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Thursday, April 16, 2015

9/11 Leaves Legacy of Chronic Ill Health among Emergency Medical Services Workers

The 9/11 attacks on the World Trade Center in New York City in 2001 have left a legacy of chronic ill health among emergency medical services workers who came to the rescue of the victims, reveals research published online in Occupational & Environmental Medicine.


Those who arrived in the immediate aftermath of the attacks are most at risk of physical and mental ailments, the findings show.

The health of 2281 New York City Fire Department emergency medical services workers deployed to the scene of the World Trade Center attacks was tracked over a period of 12 years, from the date of the incident on September 11 2001 to the end of December 2013.

The researchers looked at the mental and physical health conditions that have been certified as being linked to the aftermath of the incident under the James Zadroga 9/11 Health and Compensation Act of 2010.

Between 2001 and 2013, the cumulative incidence of acid reflux disease (GERD) was just over 12% while obstructive airways disease (OAD), which includes bronchitis and emphysema, was just under 12%. The cumulative incidences of rhinosinusitis and cancer were 10.6% and 3.1%, respectively.

Validated screening tests were used to gauge the prevalence of mental health conditions: this was 16.7% for probable depression; 7% for probable post-traumatic stress disorder (PTSD); and 3% for probable harmful alcohol use.

Compared with the workers who did not attend the aftermath of the World Trade Center attacks, those who arrived earliest on the scene were at greatest risk for nearly all the health conditions analysed.

They were almost four times as likely to have acid reflux and rhinosinusitis, seven times as likely to have probable PTSD, and twice as likely to have probable depression.

And the more intense the experience was at the time, the greater was the risk of a diagnosis of acid reflux, obstructive airways disease, or rhinosinusitis, and of testing positive for PTSD, depression, and harmful drinking.

The degree of ill health among workers attending the scene was generally lower than that of a demographically similar group of New York City firefighters, probably because of the differences in tasks performed at the World Trade Center site, suggest the authors.

The findings of a substantial amount of ill health underscore the need for continued monitoring and treatment of emergency medical services workers who helped the victims of the World Trade Center attacks, they conclude.


Contacts and sources: 
Caroline White
BMJ Company

Death of Giant Galaxies Spreads From the Core


Astronomers have shown for the first time how star formation in "dead" galaxies sputtered out billions of years ago. The NASA/ESA Hubble Space Telescope and ESO's Very Large Telescope (VLT) have revealed that three billion years after the Big Bang, these galaxies still made stars on their outskirts, but no longer in their interiors. The quenching of star formation seems to have started in the cores of the galaxies and then spread to the outer parts. The results will be published in the 17 April 2015 issue of the journal Science.

This NASA/ESA Hubble Space Telescope image shows an elliptical galaxy known as IC 2006. Massive elliptical galaxies like these are common in the modern Universe, but how they quenched their once furious rates of star formation is an astrophysical mystery.

Credit: ESA/Hubble & NASA Image acknowledgement: Judy Schmidt and J. Blakeslee (Dominion Astrophysical Observatory). Note that the image is not related to science release content. Science acknowledgement: M. Carollo (ETH, Switzerland)

A major astrophysical mystery has centred on how the massive, quiescent elliptical galaxies, common in the modern Universe, quenched their once furious rates of star formation. Such colossal galaxies, often also called spheroids because of their shape, typically pack in stars ten times as densely in the central regions as in our home galaxy, the Milky Way, and have about ten times its mass.

Astronomers refer to these big galaxies as red and dead as they exhibit an ample abundance of ancient red stars, but lack young blue stars and show no evidence of new star formation. The estimated ages of the red stars suggest that their host galaxies ceased to make new stars about ten billion years ago. This shutdown began right at the peak of star formation in the Universe, when many galaxies were still giving birth to stars at a pace about twenty times faster than nowadays.

"Massive dead spheroids contain about half of all the stars that the Universe has produced during its entire life," said Sandro Tacchella of ETH Zurich in Switzerland, lead author of the article. "We cannot claim to understand how the Universe evolved and became as we see it today unless we understand how these galaxies come to be."

Tacchella and colleagues observed a total of 22 galaxies, spanning a range of masses, from an era about three billion years after the Big Bang.  The Universe's age is about 13.8 billion years, so the galaxies studied by Tacchella and colleagues are generally seen as they were more than 10 billion years ago. They used the NASA/ESA Hubble Space Telescope's Wide Field Camera 3 (WFC3) to peer at the galaxies from above our planet's distorting atmosphere -- WFC3 snapped detailed images in the near-infrared, revealing the spatial distribution of older stars within the actively star-forming galaxies.

The researchers also used the SINFONI) instrument on ESO's Very Large Telescope to collect light from the galaxies, showing precisely where they were churning out new stars. SINFONI could make these detailed measurements of distant galaxies thanks to its adaptive optics system, which largely cancels out the blurring effects of Earth's atmosphere.

"Hubble was able to show us how the stars are distributed within these galaxies in amazing detail," commented Marcella Carollo, also of ETH Zurich and co-author of the study. "We were able to match this accuracy with SINFONI to find patches of star formation. Using the two telescope together, we were able to explore this population of galaxies in more detail than ever before."

According to the new data, the most massive galaxies in the sample kept up a steady production of new stars in their peripheries. In their bulging, densely packed centres, however, star formation had already stopped.

"The newly demonstrated inside-out nature of star formation shutdown in massive galaxies should shed light on the underlying mechanisms involved, which astronomers have long debated," says Alvio Renzini, Padova Observatory, of the Italian National Institute of Astrophysics.

A leading theory is that star-making materials are scattered by torrents of energy released by a galaxy's central supermassive black hole as it sloppily devours matter. Another idea is that fresh gas stops flowing into a galaxy, starving it of fuel for new stars and transforming it into a red and dead spheroid.

"There are many different theoretical suggestions for the physical mechanisms that led to the death of the massive spheroids," said co-author Natascha Förster Schreiber of the Max-Planck-Institut für extraterrestrische Physik in Garching, Germany. "Discovering that the quenching of star formation started from the centres and marched its way outwards is a very important step towards understanding how the Universe came to look like it does now."


Contacts and sources:
Georgia Bladon
ESA/Hubble Information Center

Meteorites Date Moon Forming Impact

Through a combination of data analysis and numerical modeling work, researchers have found a record of the ancient Moon-forming giant impact observable in stony meteorites. Their work will appear in the April 2015 issue of the Journal Science.

Artist's depiction of a collision between two planetary bodies. Such an impact between the Earth and a Mars-sized object likely formed the Moon.
Credit: NASA/JPL-Caltech

The work was done by NASA Solar System Exploration Research Virtual Institute (SSERVI) researchers led by Principal Investigator Bill Bottke of the Institute for the Science of Exploration Targets (ISET) team at the Southwest Research Institute and included Tim Swindle, director of the University of Arizona's Lunar and Planetary Laboratory.

One possible realization of the Moon-forming impact event is animated. Here it is assumed that a Mars-sized protoplanet, defined as having 13 percent of an Earth-mass, struck the proto-Earth at a 45-degree angle near the mutual escape velocity of both worlds. The "red" particles, comprising 0.3 percent of an Earth-mass, were found to escape the Earth-Moon system. Some of this debris may eventually go on to strike other solar system bodies like large main belt asteroids. "Yellow-green" particles go into the disk that makes the Moon. "Blue" particles were accreted by the proto-Earth. The details of this simulation can be found in Canup, R. (2004, Simulations of a late lunar-forming impact, Icarus 168, 433-456).
Credit: Robin Canup, Southwest Research Institute
The inner Solar System's biggest known collision was the Moon-forming giant impact between a large protoplanet and the proto-Earth. The timing of this giant impact, however, is uncertain, with the ages of the most ancient lunar samples returned by the Apollo astronauts still being debated. Numerical simulations of the giant impact indicate this event not only created a disk of debris near Earth that formed the Moon, but it also ejected huge amounts of debris completely out of the Earth-Moon system. The fate of this material, comprising as much as several percent of an Earth mass, has not been closely examined until recently. However, it is likely some of it blasted main belt asteroids, with a record plausibly left behind in their near-surface rocks. Collisions on these asteroids in more recent times delivered these shocked remnants to Earth, which scientists have now used to date the age of the Moon.

The research indicates numerous kilometer-sized fragments from the giant impact struck main belt asteroids at much higher velocities than typical main belt collisions, heating the surface and leaving behind a permanent record of the impact event. Evidence that the giant impact produced a large number of kilometer-sized fragments can be inferred from laboratory and numerical impact experiments, the ancient lunar impact record itself, and the numbers and sizes of fragments produced by major main belt asteroid collisions.

Once the team concluded that pieces of the Moon-forming impact hit main belt asteroids and left a record of shock heating events in some meteorites, they set out to deduce both the timing and the relative magnitude of the bombardment. By modeling the evolution of giant impact debris over time and fitting the results to ancient impact heat signatures in stony meteorites, the team was able to infer the Moon formed about 4.47 billion years ago, in agreement with many previous estimates. The most ancient Solar System materials found in meteorites are about one hundred million years older than this age.

Insights into the last stages of planet formation in the inner solar system can be gleaned from these impact signatures. For example, the team is exploring how they can be used to place new constraints on how many asteroid-like bodies still existed in the inner Solar System in the aftermath of planet formation. They can also help researchers deduce the earliest bombardment history of ancient bodies like Vesta, one of the targets of NASA's Dawn mission and a main belt asteroid whose fragments were delivered to Earth in the form of meteorites. It is even possible that tiny remnants of the Moon-forming impactor or proto-Earth might still be found within meteorites that show signs of shock heating by giant impact debris. This would allow scientists to explore for the first time the unknown primordial nature of our homeworld.

Co-author Swindle, who specializes in finding the times when meteorites or lunar samples were involved in large collisions, said: "Bill Bottke had the idea of looking at the asteroid belt to see what effect a Moon-forming giant impact would have, and realized that you would expect a lot of collisions in the period shortly after that.

"Here at LPL, we had been determining ages of impact events that affected meteorites, and when we got together, we found that our data matched his predictions," he added. "It's a great example of taking advantage of groups that work in two different specialties - orbital dynamics and chronology - and combining their expertise."

Intriguingly, some debris may have also returned to hit the Earth and Moon after remaining in solar orbit over timescales ranging from tens of thousands of years to 400 million years.

"The importance of giant impact ejecta returning to strike the Moon could also play an intriguing role in the earliest phase of lunar bombardment," said Bottke, who is an alumnus of the University of Arizona's Lunar and Planetary Laboratory. "This research is helping to refine our time scales for 'what happened when' on other worlds in the Solar System."

Yvonne Pendleton, Director of the NASA SSERVI Institute, notes: "This is an excellent example of the power of multidisciplinary science. By linking studies of the Moon, of main belt asteroids, and of meteorites that fall to Earth, we gain a better understanding of the earliest history of our Solar System."


Contacts and sources:
Daniel Stolte
University of Arizona

Wednesday, April 15, 2015

NASA's New Horizons Nears Historic Encounter with Pluto

NASA’s New Horizons spacecraft is three months from returning to humanity the first-ever close up images and scientific observations of distant Pluto and its system of large and small moons.

Pluto-Charon in Color: This image of Pluto and its largest moon, Charon, was taken by the Ralph color imager aboard New Horizons on April 9, 2015, from a distance of about 71 million miles (115 million kilometers). It is the first color image ever made of the Pluto system by a spacecraft on approach.
Credit: NASA

"Scientific literature is filled with papers on the characteristics of Pluto and its moons from ground based and Earth orbiting space observations, but we’ve never studied Pluto up close and personal,” said John Grunsfeld, astronaut, and associate administrator of the NASA Science Mission Directorate at the agency’s Headquarters in Washington. “In an unprecedented flyby this July, our knowledge of what the Pluto system is really like will expand exponentially and I have no doubt there will be exciting discoveries."

The fastest spacecraft ever launched, New Horizons has traveled a longer time and farther away – more than nine years and three billion miles – than any space mission in history to reach its primary target. Its flyby of Pluto and its system of at least five moons on July 14 will complete the initial reconnaissance of the classical solar system. This mission also opens the door to an entirely new “third” zone of mysterious small planets and planetary building blocks in the Kuiper Belt, a large area with numerous objects beyond Neptune’s orbit.

The flyby caps a five-decade-long era of reconnaissance that began with Venus and Mars in the early 1960s, and continued through first looks at Mercury, Jupiter and Saturn in the 1970s and Uranus and Neptune in the 1980s.

Reaching this third zone of our solar system – beyond the inner, rocky planets and outer gas giants – has been a space science priority for years. In the early 2000s the National Academy of Sciences ranked the exploration of the Kuiper Belt – and particularly Pluto and its largest moon, Charon – as its top priority planetary mission for the coming decade.

New Horizons – a compact, lightweight, powerfully equipped probe packing the most advanced suite of cameras and spectrometers ever sent on a first reconnaissance mission – is NASA’s answer to that call.

NASA's Pluto-bound New Horizons spacecraft captured this view of the giant planet Neptune and its large moon Triton on July 10, 2014, from a distance of about 2.45 billion miles (3.96 billion kilometers) - more than 26 times the distance between the Earth and sun. The 967-millisecond exposure was taken with the New Horizons telescopic Long-Range Reconnaissance Imager (LORRI).
Credit:  NASA

“This is pure exploration; we’re going to turn points of light into a planet and a system of moons before your eyes!” said Alan Stern, New Horizons principal investigator from Southwest Research Institute (SwRI) in Boulder, Colorado. “New Horizons is flying to Pluto – the biggest, brightest and most complex of the dwarf planets in the Kuiper Belt. This 21st century encounter is going to be an exploration bonanza unparalleled in anticipation since the storied missions of Voyager in the 1980s.”

Pluto, the largest known body in the Kuiper Belt, offers a nitrogen atmosphere, complex seasons, distinct surface markings, an ice-rock interior that may harbor an ocean, and at least five moons. Among these moons, the largest – Charon - may itself sport an atmosphere or an interior ocean, and possibly even evidence of recent surface activity.

“There’s no doubt, Charon is a rising star in terms of scientific interest, and we can’t wait to reveal it in detail in July,” said Leslie Young, deputy project scientist at SwRI.

Pluto’s smaller moons also are likely to present scientific opportunities. When New Horizons was started in 2001, it was a mission to just Pluto and Charon, before the four smaller moons were discovered.

The spacecraft’s suite of seven science instruments – which includes cameras, spectrometers, and plasma and dust detectors – will map the geology of Pluto and Charon and map their surface compositions and temperatures; examine Pluto’s atmosphere, and search for an atmosphere around Charon; study Pluto’s smaller satellites; and look for rings and additional satellites around Pluto.

Currently, even with New Horizons closer to Pluto than the Earth is to the Sun, the Pluto system resembles little more than bright dots in the distance. But teams operating the spacecraft are using these views to refine their knowledge of Pluto’s location, and skillfully navigate New Horizons toward a precise target point 7,750 miles (12,500 kilometers) from Pluto’s surface. That targeting is critical, since the computer commands that will orient the spacecraft and point its science instruments are based on knowing the exact time and location that New Horizons passes Pluto.

“Our team has worked hard to get to this point, and we know we have just one shot to make this work,” said Alice Bowman, New Horizons mission operations manager at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, which built and operates the spacecraft. “We’ve plotted out each step of the Pluto encounter, practiced it over and over, and we’re excited the ‘real deal’ is finally here.”

The spacecraft’s work doesn’t end with the July flyby. Because it gets one shot at its target, New Horizons is designed to gather as much data as it can, as quickly as it can, taking about 100 times as much data on close approach as it can send home before flying away. And although the spacecraft will send select, high-priority datasets home in the days just before and after close approach, the mission will continue returning the data stored in onboard memory for a full 16 months.

“New Horizons is one of the great explorations of our time,” said New Horizons Project Scientist Hal Weaver at APL. “There’s so much we don’t know, not just about Pluto, but other worlds like it. We’re not rewriting textbooks with this historic mission – we’ll be writing them from scratch.”

APL manages the New Horizons mission for NASA’s Science Mission Directorate in Washington. Alan Stern of SwRI is the principal investigator. SwRI leads the science team, payload operations and encounter science planning. New Horizons is part of the New Frontiers Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.


Contacts and sources:
Dwayne Brown
NASA

Michael Buckley
Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
 
Maria Stothoff
Southwest Research Institute, San Antonio

New Source of Methane Discovered In the Arctic Ocean


Methane, a highly effective greenhouse gas, is usually produced by decomposition of organic material, a complex process involving bacteria and microbes.

But there is another type of methane that can appear under specific circumstances: Abiotic methane is formed by chemical reactions in the oceanic crust beneath the seafloor.

Ultra-slow spreading ocean ridges were discovered in the Arctic in 2003 by scientists at Woods Hole Ocenographic Institution. They found that for large regions the sea floor splits apart by pulling up solid rock from deep within the earth. These rocks, known as peridotites (after the gemstone peridot) come from the deep layer of the earth known as the mantle.


Credit: Dr. Henry J.B. Dick, WHOI / nsf.gov.

New findings show that deep water gas hydrates, icy substances in the sediments that trap huge amounts of the methane, can be a reservoir for abiotic methane. One such reservoir was recently discovered on the ultraslow spreading Knipovich ridge, in the deep Fram Strait of the Arctic Ocean. The study suggests that abiotic methane could supply vast systems of methane hydrate throughout the Arctic.

The study was conducted by scientists at Centre for Arctic Gas Hydrate, Environment and Climate (CAGE) at UiT The Arctic Univeristy of Norway. The results were recently published inGeology online and will be featured in the journal's May issue.
Previously undescribed

"Current geophysical data from the flank of this ultraslow spreading ridge shows that the Arctic environment is ideal for this type of methane production. " says Joel Johnson associate professor at the University of New Hampshire (USA), lead author, and visiting scholar at CAGE.

This image shows the bathymetry of the area of the Arctic Ocean where the new source of methane was found: Knipovich Ridge in the Fram Strait.

Credit: CAGE

This is a previously undescribed process of hydrate formation; most of the known methane hydrates in the world are fueled by methane from the decomposition of organic matter.

"It is estimated that up to 15 000 gigatonnes of carbon may be stored in the form of hydrates in the ocean floor, but this estimate is not accounting for abiotic methane. So there is probably much more." says co-author and CAGE director Jürgen Mienert.

Life on Mars?

NASA has recently discovered traces of methane on the surface of Mars, which led to speculations that there once was life on our neighboring planet. But an abiotic origin cannot be ruled out yet.

On Earth it forms through a process called serpentinization.

"Serpentinization occurs when seawater reacts with hot mantle rocks exhumed along large faults within the seafloor. These only form in slow to ultraslow spreading seafloor crust. The optimal temperature range for serpentinization of ocean crust is 200 - 350 degrees Celsius." says Johnson.

Methane produced by serpentinization can escape through cracks and faults, and end up at the ocean floor. But in the Knipovich Ridge it is trapped as gas hydrate in the sediments. How is it possible that relatively warm gas becomes this icy substance?

"In other known settings the abiotic methane escapes into the ocean, where it potentially influences ocean chemistry. But if the pressure is high enough, and the subseafloor temperature is cold enough, the gas gets trapped in a hydrate structure below the sea floor. This is the case at Knipovich Ridge, where sediments cap the ocean crust at water depths up to 2000 meters. " says Johnson.

Stable for two million years

Another peculiarity about this ridge is that because it is so slowly spreading, it is covered in sediments deposited by fast moving ocean currents of the Fram Strait. The sediments contain the hydrate reservoir, and have been doing so for about 2 million years.

" This is a relatively young ocean ridge, close to the continental margin. It is covered with sediments that were deposited in a geologically speaking short time period -during the last two to three million years. These sediments help keep the methane trapped in the sea floor." says Stefan Bünz of CAGE, also a co-author on the paper.

Bünz says that there are many places in the Arctic Ocean with a similar tectonic setting as the Knipovich ridge, suggesting that similar gas hydrate systems may be trapping this type of methane along the more than 1000 km long Gakkel Ridge of the central Arctic Ocean.

The Geology paper states that such active tectonic environments may not only provide an additional source of methane for gas hydrate, but serve as a newly identified and stable tectonic setting for the long-term storage of methane carbon in deep-marine sediments.

Need to drill

The reservoir was identified using CAGE's high resolution 3D seismic technology aboard research ressel Helmer Hanssen. Now the authors of the paper wish to sample the hydrates 140 meters below the ocean floor, and decipher their gas composition.

Knipovich Ridge is the most promising location on the planet where such samples can be taken, and one of the two locations where sampling of gas hydrates from abiotic methane is possible.

" We think that the processes that created this abiotic methane have been very active in the past. It is however not a very active site for methane release today. But hydrates under the sediment, enable us to take a closer look at the creation of abiotic methane through the gas composition of previously formed hydrate." says Jürgen Mienert who is exploring possibilities for a drilling campaign along ultra-slow spreading Arctic ridges in the future.

Clean Energy: Harvesting Energy from Electromagnetic Waves

In the future, clean alternatives such as harvesting energy from electromagnetic waves may help ease the world's energy shortage.

For our modern, technologically-advanced society, in which technology has become the solution to a myriad of challenges, energy is critical not only for growth but also, more importantly, survival. The sun is an abundant and practically infinite source of energy, so researchers around the world are racing to create novel approaches to "harvest" clean energy from the sun or transfer that energy to other sources.

The metasurface used for collecting electromagnetic energy is shown.
Credit:  O.Ramahi/U.Waterloo

This week in the journal Applied Physics Letters, from AIP Publishing, researchers from the University of Waterloo in Canada report a novel design for electromagnetic energy harvesting based on the "full absorption concept." This involves the use of metamaterials that can be tailored to produce media that neither reflects nor transmits any power--enabling full absorption of incident waves at a specific range of frequencies and polarizations.

"The growing demand for electrical energy around the globe is the main factor driving our research," said Thamer Almoneef, a Ph.D. student. "More than 80 percent of our energy today comes from burning fossil fuels, which is both harmful to our environment and unsustainable as well. In our group, we're trying to help solve the energy crisis by improving the efficiency of electromagnetic energy-harvesting systems."

Since the inception of collecting and harvesting electromagnetic energy, classical dipole patch antennas have been used. "Now, our technology introduces 'metasurfaces' that are much better energy collectors than classical antennas," explained Omar M. Ramahi, professor of electrical and computer engineering.

Metasurfaces are formed by etching the surface of a material with an elegant pattern of periodic shapes. The particular dimensions of these patterns and their proximity to each other can be tuned to provide "near-unity" energy absorption. This energy is then channeled to a load through a conducting path that connects the metasurface to a ground plane.

The key significance of the researchers' work is that it demonstrates for the first time that it's possible to collect essentially all of the electromagnetic energy that falls onto a surface.

"Conventional antennas can channel electromagnetic energy to a load--but at much lower energy absorption efficiency levels," said Ramahi. "We can also channel the absorbed energy into a load, rather than having the energy dissipate in the material as was done in previous works."

As you can imagine, this work has a broad range of applications. Among the most important is space solar power, an emerging critical technology that can significantly help to address energy shortages. It converts solar rays into microwaves--using conventional photovoltaic solar panels--and then beams the microwave's energy to microwave collector farms at designated locations on Earth. Japan is way out in front of rest of the world in this realm, with plans to begin harvesting solar power from space by 2030.

"Our research enables significantly higher energy absorption than classical antennas," Ramahi said. "This results in a significant reduction of the energy harvesting surface footprint. Real estate is a precious commodity for energy absorption--whether it's wind, hydro, solar or electromagnetic energy."

Other key applications include "wireless power transfer--directly adaptable to power remote devices such as RFID devices and tags or even remote devices in general," Ramahi noted.

The technology can also be extended to the infrared and visible spectra. "We've already extended our work into the infrared frequency regime and we hope to report very soon about near-unity absorption in those higher-frequency regimes," added Ramahi.




Contacts and sources:
Jason Socrates Bardi
American Institute of Physics

Citation:  "Metamaterial electromagnetic energy harvester with near unity efficiency," is authored by Thamer S. Almoneef and Omar M. Ramahi. It will appear in the journal Applied Physics Letters on April 14, 2015 (DOI: 10.1063/1.4916232). After that date it can be accessed at: http://scitation.aip.org/content/aip/journal/apl/106/15/10.1063/1.4916232

The authors of this paper are affiliated with the University of Waterloo.

Five Days of Eating Fatty Foods Can Alter How Your Body's Muscle Processes Food

You might think that you can get away with eating fatty foods for a few days without it making any significant changes to your body.

Think again.

After just five days of eating a high-fat diet, the way in which the body's muscle processes nutrients changes, which could lead to long-term problems such as weight gain, obesity, and other health issues, a new study has found.

Credit: www.getyourfittogether.org

"Most people think they can indulge in high-fat foods for a few days and get away with it," said Matt Hulver, an associate professor of human nutrition, foods, and exercise in the Virginia Tech College of Agriculture and Life Sciences. "But all it takes is five days for your body's muscle to start to protest."

In an article published recently in the online version of the journal Obesity, Hulver and other Virginia Tech researchers found that the manner in which muscle metabolizes nutrients is changed in just five days of high-fat feeding. This is the first study to prove that the change happens so quickly.
Study: Five days of eating fatty foods can alter body - Virginia Tech from VirginiaTech on Vimeo.

"This shows that our bodies are can respond dramatically to changes in diet in a shorter time frame than we have previously thought," said Hulver, who is the head of the department and a Fralin Life Science Institute affiliate. "If you think about it, five days is a very short time. There are plenty of times when we all eat fatty foods for a few days, be it the holidays, vacations, or other celebrations. But this research shows that those high-fat diets can change a person's normal metabolism in a very short timeframe."

When food is eaten, the level of glucose in the blood rises. The body's muscle is a major clearinghouse for this glucose. It may break it down for energy, or it can store it for later use. Since muscle makes up about 30 percent of our body weight and it is such an important site for glucose metabolism, if normal metabolism is altered, it can have dire consequences on the rest of the body and can lead to health issues.

Hulver and his colleagues found that muscles' ability to oxidize glucose after a meal is disrupted after five days of eating a high-fat diet, which could lead to the body's inability to respond to insulin, a risk factor for the development of diabetes and other diseases.

To conduct the study, healthy college-age students were fed a fat-laden diet that included sausage biscuits, macaroni and cheese, and food loaded with butter to increase the percentage of their daily fat intake. A normal diet is made up of about 30 percent fat and students in this study had diets that were about 55 percent fat. Their overall caloric intake remained the same as it was prior to the high fat diet. Muscle samples were then collected to see how it metabolized glucose. Although the study showed the manner in which the muscle metabolized glucose was altered, the students did not gain weight or have any signs of insulin resistance.

Hulver and the team are now interested in examining how these short-term changes in the muscle can adversely affect the body in the long run and how quickly these deleterious changes in the muscle can be reversed once someone returns to a low-fat diet.



Contacts and sources:
Zeke Barlow
Virginia Tech

Age-Related Changes in the Brain Can Have Significant Impact on Individuals, Society

Gradual and variable change in mental functions that occurs naturally as people age, not as part of a neurological disease such as Alzheimer's disease, is one of the most challenging health issues encountered by older adults, says a new report from the Institute of Medicine.

Credit:  The Taub Institute for Research on Alzheimer's Disease and the Aging Brain

The aging process affects the brain just like any other part of the body. Known as "cognitive aging," the type and rate of change can vary widely among individuals. Some will experience very few, if any, effects, while others may experience changes in their memory, speed of processing information, problem solving, learning, and decision-making abilities. The committee that carried out the study and wrote the report proposed three top actions individuals can take to help maintain optimal cognitive function with age.

"Changes in mental functions and capabilities are a part of aging and occur with everyone," said committee chair Dan G. Blazer, the J.P. Gibbons Professor of Psychiatry Emeritus at Duke University Medical Center in Durham, N.C. "The extent and nature of these changes vary widely and are gradual, and aging can have both positive and negative effects on cognition. Wisdom and knowledge can increase with age, while memory and attention can decline."

Aging can affect cognitive abilities needed to perform daily tasks, such as driving, following recipes, adhering to medication schedules, and paying bills, the committee said. As they get older, individuals of all ages should take the following three steps to help promote cognitive health:
  • Be physically active.
  • Reduce and manage cardiovascular disease risk factors, including high blood pressure, diabetes, and smoking.
  • Regularly discuss and review health conditions and medications that might influence cognitive health with a health care professional. A number of medications can have a negative effect -- temporary or long term --on cognitive function when used alone or in combination with other medication.

Other actions that may promote cognitive health:
  • Be socially and intellectually active, and continually seek opportunities to learn.
  • Get adequate sleep and seek professional treatment for sleep disorders, if needed
  • Take steps to avoid a sudden acute decline in cognitive function, known as delirium, associated with medications or hospitalizations.
  • Carefully evaluate products advertised to consumers to improve cognitive health, such as medications, nutritional supplements, and cognitive training.
Communities, nonprofit organizations, and businesses can play a significant role in developing partnerships and programs to help aging individuals take charge of their cognitive health. The report noted that health care professionals need to be prepared to provide guidance to older adults and their families as the patient population ages.

There has been considerable interest over the past several years in whether cognitive stimulation -- either through formal training or everyday activities, such as completing crossword puzzles, participating in a book club, playing card games, or learning to play a musical instrument -- can assist in the maintenance or even enhancement of cognitive function. The scientific literature on cognitive stimulation and cognitive training has shown that older adults can improve on trained abilities, albeit often at a slower pace than younger adults, and that improvements on the tasks can be maintained over time. However, studies examining whether cognitive stimulation and training could transfer to real-world activities and tasks have had mixed results. For example, can a computer-based memory training program help people better remember their shopping list, medical and other appointments, and the names and faces of new acquaintances? Claims regarding the effectiveness of cognitive aging related products require careful evaluation by consumers and in regulatory review, the committee said.

Despite widespread publicity about the benefits of vitamins and supplements for brain health and the large expenditures made on these products for a wide variety of reasons, the evidence for supplements enhancing cognition or preventing decline is limited, and the medical literature does not convincingly support any vitamin supplement intervention to prevent cognitive decline, the report says.

The report emphasizes that cognitive aging has significant impacts and widespread consequences on society, including financial losses. Older adults lose an estimated $2.9 billion a year, directly and indirectly, to financial fraud. To provide necessary assistance and support to older adults, the committee called for the development of cognitive aging information resources and tools that can help individuals and families. Programs and services used by older adults, including those in financial institutions and departments of motor vehicles, should be improved to help them avoid exploitation, optimize independence, and make sound decisions. For example, the financial services industries and relevant state and federal agencies should implement systems approaches, training, and laws and regulations to help verify that financial transactions are not fraudulent or the result of diminished decision-making capacity or undue influence.

"We are only really beginning to understand how the brain changes with age," said Victor Dzau, president of the Institute of Medicine. "As the population of older Americans grows, so will the effects of cognitive aging on society. By calling attention to this issue, we can learn more about the risk and protective factors and needed research so older adults can better maintain their cognitive health to the fullest extent possible."



Contacts and sources:
Jennifer Walsh
National Academy of Sciences

Giant Planet Found 13,000 Light Years from Earth

NASA's Spitzer Space Telescope has teamed up with a telescope on the ground to find a remote gas planet about 13,000 light-years away, making it one of the most distant planets known.

The discovery demonstrates that Spitzer - from its unique perch in space - can be used to help solve the puzzle of how planets are distributed throughout our flat, spiral-shaped Milky Way galaxy. Are they concentrated heavily in its central hub, or more evenly spread throughout its suburbs?


This artist's conception shows a planet half as massive as Jupiter located 13,000 light-years from Earth. It was detected by the Optical Gravitational Lensing Experiment and NASA's Spitzer Space Telescope using microlensing. Spitzer provided parallax measurements that allowed scientists to determine how far away the planet is.
Credit: Christine Pulliam (CfA)

"We don't know if planets are more common in our galaxy's central bulge or the disk of the galaxy, which is why these observations are so important," said Jennifer Yee of the Harvard-Smithsonian Center for Astrophysics (CfA), and a NASA Sagan fellow. Yee is the lead author of one of three new studies that appeared recently in the Astrophysical Journal describing a collaboration between astronomers using Spitzer and the Poland-based Optical Gravitational Lensing Experiment, or OGLE.

OGLE's Warsaw Telescope at the Las Campanas Observatory in Chile scans the skies for planets using a method called microlensing. A microlensing event occurs when one star happens to pass in front of another, and its gravity acts as a lens to magnify and brighten the more distant star's light. If that foreground star happens to be orbited by a planet, the planet might cause a blip in the magnification.

Astronomers are using these blips to find and characterize planets up to 27,000 light-years away in the central bulge of our galaxy, where star crossings are more common. Our sun is located in the suburbs of the galaxy, about two-thirds of the way out from the center. The microlensing technique as a whole has yielded about 30 planet discoveries so far, with the farthest residing about 25,000 light-years away.

"Microlensing experiments are already detecting planets from the solar neighborhood to almost the center of the Milky Way," said co-author Andrew Gould of The Ohio State University, Columbus. "And so they can, in principle, tell us the relative efficiency of planet formation across this huge expanse of our galaxy."

Microlensing complements other planet-hunting tools, such as NASA's Kepler mission, which has found more than 1,000 planets closer to home. But it faces one key problem: This method can't always precisely narrow down the distance to the stars and planets being observed. While a passing star may magnify the light of a more distant star, it rarely can be seen itself, making the task of measuring how far away it is challenging.

Of the approximately 30 planets discovered with microlensing so far, roughly half cannot be pinned down to a precise location. The result is like a planetary treasure map lacking in X's.

That's where Spitzer can help out, thanks to its remote Earth-trailing orbit. Spitzer circles our sun, and is currently about 128 million miles (207 million kilometers) away from Earth. That's further away from Earth than Earth is from our sun. When Spitzer watches a microlensing event simultaneously with a telescope on Earth, it will see the star brighten at a different time due to the large distance between the two telescopes and their unique vantage points, a technique generally referred to as parallax.

"Spitzer is the first space telescope to make a microlens parallax measurement for a planet," said Yee. "Traditional parallax techniques that employ ground-based telescopes are not as effective at such great distances."

Using space telescopes to observe microlensing events is tricky. Ground telescopes send out alerts to the astronomy community when an event starts, but the activity can quickly fade, lasting on average about 40 days. The Spitzer team has scrambled to start microlensing campaigns as soon as three days after receiving an alert.

In the case of the newfound planet, the duration of the microlensing event happened to be unusually long, about 150 days. OGLE detected the start of the event, and Spitzer began monitoring it. Both Spitzer and OGLE's telescopes detected a telltale planetary blip in the magnification, with Spitzer seeing it occur 20 days earlier.

This time delay between OGLE's and Spitzer's viewing of the planetary event was used to calculate the distance to the star and its planet. Knowing the distance allowed the scientists also to determine the mass of the planet, which is about half that of Jupiter.

Spitzer has eyed 22 other microlensing events in collaboration with OGLE and several other ground-based telescopes. While these observations have not turned up new planets, the data are essential to learning the population statistics of stars and planets at the heart of our galaxy. Spitzer will watch approximately 120 additional microlensing events this summer.

"We've mainly explored our own solar neighborhood so far," said Sebastiano Calchi Novati, a Visiting Sagan Fellow at NASA's Exoplanet Science Institute at the California Institute of Technology, Pasadena. "Now we can use these single lenses to do statistics on planets as a whole and learn about their distribution in the galaxy."



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

First Signs of Self-Interacting Dark Matter?

Using the MUSE instrument on ESO's VLT in Chile, along with images from Hubble in orbit, a team of astronomers studied the simultaneous collision of four galaxies in the galaxy cluster Abell 3827. The team could trace out where the mass lies within the system and compare the distribution of the dark matter with the positions of the luminous galaxies.

This image from the NASA/ESA Hubble Space Telescope shows the rich galaxy cluster Abell 3827. The strange blue structures surrounding the central galaxies are gravitationally lensed views of a much more distant galaxy behind the cluster. Observations of the central four merging galaxies have provided hints that the dark matter around one of the galaxies is not moving with the galaxy itself, possibly implying dark matter-dark matter interactions of an unknown nature are occurring.
Credit: ESO

Although dark matter cannot be seen, the team could deduce its location using a technique called gravitational lensing. The collision happened to take place directly in front of a much more distant, unrelated source. The mass of dark matter around the colliding galaxies severely distorted spacetime, deviating the path of light rays coming from the distant background galaxy -- and distorting its image into characteristic arc shapes.

Our current understanding is that all galaxies exist inside clumps of dark matter. Without the constraining effect of dark matter's gravity, galaxies like the Milky Way would fling themselves apart as they rotate. In order to prevent this, 85 percent of the Universe's mass [1] must exist as dark matter, and yet its true nature remains a mystery.

In this study, the researchers observed the four colliding galaxies and found that one dark matter clump appeared to be lagging behind the galaxy it surrounds. The dark matter is currently 5000 light-years (50 000 million million kilometres) behind the galaxy -- it would take NASA's Voyager spacecraft 90 million years to travel that far.

A lag between dark matter and its associated galaxy is predicted during collisions if dark matter interacts with itself, even very slightly, through forces other than gravity [2]. Dark matter has never before been observed interacting in any way other than through the force of gravity.

Lead author Richard Massey at Durham University, explains: "We usedto think that dark matter just sits around, minding its own business, except for its gravitational pull. But if dark matter were being slowed down during this collision, it could be the first evidence for rich physics in the dark sector -- the hidden Universe all around us."

The researchers note that more investigation will be needed into other effects that could also produce a lag. Similar observations of more galaxies, and computer simulations of galaxy collisions will need to be made.

Team member Liliya Williams of the University of Minnesota adds: "We know that dark matter exists because of the way that it interacts gravitationally, helping to shape the Universe, but we still know embarrassingly little about what dark matter actually is. Our observation suggests that dark matter might interact with forces other than gravity, meaning we could rule out some key theories about what dark matter might be."

This result follows on from a recent result from the team which observed 72 collisions between galaxy clusters [3] and found that dark matter interacts very little with itself. The new work however concerns the motion of individual galaxies, rather than clusters of galaxies. Researchers say that the collision between these galaxies could have lasted longer than the collisions observed in the previous study -- allowing the effects of even a tiny frictional force to build up over time and create a measurable lag [4].

Taken together, the two results bracket the behaviour of dark matter for the first time. Dark matter interacts more than this, but less than that. Massey added: "We are finally homing in on dark matter from above and below -- squeezing our knowledge from two directions."



Contacts and sources:
Richard Hook
ESO

The Dark Side: Evidence of 'Interacting' Dark Matter Suggest It Is Not Completely Dark After All


Astronomers believe they might have observed the first potential signs of dark matter interacting with a force other than gravity.

An international team of scientists, led by researchers at Durham University, UK, made the discovery using the Hubble Space Telescope and the European Southern Observatory's Very Large Telescope to view the simultaneous collision of four distant galaxies at the centre of a galaxy cluster 1.3 billion light years away from Earth.

This is an approximately real-color image from the Hubble Space Telescope, of galaxy cluster Abell 3827. The galaxy cluster is made of hundreds of yellowish galaxies. At its core, four giant galaxies are smashing into each other. As the topmost of the four galaxies fell in, it left its dark matter trailing behind. The dark matter is invisible in this image, but its position is revealed by tell-tale gravitational lensing of an unrelated spiral galaxy behind the cluster, whose distorted image is seen as a blue arc. Trailing dark matter is predicted by theories in which dark matter is not perfectly dark, but feels more of the fundamental forces than just gravity.
Credit: Dr. Richard Massey (Durham University)

Writing in the journal Monthly Notices of the Royal Astronomical Society today (Wednesday, April 15, 2015), the researchers said one dark matter clump appeared to be lagging behind the galaxy it surrounds.

They said the clump was currently offset from its galaxy by 5,000 light years (50,000 million million km) - a distance it would take NASA's Voyager spacecraft 90 million years to travel.

Such an offset is predicted during collisions if dark matter interacts, even very slightly, with forces other than gravity.

Computer simulations show that the extra friction from the collision would make the dark matter slow down, and eventually lag behind.

Scientists believe that all galaxies exist inside clumps of dark matter - called "dark" because it is thought to interact only with gravity, therefore making it invisible.

Nobody knows what dark matter is, but it is believed to make up about 85 per cent of the Universe's mass.

Without the constraining effect of its extra gravity, galaxies like our Milky Way would fling themselves apart as they spin.

In the latest study, the researchers were able to "see" the dark matter clump because of the distorting effect its mass has on the light from background galaxies - a technique called gravitational lensing.

The researchers added that their finding potentially rules out the standard theory of Cold Dark Matter, where dark matter interacts only with gravity.

Lead author Dr Richard Massey, Royal Society Research Fellow, in Durham University's Institute for Computational Cosmology, said: "We used to think that dark matter sits around, minding its own business.

"But if it slowed down during this collision, this could be the first dynamical evidence that dark matter notices the world around it.

"Dark matter may not be completely 'dark' after all."

The researchers note that while they appear to have observed the offsetting of dark matter, more investigation will be needed into other potential effects that could also produce a lag between the dark matter and the galaxy it hosts. Similar observations of more galaxies and computer simulations of galaxy collisions are under way to confirm the interpretation.

Team member Professor Liliya Williams, of the University of Minnesota, said: "Our observation suggests that dark matter might be able to interact with more forces than just gravity.

"The parallel Universe going on around us has just got interesting. The dark sector could contain rich physics and potentially complex behaviour."

Last month (March 2015), Dr Massey and colleagues published observations [1] showing that dark matter interacted very little during 72 collisions between galaxy clusters (each containing up to 1,000 galaxies).

Today's latest research concerns the motion of individual galaxies. Researchers say that the collision between these galaxies could have lasted longer than the collisions observed in the previous study - allowing even a small frictional force to build up over time [2].

Taken together, the two results bracket the behaviour of dark matter for the first time. Dark matter interacts more than this, but less than that. Dr Massey added: "We are finally homing in dark matter from above and below - squeezing our knowledge from two directions.

"Dark matter, we're coming for you."

The research was funded by the Royal Society, the Science and Technology Facilities Council and The Leverhulme Trust.


Contacts and sources:
Leighton Kitson
Durham University

Graphene Pushes the Speed Limit of Light-To-Electricity Conversion


Researchers from ICFO, MIT and UC Riverside have been able to develop a graphene-based photodetector capable of converting absorbed light into an electrical voltage at ultrafast timescales.

This is an illustration of ultrafast photovoltage creation after light absorption at the interface of two graphene areas with different Fermi energy.
Credit:  ICFO/Achim Woessner (Image courtesy Achim Woessner).

The efficient conversion of light into electricity plays a crucial role in many technologies, ranging from cameras to solar cells. It also forms an essential step in data communication applications, since it allows for information carried by light to be converted into electrical information that can be processed in electrical circuits. Graphene is an excellent material for ultrafast conversion of light to electrical signals, but so far it was not known how fast graphene responds to ultrashort flashes of light.

ICFO researchers Klaas-Jan Tielrooij, Lukasz Piatkowski, Mathieu Massicotte and Achim Woessner led by ICFO Prof. Frank Koppens and ICREA Prof. at ICFO Niek van Hulst, in collaboration with scientists from the research group led by Pablo Jarillo-Herrero at MIT and the research group led by Jeanie Lau at UC Riverside, have now demonstrated that a graphene-based photodetector converts absorbed light into an electrical voltage at an extremely high speed. The study, entitled "Generation of photovoltage in graphene on a femtosecond timescale through efficient carrier heating", has recently been published inNature Nanotechnology.

The new device that the researchers developed is capable of converting light into electricity in less than 50 femtoseconds (a twentieth of a millionth of a millionth of a second). To do this, the researchers used a combination of ultrafast pulse-shaped laser excitation and highly sensitive electrical readout. As Klaas-Jan Tielrooij comments, "the experiment uniquely combined the ultrafast pulse shaping expertise obtained from single molecule ultrafast photonics with the expertise in graphene electronics. Facilitated by graphene's nonlinear photo-thermoelectric response, these elements enabled the observation of femtosecond photodetection response times."

The ultrafast creation of a photovoltage in graphene is possible due to the extremely fast and efficient interaction between all conduction band carriers in graphene. This interaction leads to a rapid creation of an electron distribution with an elevated electron temperature. Thus, the energy absorbed from light is efficiently and rapidly converted into electron heat. Next, the electron heat is converted into a voltage at the interface of two graphene regions with different doping. This photo-thermoelectric effect turns out to occur almost instantaneously, thus enabling the ultrafast conversion of absorbed light into electrical signals. As Prof. van Hulst states, "it is amazing how graphene allows direct non-linear detecting of ultrafast femtosecond (fs) pulses".

The results obtained from the findings of this work, which has been partially funded by the EC Graphene Flagship, open a new pathway towards ultra-fast optoelectronic conversion. As Prof. Koppens comments, "Graphene photodetectors keep showing fascinating performances addressing a wide range of applications".

 
Contacts and sources: 
Alina Hirschmann
ICFO - The Institute of Photonic Sciences


Citation: Generation of photovoltage in graphene on a femtosecond timescale through efficient carrier heating, Nature Nanotechnology.  K. J. Tielrooij, L. Piatkowski, M. Massicotte, A. Woessner, Q. Ma, Y. Lee, K.S. Myhro, C.N. Lau, P. Jarillo Herrero, N. van Hulst and F. H. L. Koppens.
DOI: 10.1038/nnano.2015.54

E.T. Phone Earth: Search for Advanced Civilizations beyond Earth Finds Nothing Obvious in 100,000 Galaxies


After searching 100,000 galaxies for signs of highly advanced extraterrestrial life, a team of scientists using observations from NASA's WISE orbiting observatory has found no evidence of advanced civilizations in them.

This is a false-color image of the mid-infrared emission from the Great Galaxy in Andromeda, as seen by Nasa's WISE space telescope. The orange color represents emission from the heat of stars forming in the galaxy's spiral arms. The G-HAT team used images such as these to search 100,000 nearby galaxies for unusually large amounts of this mid-infrared emission that might arise from alien civilizations.

Credit:  NASA/JPL-Caltech/WISE Team

"The idea behind our research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization's technologies would be detectable in mid-infrared wavelengths -- exactly the radiation that the WISE satellite was designed to detect for other astronomical purposes," said Jason T. Wright, an assistant professor of astronomy and astrophysics at the Center for Exoplanets and Habitable Worlds at Penn State University, who conceived of and initiated the research.

The research team's first paper about its Glimpsing Heat from Alien Technologies Survey (G-HAT), will be published in the Astrophysical Journal Supplement Series on April 15, 2015. Also among the team's discoveries are some mysterious new phenomena in our own Milky Way galaxy.

"Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy's stars to power computers, space flight, communication, or something we can't yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths," Wright said. "This same basic physics causes your computer to radiate heat while it is turned on."

Theoretical physicist Freeman Dyson proposed in the 1960s that advanced alien civilizations beyond Earth could be detected by the telltale evidence of their mid-infrared emissions. It was not until space-based telescopes like the WISE satellite that it became possible to make sensitive measurements of this radiation emitted by objects in space.

Roger Griffith, a postbaccalaureate researcher at Penn State and the lead author of the paper, scoured almost the entire catalog of the WISE satellite's detections -- nearly 100 million entries -- for objects consistent with galaxies emitting too much mid-infrared radiation. He then individually examined and categorized around 100,000 of the most promising galaxy images. Wright reports, "We found about 50 galaxies that have unusually high levels of mid-infrared radiation. Our follow-up studies of those galaxies may reveal if the origin of their radiation results from natural astronomical processes, or if it could indicate the presence of a highly advanced civilization."

In any case, Wright said, the team's non-detection of any obvious alien-filled galaxies is an interesting and new scientific result. "Our results mean that, out of the 100,000 galaxies that WISE could see in sufficient detail, none of them is widely populated by an alien civilization using most of the starlight in its galaxy for its own purposes. That's interesting because these galaxies are billions of years old, which should have been plenty of time for them to have been filled with alien civilizations, if they exist. Either they don't exist, or they don't yet use enough energy for us to recognize them," Wright said.

"This research is a significant expansion of earlier work in this area," said Brendan Mullan, director of the Buhl Planetarium at the Carnegie Science Center in Pittsburgh and a member of the G-HAT team. "The only previous study of civilizations in other galaxies looked at only 100 or so galaxies, and wasn't looking for the heat they emit. This is new ground."

Matthew Povich, an assistant professor of astronomy at Cal Poly Pomona, and a co-investigator on the project, said "Once we had identified the best candidates for alien-filled galaxies, we had to determine whether they were new discoveries that needed follow-up study, or well-known objects that had a lot of mid-infrared emission for some natural reason." Jessica Maldonado, a Cal Poly Pomona undergraduate, searched the astronomical literature for the best of the objects detected as part of the study to see which were well known and which were new to science. "Ms. Maldonado discovered that about a half dozen of the objects are both unstudied and really interesting looking," Povich said.

"When you're looking for extreme phenomena with the newest, most sensitive technology, you expect to discover the unexpected, even if it's not what you were looking for," said Steinn Sigurdsson, professor of astronomy and astrophysics at Penn State's Center for Exoplanets and Habitable Worlds and a co-investigator on the research team. "Sure enough, Roger and Jessica did find some puzzling new objects. They are almost certainly natural astronomical phenomena, but we need to study them more carefully before we can say for sure exactly what's going on."

Among the discoveries within our own Milky Way galaxy are a bright nebula around the nearby star 48 Librae, and a cluster of objects easily detected by WISE in a patch of sky that appears totally black when viewed with telescopes that detect only visible light. "This cluster is probably a group of very young stars forming inside a previously undiscovered molecular cloud, and the 48 Librae nebula apparently is due to a huge cloud of dust around the star, but both deserve much more careful study," Povich said.

"As we look more carefully at the light from these galaxies," said Wright, "we should be able to push our sensitivity to alien technology down to much lower levels, and to better distinguish heat resulting from natural astronomical sources from heat produced by advanced technologies. This pilot study is just the beginning."

The G-HAT survey was supported by a New Frontiers in Astronomy and Cosmology grant, funded by the John Templeton Foundation.


Contacts and sources:
Barbara K. Kennedy
Penn State University

Tuesday, April 14, 2015

Why Skin Doesn't Tear

Skin is remarkably resistant to tearing and a team of researchers from the University of California, San Diego and the Lawrence Berkeley National Laboratory now have shown why.

Using powerful X-ray beams and electron microscopy, researchers made the first direct observations of the micro-scale mechanisms that allow skin to resist tearing. They identified four specific mechanisms in collagen, the main structural protein in skin tissue, that act together to diminish the effects of stress: rotation, straightening, stretching, and sliding. Researchers say they hope to replicate these mechanisms in synthetic materials to provide increased strength and in better resistance to tearing.

Collagen fibrils at unnotched side are relaxed.

Credit: Jacobs School of Engineering/UC San Diego

"Collagen fibrils and fibers rotate, straighten, stretch and slide to carry load and reduce the stresses at the tip of any tear in the skin," said Berkeley Lab's Robert Ritchie, co-leader of this study with Marc Meyers, a professor of mechanical engineering at the UC San Diego Jacobs School of Engineering. "The movement of the collagen acts to effectively diminish stress concentrations associated with any hole, notch or tear."

"The mechanistic understanding we've identified in skin could be applied to the improvement of artificial skin, or to the development of thin film polymers for applications such as flexible electronics," Ritchie said.

 
Collagen fibril at notched side of the skin are delaminated and align closely to the direction of the tension caused by tearing.
Credit: Jacobs School of Engineering/UC San Diego

Ritchie and Meyers published their results in the March 31 issue of Nature Communication. The other authors of the study are Wen Yang, Vincent Sherman, Bernd Gludovatz, Eric Schaible and Polite Stewart.

Skin consists of three layers -- the epidermis, dermis and endodermis. Mechanical properties are largely determined in the dermis, which is the thickest layer and is made up primarily of collagen and elastin proteins. "Collagen is by far the most important protein in the skin structure because it controls its mechanical response," said Yang, who mechanically tested skin and other natural materials for the study.

The research team began their work by establishing that a tear in the skin does not propagate or induce fracture, unlike other materials such as bone or tooth dentin, which are composed of mineralized collagen fibrils. Instead, the tearing or notching of skin triggers structural changes in the collagen fibrils of the dermis layer to reduce stress concentration. Initially, these collagen fibrils are curvy and highly disordered. However, in response to a tear, they rearrange themselves in the direction in which the skin is being stressed, and prevent failure through rotation, straightening, stretching, sliding and delamination prior to fracturing.

This is a SEM image of arrangement of curved collagen fibers.
Credit: Jacobs School of Engineering/UC San Diego

"The rotation mechanisms recruit collagen fibrils into alignment with the tension axis at which they are maximally strong or can accommodate shape change," says Meyers. "Straightening and stretching allow the uptake of strain without much stress increase, and sliding allows more energy dissipation during inelastic deformation. This reorganization of the fibrils is responsible for blunting the stress at the tips of tears and notches."

This new study of the skin is part of an on-going collaboration between Ritchie and Meyers to examine how nature achieves specific properties through architecture and structure. After its online publication, the study immediately captured the attention of the public and researchers alike. Five days after it was released, it had been picked up by a number of news outlets.




Contacts and sources:
Ioana PatringenaruJacobs School of Engineering/UC San Diego

Citation:  Wen Yang, Vincent R. Sherman, Bernd Gludovatz, Eric Schaible, Polite Stewart, Robert O. Ritchie, Marc A. Meyers. On the tear resistance of skin. Nature Communications, 2015; 6: 6649 DOI: 10.1038/ncomms7649

Why We Have Chins


Look at a primate or a Neanderthal skull and compare it with a modern human's. Notice anything missing?

We have one feature that primates, Neanderthals, archaic humans--any species, for that matter--don't possess: a chin.

"In some way, it seems trivial, but a reason why chins are so interesting is we're the only ones who have them," says Nathan Holton, who studies craniofacial features and mechanics at the University of Iowa. "It's unique to us."

Notice how the modern skull, on the left, has a point at the bottom of the face compared to the Neandethal-era skull on the right. The reason: Only modern humans have chins.

Credit: Tim Schoon, University of Iowa

New research led by Holton and colleagues at the UI posits that our chins don't come from mechanical forces such as chewing, but instead results from an evolutionary adaptation involving face size and shape--possibly linked to changes in hormone levels as we became more societally domesticated.

The finding, if true, may help settle a debate that's gone on intermittently for more than a century why modern humans have chins and how they came to be.

Using advanced facial and cranial biomechanical analyses with nearly 40 people whose measurements were plotted from toddlers to adults, the UI team concludes mechanical forces, including chewing, appear incapable of producing the resistance needed for new bone to be created in the lower mandible, or jaw area. Rather, they write in a paper published online in the Journal of Anatomy, it appears the chin's emergence in modern humans arose from simple geometry: As our faces became smaller in our evolution from archaic humans to today--in fact, our faces are roughly 15 percent shorter than Neanderthals'--the chin became a bony prominence, the adapted, pointy emblem at the bottom of our face.

"In short, we do not find any evidence that chins are tied to mechanical function and in some cases we find that chins are worse at resisting mechanical forces as we grow," says Holton, assistant professor and anthropologist in the Department of Orthodontics at the UI College of Dentistry. "Overall, this suggests that chins are unlikely related to the need to dissipate stresses and strains and that other explanations are more likely to be correct."

More intriguing, UI anthropologists led by Robert Franciscus think the human chin is a secondary consequence of our lifestyle change, starting about 80,000 years ago and picking up great steam with modern humans' migration from Africa about 20,000 years later. What happened was this: Modern humans evolved from hunter-gatherer groups that were rather isolated from each other to increasingly cooperative groups that formed social networks across the landscape. These more connected groups appear to have enhanced the degree to which they expressed themselves in art and other symbolic mediums.

Males in particular became more tranquil during this period, less likely to fight over territory and belongings, and more willing to make alliances, evidenced by exchanging goods and ideas, that benefited each and all.

The change in attitude was tied to reduced hormone levels, namely testosterone, resulting in noticeable changes to the male craniofacial region: One big shift was the face became smaller--retrenching in effect--a physiological departure that created a natural opportunity for the human chin to emerge.

"What we're arguing is that modern humans had an advantage at some point to have a well-connected social network, they can exchange information, and mates, more readily, there's innovation," says Franciscus, who was on the team that first laid out the theory in a paper published last August in the journal Current Anthropology and is a contributing author on the current paper, "and for that to happen, males have to tolerate each other. There had to be more curiosity and inquisitiveness than aggression, and the evidence of that lies in facial architecture."

The new study buttresses that argument, in that it seems to rule out the chin arose from mechanical exertion, such as chewing.

The researchers examined how the jaw region generally reacted to two forces--vertical bending and wishboning. In wishboning, one side of the jaw is pulled outward, resulting in compression in the outer part of the chin. In vertical bending, the ramus--the posterior more or less vertical part on each side of the lower jaw--splays outward, tensing the chin area. In both instances, the thinking went, the chin area is being mechanically stressed; on a microscopic level, new bone is being created, much like lifting weights creates little tears that allows new muscle to be created. Thus, arose the theory that mechanical forces, such as chewing, led to our chins.

But in examinations from periodic measurements of participants' heads from 3 years of age to more than 20 years old, the UI researchers found no evidence that these imperceptible mechanical forces led to new bone in the chin region. Instead, they found nearly the opposite: Individuals with the most mechanical resistance had chins most similar to a 3 -or 4-year-old--meaning they didn't have much of a chin at all.

What the researchers did notice is chin "growth" has more to do with how each feature in our face adapts as our head size increases, much like you'd fit individual pieces together in an expanding, shape-shifting, three-dimensional puzzle.

Children, for example, have flat, nearly imperceptible chins, much like what's seen in Neanderthals. That bony prominence only becomes visible as our heads and faces grow into adulthood.

"Our study suggests that chin prominence is unrelated to function," Holton says, "and probably has more to do with spatial dynamics during development."



Contacts and sources:
Richard Lewis
University of Iowa

First Dark Matter Maps Released

Scientists on the Dark Energy Survey have released the first in a series of dark matter maps of the cosmos. These maps, created with one of the world's most powerful digital cameras, are the largest contiguous maps created at this level of detail and will improve our understanding of dark matter's role in the formation of galaxies. Analysis of the clumpiness of the dark matter in the maps will also allow scientists to probe the nature of the mysterious dark energy, believed to be causing the expansion of the universe to speed up.

This is the first Dark Energy Survey map to trace the detailed distribution of dark matter across a large area of sky. The color scale represents projected mass density: red and yellow represent regions with more dense matter. The dark matter maps reflect the current picture of mass distribution in the universe where large filaments of matter align with galaxies and clusters of galaxies. Clusters of galaxies are represented by gray dots on the map -- bigger dots represent larger clusters. This map covers three percent of the area of sky that DES will eventually document over its five-year mission.
Credit: Dark Energy Survey

The new maps were released today at the April meeting of the American Physical Society in Baltimore, Maryland. They were created using data captured by the Dark Energy Camera, a 570-megapixel imaging device that is the primary instrument for the Dark Energy Survey (DES).

Dark matter, the mysterious substance that makes up roughly a quarter of the universe, is invisible to even the most sensitive astronomical instruments because it does not emit or block light. But its effects can be seen by studying a phenomenon called gravitational lensing - the distortion that occurs when the gravitational pull of dark matter bends light around distant galaxies. Understanding the role of dark matter is part of the research program to quantify the role of dark energy, which is the ultimate goal of the survey.

This analysis was led by Vinu Vikram of Argonne National Laboratory (then at the University of Pennsylvania) and Chihway Chang of ETH Zurich. Vikram, Chang and their collaborators at Penn, ETH Zurich, the University of Portsmouth, the University of Manchester and other DES institutions worked for more than a year to carefully validate the lensing maps.

"We measured the barely perceptible distortions in the shapes of about 2 million galaxies to construct these new maps," Vikram said. "They are a testament not only to the sensitivity of the Dark Energy Camera, but also to the rigorous work by our lensing team to understand its sensitivity so well that we can get exacting results from it."

The camera was constructed and tested at the U.S. Department of Energy's Fermi National Accelerator Laboratory and is now mounted on the 4-meter Victor M. Blanco telescope at the National Optical Astronomy Observatory's Cerro Tololo Inter-American Observatory in Chile. The data were processed at the National Center for Supercomputing Applications at the University of Illinois in Urbana-Champaign.

The dark matter map released today makes use of early DES observations and covers only about three percent of the area of sky DES will document over its five-year mission. The survey has just completed its second year. As scientists expand their search, they will be able to better test current cosmological theories by comparing the amounts of dark and visible matter.

Those theories suggest that, since there is much more dark matter in the universe than visible matter, galaxies will form where large concentrations of dark matter (and hence stronger gravity) are present. So far, the DES analysis backs this up: The maps show large filaments of matter along which visible galaxies and galaxy clusters lie and cosmic voids where very few galaxies reside. Follow-up studies of some of the enormous filaments and voids, and the enormous volume of data, collected throughout the survey will reveal more about this interplay of mass and light.

"Our analysis so far is in line with what the current picture of the universe predicts," Chang said. "Zooming into the maps, we have measured how dark matter envelops galaxies of different types and how together they evolve over cosmic time. We are eager to use the new data coming in to make much stricter tests of theoretical models."

The Dark Energy Survey is a collaboration of more than 300 scientists from 25 institutions in six countries. Its primary instrument, the Dark Energy Camera, is mounted on the 4-meter Blanco telescope at the National Optical Astronomy Observatory's Cerro Tololo Inter-American Observatory in Chile, and its data is processed at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign.



Contacts and sources:
Andre Salles
Fermi Lab

Nanogenerator: Super Stretchy Material Harvest Energy

A research team led by Professor Keon Jae Lee of the Department of Materials Science and Engineering at the Korea Advanced Institute of Science and Technology (KAIST) has developed a hyper-stretchable elastic-composite energy harvesting device called a nanogenerator.

Top row shows schematics of hyper-stretchable elastic-composite generator (SEG) enabled by very long silver nanowire-based stretchable electrodes. The bottom row shows the SEG energy harvester stretched by human hands over 200% strain.

Credit: KAIST

Flexible electronics have come into the market and are enabling new technologies like flexible displays in mobile phone, wearable electronics, and the Internet of Things (IoTs). However, is the degree of flexibility enough for most applications? For many flexible devices, elasticity is a very important issue. For example, wearable/biomedical devices and electronic skins (e-skins) should stretch to conform to arbitrarily curved surfaces and moving body parts such as joints, diaphragms, and tendons.


They must be able to withstand the repeated and prolonged mechanical stresses of stretching. In particular, the development of elastic energy devices is regarded as critical to establish power supplies in stretchable applications. Although several researchers have explored diverse stretchable electronics, due to the absence of the appropriate device structures and correspondingly electrodes, researchers have not developed ultra-stretchable and fully-reversible energy conversion devices properly.

Recently, researchers from KAIST and Seoul National University (SNU) have collaborated and demonstrated a facile methodology to obtain a high-performance and hyper-stretchable elastic-composite generator (SEG) using very long silver nanowire-based stretchable electrodes. Their stretchable piezoelectric generator can harvest mechanical energy to produce high power output (~4 V) with large elasticity (~250%) and excellent durability (over 104 cycles). These noteworthy results were achieved by the non-destructive stress- relaxation ability of the unique electrodes as well as the good piezoelectricity of the device components. The new SEG can be applied to a wide-variety of wearable energy-harvesters to transduce biomechanical-stretching energy from the body (or machines) to electrical energy.

Professor Lee said, "This exciting approach introduces an ultra-stretchable piezoelectric generator. It can open avenues for power supplies in universal wearable and biomedical applications as well as self-powered ultra-stretchable electronics."


Contacts and sources:
Lan Yoon
KAIST

Invisible Objects Created Without Metamaterial Cloaking

 Physicists from ITMO University, Ioffe Institute and Australian National University managed to make homogenous cylindrical objects completely invisible in the microwave range. Contrary to the now prevailing notion of invisibility that relies on metamaterial coatings, the scientists achieved the result using a homogenous object without any additional coating layers. The method is based on a new understanding of electromagnetic wave scattering. The results of the study were published in Scientific Reports.

This is the radio-frequency anechoic chamber used for the experiment.

Credit: ITMO University

The scientists studied light scattering from a glass cylinder filled with water. In essence, such an experiment represents a two-dimensional analog of a classical problem of scattering from a homogeneous sphere (Mie scattering), the solution to which is known for almost a century. However, this classical problem contains unusual physics that manifests itself when materials with high values of refractive index are involved. In the study, the scientists used ordinary water whose refractive index can be regulated by changing temperature.

As it turned out, high refractive index is associated with two scattering mechanisms: resonant scattering, which is related to the localization of light inside the cylinder, and non-resonant, which is characterized by smooth dependence on the wave frequency. The interaction between these mechanisms is referred to as Fano resonances. The researchers discovered that at certain frequencies waves scattered via resonant and non-resonant mechanisms have opposite phases and are mutually destroyed, thus making the object invisible.

The work led to the first experimental observation of an invisible homogeneous object by means of scattering cancellation. Importantly, the developed technique made it possible to switch from visibility to invisibility regimes at the same frequency of 1.9 GHz by simply changing the temperature of the water in the cylinder from 90 °C to 50 °C.

"Our theoretical calculations were successfully tested in microwave experiments. What matters is that the invisibility idea we implemented in our work can be applied to other electromagnetic wave ranges, including to the visible range. Materials with corresponding refractive index are either long known or can be developed at will," said Mikhail Rybin, first author of the paper and senior researcher at the Metamaterials Laboratory in ITMO University.

These are scattering calculations from a single cylinder filled with water. Shown are: strong scattering in uncloaked regimes at (a,e) x = 0.485 and (c,g) x = 1.48, as well as Fano cloaking regimes at (b,f) xcloak = 0.505 and (d,h) xcloak = 1.504.
Credit: Scientific Reports

The discovery of invisibility phenomenon in a homogenous object and not an object covered with additional coating layers is also important from the engineering point of view. Because it is much easier to produce a homogeneous cylinder, the discovery could prompt further development of nanoantennas, wherein invisible structural elements could help reduce disturbances. For instance, invisible rods could be used as supports for a miniature antenna complex connecting two optical chips.

The subject of invisibility came into prominence with the development of metamaterials - artificially designed structures with optical properties that are not encountered elsewhere in nature. Metamaterials are capable of changing the direction of light in exotic ways, including making light curve around the cloaked object. Nevertheless, coating layers based on metamaterials are extremely hard to fabricate and are not compatible with many other invisibility ideas. The method developed by the group is based on a new understanding of scattering processes and leaves behind the existing ones in simplicity and cost-effectiveness.


Contacts and sources:
Dmitry Malkov
ITMO University