There’s been just one problem: the theory suggested most galaxies should have far more stars and dark matter at their cores than they actually do. The problem is most pronounced for dwarf galaxies, the most common galaxies in our own celestial neighborhood. Each contains less than 1 percent of the stars found in large galaxies such as the Milky Way.

Now an international research team, led by a University of Washington astronomer, reports Jan. 14 in Nature that it resolved the problem using millions of hours on supercomputers to run simulations of galaxy formation (1 million hours is more than 100 years). The simulations produced dwarf galaxies very much like those observed today by satellites and large telescopes around the world.

“Most previous work included only a simple description of how and where stars formed within galaxies, or neglected star formation altogether,” said Fabio Governato, a UW research associate professor of astronomy and lead author of the Nature paper.

“Instead we performed new computer simulations, run over several national supercomputing facilities, and included a better description of where and how star formation happens in galaxies.”

The simulations showed that as the most massive new stars exploded as supernovas, the blasts generated enormous winds that swept huge amounts of gas away from the center of what would become dwarf galaxies, preventing millions of new stars from forming.

With so much mass suddenly removed from the center of the galaxy, the pull of gravity on the dark matter there is diminished and the dark matter drifts away, Governato said. It is similar to what would happen if our sun suddenly disappeared and the loss of its gravitational pull allowed the Earth to drift off into space.

The cosmic explosions proved to be the missing piece of the puzzle, and adding them to the simulations generated formation of galaxies with substantially lower densities at their cores, closely matching the observed properties of dwarf galaxies.

“The cold dark matter theory works amazingly well at telling where, when and how many galaxies should form,” Governato said. “What we did was find a better description of processes that we know happen in the real universe, resulting in more accurate simulations.”

The theory of cold dark matter, first advanced in the mid 1980s, holds that the vast majority of the matter in the universe — as much as 75 percent — is made up of “dark” material that does not interact with electrons and protons and so cannot be observed from electromagnetic radiation. The term “cold” means that immediately following the big bang these dark matter particles have speeds far lower than the speed of light.

In the cold dark matter theory, smaller structures form first, then they merge with each other to form more massive halos, and finally galaxies form within the halos.

Coauthors of the Nature paper are Chris Brook of the Jeremiah Horrocks Institute in the United Kingdom; Lucio Mayer of the Institut für Astronomie and the Institute for Theoretical Physics in Switzerland; Alyson Brooks of the California Institute of Technology; George Rhee of the University of Nevada; James Wadsley and Gregory Stinson of McMaster University in Canada; Patrik Jonsson and Piero Madau of the University of California, Santa Cruz; Beth Willman of Haverford College in Pennsylvania and Thomas R. Quinn of the UW.

The research was funded by NASA and the National Science Foundation, and was conducted using facilities of NASA’s Advanced Supercomputing Division, the University of Washington Computing Center, the Arctic Region Supercomputing Center in Alaska and the TeraGrid supercomputer coordinated through the Grid Infrastructure Group at the University of Chicago.

Source: University of Washington
Photo: These images depict various stages of galaxy formation under the cold dark matter theory using new computer simulations that account for the effects of supernova explosions. (Credit: Katy Brooks)

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“We have taken the first step in identifying and preserving our collections and historic buildings,” said Antoinette Beiser, manager of Lowell Observatory’s library and archives.

Through this program, CAP will provide a general conservation assessment of the Observatory’s collections and historic buildings. A professional conservator will spend two days surveying Lowell’s Mars Hill campus and three days writing a comprehensive report to identify conservation priorities. The on-site consultation will enable Lowell Observatory to evaluate its current collections care policies, procedures and environmental conditions. The assessment report will allow the Observatory to seek funding to make appropriate improvements for the immediate, mid-range, and long-term care of important historic structures and collections.

About Historic Preservation

Historic Preservation is a national non-profit organization dedicated to preserving the cultural heritage of the United States. By identifying risks, developing innovative programs, and providing broad public access to expert advice, Heritage Preservation assists museums libraries, archives, historic preservation and other organizations, as well as individuals, in caring for our endangered heritage. To learn more, visit www.heritagepreservation.org.

About the Institute of Museum and Library Services

The Institute of Museum and Library Services is the primary source of federal support for the nation’s 123,000 libraries and 17,500 museums. The Institute’s mission is to create strong libraries and museums that connect people to information and ideas. The Institute works at the national level and in coordination with state and local organizations to sustain heritage, culture, and knowledge; enhance learning and innovation; and support professional development. To learn more, visit www.imls.org.

FOR MORE INFORMATION

Please Contact:
Steele Wotkyns, Public Relations Manager, Lowell Observatory, (928) 233-3232, steele[at]lowell[dot]edu

or:

Antoinette Beiser, Manager, Library and Archives, Lowell Observatory, (928) 233-3216, asb[at]lowell[dot]edu

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“Neuroscientists have long known that some people have a better sense of touch than others, but the reasons for this difference have been mysterious,” said Daniel Goldreich, PhD, of McMaster University in Ontario, one of the study’s authors. “Our discovery reveals that one important factor in the sense of touch is finger size.”

To learn why the sexes have different finger sensitivity, the authors first measured index fingertip size in 100 university students. Each student’s tactile acuity was then tested by pressing progressively narrower parallel grooves against a stationary fingertip — the tactile equivalent of the optometrist’s eye chart. The authors found that people with smaller fingers could discern tighter grooves.

“The difference between the sexes appears to be entirely due to the relative size of the person’s fingertips,” said Ethan Lerner, MD, PhD, of Massachusetts General Hospital, who is unaffiliated with the study. “So, a man with fingertips that are smaller than a woman’s will be more sensitive to touch than the woman.”

The authors also explored why more petite fingers are more acute. Tinier digits likely have more closely spaced sensory receptors, the authors concluded. Several types of sensory receptors line the skin’s interior and each detect a specific kind of outside stimulation. Some receptors, named Merkel cells, respond to static indentations (like pressing parallel grooves), while others capture vibrations or movement.

When the skin is stimulated, activated receptors signal the central nervous system, where the brain processes the information and generates a picture of what a surface “feels” like. Much like pixels in a photograph, each skin receptor sends an aspect of the tactile image to the brain — more receptors per inch supply a clearer image.

To find out whether receptors are more densely packed in smaller fingers, the authors measured the distance between sweat pores in some of the students, because Merkel cells cluster around the bases of sweat pores. People with smaller fingers had greater sweat pore density, which means their receptors are probably more closely spaced.

“Previous studies from other laboratories suggested that individuals of the same age have about the same number of vibration receptors in their fingertips. Smaller fingers would then have more closely spaced vibration receptors,” Goldreich said. “Our results suggest that this same relationship between finger size and receptor spacing occurs for the Merkel cells.”

Whether the total number of Merkel cell clusters remains fixed in adults and how the sense of touch fluctuates in children as they age is still unknown. Goldreich and his colleagues plan to determine how tactile acuity changes as a finger grows and receptors grow farther apart.

The research was supported by the National Eye Institute and the Natural Sciences and Engineering Research Council in Canada.

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Source: Society for Neuroscience
Photo: nesharm / iStockphoto

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It is well know that bones in the arms and legs become weak and vulnerable to breaks when they are not maintained by weight bearing exercise. However skull bone, which bears almost no weight remains particularly resistant to breaking.

The new research published in PLoS ONE* offers an explanation for this phenomenon for the first time. The researchers say that their new understanding of the differences between the two types of bone could lead to new ways to treat or prevent osteoporosis.

People who develop osteoporosis have fragile bones which are prone to breaking. The condition becomes more common as we age, especially in post-menopausal women when levels of oestrogen fall dramatically. In the over 50s it affects half of all women and a fifth of all men.

The researchers wanted to understand why the skull bones are resistant to bone thinning as they age, even in post-menopausal women.

To investigate this, they looked in detail at rat bone cells from the skull and compared them with cells from limb bone. They found differences between the appearance of the cells and how they behaved in the lab. They also noticed that treating the cells with oestrogen had a far greater effect on the cells from the limb bone.

Because the differences are so profound, the researchers believe that they are set very early on in life – probably when the bones are still forming in the womb.

The researchers also made a detailed genetic study of the two types of bone cell. They looked at which genes were active in the two types of cell and found a startling level of difference between the two. The found a total of 1236 – around four per cent of the genome – were showing different levels of activity in the two types of bone cell.

Among these they found a number of genes which are known to be involved in the process of forming healthy bones.

Lead author, Dr Simon Rawlinson, Lecturer in Oral Biology at Queen Mary, University of London, explained: “This research is exciting because it tells us why our skulls remain so tough as we age compared to the bones in our arms and legs.

“Now we understand this phenomenon better, we also understand osteoporosis better. And this has opened up many new lines of research into how the disease could be treated or even prevented.”

The research was funded by the National Institute for Health Research and the Medical Research Council.

Source: Queen Mary, University of London
Photo: iStockphoto – Raycat

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Jason, designed and operated by the Woods Hole Oceanographic Institution for the National Deep Submergence Facility, utilized a prototype, high-definition still and video camera to capture the powerful event nearly 4,000 feet below the surface of the Pacific Ocean, in an area bounded by Fiji, Tonga and Samoa.

“I felt immense satisfaction at being able to bring [the science team] the virtual presence that Jason provides,” says Jason expedition leader Alberto (Tito) Collasius Jr., who remotely piloted the ROV over the seafloor. “There were fifteen exuberant scientists in the control van who all felt like they hit a home run. “

Collasius led a team that operated the unmanned, tethered vehicle from a control van on the research vessel and used a joystick to “fly” Jason over the seafloor to within 10 feet of the erupting volcano. Its two robotic arms collected samples of rocks, hot spring waters, microbes, and macro biological specimens.

Through its fiber optic tether, ROV Jason transmitted-high definition video of the eruption as it was occurring. The unique camera system, developed and operated by the Advanced Imaging and Visualization Lab at WHOI, was installed on Jason for the expedition to acquire high quality imagery of the seafloor. The AIVL designs, develops, and operates high resolution imaging systems for scientific monitoring, survey, and entertainment purposes. AIVL imagery has been used in several IMAX films and hundreds of television programs and documentaries.

The video from the research expedition, which departed Western Samoa aboard the RV Thomas Thompson on May 5, 2009, was shown for the first time today at the American Geophysical Union fall meeting in San Francisco.

“Less than 24 hours after leaving port, we located the ongoing eruption and observed, for the first time, molten lava flowing across the deep-ocean seafloor, glowing bubbles three feet across, and explosions of volcanic rock,” reported Joe Resing, a chemical oceanographer at the University of Washington and NOAA, and chief scientist on the NOAA- and National Science Foundation-funded expedition.

For more than a decade, monitoring systems have allowed scientists to listen for seafloor eruptions but there has always been a time lag between hearing an eruption and assembling a team and a research vessel to see it. This has meant that scientists have always observed eruptions after the fact.

“We saw a lot of interesting phenomena, but we never saw an eruption because it happens so quickly,” said Robert Embley, a NOAA PMEL marine geologist and co-chief scientist on the expedition. “As geologists, you want to see the process in action. You learn a lot more about it watching the process.”

The scientists involved in the expedition had praise for the people and the technology that helped bring that dream to fruition.

“I don’t think there are too many systems in the world that could do what Jason does,” said Embley. “It takes a good vehicle, but a great group of experienced people to get close [to an eruption], hold station, and have the wisdom to understand what they can and cannot do.”

The Jason team maneuvered the vehicle to give scientists an up-close view of the glowing red vents explosively ejecting lava into the sea – often not more than a few feet away from the exploding lava – and the ability to take samples.

Enhancing the experience was the ability to view the eruption in high-definition video. Designed to operate at depths of up to 7,000 meters, the unique still and video camera system acquired 30-60 still images per second, at the same time generating motion, high def video at 30 frames per second. The system uses a high-definition zoom lens – nearly twice the focal length of Jason’s present standard definition camera — that enables researchers to see up-close details of underwater areas of interest that they otherwise could not see.

“We were lucky to have those cameras on the vehicle. They are important to the science,” said Tim Shank, a WHOI macro-biologist on the expedition. “We use the high def cameras to try to identify species. They allow us to look at the morphology of the animals — some smaller than 3 or 4 inches long.”

“In terms of understanding how the volcano is erupting, the high frame rate lets you stop the motion and look to see what is happening,” said Resing. “You can see the processes better.”

The National Science Foundation funded the installation of the camera system for this expedition. The system is being tested in advance of a permanent upgrade in 2010 to the cameras on Jason as well as the manned submersible Alvin. Maryann Keith, of WHOI’s AIVL, Shank, and other scientists operated the camera system with the assistance of the Jason team during the expedition.

In addition to the benefits to science, the cameras will serve the added purpose of giving the public more access to seafloor discoveries.

“Seeing an eruption in high definition video for the first time really brings it home for all of us, when we can see for ourselves the very exciting things happening on our planet, that we know so little about,” Embley said.

Source: Woods Hole Oceanographic Institution
Photo: The orange glow of magma is visible on the left of the sulfur-laden plume. The area shown in this image is approximately six feet across in an eruptive area approximately the length of a football field that runs along the summit. (Image courtesy of NSF, NOAA, and WHOI Advanced Imaging and Visualization Lab)

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The newest and most advanced tool for this work is called NIHTS (pronounced “nights”), the Near-Infrared High-Throughput Spectrograph. NIHTS will be used to carry out a new research program, the Kuiper Spectral Survey (KSS).

“NIHTS is designed to be a highly efficient instrument to allow us to take spectra of very faint objects,” said Henry Roe, Lowell Observatory astronomer. “NIHTS should be a fabulous tool, not only for exploring the Kuiper Belt, but also for many other projects, including identifying the coolest brown dwarfs, studying clouds on young stars, and understanding the composition of near-Earth asteroids.”

Roe plans to use NIHTS to make spectroscopic observations of hundreds of Kuiper Belt Objects (KBOs). While well over a thousand KBOs are now known, only a few dozen of the brightest ones have been studied in any significant detail. The goal with NIHTS is to observe several hundred fainter KBOs that are more representative of this icy region in the outer solar system.

Such precise study of such faint objects is possible because NIHTS collects light at near-infrared wavelengths.

When light from the sun lands on Kuiper Belt objects, much of it is reflected back. Some, however, is absorbed by molecules on the surface, leaving a distinctive pattern in the color of the reflected light – a kind of shadowy fingerprint. Each type of material that might be on the surface of a KBO leaves a distinctly different spectral pattern in the reflected light. The most interesting parts of these patterns lie in the infrared, which is why NIHTS is designed to observe at those wavelengths. However, room temperature objects emit light in the infrared. Therefore the NIHTS detector and insides of the instrument have to be kept extremely cold.

NIHTS will be one of five instruments mounted on what is called the “instrument cube” at the base of the Discovery Channel Telescope. The arrangement has been designed so that it is possible to switch from one instrument to the next in less than a minute. In other words, astronomers will not only have some of the finest instruments in the world to use in their work, but they will be able to switch between them in not much more time than it takes a carpenter to put down a hammer and pick up a screwdriver.

NIHTS was recently funded for development under a grant from NASA’s Planetary Astronomy and Planetary Major Equipment Programs to Lowell Observatory astronomer Henry Roe.

Visit DCT Science for more information.

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Source: Written and provided by Lowell Observatory Staff.
Photo: An illustration depicting the Near-Infrared High-Throughput Spectrograph (NIHTS) that will be used to carry out the Kuiper Spectral Survey (KSS).

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With the ability to enhance light 10,000 times, the air ambulance service’s new night vision goggles essentially turn night into day.

“You can see a lit cigarette 10 miles away,” said Wilson Matthews, R.N., E.M.T., chief flight nurse for LifeFlight’s base in Lebanon, Tenn., who is part of the night vision transition. “You go from seeing nothing to seeing the texture of tree leaves.”

Matthews said night vision will be most useful when making scene landings because pilots and nurses will be able to see the trees, power lines, rising terrain and other hazards on the ground.

“Night vision is absolutely amazing. I have been at LifeFlight since 1997, and this is the single best thing we have done to enhance safety,” he said.

Because military demand had dropped, this is the first time that the goggles are available to civilian aviation operations.

Three of LifeFlight’s four bases are already using night vision, and the final base should be trained by early 2010.

A five-hour training program is required for pilots and nurses, and pilots have additional required hours of use in the sky, including take-off, landing, emergency procedures and transitioning between night vision and regular vision.

Night vision works by gathering ambient light from the moon, stars or distant light sources into a special tube. The tube enhances the energy level of the light and hurls the particles at a phosphorus screen that creates the amplified image seen through the eyepiece.

Night vision is known for its eerie green hue. That color was chosen because the eye can differentiate more shades of green than any other color.

Pilot Mike Cobb dons the new night vision goggles. The goggles look like binoculars and are mounted on the front of the helmet. Matthews said one disadvantage is the loss of peripheral vision.

“It’s like looking through two tubes,” he said. “Pilots also have to transition from looking through night vision to looking down at the instrument panel with regular vision. They are also heavy on the helmet and can give you a sore neck the next day.”

Matthews cautioned that night vision will not allow LifeFlight to make flights that were deemed too risky in the past, but it will greatly enhance the safety of their current capabilities.

“LifeFlight will still have to say no when the weather is bad or we can’t land safely, but night vision is a huge step forward for us. We can be more confident in our landings and put more focus on great patient care,” he said.

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Source: Vanderbilt University Medical Center
Photo: Tim Hurst, R.N., E.M.T., poses for a photo taken through LifeFlight’s new night vision goggles. (Photo by Joe Howell)

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A related University of Utah study used gravity measurements to indicate the banana-shaped magma chamber of hot and molten rock a few miles beneath Yellowstone is 20 percent larger than previously believed, so a future cataclysmic eruption could be even larger than thought.

The study’s of Yellowstone’s plume also suggests the same “hotspot” that feeds Yellowstone volcanism also triggered the Columbia River “flood basalts” that buried parts of Oregon, Washington state and Idaho with lava starting 17 million years ago.

Those are key findings in four National Science Foundation-funded studies in the latest issue of the Journal of Volcanology and Geothermal Research. The studies were led by Robert B. Smith, research professor and professor emeritus of geophysics at the University of Utah and coordinating scientist for the Yellowstone Volcano Observatory.

“We have a clear image, using seismic waves from earthquakes, showing a mantle plume that extends from beneath Yellowstone,” Smith says.

The plume angles downward 150 miles to the west-northwest of Yellowstone and reaches a depth of at least 410 miles, Smith says. The study estimates the plume is mostly hot rock, with 1 percent to 2 percent molten rock in sponge-like voids within the hot rock.

Some researchers have doubted the existence of a mantle plume feeding Yellowstone, arguing instead that the area’s volcanic and hydrothermal features are fed by convection – the boiling-like rising of hot rock and sinking of cooler rock – from relatively shallow depths of only 185 miles to 250 miles.

The Hotspot: A Deep Plume, Blobs and Shallow Magma

Some 17 million years ago, the Yellowstone hotspot was located beneath the Oregon-Idaho-Nevada border region, feeding a plume of hot and molten rock that produced “caldera” eruptions – the biggest kind of volcanic eruption on Earth.

As North America slid southwest over the hotspot, the plume generated more than 140 huge eruptions that produced a chain of giant craters – calderas – extending from the Oregon-Idaho-Nevada border northeast to the current site of Yellowstone National Park, where huge caldera eruptions happened 2.05 million, 1.3 million and 642,000 years ago.

These eruptions were 2,500, 280 and 1,000 times bigger, respectively, than the 1980 eruption of Mount St. Helens. The eruptions covered as much as half the continental United States with inches to feet of volcanic ash. The Yellowstone caldera, 40 miles by 25 miles, is the remnant of that last giant eruption.

The new study reinforces the view that the hot and partly molten rock feeding volcanic and geothermal activity at Yellowstone isn’t vertical, but has three components:

• The 45-mile-wide plume that rises through Earth’s upper mantle from at least 410 miles beneath the surface. The plume angles upward to the east-southeast until it reaches the colder rock of the North American crustal plate, and flattens out like a 300-mile-wide pancake about 50 miles beneath Yellowstone. The plume includes several wider “blobs” at depths of 355 miles, 310 miles and 265 miles.
  
  
  “This conduit is not one tube of constant thickness,” says Smith. “It varies in width at various depths, and we call those things blobs.”
• A little-understood zone, between 50 miles and 10 miles deep, in which blobs of hot and partly molten rock break off of the flattened top of the plume and slowly rise to feed the magma reservoir directly beneath Yellowstone National Park.
• A magma reservoir 3.7 miles to 10 miles beneath the Yellowstone caldera. The reservoir is mostly sponge-like hot rock with spaces filled with molten rock.
  
  “It looks like it’s up to 8 percent or 15 percent melt,” says Smith. “That’s a lot.”

Researchers previously believed the magma chamber measured roughly 6 to 15 miles from southeast to northwest, and 20 or 25 miles from southwest to northeast, but new measurements indicate the reservoir extends at least another 13 miles outside the caldera’s northeast boundary, Smith says.

He says the gravity and other data show the magma body “is an elongated structure that looks like a banana with the ends up. It is a lot larger than we thought – I would say about 20 percent [by volume]. This would argue there might be a larger magma source available for a future eruption.”

Images of the magma reservoir were made based on the strength of Earth’s gravity at various points in Yellowstone. Hot and molten rock is less dense than cold rock, so the tug of gravity is measurably lower above magma reservoirs.

The Yellowstone caldera, like other calderas on Earth, huffs upward and puffs downward repeatedly over the ages, usually without erupting. Since 2004, the caldera floor has risen 3 inches per year, suggesting recharge of the magma body beneath it.

How to View a Plume

Seismic imaging uses earthquake waves that travel through the Earth and are recorded by seismometers. Waves travel more slowly through hotter rock and more quickly in cooler rock. Just as X-rays are combined to make CT-scan images of features in the human body, seismic wave data are melded to produce images of Earth’s interior.

The study, the Yellowstone Geodynamics Project, was conducted during 1999-2005. It used an average of 160 temporary and permanent seismic stations – and as many as 200 – to detect waves from some 800 earthquakes, with the stations spaced 10 miles to 22 miles apart – closer than other networks and better able to “see” underground. Some 160 Global Positioning System stations measured crustal movements.

By integrating seismic and GPS data, “it’s like a lens that made the upper 125 miles much clearer and allowed us to see deeper, down to 410 miles,” Smith says.

The study also shows warm rock – not as hot as the plume – stretching from Yellowstone southwest under the Snake River Plain, at depths of 20 miles to 60 miles. The rock is still warm from eruptions before the hotspot reached Yellowstone.

A Plume Blowing in the 2-inch-per-year Mantle Wind

Seismic imaging shows a “slow” zone from the top of the plume, which is 50 miles deep, straight down to about 155 miles, but then as you travel down the plume, it tilts to the northwest as it dives to a depth of 410 miles, says Smith.

That is the base of the global transition zone – from 250 miles to 410 miles deep – that is the boundary between the upper and lower mantle – the layers below Earth’s crust.

At that depth, the plume is about 410 miles beneath the town of Wisdom, Mont., which is 150 miles west-northwest of Yellowstone, says Smith.

He says “it wouldn’t surprise me” if the plume extends even deeper, perhaps originating from the core-mantle boundary some 1,800 miles deep.

Why doesn’t the plume rise straight upward? “This plume material wants to come up vertically, it wants to buoyantly rise,” says Smith. “But it gets caught in the ‘wind’ of the upper mantle flow, like smoke rising in a breeze.” Except in this case, the “breeze” of slowly flowing upper mantle rock is moving horizontally 2 inches per year.

While the crustal plate moves southwest, the warm, underlying mantle slowly boils due to convection, with warm areas moving upward and cooler areas downward. Northwest of Yellowstone, this convection is such that the plume is “blown” east-southeast by mantle convection, so it angles upward toward Yellowstone.

Scientists have debated for years whether Yellowstone’s volcanism is fed by a plume rising from deep in the Earth or by shallow churning in the upper mantle caused by movements of the overlying crust. Smith says the new study has produced the most detailed image of the Yellowstone plume yet published.

But a preliminary study by other researchers suggests Yellowstone’s plume goes deeper than 410 miles, ballooning below that depth into a wider zone of hot rock that extends at least 620 miles deep.

The notion that a deep plume feeds Yellowstone got more support from a study published this month inicating that the Hawaiian hotspot – which created the Hawaiian Islands – is fed by a plume that extends downward at least 930 miles, tilting southeast.

A Common Source for Yellowstone and the Columbia River Basalts?

Based on how the Yellowstone plume slants now, Smith and colleagues projected on a map where the plume might have originated at depth when the hotspot was erupting at the Oregon-Idaho-Nevada border area from 17 million to almost 12 million years ago.

They saw overlap, between the zones within the Earth where eruptions originated near the Oregon-Idaho-Nevada border and where the famed Columbia River Basalt eruptions originated when they were most vigorous 17 million to 14 million years ago.

Their conclusion: the Yellowstone hotspot plume might have fed those gigantic lava eruptions, which covered much of eastern Oregon and eastern Washington state.

“I argue it is the common source,” Smith says. “It’s neat stuff and it fits together.”

Smith conducted the seismic study with six University of Utah present or former geophysicists – former postdoctoral researchers Michael Jordan, of SINTEF Petroleum Research in Norway, and Stephan Husen, of the Swiss Federal Institute of Technology; postdoc Christine Puskas; Ph.D. student Jamie Farrell; and former Ph.D. students Gregory Waite, now at Michigan Technological University, and Wu-Lung Chang, of National Central University in Taiwan. Other co-authors were Bernhard Steinberger of the Geological Survey of Norway and Richard O’Connell of Harvard University.

Smith conducted the gravity study with former University of Utah graduate student Katrina DeNosaquo and Tony Lowry of Utah State University in Logan.

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Source: University of Utah
Photo: Seismic imaging was used by University of Utah scientists to construct this picture of the Yellowstone hotspot plume of hot and molten rock that feeds the shallower magma chamber beneath Yellowstone National Park. (Credit: University of Utah)

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In two studies, researchers asked subjects to identify the sex of a series of faces. In the first study, androgynous faces with lowered eyebrows and tight lips (angry expressions) were more likely to be identified as male, and faces with smiles and raised eyebrows (expressions of happiness and fear) were often labeled feminine.

The second study used male and female faces wearing expressions of happiness, anger, sadness, fear or a neutral expression. Overall, subjects were able to identify male faces more quickly than female faces, and female faces that expressed anger took the longest to identify.

“The present research shows that the association between anger and men and happiness and women is so strong that it can influence the decisions about the gender of another person when that person is viewed briefly,” said Ursula Hess, PhD, from the Department of Psychology, University of Quebec at Montreal.

According to the report, the findings from this study as well as others lead to the idea that “the face is a complex social signaling system in which signals for emotion, behavioral intentions and sex all overlap.”

Hess said that the same cues that make a face appear male — a high forehead, a square jaw and thicker eyebrows — have been linked to perceptions of dominance. Likewise, features that make a face appear female — a rounded, baby face with large eyes — have been linked to perceptions of the individual being approachable and warm.

“This difference in how the emotions and social traits of the two sexes are perceived could have significant implications for social interactions in a number of settings. Our research demonstrates that equivalent levels of anger are perceived as more intense when shown by men rather than women, and happiness as more intense when shown by women rather than men. It also suggests that it is less likely for men to be perceived as warm and caring and for women to be perceived as dominant.”

This research is part of a larger set of studies showing that men’s faces are perceived as angrier and women’s faces as happier. Hess’ team is also investigating other facial features that affect the way people perceive emotion, including the effect of signs of aging such as wrinkles and furrows on the perception of emotions in the faces of the elderly.

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Source: Association for Research in Vision and Ophthalmology
Photo: iStockphoto/CEFutcher

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Binary systems where a normal star is paired with a black hole often produce large swings in X-ray emission and blast jets of gas at speeds exceeding one-third that of light. What fuels this activity is gas pulled from the normal star, which spirals toward the black hole and piles up in a dense accretion disk.

“When a lot of gas is flowing, the dense disk reaches nearly to the black hole,” said John Tomsick at the University of California, Berkeley. “But when the flow is reduced, theory predicts that gas close to the black hole heats up, resulting in evaporation of the innermost part of the disk.” Never before have astronomers shown an unambiguous signature of this transformation.

To look for this effect, Tomsick and an international group of astronomers targeted GX 339-4, a low-mass X-ray binary located about 26,000 light-years away in the constellation Ara. There, every 1.7 days, an evolved star no more massive than the sun orbits a black hole estimated at 10 solar masses. With four major outbursts in the past seven years, GX 339-4 is among the most dynamic binaries in the sky.

In September 2008, nineteen months after the system’s most recent outburst, the team observed GX 339-4 using the orbiting Suzaku X-ray observatory, which is operated jointly by the Japan Aerospace Exploration Agency and NASA. At the same time, the team also observed the system with NASA’s Rossi X-ray Timing Explorer satellite.

Instruments on both satellites indicated that the system was faint but in an active state, when black holes are known to produce steady jets. Radio data from the Australia Telescope Compact Array confirmed that GX 339-4’s jets were indeed powered up when the satellites observed.

Despite the system’s faintness, Suzaku was able to measure a critical X-ray spectral line produced by the fluorescence of iron atoms. “Suzaku’s sensitivity to iron emission lines and its ability to measure the shapes of those lines let us see a change in the accretion disk that only happens at low luminosities,” said team member Kazutaka Yamaoka at Japan’s Aoyama Gakuin University.

X-ray photons emitted from disk regions closest to the black hole naturally experience stronger gravitational effects. The X-rays lose energy and produce a characteristic signal. At its brightest, GX 339-4’s X-rays can be traced to within about 20 miles of the black hole. But the Suzaku observations indicate that, at low brightness, the inner edge of the accretion disk retreats as much as 600 miles.

“We see emission only from the densest gas, where lots of iron atoms are producing X-rays, but that emission stops close to the black hole — the dense disk is gone,” explained Philip Kaaret at the University of Iowa. “What’s really happening is that, at low accretion rates, the dense inner disk thins into a tenuous but even hotter gas, rather like water turning to steam.”

The dense inner disk has a temperature of about 20 million degrees Fahrenheit, but the thin evaporated disk may be more than a thousand times hotter.

The study, which appears in the Dec. 10 issue of The Astrophysical Journal Letters, confirms the presence of low-density accretion flow in these systems. It also shows that GX 339-4 can produce jets even when the densest part of the disk is far from the black hole.

“This doesn’t tell us how jets form, but it does tell us that jets can be launched even when the high-density accretion flow is far from the black hole,” Tomsick said. “This means that the low-density accretion flow is the most essential ingredient for the formation of a steady jet in a black hole system.”

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Source: NASA/Goddard Space Flight Center
Photo: GX 339-4, illustrated here, is among the most dynamic binaries in the sky, with four major outbursts in the past seven years. In the system, an evolved star no more massive than the sun orbits a black hole estimated at 10 solar masses. (Credit: ESO/L. Calçada)

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