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A 12-year study of massive stars has reaffirmed that our Galaxy has four spiral arms, following years of debate sparked by images taken by NASA's Spitzer Space Telescope that only showed two arms.
Astronomers cannot see what our Galaxy, which is called the Milky Way, looks like because we are on the inside looking out. But they can deduce its shape by careful observation of its stars and their distances from us.
"The Milky Way is our galactic home and studying its structure gives us a unique opportunity to understand how a very typical spiral galaxy works in terms of where stars are born and why," said Professor Melvin Hoare, a member of the RMS Survey Team in the School of Physics & Astronomy at the University of Leeds and a co-author of the research paper.
In the 1950s astronomers used radio telescopes to map our Galaxy. Their observations focussed on clouds of gas in the Milky Way in which new stars are born, revealing four major arms. NASA's Spitzer Space Telescope, on the other hand, scoured the Galaxy for infrared light emitted by stars. It was announced in 2008 that Spitzer had found about 110 million stars, but only evidence of two spiral arms.
The astronomers behind the new study used several radio telescopes in Australia, USA and China to individually observe about 1650 massive stars that had been identified by the RMS Survey. From their observations, the distances and luminosities of the massive stars were calculated, revealing a distribution across four spiral arms.
"It isn't a case of our results being right and those from Spitzer's data being wrong – both surveys were looking for different things," said Professor Hoare. "Spitzer only sees much cooler, lower mass stars – stars like our Sun – which are much more numerous than the massive stars that we were targeting."
China's first-ever moon rover is driving on the lunar surface after successfully separating from its carrier lander to begin exploring its landing locale: the Bay of Rainbows.
China's Chang'e 3 moon lander and its Yutu rover touched down on the moon Saturday (Dec. 14) at about 8:11 a.m. EST (1311 GMT), though it was late Saturday night local time at the mission's control center in Beijing during the landing. It is the first soft-landing on the moon by any spacecraft in 37 years.
Chang'e 3 launched toward the moon on Dec. 2 Beijing time to begin its two-week trek to the lunar surface. The spacecraft arrived in lunar orbit about five days after launch, and then began preparing for landing. A camera on the spacecraft snapped 59 photos of the moon during the descent, including a view straight from the lunar surface just after touchdown.
The lander hovered some 300 feet (100 meters) altitude above the lunar landscape as it scanned for a safe and sound landing point. The vehicle then throttled down its engine, free-falling to a legged landing.
The lander itself carries scientific gear capable of observing the Earth as well as other celestial objects and is designed to serve for 12 months.
Both the Chang'e 3 rover and lander still face a battle with lunar night temperatures that plummet during 14 days of lunar night. Control of China's first robotic moon landing is being carried out at the Beijing Aerospace Control Center.
"The landing site for Chang'e 3 is in an area of basalt flows that are rich in Titanium similar to those returned by the Apollo 11 and 17 missions," saidClive Neal, a leading lunar scientist at the University of Notre Dame's Department of Civil and Environmental Engineering and Earth Sciences.
Lawrence Taylor, director of the Planetary Geosciences Institute at the University of Tennessee's Department of Earth and Planetary Sciences, is a veteran Apollo lunar scientist. He, too, had high praise for China's Chang'e 3 mission.
"We Apollo lunatics salute you and your country in this marvelous event in becoming the third soft-landing nation. May your success, as initiated by your glorious 'Jade Rabbit,' be the catalyst to spur on all lunar exploration and be a bond to unite all people," Taylor said.
By observing a high-speed component of a massive galaxy cluster, Caltech/JPL scientists and collaborators have detected for the first time in an individual object the kinetic Sunyaev-Zel'dovich effect, a change in the cosmic microwave background caused by its interaction with massive moving objects.
MACS J0717.5+3745 is an extraordinarily dynamic galaxy cluster with a total mass greater than 1015 (a million billion) times the mass of the sun or more than 1,000 times the mass of our own galaxy. It appears to contain three relatively stationary subclusters (A, C, and D) and one subcluster (B) that is being drawn into the larger galaxy cluster, moving at a speed of 3,000 kilometers per second.
The galaxy cluster was observed by a team led by Sunil Golwala, professor of physics at Caltech and director of the Caltech Submillimeter Observatory (CSO) in Hawaii. Subcluster B was observed during what appears to be its first fall into MACS J0717.5+3745. Its momentum will carry it through the center of the galaxy cluster temporarily, but the strong gravitational pull of MACS J0717.5+3745 will pull subcluster B back again. Eventually, subcluster B should settle in with its stationary counterparts, subclusters A, C, and D.
Though subcluster B's behavior is dramatic, it fits neatly within the standard cosmological model. But the details of the observations of MACS J0717.5+3745 at different wavelengths were puzzling until they were analyzed in terms of a theory called the kinetic Sunyaev-Zel'dovich (SZ) effect.
In 1972, two Russian physicists, Rashid Sunyaev and Yakov Zel'dovich, predicted that we should be able to see distortions in the cosmic microwave background (CMB)—the afterglow of the Big Bang—whenever it interacts with a collection of free electrons. These free electrons are present in the intracluster medium, which is made up primarily of gas. Gas within dense clusters of galaxies is heated to such an extreme temperature, around 100 million degrees, that it no longer coheres into atoms. According to Sunyaev and Zel'dovich, the photons of the CMB should be scattered by the high-energy electrons in the intracluster medium and take on a measurable energy boost as they pass through the galaxy cluster.
When created, single-wall carbon nanotubes (SWNTs) have a length-to-diameter ratio of up to 132,000,000:1 (think long wires that entangle, forming a one-dimensional structure). This clustering makes it difficult to achieve high purity, water solubility, and wet nanoscale applications, such a biological uses.
But what if the nanotube length could be reduced to roughly the size of its diameter — about 1 nanometer — thus creating a “zero-dimensional” carbon nanotube? That’s what Pitt researchers have achieved.
These extremely short nanotubes would be more soluble and would have the same dimensions as many proteins that compose the basic machinery of living cells. That suggests the potential for cell- or protein-level biomedical imaging, protein or nucleic acid vaccination carriers, drug-delivery vehicles, or even components of synthetic cells, the researchers say.
In addition, “zero-dimensional carbon nanotubes present the possibility to build ultrathin, superfast electronic devices, far superior to the best existing ones and it could be possible to build strong and ultralight cars, bridges, and airplanes,” said Steven R. Little, PhD, associate professor, CNG Faculty Fellow and Chair of the Department of Chemical and Petroleum Engineering, a principal investigator.
The researchers expect the process will be available commercially as soon as the process can be scaled up to manufacture bulk quantities, which is underway currently.
The nuclear receptor HNF-4α is an important transcriptional regulator of liver and pancreatic genes and its dysfunction has been linked to maturity-onset diabetes of the young, kidney failure and metabolic syndrome. Fraydoon Rastinejad and colleagues describe a crystal structure of the multidomain HNF-4α homodimer bound to its DNA response element and coactivator-derived peptides. The structure reveals a domain convergence centre connecting multiple domains and serving as an allosteric transmission system for propagating signals between the ligand-binding and DNA-binding domains. The architecture of HNF-4α is compared to the only other known structure of a multidomain nuclear receptor complex, that of PPAR-γ–RXR-α.
Researchers have determined the complete three-dimensional structure of a protein called HNF-4α. HNF-4α controls gene expression in the liver and pancreas, switching genes on or off as needed. People with mature onset diabetes of the young (MODY1) a rare form of the disease, have inherited mutations in the HNF-4α protein. This first-ever look at HNF-4α’s full structure, published in Nature, uncovers new information about how it functions. The study also reveals new pockets in the protein that could be targeted with therapeutic drugs aimed at alleviating MODY1.
“Previous structural studies of HNF-4α and related nuclear receptors only revealed smaller, isolated fragments of these proteins,” said Fraydoon Rastinejad, Ph.D., professor in Sanford-Burnham’s Diabetes and Obesity Research Center, located at the Institute’s Lake Nona campus in Orlando, Fla., and senior author of the study.
“Because those studies looked only at separate pieces of HNF-4α, many people suspected there was no coordination between different regions of the protein. But we showed those assumptions are incorrect. HNF-4α’s domains are highly organized in a way that has implications for our understanding of MODY1 and the development of treatments for the disease.”
Viruses are biological pirates, invading cells and hijacking their machinery to reproduce and infect again. Research at Harvard Medical School is shedding new light on the battle line where viral and cell membranes meet, and the key role of a protein grappling hook with which the influenza virus commandeers its prize—your cells.
An influenza virus is a collection of eight RNA strands enclosed in a lipid-bilayer membrane. When the virus encounters a cell—in your lung, for example—that cell may engulf the virus inside an internal membrane called an endosome. To escape that bubble, the virus fuses its membrane with the endosome's, opening a window into the cell's interior. Once free, the viral RNA is copied, and the hijacked cell begins to manufacture copies of the virus. To fuse the two membranes, the virus carries a protein called hemagglutinin (the "H" in H1N1). Triggered by the acidic environment of an endosome, that protein will extend from the viral membrane and attach, like a grappling hook, to the endosome's membrane. When enough hooks are set, they draw the membranes together until they fuse The flu virus carries about 300 to 400 of these hooks, and virologists had known that several are needed to fuse the membranes.
In their latest study, reported last month in the new journal eLife, the HMS team show why. Using a microscope developed by first author Tijana Ivanovic, a research fellow in the HMS Department of Biological Chemistry and Molecular Pharmacology, the team looked closely at changes in the protein throughout its assault on the endosome. They observed that three or four hemagluttinin hooks must attach in close proximity to fuse the membranes. Without the help of neighbors, an individual hook is too weak to pull the membranes together. Instead, they observed, the protein remains stretched between the two membranes, like a bridge. And that's an intriguing target, said Stephen Harrison, the study's senior author and the Giovanni Armenise-Harvard Professor of Basic Biomedical Science in the department of Biological Chemistry and Molecular Pharmacology at HMS. "That bridge can hang out there for as long as a minute," Harrison said. "That makes it an interesting target for an inhibitor, in principle, at least, because it's there for long enough to be targetable." The study also appears to settle a question about the nature of the hemagglutinin protein, and viral fusion: Are multiple hooks needed because they interact directly with each other to fuse the membranes, or because that's the number required to pull the somewhat elastic membranes together by brute force? The researchers' answer: brute force. "That observation helps us distinguish between classes of models for a stage of the fusion process," Harrison said. "That notion is probably fundamental to all viral fusion proteins—or for that matter to most cellular membrane fusion events facilitated by proteins."
Will the next generation think about diseases like Alzheimer’s and diabetes the way we think about polio and the whooping cough? Susan Solomon, the co-founder of the New York Stem Cell Foundation (NYSCF), certainly hopes so.
The Ring Nebula is one of the most famous celestial objects because of its delicate beauty. That shimmering oval of rainbow colors has popped up everywhere from dorm-room posters to book jackets to album covers to just about every TV backdrop in the history of sci-fi. But it is more than mere eye candy. The Ring is also fascinating for what it tells us about our future.
Middleweight stars like the sun expand and cool in their old age, briefly turning into red giants. After the red giant stage, the outer layers puff off, leaving behind a white dwarf: a dense, super-hot stellar cinder. Those puffed-out layers glow brightly before they disperse. That is exactly what we are seeing in this brand-new Hubble image of the Ring Nebula, along with the video interpretation of that image–a snapshot of what will happen to the sun as it runs out of nuclear fuel in about 5 billion years. The Hubble data also add a completely new twist to what astronomers know about the Ring. For the first time, researchers can get an accurate, three-dimensional understanding of the structure of the nebula.
Put that information together with other images taken using different filters and imaging techniques, and scientists have an incredibly detailed picture of how a sunlike star dies.
For comparison, I’ve collected a greatest-hits gallery of recent images of the Ring Nebula taken by other telescopes and satellites, each created using different techniques. You will notice that there is quite a bit of variation here: Most of these pictures little resemble the space-lollipop that has become an astronomy pop-culture staple. That is because the complexity of the nebula itself. It contains many types of atoms in many different states of ionization, each emitting in its own characteristic way. By choosing to zero in on a particular wavelength (or range of wavelengths) of radiation, astronomers can highlight specific elements, temperatures, and densities of the Ring Nebula.
Look at the Ring Nebula with your own eye through a good-size telescope (you’ll need at least 8″ of aperture under dark skies) and you will walk away with yet another impression. Because of the selective sensitivity of the human retina, the Ring Nebula will appear as a faint, diaphanous greenish-gray oval. That is a useful reminder that the colors of space are highly subjective. Each type of image is truthful in its own way, but none of them have a unique claim on representing what the Ring “really” looks like.
Click on each thumbnail for an explanation of how it was created and what it shows; then watch the video for the full story about the dying gasps of a sunlike star. And be glad that all this action is all unfolding far away. Before the sun produces a beautiful nebula of its own, it will have either baked the Earth to a crisp or swallowed and digested our planet entirely.
Led by Professor Mike Barlow (UCL Physics & Astronomy) the team used ESA’s Herschel Space Observatory to observe the Crab Nebula in far infrared light.
Their measurements of regions of cold gas and dust led them to the serendipitous discovery of the chemical fingerprint of argon hydride ions, published today in the journal Science. The findings support scientists’ theories of how argon forms in nature.
The Herschel Space Observatory, an ESA space telescope which recently completed its mission, is the biggest space telescope ever to have flown. Herschel’s instruments were designed to detect far-infrared light, which has much longer wavelengths than we can see with our eyes.
“We were doing a survey of the dust in several bright supernova remnants using Herschel, one of which was the Crab Nebula. Discovering argon hydride ions here was unexpected because you don’t expect an atom like argon, a noble gas, to form molecules, and you wouldn’t expect to find them in the harsh environment of a supernova remnant,” said Barlow.
Although hot objects like stars glow brightly in visible light, colder objects like the dust in nebulae radiate mainly in the infrared, wavelengths which are blocked by Earth’s atmosphere. Although nebulae can be seen in visible light, this light comes from hot excited gases within them; the cold and dusty component is invisible at optical wavelengths.
“Looking at infrared spectra is useful as it gives us the signatures of molecules, in particular their rotational signatures,” Barlow said. “Where you have, for instance, two atoms joined together, they rotate around their shared centre of mass. The speed at which they can spin comes out at very specific, quantised, frequencies, which we can detect in the form of infrared light with our telescope.”
Elements can exist in several different versions, or isotopes, which have different numbers of neutrons in their atomic nuclei. The properties of isotopes are very similar to one another in most respects, but they do differ slightly in mass. Because of this mass difference, the speed of rotation depends on which isotopes are present in a molecule.
The light coming from certain regions of the Crab Nebula showed extremely strong and unexplained peaks in intensity around 618 Gigahertz and 1235 GHz. Consulting databases of known properties of different molecules, the scientists found that the only possible explanation was that the emission was coming from spinning molecular ions of argon hydride. Moreover, the only isotope of argon whose hydride could rotate at that rate was argon-36.
Jupiter’s icy moon Europa, home to a probable buried ocean, just added another twist to its exotic cool. The Hubble Space Telescope has spotted possible plumes of water spraying from Europa’s south pole. The jets resemble the giant icy geyser seen on Saturn’s moon Enceladus. Plumes on Europa could be even more exciting because they hint at the ability to tap a subsurface habitat that might even harbour extraterrestrial life.
“If this pans out, it’s potentially the biggest news in the outer Solar System since the discovery of the Enceladus plume,” says Robert Pappalardo, a planetary scientist at the Jet Propulsion Laboratory in Pasadena, California, who was not involved in the research.
The work, reported today in Science1, comes with plenty of caveats. Although previous theoretical work suggested that plumes could exist on Europa, earlier tantalizing hints of them have come to nothing. This time, Hubble spotted the potential plumes in just one observation. And if they do turn out to be real, the plumes might not even be connected to the moon's deep subsurface ocean. “It’s a first-time discovery, and we need to go back and look some more,” says team member Joachim Saur, a planetary scientist at the University of Köln in Germany.
Saur and his colleagues have looked for Europan plumes before, to no avail2. In 2012, the group decided to take another shot. Using an ultraviolet camera on Hubble, they scrutinized Europa once in November and once in December of that year. The November study found nothing, but the 2.7-hour exposure in December spotted blobs of hydrogen and oxygen near Europa’s south pole.
Their size, shape and chemical make-up is best explained by two plumes of water vapour roughly 200 kilometres high, says team leader Lorenz Roth, a planetary scientist at the Southwest Research Institute in San Antonio, Texas. That is many times the height of potential Europa plumes calculated by some theorists3. It would mean that Europa's jets reach higher than the volcanic eruptions on Jupiter’s moon Io, but not as high as the towering plume that spouts from Enceladus.
It is possible that the plumes may not tap into the deep subsurface, says Saur. The frictional heat of ice rubbing against itself might melt parts of the icy crust and feed the plumes. Either way, the discovery could be a shot in the arm for upcoming missions. In 2022, the European Space Agency is planning to launch a probe that would explore Europa as well as Jupiter and its other moons. And Pappalardo leads a mission concept team at NASA that is outlining a possible US spacecraft to Europa.
In what has proved to be the discovery of the largest known crystals on earth, work is underway to document and preserve this historic find. While some minor damage has already occurred in the primary cave and a secondary cavern, called Cave of Dreams, iron doors have been installed by the Peñoles company to prevent damage to the giant, magnificent crystals.
Found deep in a mine in southern Chihuahua Mexico, these crystals were formed in a natural cave totally enclosed in bedrock. When I first stepped into the cavern it was like walking into the Land of the Giants. I have often admired crystal geodes held in my hand, but when photographing these unique natural structures it was almost impossible to get any sense of scale. This is a geode full of spectacular crystals as tall as pine trees, and in some cases greater in circumference. They have formed beautiful crystals that are a translucent gold and silver in color, and come in many incredible forms and shapes. Some of the largest are essentially columnar in shape and stand thirty to fifty feet high and three to four feet in diameter. Many of the smaller examples are four to six feet in circumference, have many incredible geometrical shapes, and probably weigh in excess of ten tons. The columnar pillars are at first the most striking shape, but later I noticed there were thousands of "sharks teeth" up to three feet high placed row upon row and dispersed at odd angles throughout the caverns. While some of the crystals are attached to the ceiling walls and floors of the cave as might be expected, some exist in great masses of spikes and almost float in air. These crystals seem to defy gravity, as they must weigh several tons.
The Naica mine was first discovered by early prospectors in 1794 south of Chihuahua City. They struck a vein of silver at the base of a range of hills called Naica by the Tarahumara Indians. The origin in the Tarahumara language seems to mean "a shady place". Perhaps here in the small canyon there was a grove of trees tucked away by a small canyon spring.
Using data from NASA’s Cassini spacecraft, scientists have created this beautiful mosaic mapping the northern hemisphere of Saturn’s moon Titan, which is full of rivers, lakes, and seas.
“Titan is a very alien place that looks very Earth-like,” said planetary scientist Stephen Wall, leader of Cassini’s radar team, during a press conference here at the American Geophysical Union conference.
The material filling Titan’s lakes is not water but rather hydrocarbons such as methane and ethane, which are typically gases on Earth but remain liquid at Titan’s average temperature of −180 degrees Celsius. Ever since Cassini started radar mapping the frozen moon in 2004, researchers have seen that Titan is a weird and wet world. But Cassini’s scans missed the true extent of some seas, including the biggest, Kraken Mare. This new map fills in almost all the area of Titan’s north pole and provides scientists with important answers to some of their questions.
While the northern hemisphere is dotted all over with hundreds of tiny lakes, the large seas seem confined to a specific area, mainly on the lower right side of the image above. As geophysicist Randolph Kirk of the USGS pointed out during the briefing, you could almost draw a rectangular box around this area, suggesting that geological processes are at play. The team thinks that Titan’s crust has fractured here when active tectonics created almost straight lines of parallel mountain chains. The low-lying areas are what gets filled with liquid, creating Kraken Mare and its smaller neighbor, Ligeia Mare. The scientists think the process may be analogous to flooding 12,000 years ago of similar geology in Nevada that likely created large bodies of water.
Other tectonic processes are probably behind the smaller dotted lakes, though scientists don’t yet know precisely what. Some of the lakes could be infilled calderas of former active volcanoes on Titan (which would spew molten water instead of lava). But there isn’t enough volcanic activity on the moon to account for all of them. Instead, many were probably created when liquid hydrocarbons dissolved the frozen ice, in the same way that water on Earth dissolves limestone to create features like the Bottomless Lakes in New Mexico.
“This creates a kind of exciting prospect that under the northern pole of Titan is a network of caves,” said Kirk. Caves on Earth are often filled with life, so perhaps Titan’s caves could be as well.
Australian researchers have grown a rudimentary kidney in the laboratory from human stem cells, an advance they say could lead to better ways of treating renal disease and testing drug safety.
Earlier this year, an American team announced that they had created a rat kidney from stem cells, though it was incredibly inefficient when transplanted into an organism. This organ from Little’s lab was created with human stem cells and can give researchers an unprecedented insight into how new medications will impact human kidneys, which can dramatically improve success in clinical safety trials. They also represent the potential for improved treatment of renal disease, as that is an area that is lacking at present. For those who are suffering renal disease, dialysis and organ transplantation are the two main treatments available. Eventually, decades down the road, this technology could potentially be used to create full-sized replacement organs for those who have exhausted all other options.
Currently, the kidneys are very small and are about the size that you would find in a five-week old human embryo. This technology needs to become much more advanced before it will be useful in a clinical setting, but that does not at all take from the significance of this announcement. The cellular complexity of this newly manufactured kidney is unlike anything that has been seen before in lab-grown organs. Using stem cells to create new organs for drug safety testing and transplantation purposes has been a goal among those in regenerative medicine for years, and the results from Melissa Little’s lab presents a very large step forward.
Base-2 system helped to simplify calculations centuries before Europeans rediscovered it.
When Leibniz demonstrated the advantages of the binary system for computations as early as 1703, he laid the foundation for computing machines. However, is a binary system also suitable for human cognition? One of two number systems traditionally used on Mangareva, a small island in French Polynesia, had three binary steps superposed onto a decimal structure. A recent study shows how this system functions, how it facilitated arithmetic, and why it is unique. The Mangarevan invention of binary steps, centuries before their formal description by Leibniz, attests to the advancements possible in numeracy even in the absence of notation and thereby highlights the role of culture for the evolution of and diversity in numerical cognition.
Cognitive scientist Rafael Nuñez at the University of California, San Diego, points out that the idea of binary systems is actually older than Mangarevan culture. “It can be traced back to at least ancient China, around the 9th century bc”, he says, and it can be found in the I Ching, a millennia-old Chinese text that inspired Leibniz. Nuñez adds that “other ancient groups, such as the Maya, used sophisticated combinations of binary and decimal systems to keep track of time and astronomical phenomena. Thus, the cognitive advantages underlying the Mangarevan counting system may not be unique.”
All the same, say Bender and Beller, a ‘mixed’ system such as this is not easy, nor an obvious set-up to create. “It’s puzzling that anybody would come up with such a solution, especially on a tiny island with a small population,” Bender and Beller say. But they add: “This very fact also demonstrates just how important culture is for the development of numerical cognition — for example, how in this case dealing with big numbers can motivate inventive solutions.”
Nuñez agrees; he adds that the study shows “the primacy of cultural factors underlying the invention of number systems, and the diversity in human numerical cognition”.
Researchers from the University of Houston have found a catalyst that can quickly generate hydrogen from water using sunlight, potentially creating a clean and renewable source of energy. Their research, published in Nature Nanotechnology, involved the use of cobalt oxide nanoparticles to split water into hydrogen and oxygen.
Jiming Bao, lead author of the paper and an assistant professor in the Department of Electrical and Computer Engineering at UH, said the research discovered a new photocatalyst and demonstrated the potential of nanotechnology in engineering a material’s property, although more work remains to be done.
Bao said photocatalytic water-splitting experiments have been tried since the 1970s, but this was the first to use cobalt oxide and the first to use neutral water under visible light at a high energy conversion efficiency without co-catalysts or sacrificial chemicals. The project involved researchers from UH, along with those from Sam Houston State University, the Chinese Academy of Sciences, Texas State University, Carl Zeiss Microscopy LLC, and Sichuan University.
Researchers prepared the nanoparticles in two ways, using femtosecond laser ablation and through mechanical ball milling. Despite some differences, Bao said both worked equally well.
Different sources of light were used, ranging from a laser to white light simulating the solar spectrum. He said he would expect the reaction to work equally well using natural sunlight.
Once the nanoparticles are added and light applied, the water separates into hydrogen and oxygen almost immediately, producing twice as much hydrogen as oxygen, as expected from the 2:1 hydrogen to oxygen ratio in H2O water molecules, Bao said.
The experiment has potential as a source of renewable fuel, but at a solar-to-hydrogen efficiency rate of around 5 percent, the conversion rate is still too low to be commercially viable. Bao suggested a more feasible efficiency rate would be about 10 percent, meaning that 10 percent of the incident solar energy will be converted to hydrogen chemical energy by the process.
Other issues remain to be resolved, as well, including reducing costs and extending the lifespan of cobalt oxide nanoparticles, which the researchers found became deactivated after about an hour of reaction.
Scientists from the Hamburg Center for Free-Electron Laser Science have devised a novel way to boil water in less than a trillionth of a second. The theoretical concept, which has not yet been demonstrated in practice, could heat a small amount of water by as much as 600 degrees Celsius in just half a picosecond (a trillionth of a second). That is much less than the proverbial blink of an eye: one picosecond is to a second what one second is to almost 32 millennia. This would make the technique the fastest water-heating method on Earth.
The novel concept opens up interesting new ways for experiments with heated samples of chemical or biological relevance, as the inventors report in this week's issue of the scientific journal Angewandte Chemie - International Edition (Nr. 51, 16 December). "Water is the single most important medium in which chemical and biological processes take place," explains DESY scientist Dr. Oriol Vendrell from the Center for Free-Electron Laser Science CFEL, a cooperation of DESY, the University of Hamburg and the German Max Planck Society. "Water is not just a passive solvent, but plays an important role in the dynamics of biological and chemical processes by stabilising certain chemical compounds and enabling specific reactions."
All it takes for superfast water heating is a concentrated flash of terahertz radiation. Terahertz radiation consists of electromagnetic waves with a frequency between radio waves and infrared. Terahertz flashes can be generated with devices called free-electron lasers that send accelerated electrons on a well defined slalom course. The particles emit electromagnetic waves in each bend that add up to an intense laser like pulse. The terahertz pulse changes the strength of the interaction between water molecules in a very short time, which immediately start to vibrate violently.
The scientists calculated the interaction of the terahertz flash with bulk water. The simulations were performed at the Supercomputer Center Jülich and used a total of 200,000 hours of processor time by massively parallel computing. On a single processor machine this would correspond to about 20 years of computation. "We have calculated that it should be possible to heat up the liquid to about 600 degrees Celsius within just half a picosecond, obtaining a transiently hot and structureless environment still at the density of the liquid, leaving all water molecules intact," explains Vendrell.
The novel method can only heat about one nanolitre (billionth of a liter) in one go. This may sound small, but is large enough for most experiments. For comparison, ink-jet printers fire droplets that are as small as one picolitre, which is a thousand times less than a nanolitre.
Any areas of water could be off-limits to all but the cleanest spacecraft.
Dark streaks that hint at seasonally flowing water have been spotted near the equator of Mars1. The potentially habitable oases are enticing targets for research. But spacecraft will probably have to steer clear of them unless the craft are carefully sterilized — a costly safeguard against interplanetary contamination that may rule out the sites for exploration.
River-like valleys attest to the flow of water on ancient Mars, but today the planet is dry and has an atmosphere that is too thin to support liquid water on the surface for long. However, intriguing clues suggest that water may still run across the surface from time to time.
In 2011, for example, researchers who analysed images from NASA's Mars Reconnaissance Orbiter (MRO) spacecraft observed dark streaks a few metres wide that appeared and lengthened at the warmest time of the year, then faded in cooler seasons, reappearing in subsequent years2. "This behaviour is easy to understand if these are seeps of water," says planetary scientist Alfred McEwen of the University of Arizona in Tucson, who led that study. "Water will darken most soils."
The streaks, known as recurring slope lineae, initially were found at seven sites in Mars's southern mid-latitudes. The water may have come from ice trapped about a metre below the surface; indeed, the MRO has spotted such ice in fresh impact craters at those latitudes.
McEwen and his colleagues have now found the reappearing streaks near the equator, including in the gargantuan Valles Marineris canyon that lies just south of it. The MRO has turned up 12 new sites — each of which has hundreds or thousands of streaks — within 25 degrees of the equator. The temperatures there are relatively warm throughout the year, says McEwen, and without a mechanism for replenishment, any subsurface ice would probably already have sublimated.
The possibility of running water could put the sites off-limits for future spacecraft unless they are carefully sterilized. The international guidelines of the Committee on Space Research (COSPAR) of the Paris-based International Council for Science say that sites that may host life, called 'special regions', should only be visited by probes that have been thoroughly treated to prevent microbes from hitching a ride from Earth. "You wouldn't want to send a dirty spacecraft to these places because you'd have the potential to not discover what you're looking for, but what you took with you," says John Rummel, chair of COSPAR's panel on planetary protection.
Baile Zhang, an assistant professor of physics at Nanyang Technological University in Singapore, has used the light-bending qualities of calcite - a cheap and abundant mineral that is a form of calcium carbonate - to create the first macroscopic invisibility cloak. Zhang originally came up with the technology in 2010. This short video clip is similar to what he recently demonstrated on stage at TED2013. He is placing a piece of calcite over a rolled-up Post-it note submerged in oil, making the pink tube appear to disappear. This research has applications in imaging, communication, and defense.
UC Berkeley scientists have developed a system to capture visual activity in human brains and reconstruct it as digital video clips. Eventually, this process will allow you to record and reconstruct your own dreams on a computer screen.
I just can't believe this is happening for real, but according to Professor Jack Gallant—UC Berkeley neuroscientist and coauthor of the research published today in the journal Current Biology—"this is a major leap toward reconstructing internal imagery. We are opening a window into the movies in our minds."
Indeed, it's mindblowing. I'm simultaneously excited and terrified. This is how it works: They used three different subjects for the experiments—incidentally, they were part of the research team because it requires being inside a functional Magnetic Resonance Imaging system for hours at a time. The subjects were exposed to two different groups of Hollywood movie trailers as the fMRI system recorded the brain's blood flow through their brains' visual cortex.
The readings were fed into a computer program in which they were divided into three-dimensional pixels units called voxels (volumetric pixels). This process effectively decodes the brain signals generated by moving pictures, connecting the shape and motion information from the movies to specific brain actions. As the sessions progressed, the computer learned more and more about how the visual activity presented on the screen corresponded to the brain activity.
After recording this information, another group of clips was used to reconstruct the videos shown to the subjects. The computer analyzed 18 million seconds of random YouTube video, building a database of potential brain activity for each clip. From all these videos, the software picked the one hundred clips that caused a brain activity more similar to the ones the subject watched, combining them into one final movie. Although the resulting video is low resolution and blurry, it clearly matched the actual clips watched by the subjects.
Think about those 18 million seconds of random videos as a painter's color palette. A painter sees a red rose in real life and tries to reproduce the color using the different kinds of reds available in his palette, combining them to match what he's seeing. The software is the painter and the 18 million seconds of random video is its color palette. It analyzes how the brain reacts to certain stimuli, compares it to the brain reactions to the 18-million-second palette, and picks what more closely matches those brain reactions. Then it combines the clips into a new one that duplicates what the subject was seeing. Notice that the 18 million seconds of motion video arenot what the subject is seeing. They are random bits used just to compose the brain image.
Given a big enough database of video material and enough computing power, the system would be able to re-create any images in your brain. Right now, the resulting quality is not good, but the potential is enormous. Lead research author—and one of the lab test bunnies—Shinji Nishimoto thinks this is the first step to tap directly into what our brain sees and imagines: "Our natural visual experience is like watching a movie. In order for this technology to have wide applicability, we must understand how the brain processes these dynamic visual experiences".
The brain recorders of the future - Imagine that. Capturing your visual memories, your dreams, the wild ramblings of your imagination into a video that you and others can watch with your own eyes.
This is the first time in history that we have been able to decode brain activity and reconstruct motion pictures in a computer screen. The path that this research opens boggles the mind. It reminds me of Brainstorm, the cult movie in which a group of scientists lead by Christopher Walken develops a machine capable of recording the five senses of a human being and then play them back into the brain itself.
This new development brings us closer to that goal which, I have no doubt, will happen at one point. Given the exponential increase in computing power and our understanding of human biology, I think this will arrive sooner than most mortals expect. Perhaps one day you would be able to go to sleep wearing a flexible band labeled Sony Dreamcam around your skull.
This video assembly presents the activities of the carboncopies.org non-profit advancing substrate-independent minds, whole brain emulation, mind uploading, neuroprostheses and neural interfaces. The future has just begun!
With a wingspan estimated at seven meters across, Argentavis was roughly twice the size of the largest flying bird today (Wandering Albatross), and only the long extinct pterosaurs could have rivaled and exceeded it for size. How such a large bird like Argentavis could fly has been the key area of study associated with this bird, something that has resulted in some interesting conclusions. The first is that the keel of the breastbone is quite small which suggests the main flight muscles were reduced when compared to other flying birds. This means that even though the wings were huge, Argentavis did not have the stamina to continuously flap them.
It’s most likely that as a result of these under developed muscles Argentavis relied upon prevailing wind currents to keep itself aloft with flapping only occurring during the take-off and landing phases. This would see Argentavis using its large wings to exploit a combination of thermal up draughts as well as dynamic soaring. Dynamic soaring is essentially where a flying creature uses the boundary between two air masses to pick up speed by cartwheeling into oncoming wind and using the wind speed to accelerate itself forward. Repeating this process further increases the speed of the bird and resulting effect of the next manoeuvre resulting in an extremely energy efficient form of flight, one that is now even used by human glider pilots to stay airborne longer.
Argentavis also seems to have relied more upon air currents for taking off as the immense size of its wings means that it could not flap them when outstretched without the tips hitting the ground. Instead Argentavis would have had an easier time just stretching out its wings and facing into the oncoming wind.
From this position Argentavis could run into the prevailing wind to get air moving across its wing surfaces and then use its legs to jump up into the air. This would be the most critical time for Argentavis as getting airborne is not the same as staying airborne (ask any pilot). However, if Argentavis had positioned itself to run down a slope it could have gotten itself airborne while increasing the distance between itself and the ground just by flying horizontally level. Argentavis could then flap its wings while it adjusted its course to take better advantage of the air currents.
During the 20th century, sea levels along the highly populated U.S. Mid-Atlantic coastline between New York and Virginia rose faster than in any other century during the past 4,300 years, according to a new study. And as those sea levels continue to increase as a result of global warming and local land elevation changes, the risks of coastal flooding will dramatically escalate.
The study, by geoscientists at Rutgers and Tufts Universities and published in the new journal “Earth’s Future,” took a comprehensive look at the history of sea level in the Mid-Atlantic, combining sediment records of prehistoric sea level with modern data, which includes readings from tide gauges and satellite instruments. The result is one of the most in-depth examinations of past, present, and future sea level rise of any region in the U.S.
To put recent rates of sea level rise into historical perspective, the study found there is at least a 95 percent probability that the rate of sea level rise in the Mid-Atlantic during the 20th century was faster than any century in the past 4,300 years, and a 67 percent probability that it was faster than any century in more than 6,600 years.
“The sea level rise that we’re seeing now is very significant,” including in a “prehistoric context,” said study co-author Ben Horton of Rutgers University, in an interview.
Assuming continued groundwater extraction rates at coastal plain locations, those areas would see a greater amount of sea level rise, the study found. The study projected that those areas could be in for a rise of 9.8 inches by 2030, 1.5 feet by 2050, and about 3.5 feet, by 2100.
While the study shows that the main component of future sea level rise will be from global sea level rise, local land elevation changes should be factored into development decisions, since they will influence the rate and extent of relative sea level rise at the local level. The study noted that there are currently limited tools for policymakers to use to factor in sea level rise to the planning process.
The hole in the ozone layer is stabilizing but will take until about 2070 to fully recover, according to new research by NASA scientists.
The assessment comes more than two decades after the Montreal Protocol, the international treaty that banned chlorofluorocarbons and other compounds that deplete the ozone layer, which shields the planet from harmful ultraviolet rays.
Levels of chlorine in the atmosphere are falling as a result of the treaty, but have not yet dropped below the threshold necessary to have a shrinking effect on the ozone hole that forms each year over Antarctica, according to scientists at NASA's Goddard Space Flight Center. They presented their findings this week at the annual meeting of the American Geophysical Union in San Francisco.
For now, year-to-year variations in temperature and winds, which each year carry ozone from the tropics to polar regions, are the driving factors in the size of the hole.
In 2006, the ozone hole grew larger than ever. It reached a similar extent in 2011, before shrinking to its second-smallest size in 2012. Naturally occurring meteorological conditions were mostly responsible for those fluctuations, two NASA studies found.
Over the next two decades scientists expect the ozone hole to continue to vary widely. "It’s not going to be a smooth ride," said Susan Strahan, a senior research scientist at NASA. "There will be some bumps in the road, but overall the trend is downward."
Not until chlorine falls below 1990s levels, a milestone scientists predict for sometime between 2015 and 2030, will the phase-out of ozone-depleting substances begin to have a discernible effect.
Pigeons come in all colors, shapes, and sizes. Some have feathers reaching up over their heads like a hood. Others have feathers all the way to the tips of their toes or fanned out on their tails like tiny turkeys.
"Most people think of pigeons as rats of the sky, but domestic pigeon breeds are wonderfully diverse," said Michael Shapiro of the University of Utah. "There are over 350 breeds that differ in color and color pattern, body size, beak size and shape, skeletal structure, posture, feather placement, and behavior. Our goal is to track down the DNA-level changes that control some of these interesting differences among breeds."
In fact, it's fair to say that pigeons are more diverse than any other bird species out there. In the new study, genetic comparisons of 361 individuals representing 70 domestic pigeon breeds and two free-living populations yielded some surprises.
In many cases, species with similarly bold traits are indeed closely related. But in other instances that isn't so. That means some of the pigeons' distinct characteristics may have arisen more than once on different branches of the birds' family tree or spread from one branch to another through interbreeding.
Shapiro's team also found that two feral pigeon populations -- one in Salt Lake City and another in Scotland -- have mixed with racing breeds, such that they are now genetically very similar to those used in competitions around the world.
All those pigeon breeds wouldn't exist but for the hard work and careful breeding of pigeon fanciers around the world over thousands of years, Shapiro says. Modern breeds are frequently described as having origins in England, Germany, Belgium, or elsewhere in Europe, but their progenitors were probably brought there from afar by traders or colonialists, the researchers write. Indeed, the new work traces the geographic origin of some breed groups to India and the Middle East.
The story of the pigeon is a lot like that of the familiar family dog, Shapiro notes. It's also one that holds a very special place in the history of modern evolutionary thought. Charles Darwin himself was a real pigeon aficionado, relying heavily on artificial selection in pigeons to describe how natural selection works in the wild. In his classic book The Origin of Species, many pages are dedicated to the pigeon.
As for the future, the researchers say that studies of pigeons might also help to explain variation among wild birds and perhaps other animals as well.
"The striking differences we see between breeds within this single species are characteristic of the types of differences we typically see between species," Shapiro said. "Our hope is that by understanding the genes that control pigeon diversity, we'll have a great starting point to understand diversity in the wild."
Spider webs actively spring towards prey thanks to electrically conductive glue spread across their surface, Oxford University scientists have discovered.
The researchers found that the electrostatic properties of the glue that coats spider webs causes them to reach out to grab all charged particles, from pollen and pollutants to flying insects. They also showed that the glue spirals can distort the Earth's electric field within a few millimetres of the web, which may enable insects to spot the webs with their antennae 'e-sensors'.
The study, published in Naturwissenschaften, shows how a quirk of physics causes webs to move towards all airborne objects, regardless of whether they are positively or negatively charged. This explains how webs are able to collect small airborne particles so efficiently and why they spring towards insects.
According to the researchers, common garden spider webs around the world could be used for environmental monitoring as they actively filter airborne pollutants with an efficiency comparable to expensive industrial sensors.
'The elegant physics of these webs make them perfect active filters of airborne pollutants including aerosols and pesticides,' said Professor Fritz Vollrath of Oxford University's Department of Zoology, who led the study. 'Electrical attraction drags these particles to the webs, so you could harvest and test webs to monitor pollution levels – for example, to check for pesticides that might be harming bee populations.
'Even more fascinating, you would be able to detect some airborne chemicals just by looking at the shape of the webs! Many spiders recycle their webs by eating them, and would include any particles and chemicals that are electrically drawn to the web. We already know that spiders spin different webs when on different drugs, for example creating beautiful webs on LSD and terrible webs on caffeine. As a result, the web shapes alone can tell us if any airborne chemicals affect the animal's behavior.'