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Wednesday, November 25, 2015

Volcanic Rocks Hold Clues To Earth's Interior

The journey for volcanic rocks found on many volcanic islands began deep within the Earth.

Brought to the Earth's surface in eruptions of deep volcanic material, these rocks hold clues as to what is going on deep beneath Earth's surface.

Studies of rocks found on certain volcanic islands, known as ocean island basalts, revealed that although these erupted rocks originate from Earth's interior, they are not the same chemically.

A group of former and current Arizona State University researchers say chemical differences found between rocks samples at volcanic hotspots around the world can be explained by a model of mantle dynamics that involves plumes, upwellings of abnormally hot rock within the Earth's mantle, that originate in the lower mantle and physically interact with chemically distinct piles of material.

Credit:  NASA/Jeff Schmaltz/LANCE/EOSDIS MODIS Rapid Response Team/GSFC

According to a group of current and former researchers at Arizona State University, the key to unlocking this complex, geochemical puzzle rests in a model of mantle dynamics consisting of plumes - upwelling's of abnormally hot rock within the Earth's mantle - that originate in the lower mantle and physically interact with chemically distinct piles of material.

The team revealed that this theoretical model of material transport can easily produce the chemical variability observed at hotspot volcanoes (such as Hawaii) around the world.

"This model provides a platform for understanding links between the physics and chemistry that formed our modern world as well as habitable planets elsewhere," says Curtis Williams, lead author of the study whose results are published in the Nov. 24 issue of the journalNature Communications.

Basalts collected from ocean islands such as Hawaii and those collected from mid-ocean ridges (that erupt at spreading centers deep below oceans) may look similar to the naked eye; however, in detail their trace elements and isotopic compositions can be quite distinct. These differences provide valuable insight into the chemical structure and temporal evolution of Earth's interior.

"In particular, it means that the Earth's mantle - the hot rock below Earth's crust but above the planet's iron core - is compositionally heterogeneous. Understanding when and where these heterogeneities are formed and how they are transported through the mantle directly relates to the initial composition of the Earth and how it has evolved to its current, habitable state," said Williams, a postdoc at UC Davis.

While a graduate student in ASU's School of Earth and Space Exploration, Williams and faculty members Allen McNamara and Ed Garnero conceived a study to further understand how chemical complexities that exist deep inside the Earth are transported to the surface and erupt as intraplate volcanism (such as that which formed the Hawaiian islands). Along with fellow graduate student Mingming Li and Professional Research Associate Matthijs van Soest, the researchers depict a model Earth, where in its interior resides distinct reservoirs of mantle material that may have formed during the earliest stages of Earth's evolution.

Employing such reservoirs into their models is supported by geophysical observations of two, continent-sized regions - one below the Pacific Ocean and one below parts of the Atlantic Ocean and Africa - sitting atop the core-mantle boundary.

"In the last several years, we have witnessed a sharpening of the focus knob on seismic imaging of Earth's deep interior. We have learned that the two large anomalous structures at the base of the mantle behave as if they are compositionally distinct. That is, we are talking about different stuff compared to the surrounding mantle. These represent the largest internal anomalies in Earth of unknown chemistry and origin," said Garnero.

These chemically distinct regions also underlie a majority of hotspot volcanism, via hot mantle plumes from the top of the piles to Earth's surface, suggesting a potential link between these ancient, chemically distinct regions and the chemistry of hotspot volcanism.

To test the validity of their model, Williams and coauthors compare their predictions of the variability of the ratios of helium isotopes (helium-3 and helium-4) in plumes to that observed in ocean island basalts.

3He is a so-called primordial isotope found in the Earth's mantle. It was created before the Earth was formed and is thought to have become entrapped within the Earth during planetary formation. Today, it is not being added to Earth's inventory at a significant rate, unlike 4He, which accumulates over time.

Williams explained: "The ratio of helium-3 to helium-4 in mid-ocean ridge basalts are globally characterized by a narrow range of small values and are thought to sample a relatively homogenous upper mantle. On the other hand, ocean island basalts display a much wider range, from small to very large, providing evidence that they are derived from different source regions and are thought to sample the lower mantle either partially or in its entirety."

The variability of 3He to 4He in ocean island basalts is not only observed between different hotspots, but temporally within the different-aged lavas of a single hotspot track.

"The reservoirs and dynamics associated with this variability had remained unclear and was the primary motivation behind the study presented here," said Williams.

Contacts and sources:
Karin Valentine
Arizona State University

Mars' Moon Phobos Will Break into Rings Like Saturn

Mars' largest moon, Phobos, is slowly falling toward the planet, but rather than smash into the surface, it likely will be shredded and the pieces strewn about the planet in a ring like the rings encircling Saturn, Jupiter, Uranus and Neptune.

Though inevitable, the demise of Phobos is not imminent. It will probably happen in 20 to 40 million years, leaving a ring that will persist for anywhere from one million to 100 million years, according to two young earth scientists at the University of California, Berkeley.

Mars could gain a ring in 10-20 million years when its moon Phobos is torn to shreds by tidal forces due to Mars' gravitational pull.

Image by Tushar Mittal using Celestia 2001-2010, Celestia Development Team.

In a paper appearing online this week in Nature Geoscience, UC Berkeley postdoctoral fellow Benjamin Black and graduate student Tushar Mittal estimate the cohesiveness of Phobos and conclude that it is insufficient to resist the tidal forces that will pull it apart when it gets closer to Mars.

Just as earth's moon pulls on our planet in different directions, raising tides in the oceans, for example, so too Mars tugs differently on different parts of Phobos. As Phobos gets closer to the planet, the tugs are enough to actually pull the moon apart, the scientists say. This is because Phobos is highly fractured, with lots of pores and rubble. Dismembering it is analogous to pulling apart a granola bar, Black said, scattering crumbs and chunks everywhere.

The resulting rubble from Phobos - rocks of various sizes and a lot of dust - would continue to orbit Mars and quickly distribute themselves around the planet in a ring.

While the largest chunks would eventually spiral into the planet and collide at a grazing angle to produce egg-shaped craters, the majority of the debris would circle the planet for millions of years until these pieces, too, drop onto the planet in 'moon' showers, like meteor showers. Only Mars' other moon, Deimos, would remain.

Different moons, different fates

Black and Mittal, both in UC Berkeley's Department of Earth and Planetary Science, were drawn to the question of what might happen to Phobos because its fate is expected to be so different from that of most other moons in our solar system.

"While our moon is moving away from earth at a few centimeters per year, Phobos is moving toward Mars at a few centimeters per year, so it is almost inevitable that it will either crash into Mars or break apart," Black said. "One of our motivations for studying Phobos was as a test case to develop ideas of what processes a moon might undergo as it moves inward toward a planet."

Only one other moon in the solar system, Neptune's largest moon, Triton, is known to be moving closer to its planet.

Studying such moons is relevant to conditions in our early solar system, Mittal said, when it's likely there were many more moons around the planets that have since disintegrated into rings - the suspected origins of the rings of the outer planets. Some studies estimate that during planet formation, 20-30 percent of planets acquire moons moving inward and destined for destruction, though they would have long since disappeared. Some of Mars' several thousand elliptical craters may even have been formed by remnants of such moonlets crashing to the surface at a grazing angle.

When tidal stresses overcome rock strength

To estimate the strength of Phobos, Black and Mittal looked data from similarly fractured rocks on Earth and from meteorites that struck Earth and have a density and composition similar to Phobos. They also constrained the strength of Phobos based on results from simulations of the 10-kilometer diameter Stickney impact crater, which formed in the past when a rock rammed into Phobos without quite smashing the moon apart. That crater spans about one-sixth the circumference of Phobos and looks as if someone took a scoop out of the moon.

Mars could gain a ring in 10-20 million years when its moon Phobos is torn to shreds by Mars gravity.

Credit:  Tushar Mittal using Celestia 2001-2010, Celestia Development Team.

Once they determined when and how they expected tidal forces to tear Phobos apart, Mittal modeled the evolution of the ring, adapting techniques developed to understand Saturn's rings.

"If the moon broke apart at 1.2 Mars radii, about 680 kilometers above the surface, it would form a really narrow ring comparable in density to that of one of Saturn's most massive rings," Mittal said. "Over time it would spread out and get wider, reaching the top of the Martian atmosphere in a few million years, when it would start losing material because stuff would keep raining down on Mars."

If the moon breaks up farther from Mars, the ring could persist for 100 million years before raining down on Mars, they found.

Mittal said it's not clear whether the dust and debris rings would be visible from earth, since dust does not reflect much sunlight, whereas ice in the rings of the outer planets makes them easily visible. But Mars' ring may reflect enough light to make Mars slightly brighter as seen from Earth, he said, and through a telescope the shadows of the rings might also be visible on the surface.

"Standing on the surface of Mars a few tens of millions of years from now, it would be pretty spectacular to watch," Black said.

Contacts and sources:
Robert Sanders
 University of California, Berkeley

Earth's Magnetic Field Is Not About To Flip

The intensity of earth's magnetic field has been weakening in the last couple of hundred years, leading some scientists to think that its polarity might be about to flip. But the field's intensity may simply be coming down from an abnormal high rather than approaching a reversal, scientists write in a new paper in the Proceedings of the National Academy of Sciences.

Humans have lived through dips in the field's intensity before, and there are debates about whether reversals in the more distant past had any connection to species extinctions. Today, we have something else today that would be affected by weakening of the magnetic field alone: technology. The magnetic field deflects the solar wind and cosmic rays. When the field is weaker, more radiation gets through, which can disrupt power grids and satellite communications.

This is an artistic impression of how auroras could be more widespread under a geomagnetic field much weaker than today's.

Credit: Huapei Wang, with source files courtesy of NASA's Earth Observatory/NOAA/DOD

"The field may be decreasing rapidly, but we're not yet down to the long-term average. In 100 years, the field may even go back the other direction [in intensity]," said Dennis Kent, an expert in paleomagnetism at Columbia University's Lamont-Doherty Earth Observatory and co-author of the study with his former student, Huapel Wang, now a post-doctoral research associate at MIT, and Pierre Rochette of Aix-Marseille Université.

The scientists used a new technique to measure changes in the magnetic field's strength in the past and found that its long-term average intensity over the past five million years was much weaker than the global database of paleointensity suggests - only about 60 percent of the field's strength today. The findings raise questions both about claims that the magnetic field may be nearing a reversal and about the database itself.

Geomagnetic polarity timescale: Filled and open blocks represent intervals of normal and reverse geomagnetic field polarity over the past 40 million years.

Credit: Gee and Kent, 2007

The study's results fit expectations that the magnetic field's intensity at the poles should be twice its intensity at the equator. In contrast, the time-averaged intensity calculated from the PINT paleointensity database doesn't meet the two-to-one, poles-to-equator dipole hypothesis, and the database calculation suggests that the long-term average intensity over the past 5 million years is similar to the field's intensity today.

The authors believe the difference is in how the samples are analyzed. They say the database, which catalogs paleointensity data from published papers, includes a variety of methods and doesn't clearly delineate data from two different types of magnetized mineral samples, tiny single-domain grains that come from sites that cooled quickly, like basalt glass on the outer edges of lava flows, and more common larger multi-domain grains found deeper inside lava whose magnetic behavior is more complex and require a different type of analysis.

Earth's magnetic poles have reversed several hundred times over the past 100 million years, most recently about 780,000 years ago. Some scientists believe a dip in the magnetic field's intensity 41,000 years ago was also a brief reversal. When scientists recently began noticing a decline in the magnetic field - about 10 percent over the past two centuries - it led to speculation that another reversal could be coming. That doesn't mean it would happen quickly, if it happens at all. The magnetic field's intensity rises and dips without a clear pattern, only sometimes dipping far enough to become unstable and possibly reverse. During a reversal, geomagnetic intensity declines during a transition period that typically lasts hundreds to thousands of years, then rebuilds.

For the new study, the scientists used ancient lava flows from sites near the equator and compared the paleointensity data with what had been regarded as an anomalously low intensity obtained by others from lavas from near the South Pole. As lava cools, iron-bearing minerals form inside and act like tiny magnets, aligning with the Earth's magnetic field. Scientists can analyze ancient lava to determine both the direction and the intensity of the magnetic field at the time the lava formed.

For the new study, the scientists used ancient lava flows from sites near the equator and compared the paleointensity data with from lavas collected near the South Pole. As lava cools, iron-bearing minerals form inside and act like tiny magnets, aligning with the Earth's magnetic field. Scientists can analyze ancient lava to determine both the direction and the intensity of the magnetic field at the time the lava formed.

The scientists used a new technique for analyzing multi-domain samples. They worked with a representative range from the past 5 million years using 27 lavas from the Galápagos Islands, about 1 degree of latitude from the equator. The results were then compared to those from 38 lavas with single-domain properties from a volcanic area near McMurdo Station in Antarctica, about 12 degrees from the South Pole.

When they averaged the geomagnetic intensity of each set, it revealed close to a two-to-one intensity difference between the polar site and the equatorial site, fitting the geocentric axial dipole (GAD) hypothesis, on which most paleogeographic reconstructions rely.

The results show that the time-averaged geomagnetic field intensity over the past 5 million years is about 60 percent of the field's intensity today and aligns with the GAD hypothesis, both in direction and intensity. Other studies using only single-domain basalt glass from the ocean floor have found a similar time-averaged intensity, but they did not have samples to test the polar-equator ratio. The agreement helps to validate the new multiple-domain analysis technique, Kent said.

The lower time-averaged paleointensity also suggests a shorter average magnetopause standoff distance--the distance at which the Earth's magnetic field repels the solar wind. The average is about 9 times the Earth's radius compared to nearly 11 times the Earth's radius today, according to the paper. A shorter standoff distance results in stronger radiation at Earth's surface and in the atmosphere, causing more frequent low-latitude auroras.

Contacts and sources:
 Dennis Kent
 Kevin Krajick, Senior editor, science news
The Earth Institute, Columbia University

Tuesday, November 24, 2015

Food Odors Activate Impulse Area of the Brain in Obese Children

The area of the brain associated with impulsivity and the development of obsessive-compulsive disorder is activated in obese children when introduced to food smells, according to a study being presented next week at the annual meeting of the Radiological Society of North America (RSNA).

"In order to fight obesity, it is crucial to understand the brain mechanisms of odor stimulus," said Pilar Dies-Suarez, M.D., chief radiologist at the Hospital Infantil de México Federico Gómez. "This study has given us a better understanding that obesity has a neurological disorder component, and the findings have the potential to affect treatment of obese patients."

In the United States, nearly 12.7 million children are obese, according to the Centers for Disease Control and Prevention (CDC). These children are at a higher risk to develop high blood pressure, type 2 diabetes, and breathing and joint problems, among many other health issues. They are also more likely to become obese adults.

This figure presents the different connections found for the normal weight vs. obese children depending on smell: onion (1A), acetone (1B) and chocolate (1C). The red lines correspond to connections which were larger for normal weight vs. obese children. The blue lines correspond to stronger connections between the normal weight vs. obese children.
Credit: Radiological Society of North America (RSNA).

The researchers studied 30 children between the ages of 6 and 10 years old. Half of the children had a normal body mass index (BMI) between 19 and 24, and the other half exhibited a BMI over 30, which is classified as obese. Each child was presented with three odor samples: chocolate, onion and a neutral odor of diluted acetone. As the participants smelled the samples, two MRI techniques--functional MRI (fMRI) and functional connectivity MRI (fcMRI)--were used to measure brain activity.

An evaluation of the fMRI results showed that in the obese children, the food odors triggered activation in the areas of the brain associated with impulse and the development of obsessive-compulsive disorder, while the areas of the brain associated with impulse control exhibited no activity. However, in the children with a normal BMI, the areas of the brain associated with pleasure regulation, organization and planning, as well as regions governing emotional processing or memory function, became more active.

In addition, the fcMRI results showed that when the normal-weight children smelled the onion, there was a connection between the gustatory cortex, which processes taste, and the area of the brain linked to reward anticipation. This connection did not occur in the obese children.

The chocolate smell elicited significant brain connections in obese children, compared to the normal-weight children.

"If we are able to identify the mechanisms that cause obesity, we will be able to change the way we treat these patients, and in turn, reduce obesity prevalence and save lives," Dr. Dies-Suarez said.

Contacts and sources:
Radiological Society of North America (RSNA).

Army Ants Build Bridges To Shorten Journeys Through The Rainforest

Army ants construct complex bridges from their own bodies to span gaps and create shortcuts in the floor of the tropical forests of Central America, according to a new study published in the Proceedings of the National Academy of Sciences.

Army ants are nomadic species. They relocate their colonies throughout the rainforest on a regular basis. In order to facilitate the movement of their large population -- a colony can have up to 1 million individuals in some species -- on the very uneven forest floor, some of the ant workers use their own bodies to plug holes along the path traveled by the colony. These workers can also attach to each other to span larger gaps, effectively building living bridges made of several dozens of ants in some instances. These bridges can assemble and disassemble in a matter of seconds, allowing the ant colony to travel at high speed across unknown and unpredictable terrain.

A bridge of army ants
Credit: Jonkerz Museum of Fine Arts

A collaborative team of researchers from New Jersey Institute of Technology (NJIT - Newark, N.J.), Princeton University (Princeton, N.J.), George Washington University (Washington, D.C.), Harvard University (Cambridge, Mass.), and the Max Planck Institute for Ornithology and the University of Konstanz (Konstanz, Germany) has recently discovered that these bridges move on their own from their original building point to create shortcuts across large gaps.

"These bridges change dynamically with the traffic pattern on the trail," says Dr. Christopher Reid, one of the lead authors of the study. "Imagine if the George Washington Bridge between New York City and New Jersey would reposition itself across the river depending on the direction of rush-hour traffic." Now working at the University of Sydney in Australia, Dr. Reid performed the work cited in the study while he was a postdoctoral researcher at NJIT.

Indeed, after starting at intersections between twigs or lianas traveled by the ants, the bridges slowly move away from their starting point, creating shortcuts and progressively lengthening by addition of new workers, before stopping, suspended in mid-air.

"This stopping was a complete surprise for us," adds Reid. "In many cases, the ants could have kept the bridge moving to create better shortcuts, but instead they stopped before achieving the shortest route possible."

Reid and his collaborators discovered that, while ants benefit from shorter traveling distances thanks to their living bridges, they also incur a cost by sequestering workers that could be used for other important tasks, such as prey capture or brood transportation. When building their bridges, army ants have to meet this cost-benefit tradeoff, and therefore cannot build long bridges between distant parts of their trails without risking lacking workers elsewhere.

"Our work has implications for other self-assembling systems, such as reconfigurable materials and autonomous robotic swarms," says Reid. Artificial systems made of independent robots operating via the same principles as the army ants could build large-scale structures as needed. Such swarms could accomplish remarkable tasks, such as creating bridges to navigate complex terrain, plugs to repair structural breaches, or supports to stabilize a failing structure. These systems could also enable robots to operate in complex unpredictable settings, such as in natural-disaster areas, where human presence is dangerous or problematic.

Contacts and sources:
 New Jersey Institute of Technology (NJIT)

This study by Reid et al. was published in the Proceedings of the National Academy of Scienceson November 23, 2015 and can be accessed at: http://www.pnas.org/content/early/2015/11/18/1512241112.abstract

Sea Traffic Pollutes More Than Previously Thought

New data presented by researchers at Lund University and others in the journal Oceanologia show that the air along the coasts is full of hazardous nanoparticles from sea traffic. Almost half of the measured particles stem from sea traffic emissions, while the rest is deemed to be mainly from cars but also biomass combustion, industries and natural particles from the sea.

"This is the first time an attempt has been made to estimate the proportion of nanoparticles stemming from sea traffic. The different types of nanoparticles have previously not been distinguished, but this new method makes it possible", says Adam Kristensson, researcher in Aerosol Technology at the Lund University Faculty of Engineering in Sweden.

Sea traffic pollutes our lungs more than previously thought.
Credit: Lund University

"Previously, we thought that land-based pollution from northern European countries and emissions of natural particles from the surface of the sea accounted for a much larger proportion", he says.

Nanoparticles can be hazardous to our health as they, because of their small size, can penetrate deeper into the lungs than larger particles contributing to both cardiovascular and pulmonary diseases. A cubic centimetre can contain several thousand nanoparticles.

Credit: Lund University

To arrive at these results, he and his colleagues have studied the air flow from their measuring station in southern Sweden as it passes over the Baltic Sea, all the way to the measuring station on the Lithuanian coast. The wind often travels towards the east, and the particles can travel long distances before they are trapped in our lungs or washed away by the rain. They have also studied the air flow from a station in the Finnish archipelago towards the Lithuanian station.

By comparing levels of nanoparticles, the researchers can draw conclusions about the respective proportions that stem from cars and other emissions, and sea traffic.

Particles from sea traffic in the North Sea and the Baltic Sea are expected to contribute to 10 000 premature deaths every year, but Adam Kristensson stresses that this estimate is very uncertain, and believes that it is important to continue to conduct these types of measurements.

He also advocates stricter legislation. "It is especially important to continue to set stricter caps on nitrogen oxides and sulphate content from ship fuel."

"It is especially important to continue to raise the caps on emissions of nitrogen oxides and sulphate content from ship fuel.

Future regulations will hopefully reduce the emissions of harmful nanoparticles, especially soot particles, which are considered the most hazardous.

"This year a new regulation was introduced for the North Sea and the Baltic Sea that limits the sulphate content in fuel to 0.1%. As researchers, we still have to look at what positive effects this has had so far with regard to the particle levels."

Contacts and sources:
Cecilia Schubert
Lund University

Climate Study Finds Evidence of Global Shift in the 1980s: Anthropogenic Warming and Volcanic Eruption Sparked Biggest Change In 1,000 Years

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or 'regime shift', in the Earth's biophysical systems, from the upper atmosphere to the depths of the ocean and from the Arctic to Antarctica, was centred around 1987, and was sparked by the El Chichón volcanic eruption in Mexico five years earlier.

El Chichón 

Credit; answers.com

Their study, published in Global Change Biology, documents a range of associated events caused by the shift, from a 60% increase in winter river flow into the Baltic Sea to a 400% increase in the average duration of wildfires in the Western United States. It also suggests that climate change is not a gradual process, but one subject to sudden increases, with the 1980s shift representing the largest in an estimated 1,000 years.

Philip C. Reid, Professor of Oceanography at Plymouth University's Marine Institute, and Senior Research Fellow at the Sir Alister Hardy Foundation for Ocean Science (SAHFOS), is the lead author of the report, Global impacts of the 1980s regime shift.

"We demonstrate, based on 72 long time series, that a major change took place in the world centred on 1987 that involved a step change and move to a new regime in a wide range of Earth systems," said Professor Reid.

"Our work contradicts the perceived view that major volcanic eruptions just lead to a cooling of the world. In the case of the regime shift it looks as if global warming has reached a tipping point where the cooling that follows such eruptions rebounds with a rapid rise in temperature in a very short time. The speed of this change has had a pronounced effect on many biological, physical and chemical systems throughout the world, but is especially evident in the Northern temperate zone and Arctic."

Over the course of three years, the scientists - drawing upon a range of climate models, using data from nearly 6,500 meteorological stations, and consulting innumerable scientists and their studies round the world - found evidence of the shift across a wide range of biophysical indicators, such as the temperature and salinity of the oceans, the pH level of rivers, the timing of land events, including the behaviour of plants and birds, the amount of ice and snow in the cryosphere (the frozen world), and wind speed changes.

They detected a marked decline in the growth rate of CO2 in the atmosphere after the regime shift, coinciding with a sudden growth in land and ocean carbon sinks - such as new vegetation spreading into polar areas previously under ice and snow. And they found that the annual timing of the regime shift appeared to have moved regionally around the world from west to east, starting with South America in 1984, North America (1985), North Atlantic (1986), Europe (1987), and Asia (1988).

These dates coincide with significant shifts to an earlier flowering date for cherry trees around the Earth in Washington DC, Switzerland, and Japan and coincided with the first evidence of the extinction of amphibians linked to global warming, such as the harlequin frog and golden toad in Central and South America.

Second author Renata E. Hari, Eawag, Dübendorf, Switzerland, said: "The 1980s regime shift may be the beginning of the acceleration of the warming shown by the IPCC. It is an example of the unforeseen compounding effects that may occur if unavoidable natural events like major volcanic eruptions interact with anthropogenic warming."

Contacts and sources: 
Andrew Merrington
University of Plymouth

Loneliness Triggers Cellular Changes That Can Cause Illness, Study Shows

Loneliness is more than a feeling: For older adults, perceived social isolation is a major health risk that can increase the risk of premature death by 14 percent.

Researchers have long known the dangers of loneliness, but the cellular mechanisms by which loneliness causes adverse health outcomes have not been well understood. Now a team of researchers, including UChicago psychologist and leading loneliness expert John Cacioppo, has released a study shedding new light on how loneliness triggers physiological responses that can ultimately make us sick.

Credit: Norvz Austria

The paper, which appears Nov. 23 in the Proceedings of the National Academy of Sciences, shows that loneliness leads to fight-or-flight stress signaling, which can ultimately affect the production of white blood cells.

Along with Cacioppo, the research team includes Steven W. Cole of UCLA and John P. Capitanio of the California National Primate Research Center at the University of California, Davis. The study examined loneliness in both humans and rhesus macaques, a highly social primate species.

Previous research from this group had identified a link between loneliness and a phenomenon they called "conserved transcriptional response to adversity" or CTRA. This response is characterized by an increased expression of genes involved in inflammation and a decreased expression of genes involved in antiviral responses. Essentially, lonely people had a less effective immune response and more inflammation than non-lonely people.

For the current study, the team examined gene expression in leukocytes, cells of the immune system that are involved in protecting the body against bacteria and viruses.

As expected, the leukocytes of lonely humans and macaques showed the effects of CTRA--an increased expression of genes involved in inflammation and a decreased expression of genes involved in antiviral responses. But the study also revealed several important new pieces of information about loneliness' effect on the body.

First, the researchers found that loneliness predicted future CTRA gene expression measured a year or more later. Interestingly, CTRA gene expression also predicted loneliness measured a year or more later. Leukocyte gene expression and loneliness appear to have a reciprocal relationship, suggesting that each can help propagate the other over time. These results were specific to loneliness and could not be explained by depression, stress or social support.

Next, the team investigated the cellular processes linking social experience to CTRA gene expression in rhesus macaque monkeys at the California National Primate Research Center, which had been behaviorally classified as high in perceived social isolation. Like the lonely humans, the "lonely like" monkeys showed higher CTRA activity. They also showed higher levels of the fight-or-flight neurotransmitter, norepinephrine.

Previous research has found that norepinephrine can stimulate blood stem cells in bone marrow to make more of a particular kind of immune cell--an immature monocyte that shows high levels of inflammatory gene expression and low levels of antiviral gene expression. Both lonely humans and "lonely like" monkeys showed higher levels of monocytes in their blood.

More detailed studies of the monkey white blood cells found that this difference stemmed from expansion of the pool of immature monocytes. In an additional study, monkeys repeatedly exposed to mildly stressful social conditions (unfamiliar cage-mates) also showed increases in immature monocyte levels. These analyses have finally identified one reason why CTRA gene expression is amplified in the white blood cell pool: increased output of immature monocytes.

Finally, the researchers determined that this monocyte-related CTRA shift had real consequences for health. In a monkey model of viral infection, the impaired antiviral gene expression in "lonely like" monkeys allowed simian immunodeficiency virus (the monkey version of HIV) to grow faster in both blood and brain.

Taken together, these findings support a mechanistic model in which loneliness results in fight-or-flight stress signaling, which increases the production of immature monocytes, leading to up-regulation of inflammatory genes and impaired anti-viral responses. The "danger signals" activated in the brain by loneliness ultimately affect the production of white blood cells. The resulting shift in monocyte output may both propagate loneliness and contribute to its associated health risks.

The team plans to continue research on how loneliness leads to poor health outcomes and how these effects can be prevented in older adults.

Contacts and sources:
Susie Allen
University of Chicago

Climate Grinds Mountains Faster Than They Can Rebuild, Says Study

Researchers for the first time have attempted to measure all the material leaving and entering a mountain range over millions of years and discovered that glacial erosion can, under the right circumstances, wear down mountains faster than plate tectonics can build them.

A study of the St. Elias Mountains on the Alaskan coast by researchers from The University of Texas at Austin, University of Florida, Oregon State University and elsewhere found that erosion accelerated sharply about one million years ago.

Mount Saint Elias, 2nd highest mountain in Canada and the USA. South Central Alaska, Icy Bay
Mt Saint Elias.jpg
Credit:  David Sinson, NOAA, Office of Coast Survey

The study adds insight into a longstanding debate over the balance of climate and tectonic forces that influence mountain building, which defines how landscapes are shaped by and in turn influence climate. The findings will be published this week in the Proceedings of the National Academy of Sciences.

The international research team, working under the Integrated Ocean Drilling program, included Oregon State University Professors Alan Mix and Joe Stoner and postdoctoral researcher Maureen Walczak as well as other scientists from the U.S., Germany, Brazil, Norway, India, China, Japan, Canada, Australia and the United Kingdom.

The seagoing expedition was the culmination of more than a decade of field work. On a previous expedition, the researchers first mapped a huge submarine sediment fan in the Gulf of Alaska built by sediment eroded from the nearby mountains. Next, they recovered sediment cores to understand the fan environments and recent history. The cores are now archived in the national repository at Oregon State.

Most recently, the researchers collected and dated almost four kilometers of drill cores from the floor of the gulf and the Alaskan continental shelf, revealing millions of years of geologic history.

“It turned out most sediments were younger than we anticipated, implying that erosion was higher than we expected,” said lead author and co-chief scientist Sean Gulick of the University of Texas Institute for Geophysics.

Mountain ranges form when tectonic plates thrust into one another over millions of years and scrunch up the Earth’s outer crust. But even as mountains are built by these titanic forces, other agents work to wear them down.

“About a million years ago, short, 40,000-year climate oscillations jumped into a new mode with stronger, 100,000-year long glacial cycles, and erosion of the mountains accelerated under attack from the ice,” Gulick said. “In fact, more rock was eroded than tectonics has replaced.”

Co-chief scientist John Jaeger of the University of Florida added: “People often see mountain ranges as permanent, but they aren’t really. If more rock is pushed in, they grow, and if more rock is eroded away, they shrink.”

Since the mid-Pleistocene, erosion rates have beaten tectonic inputs by 50 to 80 percent, demonstrating that climatic processes that ultimately drive the glaciers can outstrip mountain building over a span of a million years. The findings highlight the pivotal role climate fluctuations play in shaping Earth’s landforms.

“We were pleasantly surprised by how well we could establish ages of the sediment sequences and the composition of the sediment gave clear evidence of when the glaciation started and then expanded, in sync with global climate trends,” said co-author Mix of OSU’s College of Earth, Ocean, and Atmospheric Sciences. “Only by drilling the sea floor where the sediment accumulates could we see these details in focus.”

The study was funded by the U.S. National Science Foundation and the Integrated Ocean Drilling Program.

Contacts and sources: 
Michelle KlampeOregon State University

New Detector Perfect for Asteroid Mining, a Trillion Dollar Market

The grizzled asteroid miner is a stock character in science fiction. Now, a couple of recent events - one legal and the other technological - have brought asteroid mining a step closer to reality.

The legal step was taken when the Senate Commerce, Science and Transportation Committee passed a bill titled H.R. 2262--SPACE Act of 2015. The bill has a number of measures designed to facilitate commercial space development, including a provision that gives individuals or companies ownership of any material that they mine in outer space. According to one estimate, asteroid mining could ultimately develop into a trillion-dollar market.

This is a flawless two inch SrI2 crystal grown in the Burger Lab for use in new generation of gamma-ray spectrometers.
Credit: Burger Lab, Fisk University

The technological development is a new generation of gamma-ray spectroscope that appears perfectly suited for detecting veins of gold, platinum, rare earths and other valuable material hidden within the asteroids, moons and other airless objects floating around the solar system - just the type of "sensor" that will be needed by asteroid miners to sniff out these valuable materials.

The concept was developed by a team of scientists from Vanderbilt and Fisk Universities, NASA's Jet Propulsion Laboratory and the Planetary Science Institute. It is described in the article "New ultra-bright scintillators for planetary gamma-ray spectroscopy" published Oct. 23 in the SPIE Newsroom. SPIE is the International Society for Optics and Photonics and the SPIE Newsroom highlights noteworthy scientific achievements in the area of optics and photonics.

Penetrating gamma radiation identifies rock-forming elements

Planetary gamma-ray spectroscopy takes advantage of the fact that all of the objects in the solar system are continually bombarded by cosmic rays. These high-energy particles from deep space strike the exposed surfaces at relativistic velocities, smashing apart atoms in the top layers and producing a secondary shower of particles, including neutrons. The neutrons then collide repeatedly with the atoms in the material, producing gamma rays as they go. Gamma rays are a form of electromagnetic radiation like light, but they are considerably more powerful and penetrating. The decay of long-lived radioactive elements is a secondary source of gamma rays.

A gamma-ray spectroscope records the intensity and wavelengths of the gamma rays coming from a surface. This spectrum can be analyzed to determine the concentration of a number of important, rock-forming elements, including oxygen, magnesium, silicon and iron...not to mention precious metals like gold and valuable crystals like diamonds.

"Space missions to the Moon, Mars, Mercury and the asteroid Vesta among others have included low-resolution spectrometers, but it has taken months of observation time and great expense to map their elemental surface compositions from orbit," said Professor of Astronomy Keivan Stassun, the Vanderbilt co-author. "With our proposed system it should be possible to measure sub-surface elemental abundances accurately, and to do it much more cheaply because our sensors weigh less and require less power to operate. That is good news for commercial ventures where cost, power and launch weight are all at a premium."

Transparent crystal detects gamma rays

The key to the new instrument is a recently discovered material, europium-doped strontium iodide (SrI2). This is a transparent crystal that can act as an extremely efficient gamma-ray detector. It registers the passage of gamma rays by giving off flashes of light that can be detected and recorded.

"The gold standard for gamma-ray spectroscopy is the high purity germanium (HPGe) detector," said Fisk Professor of Physics Arnold Burger, who developed the SrI2 detector. "However, it requires cryogenic cooling so it is very bulky. It also needs vacuum-tube technology so it consumes too much energy to run on batteries. SrI2 isn't quite as good HPGe, but it is more than adequate to do the job and it is compact enough and its power requirements low enough so that it can be used in spacecraft and even placed on robotic landers."

Bridge Program success story

According to Stassun and Burger, the project is one of the success stories of theFisk-Vanderbilt Master's-to-Ph.D. Bridge Program which is designed to increase the number of underrepresented minority students in the science, technology, engineering and mathematics disciplines. The program has produced 15 Ph.D. graduates in physics, astronomy and materials science and is on track to produce 3-5 Ph.D.'s per year, making it one of the most prolific sources of minority Ph.D.'s in the country.

"The collaboration we have initiated with colleagues at the Planetary Science Institute in Arizona and at NASA's Jet Propulsion Laboratory in Pasadena will provide future sites for training our Bridge students and exposing them to additional facilities and capabilities outside the Vanderbilt community," Burger said.

It also provides Bridge students with a new area of research to pursue. The program has formed an astro-vaterials team to focus on the spectroscope's development. Last month, several students co-authored a paper published in the Journal of Astronomical Telescopes, Instruments and Systems that reported SrI2 performance at high gamma-ray energies.

"The opportunity to be involved in such a project as a graduate student is an amazing opportunity," said Anna Egner, who is leading the team's effort to build a mock-up of the spectroscope for an actual payload package. "Having always been enchanted and intrigued by physics and astronomy, working on an instrument that might one day fly into space is awesomely exciting."

The first commercial missions to nearby asteroids could launch as early as 2020, but it will be decades before asteroid mining begins in earnest. In the meantime, the new spectroscopic technology promises to provide planetary scientists with new details about the chemical composition of the asteroids, comets, moons and minor planets in the solar system: information that is certain to improve our understanding of how the solar system formed. In addition, it could become an important tool in the planetary defense arsenal because it can determine whether objects crossing Earth's orbit are made from rock or ice.

Contacts and sources: 

Loss of Mastodons Aided Domestication of Pumpkins, Squash

If Pleistocene megafauna -- mastodons, mammoths, giant sloths and others -- had not become extinct, humans might not be eating pumpkin pie and squash for the holidays, according to an international team of anthropologists.

"It's been suggested before and I think it's a very reasonable hypothesis, that wild species of pumpkin and squash weren't used for food early in the domestication process," said Logan Kistler, NERC Independent Research Fellow, University of Warwick, U.K. and recent Penn State postdoctoral fellow. "Rather, they might have been useful for a variety of other purposes like the bottle gourd, as containers, tools, fishnet floats, etc. At some point, as a symbiotic relationship developed, palatability evolved, but the details of that process aren't known at the present."

Cucurbita seeds were found in mastodon dung.

Credit: Lee Newsom, Penn State

Researchers believe that initially humans did not eat wild pumpkin and squash -- members of the cucurbita family -- because the wild fruit is not only bitter but also toxic to humans and smaller animals. However, clear evidence exists that very large animals -- megafauna -- that lived 12,000 years ago did eat these fruit.

"Lee Newsom (associate professor of anthropology, Penn State and study co-author) has recovered many wild gourd/squash seeds from ancient Mastodon dung, suggesting that large herbivores may have been an important feature in the natural history of these wild plants," said Kistler.

The researchers looked at varieties of modern domestic cucurbits, modern wild cucurbits and archaeological specimens. They believe that changes in distribution of the wild plants are directly related to the disappearance of the large animals.

"We performed an ancient DNA study of cucurbita including modern wild plants, domesticated plants and archaeological samples from multiple locations," said George Perry, assistant professor of anthropology and biology. "The results suggest, or confirm, that some lineages domesticated by humans are now extinct in the wild."

Without elephant-sized animals to distribute seeds, wild plants will grow only where the fruit drops -- as far as the pumpkin rolls. At the same time, the disappearance of megafauna altered the landscape from one of a patchwork of environments to something more uniform.Cucurbita are weedy plants that liked the disturbed landscape created by the megafauna, but fared less well in the new landscape of the Holocene.

This image shows squash varieties.

Credit: George Perry, Penn State

The researchers also looked at bitter taste receptors in animals and found that smaller animals with more diverse dietary patterns posses many more bitter taste receptors than large animals that ete only a few things.

"We compared bitter taste receptor genes in about 40 living mammals and found that body sizes and dietary breadth were important," said Perry. "The greater the size, the fewer receptors. The greater the dietary depth, the more receptors."

If humans initially used cucurbita for nonfood applications, they somehow eventually managed to find those plants that mutated and lost their toxicity. According to Kistler, cucurbita may have been domesticated at least six different times in six different places.

"There is a huge amount of diversity in some of the domestic species and between them as well," said Kistler. "Cucurbita pepo is probably the most variable, with jack-o-lantern pumpkins, acorn squash, zucchinis and others. Cucurbita moschata contains the butternut squashes and the kind of pumpkin that goes into the cans that a lot of folks will be baking into pies in a few weeks."

Contacts and sources:
A'ndrea Elyse Messer
Penn State

Electronic Plants Created in Sweden, Researchers Grow Digital and Analog Circuits

Researchers at Linköping University in Sweden have created analog and digital electronics circuits inside living plants. The group at the Laboratory of Organic Electronics (LOE), under the leadership of Professor Magnus Berggren, have used the vascular system of living roses to build key components of electronic circuits.

The article featured in the journal Science Advances demonstrates wires, digital logic, and even displays elements - fabricated inside the plants - that could develop new applications for organic electronics and new tools in plant science.

Augmenting plants with electronic functionality would make it possible to combine electric signals with the plant's own chemical processes.

Credit: Laboratory of Organic Electronics

Plants are complex organisms that rely on the transport of ionic signals and hormones to perform necessary functions. However, plants operate on a much slower time scale making interacting with and studying plants difficult. Augmenting plants with electronic functionality would make it possible to combine electric signals with the plant's own chemical processes. Controlling and interfacing with chemical pathways in plants could pave the way to photosynthesis-based fuel cells, sensors and growth regulators, and devices that modulate the internal functions of plants.

"Previously, we had no good tools for measuring the concentration of various molecules in living plants. Now we'll be able to influence the concentration of the various substances in the plant that regulate growth and development. Here, I see great possibilities for learning more," says Ove Nilsson, professor of plant reproduction biology and director of the Umeå Plant Science Center, as well as a co-author of the article.

The idea of putting electronics directly into trees for the paper industry originated in the 1990s while the LOE team at Linköping University was researching printed electronics on paper. Early efforts to introduce electronics in plants were attempted by Assistant Professor Daniel Simon, leader of the LOE's bioelectronics team, and Professor Xavier Crispin, leader of the LOE's solid-state device team, but a lack of funding from skeptical investors halted these projects.

Thanks to independent research money from the Knut and Alice Wallenberg Foundation in 2012, Professor Berggren was able to assemble a team of researchers to reboot the project. The team tried many attempts of introducing conductive polymers through rose stems. Only one polymer, called PEDOT-S, synthesized by Dr. Roger Gabrielsson, successfully assembled itself inside the xylem channels as conducting wires, while still allowing the transport of water and nutrients. Dr. Eleni Stavrinidou used the material to create long (10 cm) wires in the xylem channels of the rose. By combining the wires with the electrolyte that surrounds these channels she was able to create an electrochemical transistor, a transistor that converts ionic signals to electronic output. Using the xylem transistors she also demonstrated digital logic gate function.

Dr. Eliot Gomez used methods common in plant biology - vacuum infiltration - to infuse another PEDOT variant into the leaves. The infused polymer formed "pixels" of electrochemical cells partitioned by the veins. Applied voltage caused the polymer to interact with the ions in the leaf, subsequently changing the color of the PEDOT in a display-like device - functioning similarly to the roll-printed displays manufactured at Acreo Swedish ICT in Norrköping.

These results are early steps to merge the diverse fields of organic electronics and plant science. The aim is to develop applications for energy, environmental sustainability, and new ways of interacting with plants. Professor Berggren envisions the potential for an entirely new field of research:

"As far as we know, there are no previously published research results regarding electronics produced in plants. No one's done this before," he says.

Professor Berggren adds, "Now we can really start talking about 'power plants' - we can place sensors in plants and use the energy formed in the chlorophyll, produce green antennas, or produce new materials. Everything occurs naturally, and we use the plants' own very advanced, unique systems."

Contacts and sources:
Linköping University

Citation:  Electronic Plants, Eleni Stavrinidou, Roger Gabrielsson, Eliot Gomez, Xavier Crispin, Ove Nilsson, Daniel T Simon, Magnus Berggren, Science Advances 20 November 2015.

Resolving The Mystery of Uterine Vellum Used in First Pocket Bibles

A simple PVC eraser has helped an international team of scientists led by bioarchaeologists at the University of York to resolve the mystery surrounding the tissue-thin parchment used by medieval scribes to produce the first pocket Bibles.

Thousands of the Bibles were made in the 13th century, principally in France but also in England, Italy and Spain. But the origin of the parchment -- often called 'uterine vellum' -- has been a source of long standing controversy.

Non-invasive sampling extracting protein from parchment using eraser crumbs. 
Reproduced by courtesy of The John Rylands Library, University-of-Manchester.

Use of the Latin term abortivum in many sources has led some scholars to suggest that the skin of fetal calves was used to produce the vellum. Others have discounted that theory, arguing that it would not have been possible to sustain livestock herds if so much vellum was produced from fetal skins. Older scholarship even argued that unexpected alternatives such as rabbit or squirrel may have been used, while some medieval sources suggest that hides must have been split by hand through use of a lost technology.

A multi-disciplinary team of researchers, led by Dr Sarah Fiddyment and Professor Matthew Collins of the BioArCh research facility in the Department of Archaeology at York, developed a simple and objective technique using standard conservation treatments to identify the animal origin of parchment.

The non-invasive method is a variant on ZooMS (ZooArchaeology by Mass Spectrometry) peptide mass fingerprinting but extracts protein from the parchment surface simply by using electrostatic charge generated by gentle rubbing of a PVC eraser on the membrane surface.

The research, which is published in Proceedings of the National Academy of Sciences (PNAS), involved scientists and scholars from France, Belgium, Denmark, Ireland, the USA and the UK. They analysed 72 pocket Bibles originating in France, England and Italy, and 293 further parchment samples from the 13th century. The parchment samples ranged in thickness from 0.03 - 0.28mm.

Dr Fiddyment said: "We found no evidence for the use of unexpected animals; however, we did identify the use of more than one mammal species in a single manuscript, consistent with the local availability of hides.

"Our results suggest that ultrafine vellum does not necessarily derive from the use of abortive or newborn animals with ultra-thin skin, but could equally reflect a production process that allowed the skins of maturing animals of several species to be rendered into vellum of equal quality and fineness."

The research represents the first use of triboelectric extraction of protein from parchment. The method is non-invasive and requires no specialist equipment or storage. Samples can be collected without need to transport the artifacts -- researchers can sample when and where possible and analyse when required.

Bruce Holsinger, Professor of English and Medieval Studies at the University of Virginia and the initial humanities collaborator on the project, said: "The research team includes scholars and collaborators from over a dozen disciplines across the laboratory sciences, the humanities, the library and museum sciences--even a parchment maker. In addition to the discoveries we're making, what I find so exciting about this project is its potential to inspire new models for broad-based collaborative research across multiple paradigms. We think together, model together, write together."

Alexander Devine, of the Schoenberg Institute for Manuscript Studies at the University of Pennsylvania, said: "The bibles produced on a vast scale throughout the 13th century established the contents and appearance of the Christian Bible familiar to us today. Their importance and influence stem directly from their format as portable one-volume books, made possible by the innovative combination of strategies of miniaturization and compression achieved through the use of extremely thin parchment. The discoveries of this innovative research therefore enhance our understanding of how these bibles were produced enormously, and by extension, illuminate our knowledge of one of the most significant text technologies in the histories of the Bible and of Western Christianity."

Professor Collins added: "The level of access we have achieved highlights the importance of this technique. Without the eraser technique we could not have extracted proteins from so many parchment samples. Further, with no evidence of unexpected species, such as rabbit or squirrel, we believe that 'uterine vellum' was often an achievement of technological production using available resources."

Since finishing the work, parchment conservator Ji í Vnouček, a co-author on the paper, has used this knowledge to recreate parchment similar to 'uterine vellum' from old skins. He said: "It is more a question of using the right parchment making technology than using uterine skin. Skins from younger animal are of course optimal for production of thin parchment but I can imagine that every skin was collected, nothing wasted."

Contacts and sources:
David Garner
University of York

Friday, November 20, 2015

Cuckoo sheds new light on the scientific mystery of bird migration

The cuckoo is not only capable of finding its way from unknown locations; it does this through a highly complex individual decision making process. Such skills have never before been documented in migratory birds. A new study shows that navigation in migratory birds is even more complex than previously assumed. The Center for Macroecology, Evolution and Climate at the University of Copenhagen led the study with the use of miniature satellite tracking technology.

Eleven cuckoos were relocated from Denmark to Spain. Red lines show the displaced cuckoos' migration route to Central Africa via targeted stopover sites and back to Denmark. Black lines show the normal migration route of cuckoos from Denmark to Central Africa and back again. The research was led by the Center for Macroecology, Evolution and Climate at the Natural History Museum of Denmark at the University of Copenhagen.

Credit: Mikkel Willemoes

In an experiment, 11 adult cuckoos were relocated from Denmark to Spain just before their winter migration to Africa was about to begin. When the birds were released more than 1,000 km away from their well-known migration route, they navigated towards the different stopover areas used along their normal route.

"The release site was completely unknown to the cuckoos, yet they had no trouble finding their way back to their normal migratory route. Interestingly though, they aimed for different targets on the route, which we do not consider random. This individual and flexible choice in navigation indicates an ability to assess advantages and disadvantages of different routes, probably based on their health, age, experience or even personality traits. They evaluate their own condition and adjust their reaction to it, displaying a complicated behavior which we were able to document for the first time in migratory birds", says postdoc Mikkel Willemoes from the Center for Macroecology, Evolution and Climate at the University of Copenhagen.

Satellite technology has made it possible for the first time to track the complete migration of a relocated species and reveal individual responses. 
Credit: Mikkel Willemoes

Previously, in 2014, the Center also led a study mapping the complete cuckoo migration route from Denmark to Africa. Here they discovered that during autumn the birds make stopovers in different areas across Europe and Africa. It was these areas the displaced cuckoos aimed for: Of the 11 birds, one flew to Poland, one to the Balkans, one to Chad and three of them flew to the Democratic Republic of Congo. From there, they followed their familiar migration route. The last five birds lost their transmitting signal.

"In order to select an individual strategy, the birds should be capable of balancing perceived gains and risks of several different scenarios. Such a task would require knowledge of the current location in relation to all of the possible goals as well as distances to each of the goals. This tells us that bird migration in general is far more complex than previously assumed", says Mikkel Willemoes.

The study was carried out in collaboration with Doñana Biological Station in Spain and the Max Planck Institute for Ornithology in Germany.

Bird relocation studies have been carried out in the past, but recent satellite technology has made it possible for the first time to track the complete migration of a relocated species and reveal individual responses.

"We have received remarkable details on the movement of adult birds. The next step is to develop smaller transmitters that will enable us to follow young cuckoos on a relocation flight. Without prior migration experience, their choices will reveal new insight on how they navigate from unknown locations" says Associate Professor Kasper Thorup from the Center for Macroecology, Evolution and Climate.

Cuckoos are particularly suitable for navigation studies, as they lay their eggs inside the nests of other bird species. Growing up without contact to siblings or biological parents, the young cuckoo has no one to follow during migration. Flying alone and at night, it relies entirely on instincts, inherent abilities and the experiences gained later in life. Now, scientists can conclude that these traits are combined into a complex individual decision making strategy.

The study is published in Scientific Reports.

Contacts and sources:
Mikkel Willemoes
University of Copenhagen

Triangulum II Found with Highest Concentration of Dark Matter of Any Galaxy

Dark matter is called "dark" for a good reason. Although they outnumber particles of regular matter by more than a factor of 10, particles of dark matter are elusive. Their existence is inferred by their gravitational influence in galaxies, but no one has ever directly observed signals from dark matter. Now, by measuring the mass of a nearby dwarf galaxy called Triangulum II, Assistant Professor of Astronomy Evan Kirby may have found the highest concentration of dark matter in any known galaxy.

Dwarf galaxies have few stars but lots of dark matter. This Caltech FIRE (Feedback in Realistic Environments) simulation from shows the predicted distribution of stars (left) and dark matter (right) around a galaxy like the Milky Way. The red circle shows a dwarf galaxy like Triangulum II. Although it has a lot of dark matter, it has very few stars. Dark matter-dominated galaxies like Triangulum II are excellent prospects for detecting the gamma-ray signal from dark matter self-annihilation.

Credit: A. Wetzel and P. Hopkins, Caltech

Triangulum II is a small, faint galaxy at the edge of the Milky Way, made up of only about 1,000 stars. Kirby measured the mass of Triangulum II by examining the velocity of six stars whipping around the galaxy's center. "The galaxy is challenging to look at," he says. "Only six of its stars were luminous enough to see with the Keck telescope." By measuring these stars' velocity, Kirby could infer the gravitational force exerted on the stars and thereby determine the mass of the galaxy.

"The total mass I measured was much, much greater than the mass of the total number of stars--implying that there's a ton of densely packed dark matter contributing to the total mass," Kirby says. "The ratio of dark matter to luminous matter is the highest of any galaxy we know. After I had made my measurements, I was just thinking--wow."

Triangulum II could thus become a leading candidate for efforts to directly detect the signatures of dark matter. Certain particles of dark matter, called supersymmetric WIMPs (weakly interacting massive particles), will annihilate one another upon colliding and produce gamma rays that can then be detected from Earth.

While current theories predict that dark matter is producing gamma rays almost everywhere in the universe, detecting these particular signals among other galactic noises, like gamma rays emitted from pulsars, is a challenge. Triangulum II, on the other hand, is a very quiet galaxy. It lacks the gas and other material necessary to form stars, so it isn't forming new stars--astronomers call it "dead." Any gamma ray signals coming from colliding dark matter particles would theoretically be clearly visible.

It hasn't been definitively confirmed, though, that what Kirby measured is actually the total mass of the galaxy. Another group, led by researchers from the University of Strasbourg in France, measured the velocities of stars just outside Triangulum II and found that they are actually moving faster than the stars closer into the galaxy's center--the opposite of what's expected. This could suggest that the little galaxy is being pulled apart, or "tidally disrupted," by the Milky Way's gravity.

"My next steps are to make measurements to confirm that other group's findings," Kirby says. "If it turns out that those outer stars aren't actually moving faster than the inner ones, then the galaxy could be in what's called dynamic equilibrium. That would make it the most excellent candidate for detecting dark matter with gamma rays."

A paper describing this research appears in the November 17 issue of the Astrophysical Journal Letters. Judith Cohen (PhD '71), the Kate Van Nuys Page Professor of Astronomy, is a Caltech coauthor. 

Contacts and sources:
Deborah Williams-HedgesCaltech
Written by Lori Dajose

Thursday, November 19, 2015

Ancient Tropical Forests Found in Norway, Fossil Trees Reveal Dramatic Climate Shift

UK researchers have unearthed ancient fossil forests, thought to be partly responsible for one of the most dramatic shifts in the Earth's climate in the past 400 million years.

The fossil forests, with tree stumps preserved in place, were found in Svalbard, a Norwegian archipelago situated in the Arctic Ocean. They were identified and described by Dr Chris Berry of Cardiff University's School of Earth and Ocean Science.

This is a reconstructed drawing of Svalbard fossil forest. 
Credit: Dr Chris Berry - Cardiff University

Prof John Marshall, of Southampton University, has accurately dated the forests to 380 million years.

The forests grew near the equator during the late Devonian period, and could provide an insight into the cause of a 15-fold reduction in levels of carbon dioxide (CO2) in the atmosphere around that time.

Current theories suggest that during the Devonian period (420-360 million years ago) there was a huge drop in the level of CO2 in the atmosphere, thought to be largely caused by a change in vegetation from diminutive plants to the first large forest trees.

Forests pulled CO2 out of the air through photosynthesis - the process by which plants create food and tissues - and the formation of soils.

Although initially the appearance of large trees absorbed more of the sun's radiation, eventually temperatures on Earth also dropped dramatically to levels very similar to those experienced today because of the reduction in atmospheric CO2.

This is a reconstructed drawing of Svalbard fossil forest.

Credit: Dr Chris Berry - Cardiff University

Because of the high temperatures and large amount of rainfall on the equator, it is likely that equatorial forests contributed most to the drawdown of CO2. Svalbard was located on the equator around this time, before the tectonic plate drifted north by around 80° to its current position in the Arctic Ocean.

"These fossil forests shows us what the vegetation and landscape were like on the equator 380 million years ago, as the first trees were beginning to appear on the Earth," said Dr Berry.

The team found that the forests in Svalbard were formed mainly of lycopod trees, better known for growing millions of years later in coal swamps that eventually turned into coal deposits - such as those in South Wales. They also found that the forests were extremely dense, with very small gaps - around 20cm - between each of the trees, which probably reached about 4m high.

Dr Berry had previously worked with American colleagues to describe another slightly older forest, at Gilboa in upstate New York. The Gilboa forest was located at least 30° south of the equator at that time, and the tree stumps in place belonged to different types of plants.

"This demonstrates that there was already geographical diversity of forest plant types and ecology just as soon as they had evolved," Dr Berry continued.

"During the Devonian Period, it is widely believed that there was a huge drop in the level of carbon dioxide in the atmosphere, from 15 times the present amount to something approaching current levels.

"The evolution of tree-sized vegetation is the most likely cause of this dramatic drop in carbon dioxide because the plants were absorbing carbon dioxide through photosynthesis to build their tissues, and also through the process of forming soils."

Svalbard is currently one of the most northernmost inhabited areas in the world with a population of around 2,500.

Svalbard now plays host to the 'Global Seed Vault' - a secure, underground frozen seed bank in which a large variety of plant seeds are preserved. The vault functions to provide a safety net against a loss of diversity in a global crisis.

"It's amazing that we've uncovered one of the very first forests in the very place that is now being used to preserve the Earth's plant diversity," continued Dr Berry.

The new findings have been published today in the journal Geology.

Contacts and sources:
Michael Bishop
Cardiff University

Tiny, Ultracool Star Is Super Stormy

Our Sun is a relatively quiet star that only occasionally releases solar flares or blasts of energetic particles that threaten satellites and power grids. You might think that smaller, cooler stars would be even more sedate. However, astronomers have now identified a tiny star with a monstrous temper. It shows evidence of much stronger flares than anything our Sun produces. If similar stars prove to be just as stormy, then potentially habitable planets orbiting them are likely to be much less hospitable than previously thought.

Credit:  CfA

"If we lived around a star like this one, we wouldn't have any satellite communications. In fact, it might be extremely difficult for life to evolve at all in such a stormy environment," says lead author Peter Williams of the Harvard-Smithsonian Center for Astrophysics (CfA).

The research team targeted a well-known red dwarf star located about 35 light-years from Earth in the constellation Boîtes. The object is so small and cool that it's right on the dividing line between stars (which fuse hydrogen) and brown dwarfs (which don't). One of the things that makes this small star remarkable is that it spins rapidly, completing a full rotation about every 2 hours. Compare that with our Sun, which takes nearly a month to spin once on its axis.

Animation of artist's impression of red dwarf star TVLM 513-46546. ALMA observations suggest that it has an amazingly powerful magnetic field, potentially associated with a flurry of solar-flare-like eruptions.
Credit: NRAO/AUI/NSF; Dana Berry / SkyWorks

Previous data from the Karl G. Jansky Very Large Array in Socorro, NM showed that this star has a magnetic field several hundred times stronger than our Sun. This puzzled astronomers because the physical processes that generate the Sun's magnetic field shouldn't operate in such a small star.

"This star is a very different beast from our Sun, magnetically speaking," states CfA astronomer and co-author Edo Berger.

The researchers examined the star with the new Atacama Large Millimeter/submillimeter Array (ALMA) and detected emission at a frequency of 95 GHz. This is the first time that flare-like emission at such high frequencies has been detected from a red dwarf star. Our Sun generates similar emission from solar flares but only intermittently. What's more, the emission from this star is 10,000 times brighter than what our own Sun produces, even though it has less than one-tenth of the Sun's mass. The fact that ALMA detected this emission in a brief 4-hour observation suggests that the red dwarf is continuously active.

This has important implications for the search for habitable planets outside the Solar system. Red dwarfs are the most common type of star in our galaxy, which makes them promising targets for planet searches. But because a red dwarf is so cool, a planet would have to orbit very close to the star to be warm enough for liquid water to exist. That proximity would put the planet right in the bull's-eye for radiation that could strip its atmosphere or destroy any complex molecules on its surface.

"It's like living in Tornado Alley in the U.S. Your location puts you at greater risk of severe storms," explains Williams. "A planet in the habitable zone of a star like this would be buffeted by storms much stronger than those generated by the Sun."

Astronomers will study similar stars in the future to determine whether this one is an oddball or an example of an entire class of stormy stars.

Contacts and sources:
Christine Pulliam