Science News

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An international team of astronomers has looked at something very big -- a distant galaxy -- to study the behavior of things very small -- atoms and molecules -- to gain vital clues about the fundamental nature of our entire Universe. The team used the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) to test whether the laws of nature have changed over vast spans of cosmic time. http://hypography.com/gallery/files/9/9/8/gbt_thumb.jpg"The fundamental constants of physics are expected to remain fixed across space and time; that's why they're called constants! Now, however, new theoretical models for the basic structure of matter indicate that they may change. We're testing these predictions." said Nissim Kanekar, an astronomer at the National Radio Astronomy Observatory (NRAO), in Socorro, New Mexico. So far, the scientists' measurements show no change in the constants. "We've put the most stringent limits yet on some changes in these constants, but that's not the end of the story," said Christopher Carilli, another NRAO astronomer. "This is the exciting frontier where astronomy meets particle physics," Carilli explained. The research can help answer fundamental questions about whether the basic components of matter are tiny particles or tiny vibrating strings, how many dimensions the Universe has, and the nature of "dark energy." The astronomers were looking for changes in two quantities: the ratio of the masses of the electron and the proton, and a number physicists call the fine structure constant, a combination of the electron charge, the speed of light and the Planck constant. These values, considered fundamental physical constants, once were "taken as time independent, with values given once and forever" said German particle physicist Christof Wetterich. However, Wetterich explained, "the viewpoint of modern particle theory has changed in recent years," with ideas such as superstring theory and extra dimensions in spacetime calling for the "constants" to change over time, he said. The astronomers used the GBT to detect and study radio emissions at four specific frequencies between 1612 MHz and 1720 MHz coming from hydroxyl (OH) molecules in a galaxy more than 6 billion light-years from Earth, seen as it was at roughly half the Universe's current age. Each of the four frequencies represents a specific change in the energy level of the molecule. The exact frequency emitted or absorbed when the molecule undergoes a transition from one energy level to another depends on the values of the fundamental physical constants. However, each of the four frequencies studied in the OH molecule will react differently to a change in the constants. That difference is what the astronomers sought to detect using the GBT, which, Kanekar explained, is the ideal telescope for this work because of its technical capabilities and its location in the National Radio Quiet Zone, where radio interference is at a minimum. "We can place very tight limits on changes in the physical constants by studying the behavior of these OH molecules at a time when the Universe was only about half its current age, and comparing this result to how the molecules behave today in the laboratory," said Karl Menten of the Max-Planck Institute for Radioastronomy in Germany. Wetterich, a theorist, welcomes the new capability, saying the observational method "seems very promising to obtain perhaps the most accurate values for such possible time changes of the constants." He pointed out that, while some theoretical models call for the constants to change only in the early moments after the Big Bang, models of the recently-discovered, mysterious "dark energy" that seems to be accelerating the Universe's expansion call for changes "even in the last couple of billion years." "Only observations can tell," he said. This research ties together the theoretical and observational work of Wetterich and Carilli, this year's winners of the prestigious Max Planck Research Award of the Alexander von Humboldt Foundation and the Max Planck Society in Germany. Menten and Carilli have collaborated on research in this area for years, and Kanekar has pioneered the OH molecular technique. Kanekar, Carilli and Menten worked with Glen Langston of NRAO, Graca Rocha of the Cavendish Laboratory in the UK, Francoise Combes of the Paris Observatory, Ravi Subrahmanyan of the Australia Telescope National Facility (ATNF), John Stocke of the University of Colorado, Frank Briggs of the ATNF and the Australian National University, and Tommy Wiklind of the Space Telescope Science Institute in Sweden. The scientists reported their findings in the December 31 edition of the scientific journal Physical Review Letters. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. Source: National Radio Astronomy Observatory

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Nuclear physicists have created an isotope of silicon that contains twice as many neutrons as protons. Measurements made with silicon-42 - which contains 14 protons and 28 neutrons - will shed new light on the concept of "magic numbers" in nuclei (Nature 435 922). http://hypography.com/gallery/files/9/9/8/atomic.jpgMost nuclei contain similar numbers of neutrons and protons, or more neutrons than protons. However, if an isotope of a given element contains too few or too many neutrons it will not be stable. The nuclear shell model, which was first proposed in 1949, explains that nuclei with certain magic numbers of neutrons and/or protons are especially stable because the neutrons and/or protons form closed shells. Nuclei that contain magic numbers of both protons and neutrons are even more stable and are said to be "doubly magic". The magic numbers are 2, 8, 20, 28, 50 and 82. However, it had been thought that highly unstable nuclei would have magic numbers that were different from those found in their more stable counterparts. To investigate this, Paul Cottle and colleagues at Florida State University, Michigan State University, the Lawrence Berkeley National Laboratory and Surrey University in the UK decided to study the silicon-42 nucleus, which has 12 neutrons more than silicon-30, the heaviest stable isotope of the element, and six protons fewer than calcium-48, the lightest stable nucleus to contain 28 neutrons. "The surprise for us was that the magic number for protons in silicon-42, and also the full shell structure, are the same as in calcium-48," Cottle told PhysicsWeb. "Silicon-42 is very close to the limit of nuclear existence - the heaviest silicon isotope ever observed is silicon-43 - and we anticipated significant changes in proton shell structure from calcium-48." Cottle and colleagues produced the silicon-42 nuclei by crashing sulphur-44 nuclei into a beryllium target at the National Superconducting Cyclotron Lab (NSCL) at Michigan State University. The experiment was made possible by the Coupled Cyclotrons Facility at Michigan, which produces the most intense beams of short-lived nuclei, like sulphur-44, that are available anywhere. The experiments also relied on the use of fast-beam "knockout" reactions, pioneered by Gregers Hansen of the NSCL and Jeffrey Tostevin of Surrey, to eject two protons from the sulphur-44 nuclei to produce silicon-42. The results show that the silicon-42 nucleus remains stable despite containing a large excess of neutrons. The data also suggest that the proton number 14 is semi-magic because it corresponds to a closed subshell, which means that the nucleus is also spherical. Source: Physics Web

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A team of astronomers working in Canada, France and the United States have discovered an unusual small body orbiting the Sun beyond Neptune, in the region astronomers call the Kuiper belt. This new object is twice as far from the Sun as Neptune and is roughly half the size of Pluto. The body's highly unusual orbit is difficult to explain using previous theories of the formation of the outer Solar System. http://hypography.com/gallery/files/9/9/8/4b7orb_thumb.gifhttp://hypography.com/gallery/files/9/9/8/4b7inc_thumb.gifCurrently 58 astronomical units from the Sun (1 astronomical unit, or AU, is the distance between the Earth and the Sun), the new object never approaches closer than 50 AU, because its orbit is close to circular. Almost all Kuiper belt objects discovered beyond Neptune are between 30 AU and 50 AU away. Beyond 50 AU, the main Kuiper belt appears to end, and what few objects have been discovered beyond this distance have all been on very high eccentricity (non-circular) orbits. Most of these high-eccentricity orbits are the result of Neptune "flinging" the object outward by a gravitational slingshot. However, because this new object does not approach closer than 50 AU, a different theory is needed to explain its orbit. Complicating the problem, the object's orbit also has an extreme tilt, being inclined (tilted) at 47 degrees to the rest of the Solar System. The Discovery and Follow-up The object, which received the official designation 2004 XR 190 in the International Astronomical Union's official announcement, was discovered during routine operation of the Canada-France Ecliptic Plane Survey (CFEPS) running as part of the Legacy Survey on the Canada France Hawaii Telescope. For now, the discoverers are using the temporary nickname "Buffy" to identify the new object, although they have proposed a different official name in keeping with normal procedures for naming such objects. Buffy was extracted from the mountain of Legacy Survey data (about 50 gigabytes per hour of operation) by powerful computers combing through the telescopic images and producing hundreds of candidates. Astronomers then sift through the candidates to identify the distant comets. Astronomer Lynne Allen of the University of British Columbia was the first to lay eyes on the new object, as she completed the initial identification in the course of processing CFEPS data from December 2004. "It was quite bright compared to the usual Kuiper belt objects we find", said Dr. Allen, "but what was more interesting was how far away it was." The object's brightness implies it is likely between 500 and 1000 kilometers (300 to 600 miles) in diameter. Buffy is thus a very large Kuiper belt object, but about half a dozen are larger. "We immediately realized that the object was about twice as far as Neptune from the Sun and that its orbit was potentially nearly circular," said UBC professor Brett Gladman, who noticed the unusual nature of the object when determining its orbit, "but further observations were required." One to two years of observations of a Kuiper belt object are required before their orbits can be precisely measured. The first additional observations of Buffy came in October 2005 when Gladman and Phil Nicholson of Cornell University used the Hale 5-meter telescope to re-observe the object. Measurement of Buffy's new position proved that the orbit was not only extremely tilted, inclined (tilted) at 47 degrees to the plane of the planetary system (essentially tying the record for a Kuiper belt object) but confirmed that Buffy was unlike any other previously-known object because it was on a nearly circular orbit while at a very large distance. More measurements of Buffy's position on images from telescopes at Kitt Peak National Observatories in Arizona by team members Joel Parker (Southwest Research Institute), as well as JJ Kavelaars (National Research Council of Canada, Herzberg Institute of Astrophysics) and Wes Fraser (University of Victoria), through November 2005 refined the estimate for Buffy's closest approach to the Sun. Additional observations, to further confirm the orbit, where then provided by the CFHT Legacy Survey project. Astronomers will need to wait until February 2006 to measure the fine details of the Buffy's orbit. The team have reported their find to the Minor Planet Center, the clearinghouse for astronomical measurements of new minor planets. "To find the first known object with a nearly circular orbit beyond 50 AU is indeed intriguing," reacted Brian Marsden, director of the MPC. Challenging Theories Although it is neither the smallest, largest, nor most distant object discovered in this region, the new Kuiper belt object has a highly unusual orbit which challenges theories of the evolution of the Solar System. Why is Buffy's orbit considered so unusual? Only one other detected object, Sedna, remains further than 50 astronomical units (AUs) from the Sun throughout its entire orbit. However, Sedna is on a very elliptical orbit, swooping in to 76 AU before traveling back out beyond 900 AU. In contrast, Buffy spends all of its time in the narrow range between 52 and 62 AU from the Sun. Combined with the tilt in its orbit, this new object challenges current theories about the history of the early Solar System. Astronomers have detected other Kuiper belt objects that spend most of their time beyond 50 AU. These are on very elliptical orbits, and almost all approach within 38 AU of the Sun. That close approach places those objects within the reach of the gravitational influence of Neptune. These objects are generally thought to have been scattered out to their present orbits by a gravitational slingshot with Neptune. This group of objects was thus called the "Scattered Disk". Prior to the discovery of Buffy, a few other Kuiper belt objects were discovered which spend much of their time beyond 50 AU like those in the "Scattered Disk", yet did not approach within the gravitational reach of Neptune. This group has been named the "Extended Scattered Disk". Two of its members are 1995 TL8 and 2000 YW134, which approach to 40 AU of the Sun but have fairly elliptical orbits that take them back out beyond 60 AU. Two more extreme examples of the "Extended Scattered Disk" are 2000 CR105, which approaches to 44 AU, and Sedna, which never comes closer to the Sun than 76 AU. Due to their large eccentricities, these objects are likely to have been strongly perturbed by something, although it could not have been Neptune because they do not come close enough to be scattered by that planet's gravitational force. As both Sedna and 2000 CR105 also travel beyond 500 AU from the sun, one theory is that after being scattered by Neptune, a passing star could have pulled their closest approaches away from the Sun. Buffy is clearly a member of the "Extended Scattered Disk". However, Buffy's almost circular orbit makes it stand out from the other members. In addition, Buffy's large orbital tilt is not so easily explained by the passing star idea. If a star could have affected Buffy so strongly, it should also have disrupted much of the main Kuiper belt as well. Since astronomers do not detect that strong disruption, a more complex theory is needed to explain Buffy's orbit. The elusive explanation may lie in side-effects from rearrangements of the Solar System early in its history. One possibility is that as Neptune's orbit slowly expanded in the young Solar System, complex gravitational interactions could have caused some Kuiper belt orbits to circularize and tilt. While Buffy's orbit could have been created this way, this theory would not seem to explain 2000 CR105 and Sedna. This new discovery is exciting because it causes us to rethink our understanding of how the Kuiper belt formed. The Future Over the last half decade, theories about the formation of our outer Solar System have been pushed to their limits: unusual Kuiper belt objects, like Buffy, which never come close to Neptune yet have high inclination must be explained. Although theories that explain individual objects exist, reproducing the entire ensemble of known objects with one process poses a difficult challenge to current solar system models. Because the unusual objects, like Buffy, are very rare, astronomers are still scratching the surface of the dark corners of the Kuiper belt. Future large-scale surveys that systematically explore the Kuiper belt are the only way unlock the mysteries of what happened early in the history of our Solar System. Source: The Canada France Ecliptic Plane Survey

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Animal behaviorist Sean O'Donnell was having an afternoon cup of coffee when a giant earthworm exploded out of the leaf litter covering the jungle floor in an Ecuadorean nature preserve. The worm, later measured at nearly 16 inches long, was pursued by a column of hundreds of raiding army ants that quickly paralyzed or killed it. http://hypography.com/gallery/files/9/9/8/cheliomyrmex_thumb.jpgThat sighting, and another involving what turned out to be the same species of army ant feeding on the carcass of a snake, has led O'Donnell of the University of Washington and several colleagues to offer a new theory on the origin of cooperative hunting behavior in army ants, which are among the most socially complex animals known. Writing in the current issue of the journal Biotropica, O'Donnell and biologists Michael Kaspari of the University of Oklahoma and John Lattke of Universidad Central de Venezuela, propose that mass cooperative food foraging, a key element in the behavior of army ants, may have begun as a way to subdue large prey. The species that O'Donnell observed is called Cheliomyrmex andicola and it lives mainly underground in New World tropical rainforests. It had been previously identified, but little was known about its behavior or prey until the two chance encounters at the Tiputini Biodiversity Station, an ecological preserve in eastern Ecuador. The ants are brick red in color and their size would be considered medium or large when compared to most common ant species found in United States. What makes Cheliomyrmex such a fearsome predator is that its workers have claw-shaped jaws that are armed with long, spine-like teeth. These teeth may serve to help Cheliomyrmex workers attach themselves to their prey's skin during attack O'Donnell, who was bitten and stung when he collected Cheliomyrmex specimens, said the ants' stings were particularly painful and itchy, comparable to the stings of fire ants. He and his colleagues believe the venom in a Cheliomyrmex sting is toxic and/or paralytic, considering how quickly the giant earthworm became immobile after being attacked. The researchers said the species is apparently unique among New World army ants in removing and consuming vertebrate flesh, based on the observation of the ants feeding on the dead snake. They noted that raiding parties of other New World army ants occasionally sting and kill small vertebrates such as lizards, snakes and birds, but do usually not consume them. Other New World army ants prey heavily on insects and other invertebrates. O'Donnell said Cheliomyrmex is related to Old World driver ants in Africa, which also have large-toothed jaws and feed on large-bodied prey. The ancestor of Cheliomyrmex may have split from Old World army ants as long as 105 million years ago, at around the time when Africa and South America separated during the breakup of the giant continent Gondwana. "Cheliomyrmex may be telling us that cooperative hunting of large prey is an evolutionary predecessor of going after smaller prey," said O'Donnell. "Typically, army ants follow a lifestyle of attacking other social insect colonies. But Cheliomyrmex is not following this lifestyle." The discovery of Cheliomyrmex 's predation was part of a larger project to sample the number of army ant species and their activity at four New World tropical rainforest sites in Costa Rica, Panama, Venezuela and Ecuador. The research was funded by the National Geographic Society. Source: University of Washington

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Physicists have managed to "entangle" the physical state of a group of atoms with that of another group of atoms across the room. This research represents an important advance relevant to the foundations of quantum mechanics and to quantum information science, including the possibility of scalable quantum networks (i.e., a quantum Internet) in the future. Reporting in the December 8 issue of the journal Nature, California Institute of Technology physicist H. Jeff Kimble and his colleagues announce the first realization of entanglement for one "spin excitation" stored jointly between two samples of atoms. In the Caltech experiment, the atomic ensembles are located in a pair of apparatuses 2.8 meters apart, with each ensemble composed of about 100,000 individual atoms. The entanglement generated by the Caltech researchers consisted of a quantum state for which, when one quantum spin (i.e., one quantum bit) flipped for the atoms at the site L of one ensemble, invariably none flipped at the site R of the other ensemble, and when one spin flipped at R, invariably none flipped at L. Yet, remarkably, because of the entanglement, both possibilities existed simultaneously. According to Kimble, who is the Valentine Professor and professor of physics at Caltech, this research significantly extends laboratory capabilities for entanglement generation, with now-entangled "quantum bits" of matter stored with separation several thousand times greater than was heretofore possible. Moreover the experiment provides the first example of an entangled state stored in a quantum memory that can be transferred from the memory to another physical system (in this case, from matter to light). Since the work of Schrödinger and Einstein in the 1930s, entanglement has remained one of the most profound aspects and persistent mysteries of quantum theory. Entanglement leads to strong correlations between the various components of a physical system, even if those components are very far apart. Such correlations cannot be explained by classical physics and have been the subject of active experimental investigation for more than 40 years, including pioneering demonstrations that used entangled states of photons, carried out by John Clauser (son of Caltech's Millikan Professor of Engineering, Emeritus, Francis Clauser). In more recent times, entangled quantum states have emerged as a critical resource for enabling tasks in information science that are otherwise impossible in the classical realm of conventional information processing and distribution. Some tasks in quantum information science (for instance, the implementation of scalable quantum networks) require that entangled states be stored in massive particles, which was first accomplished for trapped ions separated by a few hundred micrometers in experiments at the National Institute of Standards and Technology in Boulder, Colorado, in 1998. In the Caltech experiment, the entanglement involves "collective atomic spin excitations." To generate such excitations, an ensemble of cold atoms initially all in level "a" of two possible ground levels is addressed with a suitable "writing" laser pulse. For weak excitation with the write laser, one atom in the sample is sometimes transferred to ground level "b," thereby emitting a photon. Because of the impossibility of determining which particular atom emitted the photon, detection of this first write photon projects the ensemble of atoms into a state with a single collective spin excitation distributed over all the atoms. The presence (one atom in state b) or absence (all atoms in state a) of this symmetrized spin excitation behaves as a single quantum bit. To generate entanglement between spatially separated ensembles at sites L and R, the write fields emitted at both locations are combined together in a fashion that erases any information about their origin. Under this condition, if a photon is detected, it is impossible in principle to determine from which ensemble's L or R it came, so that both possibilities must be included in the subsequent description of the quantum state of the ensembles. The resulting quantum state is an entangled state with "1" stored in the L ensemble and "0" in the R ensemble, and vice versa. That is, there exist simultaneously the complimentary possibilities for one spin excitation to be present in level b at site L ("1") and all atoms in the ground level a at site R ("0"), as well as for no spin excitations to be present in level b at site L ("0") and one excitation to be present at site R ("1"). This entangled state can be stored in the atoms for a programmable time, and then transferred into propagating light fields, which had not been possible before now. The Caltech researchers devised a method to determine unambiguously the presence of entanglement for the propagating light fields, and hence for the atomic ensembles. The Caltech experiment confirms for the first time experimentally that entanglement between two independent, remote, massive quantum objects can be created by quantum interference in the detection of a photon emitted by one of the objects. In addition to Kimble, the other authors are Chin-Wen Chou, a graduate student in physics; Hugues de Riedmatten, Daniel Felinto, and Sergey Polyakov, all postdoctoral scholars in Kimble's group; and Steven J. van Enk of Bell Labs, Lucent Technologies. Source: CalTech

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More than half of the largest galaxies in the nearby universe have collided and merged with another galaxy in the past two billion years, according to a new study using hundreds of images from two of the deepest sky surveys ever conducted. http://hypography.com/gallery/files/9/9/8/mergers_thumb.jpgThe idea of large galaxies being assembled primarily by mergers rather than evolving by themselves in isolation has grown to dominate cosmological thinking. However, a troubling inconsistency within this general theory has been that the most massive galaxies appear to be the oldest, leaving minimal time since the Big Bang for the mergers to have occurred. "Our study found these common massive galaxies do form by mergers. It is just that the mergers happen quickly, and the features that reveal the mergers are very faint and therefore difficult to detect," says Pieter van Dokkum of Yale University, lead author of the paper in the December 2005 issue of the Astronomical Journal. The paper uses two recent deep surveys done with the National Science Foundation’s 4-meter telescopes at Kitt Peak National Observatory and Cerro Tololo Inter-American Observatory, known as the NOAO Deep Wide-Field Survey and the Multiwavelength Survey by Yale/Chile. Together, these surveys covered an area of the sky 50 times larger than the size of the full Moon. "We needed data that are very deep over a very wide area to provide statistically meaningful evidence," van Dokkum explains. "As happens so often in science, fresh observations helped inform new conclusions." Van Dokkum used images from the two surveys to look for telltale tidal features around 126 nearby red galaxies, a color selection biased to select the most massive galaxies in the local universe. These faint tidal features turn out to be quite common, with 53 percent of the galaxies showing tails, broad fans of stars trailing behind them or other obvious asymmetries. "This implies that there is a galaxy that has endured a major collision and subsequent merger event for every single other ‘normal’ undisturbed field galaxy," van Dokkum notes. "Remarkably, the collisions that precede the mergers are still ongoing in many cases. This allows us to study galaxies before, during, and after the collisions." Though there are not many direct star-to-star encounters in this merger process, such galaxy collisions can have profound effects on star formation rates and the shape of the resulting galaxy. These mergers do not resemble the spectacular mergers of blue spiral galaxies that are featured in several popular Hubble Space Telescope images. But these red galaxy mergers appear to be much more common. Their ubiquity represents a direct confirmation of predictions by the most common models for the formation of large-scale structure in the Universe, with the added benefit of helping solve the apparent-age problem. "In the past, people equated stellar age with the age of the galaxy," van Dokkum explains. "We have found that, though their stars are generally old, the galaxies that result from these mergers are relatively young." It is not yet understood why the merging process does not lead to enhanced star formation in the colliding galaxies. It may be that massive black holes in the centers of the galaxies provide the energy to heat or expel the gas that needs to be able to cool in order to form new stars. Ongoing detailed study of the newly found mergers will provide better insight into the roles that black holes play in the formation and evolution of galaxies. A series of images of different galaxies in this study that, taken together, represent a time sequence of a typical red galaxy merger, is available above. More information, including an animation of the mergers, is available from Yale University. Based in Tucson, AZ, the National Optical Astronomy Observatory (NOAO) consists of Kitt Peak National Observatory near Tucson, AZ, Cerro Tololo Inter-American Observatory near La Serena, Chile, and the NOAO Gemini Science Center. NOAO is operated by the Association of Universities for Research in Astronomy (AURA) Inc., under a cooperative agreement with the National Science Foundation. Source: National Optical Astronomy Observatory

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Clues revealed by the recently sharpened view of the Hubble Space Telescope have allowed astronomers to map the location of invisible "dark matter" in unprecedented detail in two very young galaxy clusters. http://hypography.com/gallery/files/9/9/8/darkmatter_thumb.jpgA Johns Hopkins University-Space Telescope Science Institute team reports its findings in the December issue of Astrophysical Journal. (Other, less-detailed observations appeared in the January 2005 issue of that publication.) The team's results lend credence to the theory that the galaxies we can see form at the densest regions of "cosmic webs" of invisible dark matter, just as froth gathers on top of ocean waves, said study co-author Myungkook James Jee, assistant research scientist in the Henry A. Rowland Department of Physics and Astronomy in Johns Hopkins' Krieger School of Arts and Sciences. "Advances in computer technology now allow us to simulate the entire universe and to follow the coalescence of matter into stars, galaxies, clusters of galaxies and enormously long filaments of matter from the first hundred thousand years to the present," Jee said. "However, it is very challenging to verify the simulation results observationally, because dark matter does not emit light." Jee said the team measured the subtle gravitational "lensing" apparent in Hubble images - that is, the small distortions of galaxies' shapes caused by gravity from unseen dark matter - to produce its detailed dark matter maps. They conducted their observations in two clusters of galaxies that were forming when the universe was about half its present age. http://hypography.com/gallery/files/9/9/8/darkmat2_thumb.jpg"The images we took show clearly that the cluster galaxies are located at the densest regions of the dark matter haloes, which are rendered in purple in our images," Jee said. The work buttresses the theory that dark matter - which constitutes 90 percent of matter in the universe - and visible matter should coalesce at the same places because gravity pulls them together, Jee said. Concentrations of dark matter should attract visible matter, and as a result, assist in the formation of luminous stars, galaxies and galaxy clusters. Dark matter presents one of the most puzzling problems in modern cosmology. Invisible, yet undoubtedly there - scientists can measure its effects - its exact characteristics remain elusive. Previous attempts to map dark matter in detail with ground-based telescopes were handicapped by turbulence in the Earth's atmosphere, which blurred the resulting images. "Observing through the atmosphere is like trying to see the details of a picture at the bottom of a swimming pool full of waves," said Holland Ford, one of the paper's co-authors and a professor of physics and astronomy at Johns Hopkins. The Johns Hopkins-STScI team was able to overcome the atmospheric obstacle through the use of the space-based Hubble telescope. The installation of the Advanced Camera for Surveys in the Hubble three years ago was an additional boon, increasing the discovery efficiency of the previous HST by a factor of 10. The team concentrated on two galaxy clusters (each containing more than 400 galaxies) in the southern sky. "These images were actually intended mainly to study the galaxies in the clusters, and not the lensing of the background galaxies," said co-author Richard White, a STScI astronomer who also is head of the Hubble data archive for STScI. "But the sharpness and sensitivity of the images made them ideal for this project. That's the real beauty of Hubble images: they will be used for years for new scientific investigations." The result of the team's analysis is a series of vividly detailed, computer-simulated images illustrating the dark matter's location. According to Jee, these images provide researchers with an unprecedented opportunity to infer dark matter's properties. The clumped structure of dark matter around the cluster galaxies is consistent with the current belief that dark matter particles are "collision-less," Jee said. Unlike normal matter particles, physicists believe, they do not collide and scatter like billiard balls but rather simply pass through each other. "Collision-less particles do not bombard one another, the way two hydrogen atoms do. If dark matter particles were collisional, we would observe a much smoother distribution of dark matter, without any small-scale clumpy structures," Jee said. Ford said this study demonstrates that the ACS is uniquely advantageous for gravitational lensing studies and will, over time, substantially enhance understanding of the formation and evolution of the cosmic structure, as well as of dark matter. "I am enormously gratified that the seven years of hard work by so many talented scientists and engineers to make the Advanced Camera for Surveys is providing all of humanity with deeper images and understandings of the origins of our marvelous universe," said Ford, who is principal investigator for ACS and a leader of the science team. The ACS science and engineering team is concentrated at the Johns Hopkins University and the Space Telescope Science Institute on the university's Homewood campus in Baltimore. It also includes scientists from other major universities in the United States and Europe. ACS was developed by the team under NASA contract NAS5-32865 and this research was supported by NASA grant NAG5-7697. Source: John Hopkins University

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One of the most elusive questions in science has finally been answered: How do bees fly? http://hypography.com/gallery//files/9/9/8/bee_thumb.jpgAlthough the issue is not as profound as how the universe began or what kick-started life on earth, the physics of bee flight has perplexed scientists for more than 70 years. In 1934, in fact, French entomologist August Magnan and his assistant André Sainte-Lague calculated that bee flight was aerodynamically impossible. The haphazard flapping of their wings simply shouldn't keep the hefty bugs aloft. And yet, bees most certainly fly, and the dichotomy between prediction and reality has been used for decades to needle scientists and engineers about their inability to explain complex biological processes. Now, Michael H. Dickinson, the Esther M. and Abe M. Zarem Professor of Bioengineering, and his postdoctoral student Douglas L. Altshuler and their colleagues at Caltech and the University of Nevada at Las Vegas, have figured out honeybee flight using a combination of high-speed digital photography, to snap freeze-frame images of bees in motion, and a giant robotic mock-up of a bee wing. The results of their analysis appear in the November 28 issue of the Proceedings of the National Academy of Sciences. "We're no longer allowed to use this story about not understanding bee flight as an example of where science has failed, because it is just not true," Dickinson says. The secret of honeybee flight, the researchers say, is the unconventional combination of short, choppy wing strokes, a rapid rotation of the wing as it flops over and reverses direction, and a very fast wing-beat frequency. "These animals are exploiting some of the most exotic flight mechanisms that are available to insects," says Dickinson. Their furious flapping speed is surprising, Dickinson says, because "generally the smaller the insect the faster it flaps. This is because aerodynamic performance decreases with size, and so to compensate small animals have to flap their wings faster. Mosquitoes flap at a frequency of over 400 beats per second. Birds are more of a whump, because they beat their wings so slowly." Being relatively large insects, bees would be expected to beat their wings rather slowly, and to sweep them across the same wide arc as other flying bugs (whose wings cover nearly half a circle). They do neither. Their wings beat over a short arc of about 90 degrees, but ridiculously fast, at around 230 beats per second. Fruit flies, in comparison, are 80 times smaller than honeybees, but flap their wings only 200 times a second. When bees want to generate more power--for example, when they are carting around a load of nectar or pollen--they increase the arc of their wing strokes, but keep flapping at the same rate. That is also odd, Dickinson says, because "it would be much more aerodynamically efficient if they regulated not how far they flap their wings but how fast " Honeybees' peculiar strategy may have to do with the design of their flight muscles. "Bees have evolved flight muscles that are physiologically very different from those of other insects. One consequence is that the wings have to operate fast and at a constant frequency or the muscle doesn't generate enough power," Dickinson says. "This is one of those cases where you can make a mistake by looking at an animal and assuming that it is perfectly adapted. An alternate hypothesis is that bee ancestors inherited this kind of muscle and now present-day bees must live with its peculiarities," Dickinson says. How honeybees make the best of it may help engineers in the design of flying insect-sized robots: "You can't shrink a 747 wing down to this size and expect it to work, because the aerodynamics are different," he says. "But the way in which bee wings generate forces is directly applicable to these devices." Source: CalTech

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A team of ASU researchers led by Nongjian Tao and Peiming Zhang has developed a new, breakthrough technique for the detection of DNA mutations. http://hypography.com/gallery//files/9/9/8/dna_736334_thumb.jpgTheir results, published in the journal Proceedings of the National Academy of Sciences, demonstrate for the first time, the possibility of directly identifying these mutations, or single nucleotide polymorphisms (SNPs), by means of measuring the electrical conductance of a single DNA molecule. SNPs are buried in the 3 billion DNA bases of the human genome. On average, SNPs occur about once in every 1,000 DNA bases, though not every SNP found will necessarily cause a disease mutation. Cataloging these subtle DNA differences among the populace will aid the ongoing quest to understand and prevent disease. "There is a high demand to track mutations for cancer research or future applications in personalized medicine," said Zhang, an associate research professor of the Center for Single Molecule Biophysics in the Biodesign Institute at ASU. "Currently, the main issue in doing this type of detection is that it is still costly and time consuming." The team's breakthrough relies on an intrinsic physical property of DNA, conductivity, or how well the molecule can carry an electrical current. Depending on the experimental conditions, DNA has been previously shown to act as both a conductor and insulator. "We have developed a technology that allows us to wire single molecules into an electrical circuit," said Tao, professor of electrical engineering in the Ira A. Fulton School of Engineering and also a researcher in the Center for Solid State Electronics Research. "We can now directly read the biological information in a single DNA molecule." Measurement of DNA conductivity first requires wiring the molecule into an electrical circuit. "There are two things required to make a reliable measurement," said Tao. "One is that the DNA has to be tethered between two electrodes and the other is that it should be done in a slightly salty, water environment to minimize any perturbations to the structure of the molecule." Electrical engineering graduate students Joshua Hihath and Bingqian Xu carried out the measurement. "We measure a small current through the molecules using a setup developed in our lab." said Tao. "It's a conceptually simple setup. You just bring two electrodes together, separate them apart, make the measurement and repeat." In the technique, chemical linker groups that form a tight bond with gold electrodes are attached to the ends of DNA. A drop of a DNA solution is then placed between the two electrodes. The DNA sticks to the surface of the electrodes spontaneously. As the tip is pulled away and the two electrodes teased apart, the molecules of DNA are eventually dispersed to the point of measuring the current of a single DNA molecule. For a proof of concept of the potential for measuring SNPs, the group used DNA of 11 or 12 bases in length dissolved in a physiologically relevant saline solution. From one electrode tip, a small current, or bias is used to probe the internal electronic states of DNA. By measuring the conductance, the team was able to understand the sequence information in the DNA and whether there was a mismatch in comparison to a normal DNA sequence. What they found was that just a single base pair mutation in a DNA molecule, such as substituting an A for a G, can cause a significant change in the conductance of the molecule. The measurement is extremely sensitive, as the alteration of a single base in the DNA stack can either increase or decrease the conductivity of a DNA helix, depending on the type of mismatched base. Not only was the group the first measure SNPs in this manner, but they were also the first to make the measurement in a water environment relevant to that found in biological systems. How the current flows through the DNA molecule is still a subject of speculation. "One idea is that there is a tunneling process," said Tao. The DNA has properties which make the electrons easier to tunnel through, just like lowering a hill for a marathon runner. "The other may be a charge-hopping phenomenon, where the electrons get trapped in the DNA and then hop from the electrode to the DNA to the second electrode." The next goal of the research is to make the measurement steps easier and faster through automation, which will allow many different DNA sequences to be analyzed at once. Source: PNAS

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Jets of fine, icy particles streaming from Saturn's moon Enceladus were captured in recent images from NASA's Cassini spacecraft. The images provide unambiguous visual evidence the moon is geologically active. http://hypography.com/gallery/files/5/SSI120605_1_thumb.jpg"For planetary explorers like us, there is little that can compare to the sighting of activity on another solar system body," said Dr. Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, Colo. "This has been a heart-stopper, and surely one of our most thrilling results." The Cassini images clearly show multiple jets emanating from the moon's south polar region. Based on earlier data, scientists strongly suspected these jets arise from warm fractures in the region. The fractures, informally dubbed "tiger stripes," are viewed essentially broadside in the new images. The fainter, extended plume stretches at least 500 kilometers (300 miles) above the surface of Enceladus, which is only 500 kilometers wide. Cassini flew through the plume in July, when it passed a few hundred kilometers above the moon. During that flyby, Cassini's instruments measured the plume's constituent water vapor and icy particles. Imaging team members analyzed images of Enceladus taken earlier this year at similar viewing angles. It was a rigorous effort to demonstrate that earlier apparitions of the plumes, seen as far back as January, were in fact real and not due to imperfections in the camera. The recent images were part of a sequence planned to confirm the presence of the plumes and examine them in finer detail. Imaging team member Dr. Andrew Ingersoll from the California Institute of Technology in Pasadena, said, "I think what we're seeing are ice particles in jets of water vapor that emanate from pressurized vents. To form the particles and carry them aloft, the vapor must have a certain density, and that implies surprisingly warm temperatures for a cold body like Enceladus." Imaging scientists are comparing the new images to earlier Cassini data in hopes of arriving at a more detailed, three-dimensional picture of the plumes and understanding how activity has come about on such a small moon. They are not sure about the precise cause of the moon's unexpected geologic vitality. "In some ways, Enceladus resembles a huge comet," said Dr. Torrence Johnson, imaging team member from NASA's Jet Propulsion Laboratory (JPL) in Pasadena. "Only, in the case of Enceladus, the energy source for the geyser-like activity is believed to be due to internal heating by perhaps radioactivity and tides rather than the sunlight which causes cometary jets." The new data also give yet another indication of how Enceladus keeps supplying material to Saturn's gossamer E ring. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA?s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the U.S., England, France, and Germany. The imaging operations center and team leader (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo. The latest images, including a time sequence showing the plumes, can be found at http://ciclops.org, http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini. Source: EurekAlert

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Scientists using NASA's Chandra X-ray Observatory have discovered evidence of energetic plumes -- particles that extend 300,000 light years into a massive cluster of galaxies. The plumes are due to explosive venting from the vicinity of a supermassive black hole, and they provide dramatic new evidence of the influence a black hole can have over intergalactic distances. http://hypography.com/gallery//files/9/9/8/perseus_thumb.jpg"In relative terms, it is as if a heat source the size of a fingernail affects the behavior of a region the size of Earth," said Andrew Fabian of Cambridge University, U.K. Fabian is lead author of a report on this research that will appear in an upcoming issue of the Monthly Notices of the Royal Astronomical Society. Fabian's group discovered the plumes by studying data from 280 hours (more than 1 million seconds) of Chandra observations of the Perseus cluster, the longest X-ray observation ever taken of a galaxy cluster. The cluster contains thousands of galaxies immersed in a vast cloud of multi-million degree gas with the mass equivalent of trillions of suns. The plumes showed up in the X-ray data as low pressure regions in the hot gas extending outward from the giant galaxy in the center of the cluster. The low gas pressure measured in the plumes is likely the result of the displacement of the gas by bubbles of unseen high-energy particles. The bubbles appear to be generated by high-speed jets blasting away from the vicinity of the giant galaxy's supermassive black hole. Individual bubbles seen in the inner regions expand and merge to create vast plumes at larger distances. "The plumes show that the black hole has been venting for at least 100 million years, and probably much longer," said co-author Jeremy Sanders also of Cambridge University. The venting produces sound waves which heat the gas throughout the inner regions of the cluster and prevent the gas from cooling and making stars at a large rate. This process has slowed the growth of the central galaxy in the cluster, NGC 1275, which is one of the largest galaxies in the universe. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. Source:Chandra X-Ray Observatory

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Planets are everywhere these days. They have been spotted around more than 150 stars, and evidence is growing that they also circle "failed," or miniature, stars called brown dwarfs. Now, astronomers using NASA's Spitzer Space Telescope say they have found what may be planets-in-the-making in the strangest of places -- around a brown dwarf that itself is the size of a planet. http://hypography.com/gallery//files/9/9/8/sig05-022_thumb.jpgThe little brown dwarf, called Cha 110913-773444, is one of the smallest known. At eight times the mass of Jupiter, it is even smaller than several planets around other stars. Yet, this tiny orb might eventually host a tiny solar system. Spitzer's infrared eyes found, swirling around it, a flat disk made up of dust that is thought to gradually clump together to form planets. Spitzer has previously uncovered similar planet-forming disks around other brown dwarfs, but Cha 110913-773444 is the true dwarf of the bunch. "Our goal is to determine the smallest 'sun' with evidence for planet formation," said Dr. Kevin Luhman of Pennsylvania State University, University Park, lead author of a new paper describing the findings in the Dec. 10 issue of Astrophysical Journal Letters. "Here, we have a sun that is so small it is the size of a planet." Brown dwarfs are born like stars, condensing out of thick clouds of gas and dust. But unlike stars, brown dwarfs do not grow large enough to trigger nuclear fusion. They remain relatively cool spheres of gas and dust. Astronomers have become more confident in recent years that brown dwarfs share another trait in common with stars -- planets. The evidence is in the planet-forming disks. Such disks are well-documented around stars, but only recently have they been located in increasing numbers around brown dwarfs. So far, Spitzer has found dozens of disk-sporting brown dwarfs, five of which show the initial stages of the planet-building process. The dust in these five disks is beginning to stick together into what may be the "seeds" of planets. Last year, Luhman and his colleagues used Spitzer to uncover what was then the smallest of brown dwarfs hugged by a disk. At only 15 times the mass of Jupiter, the brown dwarf, called OTS 44, is comparable to the most massive extrasolar planets. Now, the team has again used Spitzer, this time to detect a disk around Cha 110913-773444, which has only about half the mass of OTS 44. The object itself was discovered by Spitzer with the help of NASA's Hubble Space Telescope, the 4-meter Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile, and the Gemini South Observatory, also in Chile. Its cool and dusty disk, however, could be seen by only Spitzer's infrared eyes. The teeny brown dwarf is young at 2 million years old, and lives 500 light-years away in the Chamaeleon constellation. So, what makes this oddball a brown dwarf and not a planet? "There are two camps when it comes to defining planets versus brown dwarfs," said Dr. Giovanni Fazio, a co-author of the new paper from the Harvard-Smithsonian Center for Astrophysics. "Some go by size and others go by how the object formed. For instance, this new object would be called a planet based on its size, but a brown dwarf based on how it formed. The question then becomes what do we call any little bodies that might be born from this disk -- planets or moons?" If one were to call the object a planet, then it would seem Spitzer has discovered its first "moon-forming" disk. But, no matter what the final label may be, one thing is clear: the universe produces some strange solar systems very different from our own. Source: Spitzer

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Alleged footprints of early Americans found in volcanic rock in Mexico are either extremely old - more than 1 million years older than other evidence of human presence in the Western Hemisphere - or not footprints at all, according to a new analysis published this week in Nature. http://hypography.com/gallery//files/9/9/8/footprint_thumb.jpgThe study was conducted by geologists at the Berkeley Geochronology Center and the University of California, Berkeley, as part of an investigative team of geologists and anthropologists from the United States and Mexico. Earlier this year, researchers in England touted these "footprints" as definitive proof that humans were in the Americas much earlier than 11,000 years ago, which is the earliest firm date for human settlements after the first Americans arrived across a northern land-bridge from Asia. These scientists, led by geologist Silvia Gonzalez of Liverpool's John Moores University, dated the volcanic rock at 40,000 years old. They hypothesized that early hunters walked across ash freshly deposited near a lake by volcanoes that are still active in the area around Puebla, Mexico. The so-called footprints, subsequently covered by more ash and inundated by lake waters, eventually turned to rock. But Paul Renne, director of the Berkeley Geochronology Center and an adjunct professor of earth and planetary science at UC Berkeley, and his colleagues in Mexico and at Texas A&M University report in the Dec. 1 issue of Nature a new age for the rock: about 1.3 million years. "You're really only left with two possibilities," Renne said. "One is that they are really old hominids - shockingly old - or they're not footprints." Renne's colleagues are Michael R. Waters, director of the Center for the Study of the First Americans at Texas A&M University; Joaquin Arroyo-Cabrales and Mario Perez-Campa of the Mexican National Institute of Anthropology and History; Patricia Ochoa Castillo of the Mexican National Museum of Anthropology; and UC Berkeley graduate students Joshua M. Feinberg and Kim B. Knight. The Berkeley Geochronology Center, located a block from the UC Berkeley campus, is one of the world's preeminent anthropological dating laboratories. Paleoanthropologist Tim White, professor of integrative biology at UC Berkeley, is familiar with the "so-called footprints" and knows Renne well, frequently collaborating with him in the dating of million-year-old sediments in an area of Ethiopia where White has excavated numerous fossils of human ancestors. He is not surprised at the new finding. "The evidence (the British team) has provided in their arguments that these are footprints is not sufficient to convince me they are footprints," said White, who did not contribute to the new work that Renne's group is reporting in Nature. "The evidence Paul has produced by dating basically means that this argument is over, unless indisputable footprints can be found sealed within the ash." Renne determined the new date using the argon/argon dating technique, which reliably dates rock as young as 2,000 years or as old as 4 billion years. The British-led researchers, however, relied mainly on carbon-14 dates of overlying sediments. Carbon-14 cannot reliably date materials older than about 50,000 years. The idea for another test that, it turns out, throws more cold water on the footprint hypothesis came to Renne one morning in the shower. Many rocks retain evidence of their orientation at the moment they cool in the form of iron oxide grains magnetized in a direction parallel to the Earth's magnetic field at the time of cooling. Because the Earth's field has repeatedly flipped throughout the planet's history, it is possible to date rock based on its magnetic polarity. Feinberg found that the rock grains in the volcanic ash had polarity opposite to the Earth's polarity today. Since the last magnetic pole reversal was 790,000 years ago, the rock must be at least that age. Because the Earth's magnetic polarity changes, on average, every 250,000 years, the argon/argon date is consistent with a time between 1.07 and 1.77 million years ago when the Earth's polarity was opposite to that of today. Moreover, Feinberg found that each individual grain in the rock is magnetized in the same direction, meaning that the rock has not been broken up and reformed since it was deposited. This makes extremely unlikely the possibility that the original ash had been weathered into sand that early humans walked through before the sand was welded into rock again. "Imagine two-millimeter-wide BBs cemented together where they're touching," Feinberg said. "The paleomagnetic data tell us that these things did not move around at all since they were deposited. They haven't been eroded and redeposited anywhere else. They fell while they were still hot, which raises the question of the validity of the footprints. If they were hot, why would anybody be walking on them?" The British researchers, funded by the United Kingdom's Natural Environment Research Council, have promoted their hypothesis widely, most prominently at a July 4, 2005, presentation and press conference at the Royal Society's Summer Science Exhibition 2005 in London. The team, which includes Gonzalez as well as Professor David Huddart from John Moores University, also involves scientists from Bournemouth University, the University of Oxford and the Australian National University. They have yet to publish a peer-reviewed analysis of the footprints. In all, the British team claims to have found 250 footprints - mostly human, but also dog, cat and cloven-hoofed animal prints - in a layer of volcanic ash deposited in a former lake bed now exposed near a reservoir outside Puebla. Its dating techniques returned a date of 40,000 years ago, in contrast to the oldest accepted human fossil from the Americas, an 11,500-year-old skull. This makes the rock "one of the most important areas in the study of early human occupation in the Americas and would support a much earlier human migration than is currently accepted," the team wrote. One of the team members, Matthew Bennett of Bournemouth, was quoted on a Royal Society Web site as saying, "Accounting for the origin of these footprints would require a complete rethink on the timing, route and origin of the first colonization of the Americas." Renne, Knight, Waters and the Mexico City archeologists visited the site at the Toluquilla quarry last year while collecting rocks from another anthropological site across the reservoir. Renne noted that the black, basaltic rock is very tough and is mined in slabs for building. Pre-Columbian Mexicans also constructed buildings from the rock, which they called xalnene, meaning "fine sand" in the Nahuatl language. Today, trucks headed toward the quarry routinely drive across the xalnene tuff in which the alleged footprints are found, and the rock itself is pockmarked with many depressions in addition to the alleged footprints. "They're scattered all over, with no more than two or three in a straight line," which would be expected if someone had walked through the ash, Renne said. If the depressions were footprints, they could not have been made by modern humans, he noted, since even in Africa, Homo sapiens did not appear until about 160,000 years ago. Given the age of the volcanic rock and lacking other evidence of early human ancestors in the Americas 1.3 million years ago, the researchers wrote in their paper, "we consider such a possibility to be extremely remote." Many paleontologists have withheld judgment on the alleged footprints, awaiting good geological dates, Feinberg said. "With this study, we're trying to nip any misrepresentation in the bud." The research was supported by the Center for the Study of the First Americans, the North Star Archaeological Research Program and the Berkeley Geochronology Center. Related links: Mexican footprints Web site, including the British team's response to the new study by Renne and his colleagues. Source: UC Berkeley

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A new Hubble image - among the largest ever produced with the Earth-orbiting observatory - gives the most detailed view so far of the entire Crab Nebula. The Crab is arguably the single most interesting object, as well as one of the most studied, in all of astronomy. The image is the largest ever taken with Hubble’s WFPC2 workhorse camera. http://hypography.com/gallery//files/9/9/8/crab_thumb.jpgThe Crab Nebula is one of the most intricately structured and highly dynamical objects ever observed. The new Hubble image of the Crab was assembled from 24 individual exposures taken with the NASA/ESA Hubble Space Telescope’s Wide Field and Planetary Camera 2 (WPFC2) and is the highest resolution image of the entire Crab Nebula ever made. The Crab Nebula is a six-light-year-wide expanding remnant of a star’s supernova explosion. Japanese and Chinese astronomers witnessed this violent event nearly 1,000 years ago in 1054. The filaments are the tattered remains of the star and consist mostly of hydrogen. The rapidly spinning neutron star embedded in the centre of the nebula, only barely visible in this Hubble image, is the dynamo powering the nebula’s eerie interior bluish glow. The blue light comes from electrons whirling at nearly the speed of light around magnetic field lines from the neutron star. The neutron star, like a lighthouse, ejects twin beams of radiation that appear to pulse 30 times a second due to the neutron star's rotation. A neutron star is the crushed ultra-dense core of the exploded star. The Crab Nebula derived its name from its appearance in a drawing made by Irish astronomer Lord Rosse in 1844, using a 36-inch telescope. When viewed by Hubble, as well as large ground-based telescopes such as ESO’s Very Large Telescope, the Crab Nebula takes on a more detailed appearance that yields clues into the spectacular demise of a star, 6,500 light-years away. The newly composed image was assembled from individual Wide Field and Planetary Camera 2 exposures taken in October 1999, January 2000, and December 2000. The colours in the image indicate the different elements that were expelled during the explosion. Blue indicates neutral oxygen, green singly ionized ionised sulphur and red doubly-ionized ionised oxygen. The Hubble data have been superimposed onto images taken with the European Southern Observatory’s Very Large Telescope at Paranal Observatory, Chile. Source: Spacetelescope.org

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As a boy growing up in Brazil 40 years ago, Marc A. Meyers marveled at the lightweight toughness of toucan beaks that he occasionally found on the forest floor. Now a materials scientist and professor of mechanical and aerospace engineering at UCSD's Jacobs School of Engineering, Meyers said makers of airplanes and automobiles may benefit from the first ever detailed engineering analysis of toucan beaks conducted in his lab. http://hypography.com/gallery//files/9/9/8/toucan_thumb.jpg"Our computer modeling shows that the beak is optimized to an amazing degree for high strength and very little weight," said Meyers. "It’s almost as if the toucan has a deep knowledge of mechanical engineering." http://hypography.com/gallery//files/9/9/8/foam_thumb.jpgIn a paper to be published Dec. 1 in Acta Materialia, Meyers and graduate students Yasuaki Seki and Matthew S. Schneider reported that the secret to the toucan beak's lightweight strength is an unusual bio-composite. The interior of the beak is rigid "foam" made of bony fibers and drum-like membranes sandwiched between outer layers of keratin, the protein that makes up fingernails, hair, and horn. Just as the hook-shaped barbs on cockleburs inspired the development of Velcro, Meyers said the avian bio-composite could inspire the design of ultra-light aircraft and vehicle components with synthetic foams made with metals and polymers. http://hypography.com/gallery//files/9/9/8/sandwich_thumb.jpg"The big surprise was our finding that the beak's sandwich structure also behaves as a high energy impact-absorption system," said Meyers. "Panels that mimic toucan beaks may offer better protection to motorists involved in crashes." Toucans are highly social, noisy residents of rainforests in the Amazon, although the birds live as far north as Mexico. They use their extremely large and often brightly colored beaks for a variety of purposes, from gathering fruit from the tips of tree branches, to defending themselves. Bird beaks are typically either short and thick or long and thin. The Meyers team decided to prospect for a novel material in toucan beaks because they are both long and thick. Emerald Forest Bird Gardens, a California breeder of exotic birds, provided beaks from toucans that had died from natural causes to Meyers's team. They analyzed the beaks' density, stiffness, hardness, and response to compression and stretching. They also examined the beaks with a scanning electron microscope. The beak’s interior is a highly organized matrix of stiff cancellous bone fibers that looks as if it was dipped into a soapy solution and dried, generating drum-like membranes that interconnect the fibers. The result is a solid "foam" of air-tight cells that gives the beak additional rigidity. "The beak is mostly air," said Meyers. "While the inner part of human bone also contains cancellous bone, we don't have the foam interconnections, which produce a much stronger structure with very little additional weight." Like a house covered by a shingled roof, the foam is covered with overlapping keratin tiles, each about 50 micrometers in diameter and 1 micrometer thick, which are glued together to produce sheets. The study in Acta Materialia also noted a hollow region extending about half the length of the upper and lower beaks. "When we did the calculations, we discovered that there are only very insignificant mechanical stresses in the center of the beak at the position of the hollow areas," said Meyers. "This is why I jokingly tell my students that toucans have a deep knowledge of mechanics. They don't bother adding structural support in a part of the beak that doesn't really need it." Source: UCSD

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Astronomers have combined two powerful astronomical assets, the Sloan Digital Sky Survey (SDSS) and NASA's Hubble Space Telescope, to identify 19 new "gravitationally lensed" galaxies. Among these 19, they have found eight new so-called "Einstein rings", which are perhaps the most elegant manifestation of the lensing phenomenon. Only three such rings had previously been seen in visible light. http://hypography.com/gallery//files/9/9/8/einstein_rings_thumb.jpgIn gravitational lensing, light from distant galaxies is deflected on its way to Earth by the gravitational field of any massive object that lies in the way. Because of this light bending, the galaxy is distorted into an arc or multiple separate images. When both galaxies are exactly lined up, the light forms a bull's-eye pattern, called an Einstein ring, around the foreground galaxy. Besides producing odd shapes, gravitational lensing gives astronomers the most direct probe of the distribution of dark matter in elliptical galaxies. Dark matter is an invisible and exotic form of matter that has not yet been directly observed. By searching for dark matter in galaxies, astronomers hope to gain insight into galaxy formation, which must have started around lumpy concentrations of dark matter in the early universe. The newly discovered lenses come from an ongoing project called the Sloan Lens Survey (SLACS). A team of astronomers, led by Adam Bolton of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and Leon Koopmans of the Kapteyn Astronomical Institute in the Netherlands, selected the candidate lenses from among several hundred thousand optical spectra of elliptical galaxies in the Sloan Digital Sky Survey. The team was looking for clear evidence of emission from galaxies twice as far from Earth and directly behind the closer galaxies. They used Hubble's Advanced Camera for Surveys to snap images of 28 of these candidate lensing galaxies. By studying the arcs and rings produced by 19 of these candidates, the astronomers precisely measured the mass of the foreground galaxies. These new discoveries add significantly to the approximately 100 gravitational lenses previously known. "Being able to study these and other gravitational lenses as far back in time as several billion years allows us to see directly whether the distribution of invisible and visible mass changes with cosmic time," says Koopmans. "With this information, we can test the commonly held idea that galaxies form from collision and mergers of smaller galaxies." The initial findings of the survey will appear in the February 2006 issue of the Astrophysical Journal. Source: NASA

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For plants, the ability to accurately sense light governs everything from seed germination, photosynthesis and pigmentation to patterns of growth and flowering. http://hypography.com/gallery//files/9/9/8/phytochrome_thumb.jpgNow, for the first time, scientists have obtained a detailed map of one of biology's most important light detectors, a protein found in many species across life's plant, fungal, and bacterial kingdoms. By resolving the three-dimensional structure of the protein known as phytochrome, scientists can now tease out the secrets of how plants, in particular, react to light, opening the door for a host of manipulations that could have sweeping implications for agriculture. Writing in the Nov. 17 issue of the journal Nature, a team of scientists from UW-Madison report that they have obtained the crystal structure of a phytochrome from a bacterium, the first such light-gathering structure depicted for all of biology. The structure of the bacterial phytochrome, according to the report, suggests its architecture first arose a billion or so years ago in a common ancestor and is shared among not only bacteria, but also by plants and fungi. "This is probably the most important light regulator in agriculture," says Richard Vierstra, a UW-Madison plant geneticist and one of two collaborating senior authors of the Nature paper. "It tells plants when to germinate. It tells them where to grow to absorb the most light and to avoid competition. It tells them when to flower. It tells them when to die at the end of the growing season." The accomplishment of the Wisconsin researchers, including first author graduate student Jeremiah Wagner, caps a 30-year quest by biologists to drill down to the inner workings of how plants, fungi and bacteria use light to guide their development. It will likely spur a rush by scientists to capitalize on the new knowledge and may one day lead to such things as plants whose growth, flowering and death can be precisely manipulated. "We can now start changing how phytochromes work in a rational way to improve how plants respond to light," says Wagner. "People have been trying to do this for a long time. Practically speaking, we can now try to re-engineer the vision system of a plant." According to Vierstra, there are many kinds of phytochromes found in every plant, and they exist in virtually all cells. They occur in greater concentrations in cells that respond directly to light, such as in root tips and new shoots. The phytochrome revealed by the Wisconsin team was derived from a microbe known as Deinococcus radiodurans, a bacterium renowned for its tolerance to ionizing radiation. It was only within the last eight years that scientists from Vierstra's and other labs discovered that, like plants, some bacteria harbor phytochromes. That finding opened the way for the Wisconsin team to define the structure of a phytochrome, as bacteria are easy to grow in the lab and their proteins are easier to purify and manipulate than plant proteins. Once isolated, the phytochrome was crystallized and its molecular structure was mapped using a beam of X-rays to develop a three-dimensional picture of the protein. That three-dimensional portrait, which reveals the atom-by-atom configuration of the molecule, is the key to understanding the "nuts and bolts" of how the photoreceptor senses light and triggers a series of downstream events that control growth and development, according to Katrina Forest, the other senior member of the team and a UW-Madison professor of bacteriology. "There were some surprises," says Forest of the ribbon-like protein. "This protein has a knot." That is a startling feature, she notes, observed in only a handful of proteins out of tens of thousands whose structures are known. The group speculates the knot may help stabilize the protein so it can do its job of capturing light and triggering the cascade of downstream events under its control. "We think that without the knot, the protein conformational changes (prompted by light) would be too floppy to be efficiently channeled to downstream proteins," Forest explains. Phytochromes have unique properties that enable them to switch between two stable states that sense red and far-red light. The light is actually detected by a specialized pigment that sits within a pocket on the protein. Red and far-red light, says Forest, have the effect of reversibly changing the structure of the pigment in the pocket, which then flips a switch on the protein to trigger the events of growth and development. Intriguingly, the phytochrome has the ability to store the light it has detected, initiating a response days after it is sensed, Vierstra says. "This memory allows the plant to predict where the light will come from each day and measure the length of daylight so that they flower in the correct season." By deducing the architecture of the phytochrome protein, according to Vierstra and Forest, it may be possible to engineer and introduce into crops phytochromes that respond to different wavelengths of light, or are more or less active. These changes, in turn, could allow plants to grow under different climate regimes or flower at different times of the year, for example. Gaining precise control over flowering events, says Vierstra, is a key to the success or failure of most crops, as most of what we eat comes from seeds and fruits produced by flowers. In another scenario, it may be possible to dampen the role of phytochromes in crop plants to avoid having them compete with each other for light when grown close together in a field. In addition to Wagner, Vierstra and Forest, the paper was authored by Joseph S. Brunzelle of Northwestern University. The work was funded primarily by the National Science Foundation. Funding was also provided by the U.S. Department of Energy and the W.M. Keck Foundation. Source: University of Wisconsin

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For some, spending more than three years working to solve a more than 40-year-old math problem sounds like a nightmare. http://hypography.com/gallery//files/9/9/8/integral.jpgFor University of Missouri-Columbia mathematics professor Steve Hofmann, solving a problem posed by one of the most famous mathematicians in the second half of the 20th Century has been a dream since his college days. The major mathematical accomplishment is earning him significant recognition. Hofmann has a speaking invitation at this summer's meeting of the International Congress of Mathematicians in Madrid, Spain, which takes place only once every four years. "It's a problem that has interested me since I was a graduate student," Hofmann said. "It was one of the biggest open problems in my field and everybody thought it was too hard and wouldn't be solved. I had toyed with it for years and then put in three years of very serious work before hitting the key breakthrough." The problem goes back to two papers written by Tosio Kato, University of California-Berkley, in 1953 and 1961. It turned out to be quite difficult and became known as the "Kato Conjecture" in mathematical circles. The one dimensional version of the problem was solved 20 years later. "I think I was the last person working on it," Hofmann joked. "I think everyone else had given up." Hofmann admits explaining the problem is difficult because it is rather technical. Its solution applies to the theory of waves propagating through different media, such as a seismic wave traveling through different types of rock. Hofmann said the solution allows mathematicians to better describe the behavior of waves traveling through a medium which itself changes over time. "To work on a problem for three years and finally crack it open feels fantastic!" Hofmann said. "It's the reason mathematicians work on problems - for moments like that." Hofmann's work is funded by the National Science Foundation. The solution to the "Kato problem" is detailed in a series of papers published with his research collaborators Pascal Auscher, Michael Lacey, John Lewis, Alan McIntosh and Philippe Tchamitchian. Source: University of Missouri

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Species evolve at very different rates, and the evolutionary line that produced humans seems to be among the slowest. The result, according to a new study by scientists at the European Molecular Biology Laboratory , is that our species has retained characteristics of a very ancient ancestor that have been lost in more quickly-evolving animals. This overturns a commonly-held view of the nature of genes in the first animals. The work appears in the current issue of the journal Science. Genes hold the recipes for proteins. The genes of animals usually contain extra bits of DNA sequence, called introns - information which has to be removed as cells create new molecules. The number of introns in genes, however, varies greatly among animals. While humans have many introns in their genes, common animal models such as flies have fewer. From an evolutionary perspective, it was long assumed that the simpler fly genes would be more ancient. The current study reveals the opposite: early animals already had a lot of introns, and quickly-evolving species like insects have lost most of them. To discover what early animals were like, scientists usually compare their descendents. This is difficult when comparing distantly-related animals such as humans and flies. In these cases, it helps to look at living organisms that have preserved many features of their ancestors. Detlev Arendt's group is doing this with a small marine worm called Platynereis dumerlii. "Similar animals are already found in the earliest fossils from the Cambrium, about 600 million years ago," Arendt explains, "arguing that Platynereis could be something like a 'living fossil'." This makes it an ideal model for evolutionary comparisons to find out what the common ancestors of humans, flies and worms were like." Until quite recently, such comparisons could only be made by looking at physical characteristics such as the structure of bones, teeth, or tissues. But DNA sequencing now permits scientists to make comparisons of the genetic code and read evolutionary history from it. An international consortium involving researchers from EMBL, the UK, France and the United States has now sequenced a part of the Platynereis genome. "The fraction of Platynereis genes we have been able to look at tells a very clear story," says researcher Florian Raible, who performed most of the computer analyses. "The worm’s genes are very similar to human genes. That's a much different picture than we've seen from the quickly-evolving species that have been studied so far." Raible is member of both Arendt's group and a second EMBL lab, that of Peer Bork, whose specialty is analyzing genomes by computer. "Human genes are typically more complex than those of flies," explains Bork. "Classicallystudied species like flies have far fewer introns, so many scientists have believed that genes have become more complex over the course of evolution. There have already been speculations that this may not be true, but proof was missing. Now we have direct evidence that genes were already quite complex in the first animals, and many invertebrates have reduced part of this complexity." Not only are the introns there - the team also discovered that their positions within genes have been preserved over the last half a billion years." This gives us two independent measurements that tell the same story," Raible explains. "Most introns are very old, and they haven't changed very much in slowly-evolving branches of life, such as vertebrates or annelid worms. This makes vertebrates into something like 'living fossils' in their own right." The discovery that Platynereis also represents a slowlyevolving branch of animal life has important implications for the study of humans. "We've already learned an incredible amount about humans from studies of the fly," Arendt says. "The marine worm might well give us an even better look at important conserved processes. Another thing that this has shown us is that evolution is not always about gain; the loss of complexity can equally be an important player in evolution." Source: European Molecular Biology Laboratory

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The genius of Albert Einstein, who added a "cosmological constant" to his equation for the expansion of the universe but later retracted it, may be vindicated by new research. http://hypography.com/gallery/files/9/9/8/stellar_thumb.jpgThe enigmatic dark energy that drives the accelerating expansion of the universe behaves just like Einstein's famed cosmological constant, according to the Supernova Legacy Survey (SNLS), an international team of researchers in France and Canada that collaborated with large telescope observers at Oxford, Caltech and Berkeley. Their observations reveal that the dark energy behaves like Einstein’s cosmological constant to a precision of 10 per cent. "The significance is huge," said Professor Ray Carlberg of the Department of Astronomy and Astrophysics at U of T. "Our observation is at odds with a number of theoretical ideas about the nature of dark energy that predict that it should change as the universe expands, and as far as we can see, it doesn’t." The results will be published in an upcoming issue of the journal Astronomy & Astrophysics. "The Supernova Legacy Survey is arguably the world leader in our quest to understand the nature of dark energy," said study co-author Chris Pritchet, a professor of physics and astronomy at the University of Victoria in British Columbia, Canada. The researchers made their discovery using an innovative, 340-million pixel camera called MegaCam, built by the Canada-France-Hawaii Telescope and the French atomic energy agency, Commissariat à l’Énergie Atomique. "Because of its wide field of view - you can fit four moons in an image - it allows us to measure simultaneously, and very precisely, several supernovae, which are rare events," said Pierre Astier, one of the scientists with the Centre National de la Recherche Scientifique (CNRS) in France. "Improved observations of distant supernovae are the most immediate way in which we can learn more about the mysterious dark energy," adds Richard Ellis, a professor of astronomy at the California Institute of Technology. "This study is a very big step forward in quantity and quality." Study co-author Saul Perlmutter, a physics professor at the University of California, Berkeley, says the findings kick off a dramatic new generation of cosmology work using supernovae. "The data is more beautiful than we could have imagined 10 years ago - a real tribute to the instrument builders, the analysis teams and the large scientific vision of the Canadian and French science communities." The SNLS is a collaborative international effort that uses images from the Canada-France-Hawaii Telescope, a 3.6-metre telescope atop Mauna Kea, a dormant Hawaiian volcano. The current results are based on about 20 nights of data, the first of over nearly 200 nights of observing time for this project. The researchers identify the few dozen bright pixels in the 340 million captured by MegaCam to find distant supernovae, then acquire their spectra using some of the largest telescopes on earth-the Frederick C. Gillett Gemini North Telescope on Mauna Kea, the Gemini South Telescope on the Cerro Pachón mountain in the Chilean Andes, the European Southern Observatory Very Large Telescopes (VLT) at the Paranal Observatory in Atacama, Chile, and the Keck telescopes on Mauna Kea. The SNLS is one component of a massive 500-night program of imaging being undertaken as the CFHT Legacy Survey. "Only the world's largest optical telescopes - those from eight to 10 metres in diameter - are capable of studying distant supernovae in detail by examining the spectrum," said Isobel Hook, an astronomer in the Department of Astrophysics at Oxford University. The current paper is based on about one-tenth of the imaging data that will be obtained by the end of the survey. Future results are expected to double or even triple the precision of these findings and conclusively solve several remaining mysteries about the nature of dark energy. The research was funded by the Canada-France-Hawaii Telescope, the Commissariat à l’Énergie Atomique (CEA), Centre National de la Recherche Scientifique, Institut National des Sciences de l’Univers du CNRS, the Natural Sciences and Engineering Research Council of Canada, the National Research Council of Canada's Herzberg Institute of Astrophysics, the Gemini Observatory, the Particle Physics and Astronomy Research Council, the W. M. Keck Observatory and the European Southern Observatory. Source: University of Toronto