour) and Olig2 (green colour).
Breaking new ground, scientists at the Max Planck Institute for Molecular Biomedicine in Münster, Germany, have succeeded in obtaining somatic stem cells from fully differentiated somatic cells. Stem cell researcher Hans Schöler and his team took skin cells from mice and, using a unique combination of growth factors while ensuring appropriate culturing conditions, have managed to induce the cells' differentiation into neuronal somatic stem cells.
"Our research shows that reprogramming somatic cells does not require passing through a pluripotent stage," explains Schöler. "Thanks to this new approach, tissue regeneration is becoming a more streamlined -- and safer -- process."
Up until now, pluripotent stem cells were considered the 'be-all and end-all' of stem cell science. Historically, researchers have obtained these 'jack-of-all-trades' cells from fully differentiated somatic cells. Given the proper environmental cues, pluripotent stem cells are capable of differentiating into every type of cell in the body, but their pluripotency also holds certain disadvantages, which preclude their widespread application in medicine. According to Schöler, "pluripotent stem cells exhibit such a high degree of plasticity that under the wrong circumstances they may form tumours instead of regenerating a tissue or an organ." Schöler's somatic stem cells offer a way out of this dilemma: they are 'only' multipotent, which means that they cannot give rise to all cell types but merely to a select subset of them -- in this case, a type of cell found in neural tissue -- a property, which affords them an edge in terms of their therapeutic potential.
To allow them to interconvert somatic cells into somatic stem cells, the Max Planck researchers cleverly combined a number of different growth factors, proteins that guide cellular growth. "One factor in particular, called Brn4, which had never been used before in this type of research, turned out to be a genuine 'captain' who very quickly and efficiently took command of his ship -- the skin cell -- guiding it in the right direction so that it could be converted into a neuronal somatic stem cell," explains Schöler. This interconversion turns out to be even more effective if the cells, stimulated by growth factors and exposed to just the right environmental conditions, divide more frequently. "Gradually, the cells lose their molecular memory that they were once skin cells," explains Schöler. It seems that even after only a few cycles of cell division the newly produced neuronal somatic stem cells are practically indistinguishable from stem cells normally found in the tissue......
New Understanding of Earth's Mantle Beneath the Pacific Ocean
The generation of partially molten rock locally sharpens the lithosphere-asthenosphere boundary (LAB), allowing seismic waves to reflect from the interface. Shear waves from an earthquake (star) travel through the Earth and reflect from the surface, and also where melt has ponded at the base of the lithosphere. The waves are recorded by seismometers (blue inverted triangle) deployed around the globe, providing a complete view of the LAB beneath the Pacific. Regions without melt will not produce a deeper reflection, signifying that melt is not the primary mechanism for weakening of rock in the asthenosphere.
Scientists have long speculated about why there is a large change in the strength of rocks that lie at the boundary between two layers immediately under Earth's crust: the lithosphere and underlying asthenosphere. Understanding this boundary is central to our knowledge of plate tectonics and thus the formation and evolution of our planet as we know it today. A new technique for observing this transition, particularly in the portion of Earth's mantle that lies beneath the Pacific Ocean basin, has led Carnegie and NASA Goddard scientist Nick Schmerr to new insight on the origins of the lithosphere and asthenosphere.
His work is published March 23 inScience.
The lithosphere-asthenosphere boundary, or LAB, represents the transition from hot, convecting mantle asthenosphere to overlying cold and rigid lithosphere. The oceanic lithosphere thickens as it cools over time, and eventually sinks back into the mantle at Earth's so-called subduction zones. Studies of seismic waves traveling across the LAB show higher wave speeds in the lithosphere and lower speeds in the asthenosphere. In some regions, seismic waves indicate an abrupt 5 to 10% decrease in wave speeds between 35 and 120 km depth, forming a boundary known as the Gutenberg discontinuity. In many cases, the depth of the Gutenberg discontinuity is roughly coincident with the expected depth of the LAB, leading to the suggestion that the two boundaries are closely inter-related.
However, temperature alone cannot fully explain the abrupt change in the mechanical and seismic properties that have been observed at the Gutenberg discontinuity. This has led many scientists to suggest that other factors--such as the presence of molten rock, water, and/or a decrease in the grain size of minerals--may also play important roles.
Older techniques made imaging seismic discontinuities shallower than 100 kilometers quite difficult, and regions beneath the oceans could only be accessed where seismic stations were installed on ocean islands or by deploying ocean bottom seismometers, giving an incomplete picture of where the Gutenberg occurs beneath the Pacific Ocean.
But an innovative observation technique -- one that incorporates seismic waves that sample beneath remote regions of Earth at higher frequencies, and new signal processing techniques--enabled Schmerr to hone in on the Gutenberg discontinuity.......
Certain personality traits may have biological base, as opposed to pure mental one: "...A personality profile marked by overly gregarious yet anxious behavior
is rooted in abnormal development of a circuit hub buried deep in the
front center of the brain, say scientists at the National Institutes of
Health. They used three different types of brain imaging to pinpoint the
suspect brain area in people with Williams syndrome, a rare genetic
disorder characterized by these behaviors. Matching the scans to scores
on a personality rating scale revealed that the more an individual with
Williams syndrome showed these personality/temperament traits, the more
abnormalities there were in the brain structure, called the insula....
"Scans of the brain's tissue composition, wiring, and activity produced
converging evidence of genetically-caused abnormalities in the structure
and function of the front part of the insula and in its connectivity to
other brain areas in the circuit," explained Karen Berman, M.D., of the
NIH's National Institute of Mental Health (NIMH).
... Evidence suggests that genes influence our temperament and the
development of mental disorders via effects on brain circuits that
regulate behavior. Yet direct demonstration of this in humans has proven
elusive. Since the genetic basis of Williams syndrome is well known, it
offers a unique opportunity to explore such effects with neuroimaging,
reasoned the researchers...." http://www.medicalnewstoday.com/releases/243165.php
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Topic: Science and Nature News Redux
