Rice Wireless Engineers Unveil a Multiuser, Multiantenna Transmission Scheme for UHF

Rice University’s Wireless Network Group has created a multiuser, multiantenna transmission scheme for UHF, a portion of the radio spectrum that could be useful for broadband Internet service in rural areas. CREDIT: Jeff Fitlow/Rice University

By combining several proven technologies that are already widely used in wireless data transmission, engineers from Rice University have created a multiuser, multiantenna scheme to make the most of the unused UHF TV spectrum.

Rice University wireless researchers have found a way to make the most of the unused UHF TV spectrum by serving up fat streams of data over wireless hotspots that could stretch for miles.

In a presentation September 9 at the Association for Computing Machinery’s MobiCom 2014 conference in Maui, Hawaii, researchers from Rice’s Wireless Network Group unveiled a multiuser, multiantenna transmission scheme for UHF, a portion of the radio spectrum that is traditionally reserved for television broadcasts.

“The holy grail of wireless communications is to go both fast and far,” said lead researcher Edward Knightly, professor and chair of Rice’s Department of Electrical and Computer Engineering. “Usually, you can have one or the other but not both. Wireless local area networks today can serve data very fast, but one brick wall and they’re done. UHF can travel far, but it hasn’t had the high capacity of WiFi.

“This provides the best of both worlds,” he said of the new technology.

Rice’s technology combines several proven technologies that are already widely used in wireless data transmission. One of these is “multiple-input, multiple-output” (MIMO), a scheme that employs multiple antennae to boost data rates without the need for additional channels or transmitter power. In effect, MIMO allows for a larger wireless “pipeline,” and the technology is standard in the latest generation of wireless routers and networking equipment.

Parts of the UHF spectrum were opened after the recent switch to digital television, which has a smaller broadcast footprint than analog TV. UHF is often referred to as the “beach front” portion of the wireless spectrum because the signals travel for miles, and one popular idea for the liberated portion of the spectrum is for “open” wireless access points like those used for today’s WiFi hotspots. Using UHF for broadband Internet is particularly appealing for rural areas where wired brandband is unavailable.

“When comparing UHF and WiFi, there’s usually a tradeoff of capacity for range or vice versa,” said Rice graduate student Narendra Anand, the lead author of the new study. “Imagine that the WiFi access point in your home or office sends data down a 100-lane highway, but it’s only one mile long. For UHF, the highway is 100 miles long but only three or four lanes wide. And you cannot add any lanes.

“To be able to leverage the best characteristics of the UHF band, we need to be able to efficiently use the lanes that we have,” Anand said. “One way to do that is with multiuser MIMO, a multiantenna transmission technique that serves multiple users over the same channel simultaneously.”

Knightly, Anand and Rice graduate student Ryan Guerra designed the first open-source UHF multiuser MIMO test system. Based on Rice’s “wireless open-access research platform,” or WARP, the system allowed the team to perform a side-by-side comparison of multiuser MIMO for UHF and for both 2.4 gigahertz and 5.8 gigahertz WiFi.

“Based on over-the-air experiments in a range of indoor and outdoor operating environments, we found that UHF-band multiuser MIMO compared favorably and produced high spectral efficiency as well as low-overhead wireless access,” Knightly said.

This research was supported by the National Science Foundation and Cisco Systems Inc.

A New Catalog of the Visible Milky Way

A density map of part of the Milky Way disk, constructed from IPHAS data. The axes show galactic latitude and longitude, coordinates that relate to the position of the center of the galaxy. The mapped data are the counts of stars detected in i, the longer (redder) wavelength broad band of the survey, down to a faint limit of 19th magnitude. Although this is just a small section of the full map, it portrays in exquisite detail the complex patterns of obscuration due to interstellar dust. Credit: Hywel Farnhill, University of Hertfordshire. Click for a full resolution image

Astronomers used IPHAS data to create a new catalog of the visible part of the Milky Way, revealing no fewer than 219 million stars.

A new catalog of the visible part of the northern part of our home Galaxy, the Milky Way, includes no fewer than 219 million stars. Geert Barentsen of the University of Hertfordshire led a team who assembled the catalog in a ten year program using the Isaac Newton Telescope (INT) on La Palma in the Canary Islands. Their work appears today in the journal Monthly Notices of the Royal Astronomical Society.

From dark sky sites on Earth, the Milky Way appears as a glowing band stretching across the sky. To astronomers, it is the disk of our own galaxy, a system stretching across 100,000 light-years, seen edge-on from our vantage point orbiting the Sun. The disk contains the majority of the stars in the galaxy, including the Sun, and the densest concentrations of dust and gas.

The unaided human eye struggles to distinguish individual objects in this crowded region of the sky, but the 2.5-metre mirror of the INT enabled the scientists to resolve and chart 219 million separate stars. The INT program charted all the stars brighter than 20th magnitude – or 1 million times fainter than can be seen with the human eye.

Using the catalog, the scientists have put together an extraordinarily detailed map of the disk of the Galaxy that shows how the density of stars varies, giving them a new and vivid insight into the structure of this vast system of stars, gas and dust.

The image included here, a cut-out from a stellar density map mined directly from the released catalog, illustrates the new view obtained. The Turner-like brush strokes of dust shadows would grace the wall of any art gallery. Maps like these also stand as useful tests of new-generation models for the Milky Way.

The production of the catalog, IPHAS DR2 (the second data release from the survey program The INT Photometric H-alpha Survey of the Northern Galactic Plane, IPHAS), is an example of modern astronomy’s exploitation of ‘big data’. It contains information on 219 million detected objects, each of which is summarized in 99 different attributes.

With this catalog release, the team are offering the world community free access to measurements taken through two broad band filters capturing light at the red end of the visible spectrum, and in a narrow band capturing the brightest hydrogen emission line, H-alpha. The inclusion of H-alpha also enables exquisite imaging of the nebulae (glowing clouds of gas) found in greatest number within the disk of the Milky Way. The stellar density map illustrated here is derived from the longest (reddest) wavelength band in which the darkening effect of the dust is moderated in a way that brings out more of its structural detail, compared to maps built at shorter (bluer) wavelengths.

Publication: Geert Barentsen, et al., “The second data release of the INT Photometric Hα Survey of the Northern Galactic Plane (IPHAS DR2),” MNRAS (November 11, 2014) 444 (4): 3230-3257; doi: 10.1093/mnras/stu1651

New PhenIX Diagnostic Procedure Identifies Genetic Diseases

A team of scientists has developed a test procedure that significantly increases the prospect of identifying genetic diseases quickly and reliably based on analyses of genes and symptoms.

People with genetic diseases often have to embark on an odyssey from one doctor to the next. Fewer than half of all patients who are suspected of having a genetic disease actually receive a satisfactory diagnosis. Scientists from the Charité – Universitätsmedizin Berlin and the Max Planck Institute for Molecular Genetics have now developed a test procedure that significantly increases the prospect of a diagnosis for affected patients. The procedure is freely available to the relevant medical institutions and can be used with immediate effect.

The first step to the right treatment is an accurate diagnosis – even in untreatable cases, it is invaluable. “At the least, it provides the reassurance that the illness is not self-inflicted,” says Peter Robinson, one of the developers of the PhenIX diagnostic procedure. PhenIX stands for “Phenotypic Interpretation of eXomes”. In the past, only a genetic analysis was carried out for such diseases. However, this is often not enough to accurately detect the illness. The problem with all the tests is that the individual diversity of patients makes a diagnostic analysis difficult – among the millions of genetic deviations from the norm inherent in every single person, the crucial difference must be found.

To solve this problem, the Berlin-based scientists developed an innovative diagnostic procedure. In contrast to previous diagnostic tests, PhenIX combines the analysis of genetic irregularities with the patient’s clinical presentation. In the first step, a specific search is conducted for around 3,000 genes that are known to cause diseases. To find out which ones they are, the scientists systematically search through publicly available databases and create a list of known genetic defects. Once this is complete, several hundred genetic irregularities usually still remain in the patient’s genome as candidates for the cause of the disease.

In the second step, the attending doctor browses the Human Phenotype Ontology (HPO), a database already developed at the Charité, to search for the patient’s symptoms. This also contains a list of genetic defects that could be responsible for the disease. When the doctor then examines the overlap between the two analysis methods, he or she is left with a list of candidates of often no more than 20 possible causes of the illness, including a ranking in order of probability. It is relatively easy to go through this list and test it.

In a pilot study, a group of patients, whose genetic disease was already known, were examined. In every single case, PhenIX diagnosed the illness correctly. Other sick persons also presented for treatment. These were individuals who had not been able to obtain a diagnosis, despite intensive and in some cases years of effort and investigation. More than 25 percent of these patients were able to find out the exact cause of their illness when the PhenIX method was used.

PhenIX is already available to hospitals that have the necessary technical equipment. “Through a combination of clinical findings and genetic analysis, we have taken a major step forward – the new method means just two hours of work for the doctor,” says Robinson. And he promises: “Even in the future, a free version of this programme will always be available.” He sees the potential for further improvement in a more standardized handling of the databases. “Doctors sometimes do not know exactly how they should describe a symptom, or they know a particular symptom under a different name.” Certain guidelines could make the search process more successful, so that the diagnosis can be even faster and more accurate in the future.

NuSTAR Discovers Pulsar Powering Intense Gamma Rays

The blue dot in this image marks the spot of an energetic pulsar — the magnetic, spinning core of star that blew up in a supernova explosion. Image Credit: NASA/JPL-Caltech/SAO

Using NASA’s Nuclear Spectroscopic Telescope Array, astronomers have discovered a pulsar spinning five times per second and the ultimate power source of both the high-energy X-rays and gamma rays.

Our Milky Way galaxy is littered with the still-sizzling remains of exploded stars.

When the most massive stars explode as supernovas, they don’t fade into the night, but sometimes glow ferociously with high-energy gamma rays. What powers these energetic stellar remains?

NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, is helping to untangle the mystery. The observatory’s high-energy X-ray eyes were able to peer into a particular site of powerful gamma rays and confirm the source: A spinning, dead star called a pulsar. Pulsars are one of several types of stellar remnants that are left over when stars blow up in supernova explosions.

This is not the first time pulsars have been discovered to be the culprits behind intense gamma rays, but NuSTAR has helped in a case that was tougher to crack due to the distance of the object in question. NuSTAR joins NASA’s Chandra X-ray Observatory and Fermi Gamma-ray Space Telescope, and the High Energy Stereoscopic System (H.E.S.S.) in Namibia, each with its own unique strengths, to better understand the evolution of these not-so-peaceful dead stars.

“The energy from this corpse of a star is enough to power the gamma-ray luminosity we are seeing,” said Eric Gotthelf of Columbia University, New York. Gotthelf explained that while pulsars are often behind these gamma rays in our galaxy, other sources can be as well, including the outer shells of the supernova remnants, X-ray binary stars and star-formation regions. Gotthelf is lead author of a new paper describing the findings in the Astrophysical Journal.

In recent years, the Max-Planck Institute for Astronomy’s H.E.S.S. experiment has identified more than 80 incredibly powerful sites of gamma rays, called high-energy gamma-ray sources, in our Milky Way. Most of these have been associated with prior supernova explosions, but for many, the primary source of observed gamma rays remains unknown.

The gamma-ray source pinpointed in this new study, called HESS J1640-465, is one of the most luminous discovered so far. It was already known to be linked with a supernova remnant, but the source of its power was unclear. While data from Chandra and the European Space Agency’s XMM-Newton telescopes hinted that the power source was a pulsar, intervening clouds of gas blocked the view, making it difficult to see.

NuSTAR complements Chandra and XMM-Newton in its capability to detect higher-energy range of X-rays that can, in fact, penetrate through this intervening gas. In addition, the NuSTAR telescope can measure rapid X-ray pulsations with fine precision. In this particular case, NuSTAR was able to capture high-energy X-rays coming at regular fast-paced pulses from HESS J1640-465. These data led to the discovery of PSR J1640-4631, a pulsar spinning five times per second — and the ultimate power source of both the high-energy X-rays and gamma rays.

How does the pulsar produce the high-energy rays? The pulsar’s strong magnetic fields generate powerful electric fields that accelerate charged particles near the surface to incredible speeds approaching that of light. The fast-moving particles then interact with the magnetic fields to produce the powerful beams of high-energy gamma rays and X-rays.

“The discovery of a pulsar engine powering HESS J1640-465 allows astronomers to test models for the underlying physics that result in the extraordinary energies generated by these rare gamma-rays sources,” said Gotthelf.

“Perhaps other luminous gamma-ray sources harbor pulsars that we can’t detect,” said Victoria Kaspi of McGill University, Montreal, Canada, a co-author on the study. “With NuSTAR, we may be able to find more hidden pulsars.”

The new data also allowed astronomers to measure the rate at which the pulsar slows, or spins down (about 30 microseconds per year), as well as how this spin-down rate varies over time. The answers will help researchers understand how these spinning magnets — the cores of dead stars — can be the source of such extreme radiation in our galaxy.

Publication: E. V. Gotthelf, et al., “NuSTAR Discovery of a Young, Energetic Pulsar Associated with the Luminous Gamma-Ray Source HESS J1640–465,” 2014, ApJ, 788, 155; doi:10.1088/0004-637X/788/2/155

PDF Copy of the Study: NuSTAR Discovery of a Young, Energetic Pulsar Associated with the Luminous Gamma-ray Source HESS J1640-465

WASP-18b: A ‘Hot Jupiter’ That is Changing the Internal Structure of the Star it Orbits

This artist’s illustration depicts WASP-18b and its star, which are about 330 light years away.

A new study from NASA’s Chandra X-ray Observatory shows that a giant exoplanet, WASP-18b, is making the star that it orbits act much older than it actually is. WASP-18b is over ten times Jupiter’s mass and is so close to its star that it completes an orbit in less than a day, causing extreme tidal forces that are apparently changing the internal structure of the star.

A planet may be causing the star it orbits to act much older than it actually is, according to new data from NASA’s Chandra X-ray Observatory. This discovery shows how a massive planet can affect the behavior of its parent star.

The star, WASP-18, and its planet, WASP-18b, are located about 330 light-years from Earth. WASP-18b has a mass about 10 times that of Jupiter and completes one orbit around its star in less than 23 hours, placing WASP-18b in the “hot Jupiter” category of exoplanets, or planets outside our solar system.

WASP-18b is the first known example of an orbiting planet that has apparently caused its star, which is roughly the mass of our sun, to display traits of an older star.

“WASP-18b is an extreme exoplanet,” said Ignazio Pillitteri of the Istituto Nazionale di Astrofisica (INAF)-Osservatorio Astronomico di Palermo in Italy, who led the study. “It is one of the most massive hot Jupiters known and one of the closest to its host star, and these characteristics lead to unexpected behavior. This planet is causing its host star to act old before its time.”

Pillitteri’s team determined WASP-18 is between 500 million and 2 billion years old, based on theoretical models and other data. While this may sound old, it is considered young by astronomical standards. By comparison, our sun is about 5 billion years old and thought to be about halfway through its lifetime.

Younger stars tend to be more active, exhibiting stronger magnetic fields, larger flares, and more intense X-ray emission than their older counterparts. Magnetic activity, flaring, and X-ray emission are linked to the star’s rotation, which generally declines with age. However, when astronomers took a long look with Chandra at WASP-18 they didn’t detect any X-rays. Using established relations between the magnetic activity and X-ray emission of stars, as well as its actual age, researchers determined WASP-18 is about 100 times less active than it should be.

“We think the planet is aging the star by wreaking havoc on its innards,” said co-author Scott Wolk of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

The researchers argue that tidal forces created by the gravitational pull of the massive planet – similar to those the moon has on Earth’s tides, but on a much larger scale – may have disrupted the magnetic field of the star.

The strength of the magnetic field depends on the amount of convection in the star, or how intensely hot gas stirs the interior of the star.

“The planet’s gravity may cause motions of gas in the interior of the star that weaken the convection,” said co-author Salvatore Sciortino also of INAF-Osservatorio Astronomico di Palermo in Italy. “This has a domino effect that results in the magnetic field becoming weaker and the star to age prematurely.”

WASP-18 is particularly susceptible to this effect because its convection zone is narrower than most stars. This makes it more vulnerable to the impact of tidal forces that tug at it.

The effect of tidal forces from the planet may also explain an unusually high amount of lithium found in earlier optical studies of WASP-18. Lithium is usually abundant in younger stars, but over time convection carries lithium to the hot inner regions of a star, where it is destroyed by nuclear reactions. If there is less convection, the lithium does not circulate into the interior of the star as much, allowing more lithium to survive.

These results were published in the July issue of Astronomy and Astrophysics.

NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

Publication: Ignazio Pillitteri, et al., “No X-rays from WASP-18. Implications for its age, activity, and the influence of its massive hot Jupiter,” A&A, 567, A128 (2014); doi:10.1051/0004-6361/201423579

Yale Study Shows Risk Patterns for Autism and Schizophrenia Associated with Birth Size

A new study from Yale University shows that bigger babies do have increased risk of autism, while smaller babies are more likely to develop schizophrenia.

The size of babies and even human behavior may be shaped during early fetal development by a molecular tug of war between paternal and maternal genes, according to an emerging theory in evolutionary biology.

Yale evolutionary biologist Stephen Stearns and colleagues at the University of Copenhagen wanted to test a corollary of this theory: that autism and schizophrenia are extremes on a behavioral continuum that may arise from the same genomic conflict of interest.

Their analysis of 1.75 million Danish babies published online September 17 in the Proceedings of Royal Society B shows that, as the theory predicts, bigger babies do have increased risk of autism, while smaller babies are more likely to develop schizophrenia.

“I was startled at how clear the data were,” Stearns said. “The theory isn’t generally accepted yet, but I think there is a growing awareness that this sort of variation may be underlying some forms of human behavior, only grading into mental disorders at the extremes.”

The theory is that the activation of select paternal genes that favor larger and more demanding babies — even though this may endanger the health of the mother and her ability to have more offspring — might also increase the risk of autism. Conversely, maternal genes that favor smaller and easier-to-handle babies — thereby protecting the mother’s ability to deliver more children — might confer greater risk of schizophrenia.

Stearns says a possible explanation begins very early in the development of placenta and brains, when either the male copies or the female copies of certain genes are inactivated. Genes inherited from the father will tend to favor growth of larger — and more resource-demanding — infants who have a greater chance of survival. The interests of genes inherited from the mother are different; they tend to produce smaller babies, which require less resources and investment of time. In other words, male genetic interests are weighted more toward the health of the infant even at some cost to the health of the mother, while female interest is in preserving her ability to produce more offspring.

In the extension of this theory to behavior, autism is the extreme form of a behaviorally demanding infant, while schizophrenia is the opposite end of the behavioral spectrum, favoring a more social and easy-going child.

“These conditions may just be extreme exaggeration of normal behaviors,” Stearns said.

For instance, natural selection in a tool-making culture might favor a mixture of individuals with different degrees of these personality traits — some slightly anti-social but mechanically-oriented individuals in a mix with more creative empathetic persons.

In this view, variations in both birth size and mental disposition are seen as different, independent reflections of an underlying continuum from demanding to non-demanding offspring, said Stearns.

Publication: Sean G. Byars, et al., “Opposite risk patterns for autism and schizophrenia are associated with normal variation in birth size: phenotypic support for hypothesized diametric gene-dosage effects,” Proc. R. Soc. B, 2014, vol. 281 no. 1794 20140604; doi: 10.1098/rspb.2014.0604

Engineers Create Synthetic Materials That Can Change Colors and Textures

Images show textures (top) and fluorescent light (bottom) produced by the new synthetic elastomer material that can mimic some of the camouflage abilities of octopuses and other cephalopods.

A team of engineers has developed a new synthetic material that can change its fluorescence and texture in response to a change in voltage applied to it.

Cephalopods, which include octopuses, squid, and cuttlefish, are among nature’s most skillful camouflage artists, able to change both the color and texture of their skin within seconds to blend into their surroundings — a capability that engineers have long struggled to duplicate in synthetic materials. Now a team of researchers has come closer than ever to achieving that goal, creating a flexible material that can change its color or fluorescence and its texture at the same time, on demand, by remote control.

The results of their research have been published in the journal Nature Communications, in a paper by a team led by MIT Assistant Professor of Mechanical Engineering Xuanhe Zhao and Duke University Professor of Chemistry Stephen Craig.

Zhao, who joined the MIT faculty from Duke this month and holds a joint appointment with the Department of Civil and Environmental Engineering, says the new material is essentially a layer of electro-active elastomer that could be quite easily adapted to standard manufacturing processes and uses readily available materials. This could make it a more economical dynamic camouflage material than others that are assembled from individually manufactured electronic modules.

While its most immediate applications are likely to be military, Zhao says the same basic approach could eventually lead to production of large, flexible display screens and anti-fouling coatings for ships.

In its initial proof-of-concept demonstrations, the material can be configured to respond with changes in both texture and fluorescence, or texture and color. In addition, while the present version can produce a limited range of colors, there is no reason that the range of the palette cannot be increased, Craig says.

Researchers create materials that reproduce cephalopods’ ability to quickly change colors and textures. Credit: Melanie Gonick/MIT

Learning from nature

Cephalopods achieve their remarkable color changes using muscles that can alter the shapes of tiny pigment sacs within the skin — for example, contracting to change a barely visible round blob of color into a wide, flattened shape that is clearly seen. “In a relaxed state, it is very small,” Zhao says, but when the muscles contract, “they stretch that ball into a pancake, and use that to change color. The muscle contraction also varies skin textures, for example, from smooth to bumpy.” Octopuses use this mechanism both for camouflage and for signaling, he says, adding, “We got inspired by this idea, from this wonderful creature.”

The new synthetic material is a form of elastomer, a flexible, stretchable polymer. “It changes its fluorescence and texture together, in response to a change in voltage applied to it — essentially, changing at the flip of a switch,” says Qiming Wang, an MIT postdoc and the first author of the paper.

“We harnessed a physical phenomenon that we discovered in 2011, that applying voltage can dynamically change surface textures of elastomers,” Zhao says.

“The texturing and deformation of the elastomer further activates special mechanically responsive molecules embedded in the elastomer, which causes it to fluoresce or change color in response to voltage changes,” Craig adds. “Once you release the voltage, both the elastomer and the molecules return to their relaxed state — like the cephalopod skin with muscles relaxed.”

Multiple uses for quick changes

While troops and vehicles often move from one environment to another, they are presently limited to fixed camouflage patterns that might be effective in one environment but stick out like a sore thumb in another. Using a system like this new elastomer, Zhao suggests, either on uniforms or on vehicles, could allow the camouflage patterns to constantly change in response to the surroundings.

“The U.S. military spends millions developing different kinds of camouflage patterns, but they are all static,” Zhao says. “Modern warfare requires troops to deploy in many different environments during single missions. This system could potentially allow dynamic camouflage in different environments.”

Another important potential application, Zhao says, is for an anti-fouling coating on the hulls of ships, where microbes and creatures such as barnacles can accumulate and significantly degrade the efficiency of the ship’s propulsion. Earlier experiments have shown that even a brief change in the surface texture, from the smooth surface needed for fast movement to a rough, bumpy texture, can quickly remove more than 90 percent of the biological fouling.

Zhenan Bao, a professor of chemical engineering at Stanford University who was not involved in this research, says this is “inspiring work” and a “clever idea.” She adds, “I think the significant part is to combine the ability of mechanochemical response with electrical addressing so that they can induce fluorescence patterns by demand, reversibly.” Bao cautions that the researchers still face one significant challenge: “Currently they can only induce one kind of pattern in each type of material. It will be important to be able to change the patterns.”

In addition to Zhao, Craig, and Wang, the team also included Duke student Gregory Grossweiler. The work was supported by the U.S. Office of Naval Research, the U.S. Army Research Laboratory and Army Research Office, and the National Science Foundation.

Publication: Qiming Wang, et al., “Cephalopod-inspired design of electro-mechano-chemically responsive elastomers for on-demand fluorescent patterning,” Nature Communications 5, Article number: 4899; doi:10.1038/ncomms5899

Scientists Develop First Water-Based Nuclear Battery

(a), Cross-sectional schematic illustration of nanoporous TiO2 prepared by anodising and thermally oxidising a thin Ti film deposited on a glass substrate. The thin Pt film is deposited on top of the TiO2 nanopores using an RF sputtering system. (b), Energy level diagram of a surface-plasmon-assisted radiolytic water splitter. CB, conduction band; VB, valence band; EF, Fermi energy; eaq−, aqueous electron; ·OH, hydroxyl free radical; β, beta radiation. Credit: Scientific Reports; doi:10.1038/srep05249

Using a water-based solution, researchers at the University of Missouri have created a long-lasting and more efficient nuclear battery.

Columbia, Missouri – From cell phones to cars and flashlights, batteries play an important role in everyday life. Scientists and technology companies constantly are seeking ways to improve battery life and efficiency. Now, for the first time using a water-based solution, researchers at the University of Missouri have created a long-lasting and more efficient nuclear battery that could be used for many applications such as a reliable energy source in automobiles and also in complicated applications such as space flight.

“Betavoltaics, a battery technology that generates power from radiation, has been studied as an energy source since the 1950s,” said Jae W. Kwon, an associate professor of electrical and computer engineering and nuclear engineering in the College of Engineering at MU. “Controlled nuclear technologies are not inherently dangerous. We already have many commercial uses of nuclear technologies in our lives including fire detectors in bedrooms and emergency exit signs in buildings.”

The battery uses a radioactive isotope called strontium-90 that boosts electrochemcial energy in a water-based solution. A nanostructured titanium dioxide electrode (the common element found in sunscreens and UV blockers) with a platinum coating collects and effectively converts energy into electrons.

“Water acts as a buffer and surface plasmons created in the device turned out to be very useful in increasing its efficiency,” Kwon said. “The ionic solution is not easily frozen at very low temperatures and could work in a wide variety of applications including car batteries and, if packaged properly, perhaps spacecraft.”

Publication: Baek Hyun Kim & Jae W. Kwon, “Plasmon-assisted radiolytic energy conversion in aqueous solutions,” Scientific Reports 4, Article number: 5249;

International Team Explains the Mystery Behind a Rare 5-Hour Space Explosion

The X-ray image from the Swift X-ray Telescope of the gamma-ray burst GRB 130925. The white object in the center is the gamma-ray burst. The large diffuse region to the right is a cluster of galaxies. The other objects are X-ray-emitting celestial objects, most likely supermassive black holes at the centers of distant galaxies. The full image is approximately the size of the full moon. Credit: Phil Evans/ University of Leicester

New international research reveals that rare gamma-ray bursts, which can last for hours, can be explained as standard explosions occurring in a region with a low density of matter that is located behind a cloud of dust when viewed from Earth.

University Park, Pennsylvania – Next week in St. Petersburg, Russia, scientists on an international team that includes Penn State astronomers will present a paper that provides a simple explanation for mysterious ultra-long gamma-ray bursts — a very rare form of the most powerful explosions in the universe.

“The recent discovery of ultra-long gamma-ray bursts raised questions about whether some new physics is required to explain them, but our work suggests a much simpler explanation,” said David Burrows, a Penn State professor of astronomy and astrophysics. “Our analysis reveals that these rare gamma-ray bursts, which can last for hours, can be explained as standard explosions occurring in a region with a low density of matter that is located behind a cloud of dust when viewed from Earth.”

Dick Willingale, an astronomer at the University of Leicester and a co-author of the study, said, “Not only is this result significant scientifically, but it shows the importance of international collaborations to build observatories, and of sharing information between those observatories.”

Burrows is the lead scientist for the X-Ray Telescope on board the Swift satellite — one of two space observatories that the scientists used to collect data from the gamma-ray burst named GRB 130925A, which they observed last year while the energy from its explosion streamed toward Earth for more than five hours. Swift is a NASA-led collaboration with Penn State in the United States, the University of Leicester and University College-London in the United Kingdom, and the Italian space agency and Brera Observatory in Italy. The scientists also observed the ultra-long gamma-ray burst with the U.S./Russian satellite Konus-Wind. “We could not have reached our conclusions without the Swift and Konus teams working together,” Willingale said.

Burrows said it is not surprising that some gamma-ray bursts occur in a low-density region, nor is it surprising when one occurs behind a dust cloud. “Our analysis of the observations from the two observatories shows that these two conditions existing simultaneously can explain our observations of the ultra-long gamma-ray burst GRB 130925A,” Burrows said. “One reason that these results are satisfying is that scientists generally prefer to find the simplest explanations for mysterious phenomena,” he said.

Science and flight operations for Swift are controlled by Penn State from the Mission Operations Center at the University Park campus. The principal investigator of the Swift mission is Neil Gehrels at NASA’s Goddard Space Flight Center, who also is an adjunct professor of astronomy and astrophysics at Penn State. In addition to its X-Ray Telescope, Swift also carries an Ultraviolet/Optical Telescope for which Michael Siegel, a research associate at Penn State, is the lead scientist; and a Burst Alert Telescope, for which Scott Barthelmy at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is the lead scientist. These instruments have been providing vital measurements of the afterglows of the gamma-ray bursts since Swift was launched in November 2004. John Nousek, professor of astronomy and astrophysics at Penn State, is the director of the Penn State Mission Operations Center for Swift.

Hubble Reveals Smallest Known Galaxy with Supermassive Black Hole

This is an illustration of the supermassive black hole located in the middle of the very dense galaxy M60-UCD1. It weighs as much as 21 million times the mass of our Sun. NASA, ESA, D. Coe, G. Bacon (STScI)

A team of researchers has discovered a supermassive black hole at the center of ultra-compact galaxy M60-UCD1, making this galaxy the smallest ever found to host a supermassive black hole.

Astronomers using the NASA/ESA Hubble Space Telescope have found a monster lurking in a very unlikely place. New observations of the ultra-compact dwarf galaxy M60-UCD1 have revealed a supermassive black hole at its heart, making this tiny galaxy the smallest ever found to host a supermassive black hole. This suggests that there may be many more supermassive black holes that we have missed, and tells us more about the formation of these incredibly dense galaxies. The results are published in the journal Nature.

Lying about 50 million light-years away, M60-UCD1 is a tiny galaxy with a diameter of 300 light-years — just 1/500th of the diameter of the Milky Way. Despite its size it is pretty crowded, containing some 140 million stars. While this is characteristic of an ultra-compact dwarf galaxy (UCD) like M60-UCD1, this particular UCD happens to be the densest ever seen [1].

Despite their huge numbers of stars, UCDs always seem to be heavier than they should be. Now, an international team of astronomers has made a new discovery that may explain why — at the heart of M60-UCD1 lurks a supermassive black hole [2] with the mass of 20 million Suns.

“We’ve known for some time that many UCDs are a bit overweight. They just appear to be too heavy for the luminosity of their stars,” says co-author Steffen Mieske of the European Southern Observatory in Chile. “We had already published a study that suggested this additional weight could come from the presence of supermassive black holes, but it was only a theory. Now, by studying the movement of the stars within M60-UCD1, we have detected the effects of such a black hole at its center. This is a very exciting result and we want to know how many more UCDs may harbor such extremely massive objects.”

This Hubble Space Telescope image compares the size of M60-UCD1 to the gigantic NGC 4647 galaxy.

The supermassive black hole at the center of M60-UCD1 makes up a huge 15 percent of the galaxy’s total mass, and weighs five times that of the black hole at the center of the Milky Way. “That is pretty amazing, given that the Milky Way is 500 times larger and more than 1000 times heavier than M60-UCD1,” explains Anil Seth of the University of Utah, USA, lead author of the international study. “In fact, even though the black hole at the center of our Milky Way galaxy has the mass of 4 million Suns it is still less than 0.01 percent of the Milky Way’s total mass, which makes you realize how significant M60-UCD1’s black hole really is.”

The team discovered the supermassive black hole by observing M60-UCD1 with both the NASA/ESA Hubble Space Telescope and the Gemini North 8-metre optical and infrared telescope on Hawaii’s Mauna Kea, USA. The sharp Hubble images provided information about the galaxy’s diameter and stellar density, whilst Gemini was used to measure the movement of stars in the galaxy as they were affected by the black hole’s gravitational pull. These data were then used to calculate the mass of the unseen black hole.

The finding implies that there may be a substantial population of previously unnoticed black holes. In fact, the astronomers predict there may be as many as double the known number of black holes in the local Universe.

Additionally, the results could affect theories of how such UCDs form. “This finding suggests that dwarf galaxies may actually be the stripped remnants of larger galaxies that were torn apart during collisions with other galaxies, rather than small islands of stars born in isolation,” explains Seth. “We don’t know of any other way you could make a black hole so big in an object this small.”

One explanation is that M60-UCD1 was once a large galaxy containing 10 billion stars, and a supermassive black hole to match. “This galaxy may have passed too close to the center of its much larger neighboring galaxy, Messier 60,” explains co author Remco van den Bosch of the Max Planck Institute for Astronomy in Heidelberg, Germany. “In that process the outer part of the galaxy would have been torn away to become part of Messier 60, leaving behind only the small and compact galaxy we see today.”

The team believes that M60-UDC1 may one day merge with Messier 60 to form a single galaxy. Messier 60 also has its own monster black hole an amazing 4.5 billion times the size of our Sun and more than 1000 times bigger than the black hole in our Milky Way. A merger between the two galaxies would also cause the black holes to merge, creating an even more monstrous black hole.

Notes

[1] In fact, if you lived inside this galaxy the night sky would dazzle with the light of at least a million stars, all visible to the naked eye. On Earth, a comparatively measly 4000 stars are visible.

[2] Black holes are ultracompact objects with a gravitational pull so strong that even light cannot escape. Supermassive black holes — those with the mass of at least 1 million stars like our Sun — are thought to be at the centers of many galaxies.

Publication: Anil C. Seth, et al., “A supermassive black hole in an ultra-compact dwarf galaxy,” Nature 513, 398–400 (18 September 2014); doi:10.1038/nature13762

Source: Hubble Space teelscope