Scientists at Emory's Yerkes National Primate Research Center have achieved some insight into how fleeting experiences become memories in the brain. Their experimental system could be a way to test or refine treatments aimed at enhancing learning and memory, or interfering with troubling memories. The results were published in the Journal of Neuroscience. The researchers set up a system where rats were exposed to a light followed by a mild shock. A single light-shock event isn't enough to make the rat afraid of the light, but a repeat of the pairing of the light and shock is, even a few days later. "I describe this effect as 'priming'," says the first author of the paper, postdoctoral fellow Ryan Parsons. "The animal experiences all sorts of things, and has to sort out what's important. If something happens just once, it doesn't register. But twice, and the animal remembers." Parsons worked with Michael Davis, Robert W. Woodruff professor of psychiatry and behavioral sciences at Emory's School of Medicine, who studies the molecular basis for fear memory. Even though a robust fear memory was not formed after the first priming event, at that point Parsons could already detect chemical changes in the amygdala, part of the brain critical for fear responses. Long-term memory formation could be blocked by infusing a drug into the amygdala. The drug inhibits protein kinase A, which is involved in the chemical changes Parsons observed. It is possible to train rats to become afraid of something like a sound or a smell after one event, Parsons says. However, rats are less sensitive to light compared with sounds or smells, and a relatively mild shock was used. Fear memories only formed when shocks were paired with light, instead of noise or nothing at all, for both the priming and the confirmation event. Parsons measured how afraid the rats were by gauging their "acoustic startle response" (how jittery they were in response to a loud noise) in the presence of the light, compared to before training began. Scientists have been able to study the chemical changes connected with the priming process extensively in neurons in culture dishes, but not as much in live animals. The process is referred to as "metaplasticity," or how the history of the brain's experiences affects its readiness to change and learn. "This could be a good model for dissecting the mechanisms involved in learning and memory," Parsons says. "We're going to be able to look at what's going on in that first priming event, as well as when the long-term memory is triggered." The research was supported by the National Institute of Mental Health Source: eScienceCommons
How rats are 'primed' to remember fear
Scientists at Emory's Yerkes National Primate Research Center have achieved some insight into how fleeting experiences become memories in the brain. Their experimental system could be a way to test or refine treatments aimed at enhancing learning and memory, or interfering with troubling memories. The results were published in the Journal of Neuroscience. The researchers set up a system where rats were exposed to a light followed by a mild shock. A single light-shock event isn't enough to make the rat afraid of the light, but a repeat of the pairing of the light and shock is, even a few days later. "I describe this effect as 'priming'," says the first author of the paper, postdoctoral fellow Ryan Parsons. "The animal experiences all sorts of things, and has to sort out what's important. If something happens just once, it doesn't register. But twice, and the animal remembers." Parsons worked with Michael Davis, Robert W. Woodruff professor of psychiatry and behavioral sciences at Emory's School of Medicine, who studies the molecular basis for fear memory. Even though a robust fear memory was not formed after the first priming event, at that point Parsons could already detect chemical changes in the amygdala, part of the brain critical for fear responses. Long-term memory formation could be blocked by infusing a drug into the amygdala. The drug inhibits protein kinase A, which is involved in the chemical changes Parsons observed. It is possible to train rats to become afraid of something like a sound or a smell after one event, Parsons says. However, rats are less sensitive to light compared with sounds or smells, and a relatively mild shock was used. Fear memories only formed when shocks were paired with light, instead of noise or nothing at all, for both the priming and the confirmation event. Parsons measured how afraid the rats were by gauging their "acoustic startle response" (how jittery they were in response to a loud noise) in the presence of the light, compared to before training began. Scientists have been able to study the chemical changes connected with the priming process extensively in neurons in culture dishes, but not as much in live animals. The process is referred to as "metaplasticity," or how the history of the brain's experiences affects its readiness to change and learn. "This could be a good model for dissecting the mechanisms involved in learning and memory," Parsons says. "We're going to be able to look at what's going on in that first priming event, as well as when the long-term memory is triggered." The research was supported by the National Institute of Mental Health Source: eScienceCommons
The 2012 Transit of Venus
It won't happen again until December 2117. On June 5th, 2012, Venus will transit the face of the sun in an event of both historical and observational importance. The best places to watch are in the south Pacific, but travel is not required. The event will also be visible around sunset from the USA. Credit: Science@NASA On June 5th, 2012, Venus will pass across the face of the sun, producing a silhouette that no one alive today will likely see again. Transits of Venus are very rare, coming in pairs separated by more than a hundred years. This June's transit, the bookend of a 2004-2012 pair, won't be repeated until the year 2117. Fortunately, the event is widely visible. Observers on seven continents, even a sliver of Antarctica, will be in position to see it. The nearly 7-hour transit begins at 3:09 pm Pacific Daylight Time (22:09 UT) on June 5th. The timing favors observers in the mid-Pacific where the sun is high overhead during the crossing. In the USA, the transit will be at its best around sunset. That's good, too. Creative photographers will have a field day imaging the swollen red sun "punctured" by the circular disk of Venus. Observing tip: Do not stare at the sun. Venus covers too little of the solar disk to block the blinding glare. Instead, use some type of projection technique or a solar filter. A #14 welder's glass is a good choice. Many astronomy clubs will have solar telescopes set up to observe the event; contact your local club for details. Transits of Venus first gained worldwide attention in the 18th century. In those days, the size of the solar system was one of the biggest mysteries of science. The relative spacing of planets was known, but not their absolute distances. How many miles would you have to travel to reach another world? The answer was as mysterious then as the nature of dark energy is now. Venus was the key, according to astronomer Edmund Halley. He realized that by observing transits from widely-spaced
Image above: A double transit: the International Space Station and Venus on June 8, 2004. Photo courtesy of Tomas Maruska.
locations on Earth it should be possible to triangulate the distance to Venus using the principles of parallax. The idea galvanized scientists who set off on expeditions around the world to view a pair of transits in the 1760s. The great explorer James Cook himself was dispatched to observe one from Tahiti, a place as alien to 18th-century Europeans as the Moon or Mars might seem to us now. Some historians have called the international effort the "the Apollo program of the 18th century." In retrospect, the experiment falls into the category of things that sound better than they actually are. Bad weather, primitive optics, and the natural "fuzziness" of Venus’s atmosphere and other factors prevented those early observers from gathering the data they needed. Proper timing of a transit would have to wait for the invention of photography in the century after Cook’s voyage. In the late 1800s, astronomers armed with cameras finally measured the size of the Solar System as Edmund Halley had suggested. This year’s transit is the second of an 8-year pair. Anticipation was high in June 2004 as Venus approached the sun. No one alive at the time had seen a Transit of Venus with their own eyes, and the hand-drawn sketches
and grainy photos of previous centuries scarcely prepared them for what was about to happen. Modern solar telescopes captured unprecedented view of Venus’s atmosphere backlit by solar fire. They saw Venus transiting the sun’s ghostly corona, and gliding past magnetic filaments big enough to swallow the planet whole. 2012 should be even better as cameras and solar telescopes have improved. Moreover, NASA’s Solar Dynamics Observatory is going to be watching too. SDO will produce Hubble-quality images of this rare event. World visibility map for June 5-6, 2012 Venus Transit. Credit: M. Zeiler. (Click on the image for enlarge) Images (mentioned), Video (mentioned), Text, Credit: NASA / Dr. Tony Phillips. Cheers, Orbiter.ch, Source: Orbiter.ch Space News: The 2012 Transit of Venus
Gravitational waves detected for the first time
Credits: R. Hurt/Caltech-JPL
In a historical scientific landmark, researchers have announced the first detection of gravitational waves, as predicted by Einstein's general theory of relativity 100 years ago. This major discovery opens a new era of astronomy.
For the first time, scientists have directly observed "ripples" in the fabric of spacetime called gravitational waves, arriving at the Earth from a cataclysmic event in the distant universe. This confirms a major prediction of Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos. The observation was made at 09:50:45 GMT on 14th September 2015, when two black holes collided. However, given the enormous distance involved and the time required for light to reach us, this event actually occurred some 1.3 billion years ago, during the mid-Proterozoic Eon. For context, this is so far back that multicellular life here on Earth was only just beginning to spread. The signal came from the Southern Celestial Hemisphere, in the rough direction of (but much further away than) the Magellanic Clouds. The two black holes were spinning together as a binary pair, turning around each other several tens of times a second, until they eventually collided at half the speed of light. These objects were 36 and 29 times the mass of our Sun. As their event horizons merged, they became one – like two soap bubbles in a bath. During the fraction of a second that this happened, three solar masses were converted to gravitational waves, and for a brief instant the event hit a peak power output 50 times
The gravitational waves were detected by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. The discovery was published yesterday in the journal Physical Review Letters.
that of the entire visible universe. Prof. Stephen Hawking told BBC News: "Gravitational waves provide a completely new way of looking at the Universe. The ability to detect them has the potential to revolutionise astronomy. This discovery is the first detection of a black hole binary system and the first observation of black holes merging. Apart from testing General Relativity, we could hope to see black holes through the history of the Universe. We may even see relics of the very early Universe during the Big Bang at some of the most extreme energies possible." "There is a Nobel Prize in it – there is no doubt," said Prof. Karsten Danzmann, from the Max Planck Institute for Gravitational Physics and Leibniz University in Hannover, Germany, who collaborated on the study. In an interview with the BBC, he claimed the significance of this discovery is on a par with the determination of the structure of DNA. "It is the first ever direct detection of gravitational waves; it's the first ever direct detection of black holes and it is a confirmation of General Relativity because the property of these black holes agrees exactly with what Einstein predicted almost exactly 100 years ago." "We found a beautiful signature of the merger of two black holes and it agrees exactly – fantastically – with the numerical solutions to Einstein equations ...
LIGO measurement of gravitational waves at the Hanford (left) and Livingston (right) detectors, compared to the theoretical predicted values.By Abbott et al. [CC BY 3.0]
it looked too beautiful to be true." "Scientists have been looking for gravitational waves for decades – but we’ve only now been able to achieve the incredibly precise technologies needed to pick up these very, very faint echoes from across the universe," said Danzmann. "This discovery would not have been possible without the efforts and the technologies developed by the Max Planck, Leibniz Universität, and UK scientists working in the GEO collaboration." Researchers at the LIGO Observatories were able to measure tiny and subtle disturbances the waves made to space and time as they passed through the Earth, with machines detecting changes just fractions of the width of an atom. At each observatory, the two-and-a-half-mile (4-km) long L-shaped LIGO interferometer uses laser light split into two beams that travel back and forth along tubes kept at a near-perfect vacuum. The beams are used to monitor the distance between mirrors precisely positioned at the ends of the arms. According to Einstein’s theory, the distance between the mirrors will change by an infinitesimal amount when gravitational waves pass by the detector. A change in the lengths of the arms smaller than one-ten-thousandth the diameter of a proton can be detected; equivalent to a human hair's diameter over three light years from Earth. "The Advanced LIGO detectors are a tour de force of science and technology, made possible by a truly exceptional international team of technicians, engineers, and scientists," says David Shoemaker of MIT. "We are very proud that we finished this NSF-funded project on time and on budget." "We spent years modelling the gravitational-wave emission from one of the most extreme events in the universe: pairs of massive black holes orbiting with each other and then merging. And that’s exactly the kind of signal we detected!" says Prof. Alessandra Buonanno, director at the Max Planck Institute for Gravitational Physics in Potsdam. "With this discovery, we humans are embarking on a marvellous new quest: the quest to explore the warped side of the universe – objects and phenomena that are made from warped spacetime," says Kip Thorne, Feynman Professor of Theoretical Physics at Caltech. "Colliding black holes and gravitational waves are our first beautiful examples." Advanced LIGO is among the most sensitive instruments ever built. During its next observing stage, it is expected to detect five more black hole mergers and to detect around 40 binary star mergers each year, in addition to an unknown number of more exotic gravitational wave sources, some of which may not be anticipated by current theory. Source: Futurtimeline.net
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