Thursday, April 23, 2015

Earth Formed from Millimeter Sized Stones

Fragments of asteroids regularly land on Earth as meteorites. If you examine such a find, you can see that it comprises millimetre-sized round stones, known as chondrules. These small particles are believed to be the original building blocks of the solar system. However, the research community has not previously been able to explain how the chondrules formed asteroids. A new study shows that asteroids were formed by capturing chondrules with the help of gravitational force.

Earth formed from millimeter sized stones
Credit: Lund University

"The chondrules are of exactly the right size to be slowed down by the gas that orbited the young sun, and they could then be captured by the asteroids' gravity", says Dr Anders Johansen, an astronomy researcher at Lund University.

"This causes them to fall down and accumulate like sand piling up in a sandstorm", adds co-author Mordecai-Mark Mac Low from the American Museum of Natural History.

Working with colleagues from the USA, Denmark and Germany, Anders Johansen has developed a computer simulation for what the process may have looked like. They assumed that the asteroids were formed in a kind of cosmic ocean of chondrules and that the asteroids started out much smaller than they are today.

According to the computer simulations, the asteroids grew quickly to a diameter of up to 1 000 km, the same size as those found today in the asteroid belt between Mars and Jupiter. The largest asteroids continued to grow to the same mass as the planet Mars, which has ten per cent of the mass of Earth.

"We suddenly realised that this rapid process could say something about the formation of the Earth as well", explains Anders Johansen.

The research community had previously believed that the Earth was formed through collisions between protoplanets, of the size of Mars, over a period of 100 million years. However, the researchers have not yet understood how the protoplanets themselves were formed.

"Our study shows that protoplanets may have formed very quickly from asteroids, by capturing chondrules in the same way as the asteroids did", says Martin Bizzarro, an expert on chondrules from Copenhagen University and also co-author of the paper.

The researchers' theory is supported by studies of meteorites from Mars. These studies have previously shown that Mars was formed over a period of only 1-3 million years, which is within the same time span as the researchers have obtained in the computer simulation.

"Traces of this process remain in asteroids that still contain intact chondrules. The terrestrial planets, however, have all melted after their birth and therefore do not show any direct traces of their original building blocks", concludes Anders Johansen.

The study has been published in the journal Science Advances.

Contacts and sources:
Dr. Anders Johansen
Lund University

Scientists Create the Sensation of Invisibility

The power of invisibility has long fascinated man and inspired the works of many great authors and philosophers. In a study from Sweden's Karolinska Institutet, a team of neuroscientists now reports a perceptual illusion of having an invisible body, and show that the feeling of invisibility changes our physical stress response in challenging social situations.

Ph.D. student Zakaryah Abdulkarim, M.D., shows how to create the illusion of invisibility in the lab (photomontage).
Credit: Staffan Larsson

The history of literature features many well-known narrations of invisibility and its effect on the human mind, such as the myth of Gyges' ring in Plato's dialogue The Republic and the science fiction novel The Invisible Man by H.G. Wells. Recent advances in materials science have shown that invisibility cloaking of large-scale objects, such as a human body, might be possible in the not-so-distant future; however, it remains unknown how invisibility would affect our brain and body perception.

In an article in the journal Scientific Reports, the researchers describe a perceptual illusion of having an invisible body. The experiment involves the participant standing up and wearing a set of head-mounted displays. The participant is then asked to look down at her body, but instead of her real body she sees empty space. To evoke the feeling of having an invisible body, the scientist touches the participant's body in various locations with a large paintbrush while, with another paintbrush held in the other hand, exactly imitating the movements in mid-air in full view of the participant.

"Within less than a minute, the majority of the participants started to transfer the sensation of touch to the portion of empty space where they saw the paintbrush move and experienced an invisible body in that position," says Arvid Guterstam, lead author of the present study. "We showed in a previous study that the same illusion can be created for a single hand. The present study demonstrates that the 'invisible hand illusion' can, surprisingly, be extended to an entire invisible body."

The study examined the illusion experience in 125 participants. To demonstrate that the illusion actually worked, the researchers would make a stabbing motion with a knife toward the empty space that represented the belly of the invisible body. The participants' sweat response to seeing the knife was elevated while experiencing the illusion but absent when the illusion was broken, which suggests that the brain interprets the threat in empty space as a threat directed toward one's own body.

In another part of the study, the researchers examined whether the feeling of invisibility affects social anxiety by placing the participants in front of an audience of strangers.

"We found that their heart rate and self-reported stress level during the 'performance' was lower when they immediately prior had experienced the invisible body illusion compared to when they experienced having a physical body," says Arvid Guterstam. "These results are interesting because they show that the perceived physical quality of the body can change the way our brain processes social cues."

The researches hope that the results of the study will be of value to future clinical research, for example in the development of new therapies for social anxiety disorder.

"Follow-up studies should also investigate whether the feeling of invisibility affects moral decision-making, to ensure that future invisibility cloaking does not make us lose our sense of right and wrong, which Plato asserted over two millennia ago," says principal investigator Dr. Henrik Ehrsson, professor at the Department of Neuroscience.

Contacts and sources:
Karolinska Institutet

This research was funded by the Swedish Research Council, and the Söderberg Foundation.

Publikation: 'Illusory ownership of an invisible body reduces autonomic and subjective social anxiety responses', Arvid Guterstam, Zakaryah Abdulkarim & Henrik Ehrsson, Scientific Reports, online 23 April 2015, doi: 10.1038/srep09831.

Huge Magma Reservoir Discovered beneath Yellowstone's Magma Chamber

University of Utah seismologists discovered and made images of a reservoir of hot, partly molten rock 12 to 28 miles beneath the Yellowstone supervolcano, and it is 4.4 times larger than the shallower, long-known magma chamber.

The hot rock in the newly discovered, deeper magma reservoir would fill the 1,000-cubic-mile Grand Canyon 11.2 times, while the previously known magma chamber would fill the Grand Canyon 2.5 times, says postdoctoral researcher Jamie Farrell, a co-author of the study published online today in the journal Science.
A new University of Utah study in the journal Science provides the first complete view of the plumbing system that supplies hot and partly molten rock from the Yellowstone hotspot to the Yellowstone supervolcano. The study revealed a gigantic magma reservoir beneath the previously known magma chamber. This cross-section illustration cutting southwest-northeast under Yelowstone depicts the view revealed by seismic imaging. Seismologists say new techniques have provided a better view of Yellowstone's plumbing system, and that it hasn't grown larger or closer to erupting. They estimate the annual chance of a Yellowstone supervolcano eruption is 1 in 700,000.
Credit: Hsin-Hua Huang, University of Utah

"For the first time, we have imaged the continuous volcanic plumbing system under Yellowstone," says first author Hsin-Hua Huang, also a postdoctoral researcher in geology and geophysics. "That includes the upper crustal magma chamber we have seen previously plus a lower crustal magma reservoir that has never been imaged before and that connects the upper chamber to the Yellowstone hotspot plume below."

Contrary to popular perception, the magma chamber and magma reservoir are not full of molten rock. Instead, the rock is hot, mostly solid and spongelike, with pockets of molten rock within it. Huang says the new study indicates the upper magma chamber averages about 9 percent molten rock - consistent with earlier estimates of 5 percent to 15 percent melt - and the lower magma reservoir is about 2 percent melt.

So there is about one-quarter of a Grand Canyon worth of molten rock within the much larger volumes of either the magma chamber or the magma reservoir, Farrell says.

No increase in the danger

The researchers emphasize that Yellowstone's plumbing system is no larger - nor closer to erupting - than before, only that they now have used advanced techniques to make a complete image of the system that carries hot and partly molten rock upward from the top of the Yellowstone hotspot plume - about 40 miles beneath the surface - to the magma reservoir and the magma chamber above it.

NSF Yellowstone Discovery Video from The University of Utah on Vimeo.

"The magma chamber and reservoir are not getting any bigger than they have been, it's just that we can see them better now using new techniques," Farrell says.

Study co-author Fan-Chi Lin, an assistant professor of geology and geophysics, says: "It gives us a better understanding the Yellowstone magmatic system. We can now use these new models to better estimate the potential seismic and volcanic hazards."

The researchers point out that the previously known upper magma chamber was the immediate source of three cataclysmic eruptions of the Yellowstone caldera 2 million, 1.2 million and 640,000 years ago, and that isn't changed by discovery of the underlying magma reservoir that supplies the magma chamber.

"The actual hazard is the same, but now we have a much better understanding of the complete crustal magma system," says study co-author Robert B. Smith, a research and emeritus professor of geology and geophysics at the University of Utah.

The three supervolcano eruptions at Yellowstone - on the Wyoming-Idaho-Montana border - covered much of North America in volcanic ash. A supervolcano eruption today would be cataclysmic, but Smith says the annual chance is 1 in 700,000.

Before the new discovery, researchers had envisioned partly molten rock moving upward from the Yellowstone hotspot plume via a series of vertical and horizontal cracks, known as dikes and sills, or as blobs. They still believe such cracks move hot rock from the plume head to the magma reservoir and from there to the shallow magma chamber.

Anatomy of a supervolcano

The study in Science is titled, "The Yellowstone magmatic system from the mantle plume to the upper crust." Huang, Lin, Farrell and Smith conducted the research with Brandon Schmandt at the University of New Mexico and Victor Tsai at the California Institute of Technology. Funding came from the University of Utah, National Science Foundation, Brinson Foundation and William Carrico.

Yellowstone is among the world's largest supervolcanoes, with frequent earthquakes and Earth's most vigorous continental geothermal system.

The three ancient Yellowstone supervolcano eruptions were only the latest in a series of more than 140 as the North American plate of Earth's crust and upper mantle moved southwest over the Yellowstone hotspot, starting 17 million years ago at the Oregon-Idaho-Nevada border. The hotspot eruptions progressed northeast before reaching Yellowstone 2 million years ago.

Here is how the new study depicts the Yellowstone system, from bottom to top:

-- Previous research has shown the Yellowstone hotspot plume rises from a depth of at least 440 miles in Earth's mantle. Some researchers suspect it originates 1,800 miles deep at Earth's core. The plume rises from the depths northwest of Yellowstone. The plume conduit is roughly 50 miles wide as it rises through Earth's mantle and then spreads out like a pancake as it hits the uppermost mantle about 40 miles deep. Earlier Utah studies indicated the plume head was 300 miles wide. The new study suggests it may be smaller, but the data aren't good enough to know for sure.

-- Hot and partly molten rock rises in dikes from the top of the plume at 40 miles depth up to the bottom of the 11,200-cubic mile magma reservoir, about 28 miles deep. The top of this newly discovered blob-shaped magma reservoir is about 12 miles deep, Huang says. The reservoir measures 30 miles northwest to southeast and 44 miles southwest to northeast. "Having this lower magma body resolved the missing link of how the plume connects to the magma chamber in the upper crust," Lin says.

-- The 2,500-cubic mile upper magma chamber sits beneath Yellowstone's 40-by-25-mile caldera, or giant crater. Farrell says it is shaped like a gigantic frying pan about 3 to 9 miles beneath the surface, with a "handle" rising to the northeast. The chamber is about 19 miles from northwest to southeast and 55 miles southwest to northeast. The handle is the shallowest, long part of the chamber that extends 10 miles northeast of the caldera.

Scientists once thought the shallow magma chamber was 1,000 cubic miles. But at science meetings and in a published paper this past year, Farrell and Smith showed the chamber was 2.5 times bigger than once thought. That has not changed in the new study.

Discovery of the magma reservoir below the magma chamber solves a longstanding mystery: Why Yellowstone's soil and geothermal features emit more carbon dioxide than can be explained by gases from the magma chamber, Huang says. Farrell says a deeper magma reservoir had been hypothesized because of the excess carbon dioxide, which comes from molten and partly molten rock.

A better, deeper look at Yellowstone

As with past studies that made images of Yellowstone's volcanic plumbing, the new study used seismic imaging, which is somewhat like a medical CT scan but uses earthquake waves instead of X-rays to distinguish rock of various densities. Quake waves go faster through cold rock, and slower through hot and molten rock.

For the new study, Huang developed a technique to combine two kinds of seismic information: Data from local quakes detected in Utah, Idaho, the Teton Range and Yellowstone by the University of Utah Seismograph Stations and data from more distant quakes detected by the National Science Foundation-funded EarthScope array of seismometers, which was used to map the underground structure of the lower 48 states.

The Utah seismic network has closely spaced seismometers that are better at making images of the shallower crust beneath Yellowstone, while EarthScope's seismometers are better at making images of deeper structures.

"It's a technique combining local and distant earthquake data better to look at this lower crustal magma reservoir," Huang says.

Contacts and sources:
Lee J. Siegel
University of Utah 

11 Runaway Galaxies Found

We know of about two dozen runaway stars, and have even found one runaway star cluster escaping its galaxy forever. Now, astronomers have spotted 11 runaway galaxies that have been flung out of their homes to wander the void of intergalactic space.

This schematic illustrates the creation of a runaway galaxy. In the first panel, an "intruder" spiral galaxy approaches a galaxy cluster center, where a compact elliptical galaxy (cE) already revolves around a massive central elliptical galaxy. In the second panel, a close encounter occurs and the compact elliptical receives a gravitational kick from the intruder. In the third panel, the compact elliptical escapes the galaxy cluster while the intruder is devoured by the giant elliptical galaxy in the cluster center.

Credit:  NASA, ESA, and the Hubble Heritage Team

"These galaxies are facing a lonely future, exiled from the galaxy clusters they used to live in," said astronomer Igor Chilingarian (Harvard-Smithsonian Center for Astrophysics/Moscow State University). Chilingarian is the lead author of the study, which is appearing in the journalScience.

An object is a runaway if it's moving faster than escape velocity, which means it will depart its home never to return. In the case of a runaway star, that speed is more than a million miles per hour (500 km/s). A runaway galaxy has to race even faster, traveling at up to 6 million miles per hour (3,000 km/s).

Chilingarian and his co-author, Ivan Zolotukhin (L'Institut de Recherche en Astrophysique et Planetologie/Moscow State University), initially set out to identify new members of a class of galaxies called compact ellipticals. These tiny blobs of stars are bigger than star clusters but smaller than a typical galaxy, spanning only a few hundred light-years. In comparison, the Milky Way is 100,000 light-years across. Compact ellipticals also weigh 1000 times less than a galaxy like our Milky Way.

Prior to this study, only about 30 compact elliptical galaxies were known, all of them residing in galaxy clusters. To locate new examples Chilingarian and Zolotukhin sorted through public archives of data from the Sloan Digital Sky Survey and the GALEX satellite.

Their search identified almost 200 previously unknown compact ellipticals. Of those, 11 were completely isolated and found far from any large galaxy or galaxy cluster.

"The first compact ellipticals were all found in clusters because that's where people were looking. We broadened our search, and found the unexpected," said Zolotukhin.

These isolated compact galaxies were unexpected because theorists thought they originated from larger galaxies that had been stripped of most of their stars through interactions with an even bigger galaxy. So, the compact galaxies should all be found near big galaxies.

Not only were the newfound compact ellipticals isolated, but also they were moving faster than their brethren in clusters.

"We asked ourselves, what else could explain them? The answer was a classic three-body interaction," stated Chilingarian.

A hypervelocity star can be created if a binary star system wanders close to the black hole at the center of our galaxy. One star gets captured while the other is thrown away at tremendous speed.

Similarly, a compact elliptical could be paired with the big galaxy that stripped it of its stars. Then a third galaxy blunders into the dance and flings the compact elliptical away. As punishment, the intruder gets accreted by the remaining big galaxy.

This discovery represents a prominent success of the Virtual Observatory - a project to make data from large astronomical surveys easily available to researchers. So-called data mining can result in finds never anticipated when the original data was collected.

"We recognized we could use the power of the archives to potentially unearth something interesting, and we did," added Chilingarian.

Contacts and sources:
Christine Pulliam
Harvard-Smithsonian Center for Astrophysics

Entire Galaxy Flung From Its Home Cluster

Astronomers think, that there are dozens of billions undetectable free floating planets that straggle along our Milky Way galaxy, being not gravitationally bound to any star. Moreover, there are about two dozens known stars that escaped from our Galaxy at high velocities, and even one runaway star cluster hosting a million stars that fled the giant galaxy Messier87 in the Virgo cluster.

An artwork demonstrates several stages of the process of a close three-body encounter with a gravitation kick of a compact elliptical galaxy that explains the phenomenon of an isolated compact elliptical galaxy.
Credit:  ESA/Hubble. Artwork by Andrey Zolotov

All those objects have one thing in common - they have been thrown away from their home systems by gravitational perturbations. Two Russian astronomers, Igor Chilingarian and Ivan Zolotukhin of Sternberg Astronomical Institute, Moscow State University, who currently works at Harvard-Smithsonian Center for Astrophysics, USA and L'Institut de Recherche en Astrophysique et Planétologie, Toulouse, France, respectively, have shown that some galaxies can also be thrown away from their host clusters and groups by interacting with their neighbours.

Until 2006 scientists knew only 6 extremely compact elliptical galaxies like the Andromeda satellite Messier32 that host up-to several billion stars. They are so small, that they look like stripped cores of ordinary galaxies. All these stellar systems were found next to giant galaxies in centers of large clusters of galaxies. Numerical simulations demonstrated that these compact ellipticals could be the remnants of ancient larger galaxies, stripped out to the central core by tidal interactions with a massive galaxy after falling on it. In 2009 Igor Chilingarian discovered another 20 such rare galaxies.

However, in 2013, the first compact elliptical was found far away from any massive galaxy, so that it became unclear where it came from and whether it was formed through tidal stripping. It became clear that astronomers should search such objects not only in clusters of galaxies and groups, but also between them.

Chilingarian and Zolotukhin have processed a huge amount of astronomical data, publicly available thanks to the Virtual Observatory initiative. They discovered almost 200 additional compact ellipticals. Most of them, as expected, were found inside massive clusters and groups of galaxies, but 11 are indeed isolated, flying free in space some millions of light years from nearest clusters.

"We asked ourselves, how we could explain them?", -- stated Igor Chilingarian, the first author of the paper that will appear in the journal Science. As far as isolated compact ellipticals and those found in clusters shared very similar properties, it looked like they must have had the common origin in the past. Initially, a massive galaxy in a cluster striped away outer parts of a an in-falling smaller galaxy, leaving behind only a compact core, and later, some other galaxy threw this core away into the inter-cluster space.

Similar processes are known to take place near Milky Way's center: a supermassive black hole can fling away one of two stars in a binary system, that came too close to it, and swallow the other one.

"This is the same phenomenon, but working on a different scale, a slingshot effect, when during a three-body encounter the lightest body flies away from the system", -- explained Zolotukhin. To support this statement, astronomers analyzed the velocity spread of compact ellipticals in galaxy clusters that shows that some of them are on a verge of escaping their host clusters.

"These small galaxies face a lonely future, exiled from galaxy clusters they were formed and used to live in", -- Igor Chilingarian said. But this helps them to survive, because otherwise they would spiral in and be devoured by their massive hosts in about a billion years.

To escape the Earth, a body must be thrown faster than 11 km/s, to leave the Solar system from the Earth's orbit that speed is over 42 km/s. A galaxy has to reach approximately 2500 km/s in order to run away, astronomers calculated. Chilingarian and Zolotukhin hope their discovery will shed light on the structure and evolution of compact elliptical galaxies, because they think that these galaxies don't contain dark matter that is thought keeps stable most galaxies of other types.

This is the first time when an astronomical discovery published in interdisciplinary journal made without a single new photon collected but based solely on publicly available observations. This is a new era in astronomy, when any Internet user can use observations in archives and make discoveries from her or his office without the need to travel to an observatory and collect the data.

Contacts and sources:
Vladimir Koryagin
Moscow State University

Wednesday, April 22, 2015

Light Converts To Storable Energy When Pseudoparticles Travel through Photoactive Material

Researchers of Karlsruhe Institute of Technology (KIT) have unveiled an important step in the conversion of light into storable energy: Together with scientists of the Fritz Haber Institute in Berlin and the Aalto University in Helsinki/Finland, they studied the formation of so-called polarons in zinc oxide.

Using the photoactive zinc oxide material, scientists studied the formation and migration of so-called polarons. 
Credit: Patrick Rinke/Aalto University

 The pseudoparticles travel through the photoactive material until they are converted into electrical or chemical energy at an interface. Their findings that are of relevance to photovoltaics among others are now published in the renowned journal Nature Communications.

Processes converting light into storable energy may contribute decisively to a sustainable energy supply. For billions of years, nature has been using such processes for photosynthesis to form carbohydrates with the help of light. In research, phototcatalysis that uses light to accelerate chemical processes is gaining importance. In the past years, researchers also achieved considerable progress in photovoltaics converting incident sunlight directly into electrical energy. Efficiency constantly improved.

However, the processes underlying photovoltaics have hardly been studied in detail so far. “Conversion of photons, i.e. light particles, into electricity takes several steps,” Professor Christof Wöll, Head of the Institute of Functional Interfaces (IFG) of KIT, explains. 

First, light is absorbed in a photoactive material. Single electrons are removed from their site and leave a hole there. The electron-hole pairs are stable for a short term only. Then, they either decay under the emission of light or are separated into an electron and a hole that move in the material independently of each other. The fate of this charged particle then depends on the material.

In most materials, free holes are not stable, but converted into so-called polarons under energy loss. A polaron is a special pseudoparticle composed of a particle and its interaction with the environment. The polarons formed are stable for a longer term and travel through the photoactive material until they are converted into electrical or chemical energy at an interface.

Researchers of KIT under the direction of Professor Christof Wöll have now carried out experiments using photoactive zinc oxide material in order to study the formation and migration of polarons. They employed a worldwide unique experimental setup for infrared reflection absorption spectroscopy (IRRAS) with a temporal resolution of 100 milliseconds and measured infrared spectra of zinc oxide monocrystals and observed intensive absorption bands, i.e. fingerprints, of a so far unknown pseudoparticle. 

Interpretation of the data and identification of this new particle were big challenges for the KIT scientists. In cooperation with a group working at the Fritz Haber Institute and the Excellence Center for Computational Nanoscience (COMP) of Aalto University, however, they succeeded in unambiguously allocating the absorption bands to so-called hole polarons. “This is an important finding made in 2015, the International Year of Light and Light-based Technologies,” Professor Wöll says.

Contacts and sources:
Karlsruhe Institute of Technology (KIT)

Citation:  Hikmet Sezen, Honghui Shang, Fabian Bebensee, Chengwu Yang, Maria Buchholz, Alexei Nefedov, Stefan Heissler, Christian Carbogno, Matthias Scheffler, Patrick Rinke, and Christof Wöll: Evidence for photogenerated intermediate hole polarons in ZnO. Nature Communications, 22nd April 2015. DOI 10.1038/ncomms7901.

Tau Ceti: The Next Earth?

As the search continues for Earth-size planets orbiting at just the right distance from their star, a region termed the habitable zone, the number of potentially life-supporting planets grows. In two decades we have progressed from having no extrasolar planets to having too many to search. 

Narrowing the list of hopefuls requires looking at extrasolar planets in a new way. Applying a nuanced approach that couples astronomy and geophysics, Arizona State University researchers report that from that long list we can cross off cosmic neighbor Tau Ceti.

How would an alien world like this look? That's the question that ASU undergraduate art major Joshua Gonzalez attempted to answer. He worked with Professor Patrick Young's group to learn how to analyze stellar spectra to find chemical abundances, and inspired by the scientific results, he created two digital paintings of possible unusual extrasolar planets, one being Tau Ceti for his Barrett Honors Thesis.
Credit: Joshua Gonzalez 

The Tau Ceti system, popularized in several fictional works, including Star Trek, has long been used in science fiction, and even popular news, as a very likely place to have life due to its proximity to Earth and the star's sun-like characteristics. Since December 2012 Tau Ceti has become even more appealing, thanks to evidence of possibly five planets orbiting it, with two of these - Tau Ceti e and f - potentially residing in the habitable zone.

Using the chemical composition of Tau Ceti, the ASU team modeled the star's evolution and calculated its habitable zone. Although their data confirms that two planets (e and f) may be in the habitable zone it doesn't mean life flourishes or even exists there.

"Planet e is in the habitable zone only if we make very generous assumptions. Planet f initially looks more promising, but modeling the evolution of the star makes it seem probable that it has only moved into the habitable zone recently as Tau Ceti has gotten more luminous over the course of its life," explains astrophysicist Michael Pagano, ASU postdoctoral researcher and lead author of the paper appearing in the Astrophysical Journal. The collaboration also included ASU astrophysicists Patrick Young and Amanda Truitt and mineral physicist Sang-Heon (Dan) Shim.

Based upon the team's models, planet f has likely been in the habitable zone much less than 1 billion years. This sounds like a long time, but it took Earth's biosphere about 2 billion years to produce potentially detectable changes in its atmosphere. A planet that entered the habitable zone only a few hundred million years ago may well be habitable and even inhabited, but not have detectable biosignatures. 

This is an artist's impression of the Tau Ceti system.
Credit:  J. Pinfield for the RoPACS network at the University of Hertfordshire, 2012

According to Pagano, he and his collaborators didn't pick Tau Ceti "hoping, wanting, or thinking" it would be a good candidate to look for life, but for the idea that these might be truly alien new worlds.

Tau Ceti has a highly unusual composition with respect to its ratio of magnesium and silicon, which are two of the most important rock forming minerals on Earth. The ratio of magnesium to silicon in Tau Ceti is 1.78, which is about 70% more than our sun.

The astrophysicists looked at the data and asked, "What does this mean for the planets?"

Building on the strengths of ASU's School of Earth and Space Exploration, which unites earth and space scientists in an effort to tackle research questions through a holistic approach, Shim was brought on board for his mineral expertise to provide insights into the possible nature of the planets themselves.

"With such a high magnesium and silicon ratio it is possible that the mineralogical make-up of planets around Tau Ceti could be significantly different from that of Earth. Tau Ceti's planets could very well be dominated by the mineral olivine at shallow parts of the mantle and have lower mantles dominated by ferropericlase," explains Shim.

Considering that ferropericlase is much less viscous, or resistant to flowing, hot, yet solid, mantle rock would flow more easily, possibly having profound effects on volcanism and tectonics at the planetary surface, processes which have a significant impact on the habitability of Earth.

"This is a reminder that geological processes are fundamental in understanding the habitability of planets," Shim adds.

"Tau Ceti has been a popular destination for science fiction writers and everyone's imagination as somewhere there could possibly be life, but even though life around Tau Ceti may be unlikely, it should not be seen as a letdown, but should invigorate our minds to consider what exotic planets likely orbit the star, and the new and unusual planets that may exist in this vast universe," says Pagano.

Contacts and sources:
Nikki Cassis
Arizona State University

Tuesday, April 21, 2015

Myth of Tolerant Dogs and Aggressive Wolves Refuted

The good relationship between humans and dogs was certainly influenced by domestication. For long, it was assumed that humans preferred particularly tolerant animals for breeding. Thus, cooperative and less aggressive dogs could develop. Recently, however, it was suggested that these qualities were not only specific for human-dog interactions, but characterize also dog-dog interactions. Friederike Range and Zsófia Virányi from the Messerli Research Institute investigated in their study if dogs are in fact less aggressive and more tolerant towards their conspecifics than wolves.
Wolves are more tolerant towards conspecifics than dogs.
Credit: Walter Vorbeck
They carried out several behavioural tests on dogs and wolves. The animals were hand-raised in the Wolf Science Center in Ernstbrunn, Lower Austria, and kept in separated packs of wolves and dogs. Range and her colleagues tested nine wolves and eight mongrel dogs.

Dogs express a steeper dominance hierarchy

To test how tolerant wolves and dogs are towards their pack members, pairs consisting of a high-ranked and a low-ranked animal were fed together. They were fed either a bowl of raw meat or a large bone.

While low-ranked wolves often defended their food against the high-ranked partner and showed aggressive behaviour as often as higher-ranked wolves, this was different in dogs. Low-ranked dogs held back and accepted the threats of the dominant dog. Overall, however, neither wolves nor dogs showed a lot of aggressive behaviour. If any, they showed threat signs.

"Wolves seem to be more tolerant towards conspecifics than dogs that seem to be more sensitive to the dominance hierarchy", explains lead author Range. "This was shown by the fact that also low-ranked wolves can challenge their higher-ranked partners and the dominant animals tolerate it, while in dogs aggression was a privilege of the higher-ranked partners."

"When humans domesticated wolves, they probably chose the submissive animals that were ready to adjust", says Virányi. Dog-human interactions are more about living together without conflicts, not about equality. Their ability to respect and follow others made dogs the ideal partners of humans.

Wolves are more tolerant than dogs

Dogs and wolves are rarely aggressive towards conspecifics. Range draws the following conclusion: "Wolves are already very tolerant to their conspecifics. This was shown by the fact that high-ranked wolves accepted the threat behaviours by their lower-ranked conspecifics in the feeding experiment. This tolerance enables wolf-wolf cooperation which in turn could have provided a good basis for the evolution of human-dog cooperation."

Contacts and sources: 
Susanna Kautschitsch 
University of Veterinary Medicine, Vienna

Citation: The article „Testing the Myth: Tolerant dogs and aggressive wolves", by Friederike Range, Caroline Ritter and Zsófia Virányi will be published in the journal Proceedings of the Royal Society B. doi: 10.1098/rspb.2015.0220


Machine Transmits Emotions Through The Air Using UltraHaptics

Human emotion can be transferred by technology that stimulates different parts of the hand without making physical contact with your body, a University of Sussex-led study has shown.

Sussex scientist Dr Marianna Obrist, Lecturer at the Department of Informatics, has pinpointed how next-generation technologies can stimulate different areas of the hand to convey feelings of, for example, happiness, sadness, excitement or fear.

For example, short, sharp bursts of air to the area around the thumb, index finger and middle part of the palm generate excitement, whereas sad feelings are created by slow and moderate stimulation of the outer palm and the area around the 'pinky' finger.

University of Sussex researchers used a system called UltraHaptics to pinpoint areas of the hand that could be stimulated to evoke different emotions.
Credit: Image courtesy of SCHI Lab, University of Sussex, copyright © 2015.

The findings, which were presented on Tuesday 21 April  at the CHI 2015 conference in South Korea, provide "huge potential" for new innovations in human communication, according to Dr Obrist.

Dr Obrist said: "Imagine a couple that has just had a fight before going to work. While she is in a meeting she receives a gentle sensation transmitted through her bracelet on the right part of her hand moving into the middle of the palm. That sensation comforts her and indicates that her partner is not angry anymore.

"These sensations were generated in our experiment using the Ultrahaptics system.

"A similar technology could be used between parent and baby, or to enrich audio-visual communication in long-distance relationships.

"It also has huge potential for 'one-to-many' communication - for example, dancers at a club could raise their hands to receive haptic stimulation that enhances feelings of excitement and stability."

Using the Ultrahaptics system - which enables creating sensations of touch through air to stimulate different parts of the hand - one group of participants in the study was asked to create patterns to describe the emotions evoked by five separate images: calm scenery with trees, white-water rafting, a graveyard, a car on fire, and a wall clock. The participants were able to manipulate the position, direction, frequency, intensity and duration of the stimulations.

A second group then selected the stimulations created by the first group that they felt best described the emotions evoked by the images. They chose the best two for each image, making a total of 10.

Finally, a third group experienced all 10 selected stimulations while viewing each image in turn and rated how well each stimulation described the emotion evoked by each image.

The third group gave significantly higher ratings to stimulations when they were presented together with the image they were intended for, proving that the emotional meaning had been successfully communicated between the first and third groups.

Now Dr Obrist has been awarded £1 million by the European Research Council for a five-year project to expand the research into taste and smell, as well as touch.

The SenseX project will aim to provide a multisensory framework for inventors and innovators to design richer technological experiences.

Dr Obrist said: "Relatively soon, we may be able to realise truly compelling and multi-faceted media experiences, such as 9-dimensional TV, or computer games that evoke emotions through taste.

"Longer term, we will be exploring how multi-sensory experiences can benefit people with sensory impairments, including those that are widely neglected in Human-Computer Interaction research, such as a taste disorder."

Catherine Bearder, Liberal Democrat MEP for south-east England, said: "I am thrilled Dr Obrist has been awarded this EU funding for her incredible research into such a ground-breaking side of science.

"This is an example of the EU investing in those research projects it sees as having great potential to change our lives."

Contacts and sources:
James Hakner
University of Sussex

Cannabis Consumers Show Greater Susceptibility to False Memories

A new study published in the American journal with the highest impact factor in worldwide, Molecular Psychiatry, reveals that consumers of cannabis are more prone to experiencing false memories.

The study was conducted by researchers from the Human Neuropsychopharmacology group at the Biomedical Research Institute of Hospital de Sant Pau ( and from Universitat Autònoma de Barcelona, in collaboration with the Brain Cognition and Plasticity group of the Bellvitge Institute for Biomedical Research (IDIBELL - University of Barcelona). 

The image shows the brain activation pattern which permits ruling out a stimulus as a false memory. In the control group, the activations are much more intense and extensive than in the group of cannabis consumers.
Credit: Universitat Autònoma de Barcelona

One of the known consequences of consuming this drug is the memory problems it can cause. Chronic consumers show more difficulties than the general population in retaining new information and recovering memories. The new study also reveals that the chronic use of cannabis causes distortions in memory, making it easier for imaginary or false memories to appear.

On occasions, the brain can remember things that never happened. Our memory consists of a malleable process which is created progressively and therefore is subject to distortions or even false memories. These memory “mistakes” are seen more frequently in several neurological and psychiatric disorders, but can also be observed in the healthy population, and become more common as we age. 

One of the most common false memories we have are of situations from our childhood which we believe to remember because the people around us have explained them to us over and over again. Maintaining an adequate control over the “veracity” of our memories is a complex cognitive task which allows us to have our own sense of reality and also shapes our behaviour, based on past experiences.

In the study published in the journal Molecular Psychiatry, researchers from Sant Pau and Bellvitge compared a group of chronic consumers of cannabis to a healthy control group while they worked on learning a series of words. After a few minutes they were once again shown the original words, together with new words which were either semantically related or unrelated. 

All participants were asked to identify the words belonging to the original list. Cannabis consumers believed to have already seen the semantically related new words to a higher degree than participants in the control group. By using magnetic resonance imaging, researchers discovered that cannabis consumers showed a lower activation in areas of the brain related to memory procedures and to the general control of cognitive resources.

The study found memory deficiencies despite the fact that participants had stopped consuming cannabis one month before participating in the study. Although they had not consumed the drug in a month, the more the patient had used cannabis throughout their life, the lower the level of activity in the hippocampus, key to storing memories.

The results show that cannabis consumers are more vulnerable to suffering memory distortions, even weeks after not consuming the drug. This suggests that cannabis has a prolonged effect on the brain mechanisms which allow us to differentiate between real and imaginary events. These memory mistakes can cause problems in legal cases, for example, due to the effects the testimonies of witnesses and their victims can have. Nevertheless, from a clinical viewpoint, the results point to the fact that a chronic use of cannabis could worsen problems with age-related memory loss.

Contacts and sources:
Universitat Autònoma de Barcelona

Citation: Telling true from false: cannabis users show increased susceptibility to false memories

New Details about Star Formation in Ancient Galaxy Protoclusters Found

Ongoing studies of distant galaxy protoclusters using the Multi-Object Infrared Camera and Spectrograph (MOIRCS) instrument on the Subaru Telescope is giving astronomers a closer look at the characteristics of star-forming regions in galaxies in the early universe. 

A team of astronomers from the National Astronomical Observatory of Japan (NAOJ) and SOKENDAI (Graduate University of Advanced Studies, Japan) are tracking velocity structures and gaseous metallicities in galaxies in two protoclusters located in the direction of the constellation Serpens. These appear around the radio galaxies PKS 1138-262 (at a redshift of 2.2, Figure 1) and USS 1558-003 (at a redshift of 2.5). The clusters appear as they would have looked 11 billion years ago, and the team concluded that they are in the process of cluster formation that has led to present-day galaxy clusters.

Figure 1: Psudo-color composite image of PKS 1138-262 region, derived from Hubble Space Telescope's ACS/WFC data archive (F814W and F475W). This region is one of the target protoclusters observed by MOIRCS on Subaru Telescope. 

Credit: NAOJ/HST

The MOIRCS near-infrared spectrograph is very effective for studies focused on the distant, early universe because strong emission lines from star-forming galaxies are redshifted from the optical to the near-infrared regime. This gives astronomers unique insights into these activities. (Note 1)

Based on the MOIRCS data, the team estimated that both protoclusters have a weight of about 10^14 solar masses (Figure 2). These follow the typical mass growth history of the today's most massive clusters, such as the 'Coma Cluster.' That makes the two protoclusters ideal laboratories for exploring early phasesof galaxy formation in a unique clustered environment.

The metallicity of the gases in the protocluster galaxies was studied using multiple spectral lines emitted from them. The result shows their gaseous metallicities are chemically enriched compared with those of galaxies in the general fields (Figure 3). Metals (elements heavier than hydrogen and helium) are created in the interiors of stars as they evolve and then released into surrounding gas through supernova explosions or stellar winds (often referred to as chemical evolution; Figure 4a).

The difference in gaseous metallicity between protoclusters and general fields suggests that star-formation histories and/or gas inflow/outflow processes should be different in the protocluster regions. The result also suggests that galaxy formation has already been influenced by environmental conditions in the era that star-formation activities are the most active across the universe. This would be an early phase of strong environmental effects seen in the present galaxy clusters.

In order to explain the metallicity excess in the protoclusters, the team members focused attention on the environmental effects of inflow and outflow mechanism on the galaxy formation process. Recent works report that inflow and outflow activities were most significant eleven billion years ago (at redshift ~2), and were about a hundred times more active relative to those in the local universe.

Clusters of galaxies are large self-gravitating systems in which galaxies and ionized gas are bound by massive amounts of dark matter. In such unique, dense environments, galaxies move at a speed of about 1000 kilometers per second. Due to this high speed, the galaxies are exposed to high pressure from intercluster medium. As a result, the outer regions with relatively poor metallicity are stripped. It is like the strong air resistance of air a bicycle rider experiences. In this case, the gaseous metallicities become higher because the chemical enrichment process takes place mainly in metal-rich central regions (Figure 4b). Another possibility is that the surrounding high-pressure, inter-cluster medium prevents outflowing gas from escaping from the galaxies (Figure 4c). This also results in higher gaseous metallicities of the cluster galaxies.

The research team concludes that the metallicity excess in the protocluster regions results from unique phenomena occurring in the cluster environment. The PI of this research, Mr. Rhythm Shimakawa of NAOJ and SOKENDAI (Note 2), is determined to continue studying the detailed physical properties of individual forming galaxies in the protoclusters to find clear evidence that proves this hypothesis.

This article is based on results from two research papers published in the Monthly Notices of the Royal Astronomical Society:

Contacts and sources:
National Astronomical Observatory of Japan

Citation: Rhythm Shimakawa, Tadayuki Kodama, Ken-ichi Tadaki, Ichi Tanaka, Masao Hayashi and Yusei Koyama, "Identification of the progenitors of rich clusters and member galaxies in rapid formation at z > 2", Volume 441, Issue 1, p.L1-L5, published in June 11, 2014, and Rhythm Shimakawa, Tadayuki Kodama, Ken-ichi Tadaki, Masao Hayashi, Yusei Koyama, Ichi Tanaka "An early phase of environmental effects on galaxy properties unveiled by near-infrared spectroscopy of protocluster galaxies at z>2", Volume 448, Issue 1, p.666-680, published in March 21, 2015.

Household Pets Can Transmit Infections to People

Household pets can transmit infection to people, especially those with weak immune systems, young children, pregnant women and seniors, according to an article in CMAJ (Canadian Medical Association Journal). Health care providers and pet owners should be aware of this risk to prevent illness in vulnerable people.

Surveys suggest that the general public and people at high risk for pet-associated disease are not aware of the risks associated with high-risk pet practices or recommendations to reduce them; for example, 77% of households that obtained a new pet following a cancer diagnosis acquired a high-risk pet," states Dr. Jason Stull, assistant professor, Department of Veterinary Preventive Medicine, Ohio State University, Columbus, Ohio.

Credit: Trillium Poncho,   Licensed under CC BY 2.5 via Wikimedia Commons  

The review explains the types of infections, how infections are transmitted from pets, prevention and the role of health care providers.

"Studies suggest physicians do not regularly ask about pet contact, nor do they discuss the risks of zoonotic diseases with patients, regardless of the patient's immune status ," writes writes Dr. Stull, with coauthors Dr. Jason Brophy, Children's Hospital of Eastern Ontario (CHEO) and Dr. J.S. Weese, Ontario Veterinary College.

All pets can transmit diseases to people. For instance, dogs, cats, rodents, reptiles and amphibians can transmit Salmonella, multidrug resistant bacteria (including Clostridium difficile), Campylobacter jejuni and other diseases. Parasites such as hookworm, roundworm and Toxoplasma can also be transmitted. Infection can be contracted from bites, scratches, saliva and contact with feces. Reptiles and amphibians can transmit disease indirectly, such as via contaminated surfaces.

"Reptiles and amphibians are estimated to be responsible for 11% of all sporadic Salmonella infections among patients less than 21 years of age, and direct contact with such animals is not required for zoonotic transmission," write the authors. "In one study, 31% of reptile-associated salmonellosis cases occurred in children less than 5 years of age and 17% occurred in children aged 1 year or younger; these findings highlight the heightened risk in children and the potential for reptile-associated Salmonella to be transmitted without direct contact with the animal or its enclosure."

For healthy people, the risk of pet-associated disease is low, but vulnerable people are at risk, including newborns, children with leukemia and adults with cancer.

"Given the health benefits of animal ownership and the reluctance of patients to give up their pets, resources highlight the importance of following specific precautions," states Dr. Stull. "Patients at high risk and their households should have increased vigilance of their pets' health and take precautions to reduce pathogen transmission." Simple steps can dramatically reduce the risk.

Recommendations for reducing transmission of infection include:
  • wearing protective gloves to clean aquariums and cages and remove feces
  • proper handwashing after pet contact
  • discouraging pets from face licking
  • covering playground boxes when not in use
  • avoiding contact with exotic animals
  • regular cleaning and disinfection of animal cages, feeding areas and bedding
  • locating litter boxes away from areas where eating and food preparation occur
  • waiting to acquire a new pet until immune status has improved
  • regularly scheduling veterinary visits for all pets.
Physicians and other health care providers should enquire about pets and repeat questions in light of illness in vulnerable people, as well as advise on the risks of pet ownership and how to reduce risks of disease.

The authors also recommend that veterinarians can be a resource for physicians seeking more information on zoonotic infections and risks associated with unusual pets.

Contacts and sources: 
Kim Barnhardt

Inner Region of Young Star and Its Planets Probed

Astronomers have probed deeper than before into a planetary system 130 light-years from Earth. The observations mark the first results of a new exoplanet survey called LEECH (LBT Exozodi Exoplanet Common Hunt), and are published  in the journal Astronomy and Astrophysics.

The planetary system of HR8799, a young star only 30 million years old, was the first to be directly imaged, with three planets found in in 2008 and a fourth one in 2010.

The planetary system of HR 8799. Most of the light of the star has been erased by the processing of the images and the four planets, identified from b to e in the order of their discovery, are easily detected.
Credit: A.-L. Maire / LBTO

"This star was therefore a target of choice for the LEECH survey, offering the opportunity to acquire new images and better define the dynamical properties of the exoplanets orbiting," said Christian Veillet, director of the Large Binocular Telescope Observatory (LBTO).

The LEECH survey began at the Large Binocular Telescope (LBT) in southeastern Arizona in February 2013 to search for and characterize young and adolescent exoplanets in the near-infrared spectrum (specifically, at a wavelength of 3.8 micrometers that astronomers call the L' band). LEECH exploits the superb performance of the LBT adaptive optics system to image exoplanets with the L/M-band infrared camera (LMIRCam) installed in the LBT Interferometer (LBTI).

The LBTI (green structure in the center of the frame) between the two 8.4m mirrors of the LBT.
Credit: LBTO - Enrico Sacchetti

"The LBT enables us to look at those planets at a wavelength that nobody else is really using," Veillet explained. "Because they are gas giants and still very young, they glow nicely at the L' band, and because they appear so bright there, they stand out, allowing us to observe closer to the star. This has allowed us to nail down the orbits of this system, which is pretty far away."

"Normally the problem with this approach would be that at 4 microns, telescope optics glow themselves," said Andy Skemer, a Hubble Fellow at the University of Arizona's Department of Astronomy and Steward Observatory and the lead of the survey. "However, with LBT, everything about the telescope, its adaptive optics system and science camera have been optimized to minimize this glow. As a result, LEECH is more sensitive than previous exoplanet imaging surveys, and this new image of HR 8799 is proof."

The study was dedicated to studying the planet architecture of the HR 8799 system, according to the leading author, Anne-Lise Maire, a postdoctoral fellow at INAF-Padova Observatory in Padova, Italy. The team sought to constrain the orbital parameters of the four known giant planets and the physical properties of a putative fifth planet inside the known planets.

"To address the first point, we investigated in particular the types of resonances between the planet orbits," Maire explained. "From the resonances, we learn not only about the overall architecture of the planetary system, but also about the mass range of the planets."

"They cannot be too massive, or else the system would be dynamically unstable, as previous studies have suggested. Moreover, the presence of resonances between the planets indicates that they gravitationally interact with each other, which gives us a lower limit on their masses."

The results of this study favor an architecture for the system based on multiple double resonances, in other words, each of the three outer planets takes about twice as long to complete an orbit around the star as its neighbor closer to the star.

"LEECH's unique sensitivity enabled us to probe the inner region of this planetary system," added Wolfgang Brandner, a scientist at the Max Planck Institute for Astronomy in Heidelberg, Germany. "A fifth massive giant planet in an inner resonant orbit was excluded. This could mean that the HR 8799 planetary system has an architecture similar to the solar system, with four massive planets at larger distances, and potentially lower mass planets - which haven't been detected, yet - in the inner planetary system."

"Our observations give us good idea that this system is pretty stable," Veillet added, "in other words, there is no indication those planets are going to collide with each other in a few million years."

In its current configuration, the inner planet LEECH can see approaches the star to about 15 Astronomical Units (AU), Veillet explained, or fifteen times the average distance between the earth and our sun.

"If there were planets of similar brightness closer to the star, we should see it as close as 10 AU," he said, "which corresponds to the orbit of Saturn."

According to Veillet, the LEECH survey is an exemplary project in two ways.

"It takes full advantage of the adaptive optics performance offered by our adaptive secondary mirrors, and it combines resources from most of the LBTO partners - four U.S. universities, two institutes in Germany, and the Italian community - to build a large program of more than 100 observing nights. This would not be possible for a single partner on a reasonable time scale."

Contacts and sources:
Daniel Stolte

Monday, April 20, 2015

Tiny Sensor Detects Spoiled Meat: Use In “Smart Packaging” Could Improve Food Safety.

MIT chemists have devised an inexpensive, portable sensor that can detect gases emitted by rotting meat, allowing consumers to determine whether the meat in their grocery store or refrigerator is safe to eat.

The sensor, which consists of chemically modified carbon nanotubes, could be deployed in “smart packaging” that would offer much more accurate safety information than the expiration date on the package, says Timothy Swager, the John D. MacArthur Professor of Chemistry at MIT.

This MIT device, based on modified carbon nanotubes, can detect amines produced by decaying meat.

Photo: Sophie Liu

It could also cut down on food waste, he adds. “People are constantly throwing things out that probably aren’t bad,” says Swager, who is the senior author of a paper describing the new sensor this week in the journal Angewandte Chemie.

The paper’s lead author is graduate student Sophie Liu. Other authors are former lab technician Alexander Petty and postdoc Graham Sazama.

The sensor is similar to other carbon nanotube devices that Swager’s lab has developed in recent years, including one that detects the ripeness of fruit. All of these devices work on the same principle: Carbon nanotubes can be chemically modified so that their ability to carry an electric current changes in the presence of a particular gas.

In this case, the researchers modified the carbon nanotubes with metal-containing compounds called metalloporphyrins, which contain a central metal atom bound to several nitrogen-containing rings. Hemoglobin, which carries oxygen in the blood, is a metalloporphyrin with iron as the central atom.

For this sensor, the researchers used a metalloporphyrin with cobalt at its center. Metalloporphyrins are very good at binding to nitrogen-containing compounds called amines. Of particular interest to the researchers were the so-called biogenic amines, such as putrescine and cadaverine, which are produced by decaying meat.

When the cobalt-containing porphyrin binds to any of these amines, it increases the electrical resistance of the carbon nanotube, which can be easily measured.

“We use these porphyrins to fabricate a very simple device where we apply a potential across the device and then monitor the current. When the device encounters amines, which are markers of decaying meat, the current of the device will become lower,” Liu says.

In this study, the researchers tested the sensor on four types of meat: pork, chicken, cod, and salmon. They found that when refrigerated, all four types stayed fresh over four days. Left unrefrigerated, the samples all decayed, but at varying rates.

There are other sensors that can detect the signs of decaying meat, but they are usually large and expensive instruments that require expertise to operate. “The advantage we have is these are the cheapest, smallest, easiest-to-manufacture sensors,” Swager says.

“There are several potential advantages in having an inexpensive sensor for measuring, in real time, the freshness of meat and fish products, including preventing foodborne illness, increasing overall customer satisfaction, and reducing food waste at grocery stores and in consumers’ homes,” says Roberto Forloni, a senior science fellow at Sealed Air, a major supplier of food packaging, who was not part of the research team.

The new device also requires very little power and could be incorporated into a wireless platform Swager’s lab recently developed that allows a regular smartphone to read output from carbon nanotube sensors such as this one.

The researchers have filed for a patent on the technology and hope to license it for commercial development. The research was funded by the National Science Foundation and the Army Research Office through MIT’s Institute for Soldier Nanotechnologies.

Contacts and sources: 
Anne Trafton 
MIT News Office

NailO: Wireless Mouse Worn On Thumb

Researchers at the MIT Media Laboratory are developing a new wearable device that turns the user’s thumbnail into a miniature wireless track pad.

They envision that the technology could let users control wireless devices when their hands are full — answering the phone while cooking, for instance. It could also augment other interfaces, allowing someone texting on a cellphone, say, to toggle between symbol sets without interrupting his or her typing. Finally, it could enable subtle communication in circumstances that require it, such as sending a quick text to a child while attending an important meeting.
A new wearable device, NailO, turns the user’s thumbnail into a miniature wireless track pad. Here, it works as a X-Y coordinate touch pad for a smartphone
Credit: MIT Media Lab

The researchers describe a prototype of the device, called NailO, in a paper they’re presenting next week at the Association for Computing Machinery’s Computer-Human Interaction conference in Seoul, South Korea.

According to Cindy Hsin-Liu Kao, an MIT graduate student in media arts and sciences and one of the new paper’s lead authors, the device was inspired by the colorful stickers that some women apply to their nails. “It’s a cosmetic product, popular in Asian countries,” says Kao, who is Taiwanese. “When I came here, I was looking for them, but I couldn’t find them, so I’d have my family mail them to me.”

Indeed, the researchers envision that a commercial version of their device would have a detachable membrane on its surface, so that users could coordinate surface patterns with their outfits. To that end, they used capacitive sensing — the same kind of sensing the iPhone’s touch screen relies on — to register touch, since it can tolerate a thin, nonactive layer between the user’s finger and the underlying sensors.

Designed in the MIT Media Lab, NailO is a thumbnail-mounted wireless track pad that controls digital devices. Watch it in action.

Video: Melanie Gonick/MIT

Instant access

As the site for a wearable input device, however, the thumbnail has other advantages: It’s a hard surface with no nerve endings, so a device affixed to it wouldn’t impair movement or cause discomfort. And it’s easily accessed by the other fingers — even when the user is holding something in his or her hand.

“It’s very unobtrusive,” Kao explains. “When I put this on, it becomes part of my body. I have the power to take it off, so it still gives you control over it. But it allows this very close connection to your body.”

To build their prototype, the researchers needed to find a way to pack capacitive sensors, a battery, and three separate chips — a microcontroller, a Bluetooth radio chip, and a capacitive-sensing chip — into a space no larger than a thumbnail. “The hardest part was probably the antenna design,” says Artem Dementyev, a graduate student in media arts and sciences and the paper’s other lead author. “You have to put the antenna far enough away from the chips so that it doesn’t interfere with them.”

Kao and Dementyev are joined on the paper by their advisors, principal research scientist Chris Schmandt and Joe Paradiso, an associate professor of media arts and sciences. Dementyev and Paradiso focused on the circuit design, while Kao and Schmandt concentrated on the software that interprets the signal from the capacitive sensors, filters out the noise, and translates it into movements on screen.

For their initial prototype, the researchers built their sensors by printing copper electrodes on sheets of flexible polyester, which allowed them to experiment with a range of different electrode layouts. But in ongoing experiments, they’re using off-the-shelf sheets of electrodes like those found in some track pads.

Slimming down

They’ve also been in discussion with battery manufacturers — traveling to China to meet with several of them — and have identified a technology that they think could yield a battery that fits in the space of a thumbnail, but is only half a millimeter thick. A special-purpose chip that combines the functions of the microcontroller, radio, and capacitive sensor would further save space.

At such small scales, however, energy efficiency is at a premium, so the device would have to be deactivated when not actually in use. In the new paper, the researchers also report the results of a usability study that compared different techniques for turning it off and on. They found that requiring surface contact with the operator’s finger for just two or three seconds was enough to guard against inadvertent activation and deactivation.

“Keyboards and mice — still — are not going away anytime soon,” says Steve Hodges, who leads the Sensors and Devices group at Microsoft Research in Cambridge, England. “But more and more that’s being complemented by use of our devices and access to our data while we’re on the move. I’ve got desktop, I’ve got a mobile phone, but that’s still not enough. Different ways of displaying and controlling devices while we’re on the go are, I believe, going to be increasingly important.”

“Is it the case that we’ll all be walking around with digital fingernails in five years’ time?” Hodges asks. “Maybe it is. Most likely, we’ll have a little ecosystem of these input devices. Some will be audio based, which is completely hands free. But there are a lot of cases where that’s not going to be appropriate. NailO is interesting because it’s thinking about much more subtle interactions, where gestures or speech input are socially awkward.”

Contacts and sources: 
Larry Hardesty  
MIT News Office

Astronomers Solve Decades-Long Mystery of the "Lonely Old Stars"

Many, perhaps most, stars in the Universe live their lives with companions by their sides – in so-called binary systems. Until recently, however, the ancient RR Lyrae stars appeared, for mysterious reasons, to live their lives all alone. A recent study led by Chilean astronomers shows that RR Lyrae stars may not be as lonely as previously thought. The new research is published in Monthly Notices of the Royal Astronomical Society Letters.

Map of the sky towards the central bulge of the Milky Way, with the positions of the binary candidates indicated as red circles. The background image is based on near-infrared observations obtained in the course of the Vista Variables in the Vía Láctea (VVV) ESO Public Survey. The scale is approximately 20 by 15 degrees.  
Credit: D. Minniti. 

Stars are very often found not in isolation, but rather in pairs. In these so-called binary systems, two stars orbit around their common centre of gravity. Suitable binary systems are of extreme importance in astrophysics, as their properties can be inferred with unparalleled accuracy from detailed analysis of their orbital properties.

Puzzlingly, however, an overwhelming majority of the known members of a very important family of stars, known to astronomers as RR Lyrae variables, have for long appeared to live their lives all alone. These stars, being among the oldest known in the cosmos, contain precious information about the origin and evolution of the stellar systems that harbour them, such as the Milky Way itself. However, the lack of RR Lyrae stars in binary systems has made a direct assessment of some of their key properties difficult. Most often, theory had to be invoked to fill the gap.

This apparent solitude has always intrigued astronomers. Now, however, an international research team led by experts of theMillennium Institute of Astrophysics (MAS) and the Pontificia Universidad Católica de Chile's Institute of Astrophysics (IA-PUC) have found evidence that these stars may not abhor companionship so thoroughly after all. In a Letter published in the journal Monthly Notices of the Royal Astronomical Society, the team reports on the identification of as many as 20 candidate RR Lyrae binaries – an increase of up to 2000% with respect to previous tallies. Twelve of those candidates have enough measurements to conclude with high confidence that they do indeed consist of two stars orbiting each other.

"In the solar neighbourhood, about every second star is in a binary. The problem with RR Lyrae variables is that for a long time only one of them was known to be in a long-period binary system. The fact that among 100,000 known RR Lyrae stars only one of them had been seen to have such a companion was something really intriguing for astronomers," explains Gergely Hajdu, IA-PUC Ph.D. student, MAS researcher, and lead author of the study.

Animation showing the light-travel time effect. The upper plot shows the brightness of a binary RR Lyrae star (OGLE-RRLYR-06498) as a function of time. Grey symbols indicate all the available individual measurements, whereas the red symbols show an selection of the data points as they were collected over time. The bottom plot shows the same data, but folded according to the pulsation period. The main brightness variations show up as a sawtooth-like distribution corresponding to the pulsation of the RR Lyrae variable, whilst the back-and-forth movement shown by the red dots is the signal that is brought about by the presence of a binary companion.
Credit:  Royal Astronomical Society

In their paper, the authors used a method that astronomers call the "light-travel time effect," which exploits subtle differences in the time it takes starlight to reach us.

"The RR Lyrae stars pulsate regularly, significantly increasing, and then decreasing, their sizes, temperatures, and brightness, in a matter of just a few hours. When a pulsating star is in a binary system, the changes in brightness perceived by us can be affected by where exactly the star is in the course of its orbit around the companion. Thus, the starlight takes longer to reach us when it is at the farthest point along its orbit, and vice-versa. This subtle effect is what we have detected in our candidates," according to Hajdu.

"Our measurements were based on data published by the Polish OGLE Project. The OGLE team have obtained their data using the 1.3m Warsaw telescope, located in Las Campanas Observatory, northern Chile, repeatedly observing the same patches of the sky for many years. Our 20 candidates were found analysing the roughly 2000 best observed RR Lyrae stars towards the central parts of the Milky Way. That's about 5% of the known ones. It was only thanks to the high quality of the OGLE data and the long timespan of these observations that we could finally find signs of companions around so many of these stars," says Hajdu.

Indeed, the systems detected by Hajdu et al. have orbital periods of several years, which indicates that the companions, though bound together by gravity, are not very close to one another. "Binaries with even longer periods may also exist, but the current data do not extend long enough for us to reach strong conclusions in this respect," he adds.

For co-author Márcio Catelan, MAS Associate Researcher, IA-PUC astrophysicist and Hajdu's thesis advisor, these results have significant implications for astrophysics. "These are extremely old stars, which have witnessed the formation of galaxies like our own Milky Way, and survived to tell us the story. Besides, they are easy to identify, since they show characteristic, cyclical brightness variations, which make them excellent distance indicators for the nearby Universe. However, a lot of what we know about them relies on theoretical modelling. We can now exploit the orbital information contained in these binary systems – and there are quite a few of them now – in order to directly measure their physical properties, especially their masses but possibly also their diameters, thus opening new doors to discoveries that until recently seemed impossible.", he says.

This is just the first step towards achieving these goals, however: according to Catelan, more data will be needed, particularly follow-up observations of the binary candidates with sophisticated techniques like spectroscopy and astrometry. The rewards awaiting at the end of the road seem well worth the long journey, and the RR Lyrae will happily traverse that path with their companions firmly by their sides.

Contacts and sources:
Dr Keith Smith
Royal Astronomical Society

Gergely Hajdu
Instituto de Astrofísica, Pontificia Universidad Católica de Chile & Millennium Institute of Astrophysics

The new work appears in G. Hajdu, "New RR Lyrae variables in binary systems", Monthly Notices of the Royal Astronomical Society, vol. 449, pp. L113-L117, 2015, published by Oxford University Press.

Largest Structure In Universe: A Supervoid 1.3 Billion Light Years Across

Astronomers may have found "the largest individual structure ever identified by humanity", according to Dr István Szapudi of the University of Hawaii at Manoa. Dr Szapudi and his team report their findings in the journal Monthly Notices of the Royal Astronomical Society.

A map of the cosmic microwave background made using the Planck satellite. The Cold Spot, the ellipse at the bottom right, area resides in the constellation Eridanus in the southern galactic hemisphere. The insets show the environment of this anomalous patch of the sky, as mapped by Szapudi’s team using PS1 and WISE data and as observed in the cosmic microwave background temperature data. The angular diameter of the vast supervoid aligned with the Cold Spot, which exceeds 30 degrees, is marked by the white circles. Graphics by Gergő Kránicz.
Image credit: ESA Planck Collaboration.

In 2004, astronomers examining a map of the radiation left over from the Big Bang (the cosmic microwave background, or CMB) discovered the Cold Spot, a larger-than-expected unusually cold area of the sky. The physics surrounding the Big Bang theory predicts warmer and cooler spots of various sizes in the infant universe, but a spot this large and this cold was unexpected. Now astronomers may have found an explanation for the existence of the Cold Spot.

If the Cold Spot originated from the Big Bang itself, it could be a rare sign of exotic physics that the standard cosmology (basically, the Big Bang theory and related physics) does not explain. If, however, it is caused by a foreground structure between us and the CMB, it would be a sign that there is an extremely rare large-scale structure in the mass distribution of the universe.

Using data from Hawaii’s Pan-STARRS1 (PS1) telescope located on Haleakala, Maui, and NASA’s Wide Field Survey Explorer(WISE) satellite, Szapudi’s team discovered a large supervoid, a vast region 1.8 billion light-years across, in which the density of galaxies is much lower than usual in the known universe. This void was found by combining observations taken by PS1 at optical wavelengths with observations taken by WISE at infrared wavelengths to estimate the distance to and position of each galaxy in that part of the sky.

Earlier studies, also done in Hawaii, observed a much smaller area in the direction of the Cold Spot, but they could establish only that no very distant structure is in that part of the sky. Paradoxically, identifying nearby large structures is harder than finding distant ones, since we must map larger portions of the sky to see the closer structures. The large three-dimensional sky maps created from PS1 and WISE by Dr András Kovács (Eötvös Loránd University, Budapest, Hungary) were thus essential for this study. The supervoid is only about 3 billion light-years away from us, a relatively short distance in the cosmic scheme of things.

Imagine there is a huge void with very little matter between you (the observer) and the CMB. Now think of the void as a hill. As the light enters the void, it must climb this hill. If the universe were not undergoing accelerating expansion, then the void would not evolve significantly, and light would descend the hill and regain the energy it lost as it exits the void. But with the accelerating expansion, the hill is measurably stretched as the light is traveling over it. By the time the light descends the hill, the hill has gotten flatter than when the light entered, so the light cannot pick up all the speed it lost upon entering the void. The light exits the void with less energy, and therefore at a longer wavelength, which corresponds to a colder temperature.

Getting through a supervoid takes hundreds of millions of years, even at the speed of light, so this measurable effect (known as the Integrated Sachs-Wolfe (ISW) effect) might provide the an explanation for the Cold Spot. The spot is one of the most significant anomalies found to date in the CMB, first by a NASA satellite called the Wilkinson Microwave Anisotropy Probe(WMAP), and more recently by Planck, a satellite launched by the European Space Agency.

While the existence of the supervoid and its expected effect on the CMB do not fully explain all the properties of the Cold Spot, it is very unlikely that the supervoid and the Cold Spot at the same location are a coincidence. The team will continue its work using improved data from PS1, and from the Dark Energy Survey being conducted with a telescope in Chile to study the Cold Spot and supervoid, as well as another large void located near the constellation Draco.

Contacts and sources:
Louise Good
Royal Astronomical Society
Dr István Szapudi
Institute for Astronomy at the University of Hawaii at Manoa

Citation: The study appears in István Szapudi et al., "Detection of a supervoid aligned with the cold spot of the cosmic microwave background", Monthly Notices of the Royal Astronomical Society, vol. 450, pp. 288-294, 2015, published by Oxford University Press.

A preprint of the paper is available on the arXiv server.

Ocean Winds Blow Away Hopes El Nino Would End California Drought

A UMD study points to prolonged wind bursts originating in the western Pacific as the reason that the 2014/2015 El Nino will be far less powerful than anticipated and thus unlikely to deliver much-needed rain to California and other western states.

An El Nino is a sporadic warming of ocean temperatures in the central and eastern tropical Pacific that can have

ripple effects in weather systems around the globe. Last month, the federal Center for Weather and Climate Prediction in College Park, Md. announced a long-predicted El Niño had finally arrived, but was far less powerful than expected.

The new study, published online April 13, 2015, in the journal Nature Geoscience, found that prolonged westerly wind bursts can have a strong effect on whether an El Niño event will occur and how strong it is likely to be. In addition, the paper identifies three distinct varieties or “flavors” of El Niño, and explains how these westerly wind bursts (WWBs) can determine which of these flavors will take shape. The findings should help refine future predictions of these global-scale climate events.

In addition, the paper identifies three distinct varieties or “flavors” of El Nino, and explains how these westerly wind bursts (WWBs) can determine which of these flavors will take shape. The findings should help refine future predictions of these global-scale climate events.

“These westerly wind bursts are intraseasonal—they’re not weather, they’re not climate, but somewhere in between,” said Raghu Murtugudde, a professor of atmospheric and oceanic science at the University of Maryland who is a co-author on the study. “Our study shows that the wind bursts are definitely having an effect. We better learn to predict them if we are going to have skillful El Nino predictions.”

The researchers analyzed 50 years of tropical Pacific sea surface temperature and westerly wind burst data. They found differences, especially when comparing the data from this year’s weak El Nino event with the record-breaking event of 1997/98.

“The most notable difference was the existence of strong westerly winds extending from the western to central equatorial Pacific in May 1997, which were not seen in 2014,” said Murtugudde, who also has an appointment in the university’s Earth System Science Interdisciplinary Center (ESSIC). “The development of strong westerly winds in the central equatorial Pacific in association with the warming to its east appears to be an essential element of large El Nino events.”

After adding westerly wind bursts to their intermediate ocean-atmosphere coupled model, the researchers consistently found three “flavors” of El Nino (rather than one, which was the model’s output without the winds). The three warm patterns included extremely strong events with the largest warming near the South American coast, a cluster of weak warm events centered near the dateline, or moderate warming in the central-eastern equatorial Pacific. For strong El Nino events, the westerly wind bursts grow strong and extend east of the dateline.

According to the research team, the wind bursts affect ocean dynamics by exciting Kelvin waves that produce surface warming in the eastern equatorial Pacific and by generating strong equatorial surface currents that extend the eastern edge of the warm pool.

“We hope this study helps other climate modeling researchers realize the importance of westerly wind bursts on El Nino severity and diversity, and the importance of extending our weather forecast capabilities from two to four weeks to capture WWB variability. Fortunately, the latter is now a focus at the National Atmospheric and Oceanic Administration, which develops our weather forecasts,” said Murtugudde.

Additional information on the study can be found here.

Contacts and sources:
Abby Robinson