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  • richardmitnick 2:02 pm on February 9, 2018 Permalink | Reply
    Tags: ANL MIRA supercomputer, , Astrophysicists settle century-old cosmic debate on magnetism of planets and stars, , , , OMEGA Laser Facility in Rochester N.Y, U Chicago   

    From University of Chicago: “Astrophysicists settle century-old cosmic debate on magnetism of planets and stars” 

    U Chicago bloc

    University of Chicago

    February 9, 2018
    Rob Mitchum

    Laser experiments verify ‘turbulent dynamo’ theory of how cosmic magnetic fields are created

    1
    Three-dimensional FLASH simulation of the experimental platform, performed on the Mira supercomputer. Shown are renderings of the simulated magnetic fields before the flows collide. Courtesy of the Flash Center for Computational Science.

    The universe is highly magnetic, with everything from stars to planets to galaxies producing their own magnetic fields. Astrophysicists have long puzzled over these surprisingly strong and long-lived fields, with theories and simulations seeking a mechanism that explains their generation.

    Using one of the world’s most powerful laser facilities, a team led by University of Chicago scientists experimentally confirmed one of the most popular theories for cosmic magnetic field generation: the turbulent dynamo. By creating a hot turbulent plasma the size of a penny, which lasts a few billionths of a second, the researchers recorded how the turbulent motions can amplify a weak magnetic field to the strengths of those observed in our sun, distant stars and galaxies.

    The paper, published this week in Nature Communications, is the first laboratory demonstration of a theory explaining the magnetic field of numerous cosmic bodies, which has been debated by physicists for nearly a century. Using the FLASH physics simulation code, developed by the Flash Center for Computational Science at UChicago, the researchers designed an experiment conducted at the OMEGA Laser Facility in Rochester, N.Y. to recreate turbulent dynamo conditions.

    U Rochester Omega Laser

    Confirming decades of numerical simulations, the experiment revealed that turbulent plasma could dramatically boost a weak magnetic field up to the magnitude observed by astronomers in stars and galaxies.

    “We now know for sure that turbulent dynamo exists, and that it’s one of the mechanisms that can actually explain magnetization of the universe,” said Petros Tzeferacos, research assistant professor of astronomy and astrophysics at the University of Chicago and associate director of the Flash Center. “This is something that we hoped we knew, but now we do.”

    A mechanical dynamo produces an electric current by rotating coils through a magnetic field. In astrophysics, dynamo theory proposes the reverse: the motion of electrically-conducting fluid creates and maintains a magnetic field. In the early 20th century, physicist Joseph Larmor proposed that such a mechanism could explain the magnetism of the Earth and sun, inspiring decades of scientific debate and inquiry.

    While numerical simulations demonstrated that turbulent plasma can generate magnetic fields at the scale of those observed in stars, planets and galaxies, creating a turbulent dynamo in the laboratory was far more difficult. Confirming the theory requires producing plasma at an extremely high temperature and volatility to produce the sufficient turbulence to fold, stretch and amplify the magnetic field.

    To design an experiment that creates those conditions, Tzeferacos and colleagues at UChicago and the University of Oxford ran hundreds of two- and three-dimensional simulations with FLASH on the Mira supercomputer at Argonne National Laboratory.

    MIRA IBM Blue Gene Q supercomputer at the Argonne Leadership Computing Facility

    The final setup involved blasting two penny-sized pieces of foil with powerful lasers, propelling two jets of plasma through grids and into collision with each other, creating turbulent fluid motion.

    3

    “People have dreamed of doing this experiment with lasers for a long time, but it really took the ingenuity of this team to make this happen,” said Donald Lamb, the Robert A. Millikan Distinguished Service Professor Emeritus in Astronomy and Astrophysics and director of the Flash Center. “This is a huge breakthrough.”

    The team also used FLASH simulations to develop two independent methods for measuring the magnetic field produced by the plasma: proton radiography, the subject of a recent paper [AIP]from the FLASH group, and polarized light, based on how astronomers measure the magnetic fields of distant objects. Both measurements tracked the growth in mere nanoseconds of the magnetic field from its weak initial state to over 100 kiloGauss—stronger than a high-resolution MRI scanner and a million times stronger than the magnetic field of the Earth.

    “This work opens up the opportunity to experimentally verify ideas and concepts about the origin of magnetic fields in the universe that have been proposed and studied theoretically over the better part of a century,” said Fausto Cattaneo, professor of astronomy and astrophysics at the University of Chicago and a co-author of the paper.

    Now that a turbulent dynamo can be created in a laboratory, scientists can explore deeper questions about its function: How quickly does the magnetic field increase in strength? How strong can the field get? How does the magnetic field alter the turbulence that amplified it?

    “It’s one thing to have well-developed theories, but it’s another thing to really demonstrate it in a controlled laboratory setting where you can make all these kinds of measurements about what’s going on,” Lamb said. “Now that we can do it, we can poke it and probe it.”

    In addition to Tzeferacos and Lamb, UChicago co-authors on the paper include Carlo Graziani and Gianluca Gregori, who is also professor of physics at the University of Oxford. The research was funded by the European Research Council and the U.S. Department of Energy.

    See the full article here .

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    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

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  • richardmitnick 10:31 am on January 5, 2018 Permalink | Reply
    Tags: , , Computational astrophysics team uncloaks magnetic fields of cosmic events, Flash Center for Computational Science, , , OMEGA Laser Facility U Rochester, , U Chicago   

    From U Chicago: “Computational astrophysics team uncloaks magnetic fields of cosmic events” 

    U Chicago bloc

    University of Chicago

    January 4, 2018
    Rob Mitchum

    New method enhances study of stars, black holes in laboratory settings.

    1
    Computational astrophysicists describe a new method for acquiring information on experiments using laser beams to reproduce cosmic conditions. Courtesy of
    Lawrence Livermore National Laboratory

    The development of ultra-intense lasers delivering the same power as the entire U.S. power grid has enabled the study of cosmic phenomena such as supernovae and black holes in earthbound laboratories. Now, a new method developed by computational astrophysicists at the University of Chicago allows scientists to analyze a key characteristic of these events: their powerful and complex magnetic fields.

    In the field of high-energy density physics, or HEDP, scientists study a wide range of astrophysical objects—stars, supermassive black holes at the center of galaxies and galaxy clusters—with laboratory experiments as small as a penny and lasting only a few billionths of a second. By focusing powerful lasers on a carefully designed target, researchers can produce plasmas that reproduce conditions observed by astronomers in our sun and distant galaxies.

    Planning these complex and expensive experiments requires large-scale, high-fidelity computer simulation beforehand. Since 2012, the Flash Center for Computational Science of the Department of Astronomy & Astrophysics at UChicago has provided the leading open computer code, called FLASH, for these HEDP simulations, enabling researchers to fine-tune experiments and develop analysis methods before execution at sites such as the National Ignition Facility at Lawrence Livermore National Laboratory or the OMEGA Laser Facility in Rochester, N.Y.


    LLNL/NIF

    2
    OMEGA Laser Facility, U Rochester

    “As soon as FLASH became available, there was kind of a stampede to use it to design experiments,” said Petros Tzeferacos, research assistant professor of astronomy and astrophysics and associate director of the Flash Center.

    During these experiments, laser probe beams can provide researchers with information about the density and temperature of the plasma. But a key measurement, the magnetic field, has remained elusive. To try and tease out magnetic field measurements from extreme plasma conditions, scientists at MIT developed an experimental diagnostic technique that uses charged particles instead, called proton radiography.

    In a new paper for the journal Review of Scientific Instruments, Flash Center scientists Carlo Graziani, Donald Lamb and Tzeferacos, with MIT’s Chikang Li, describe a new method for acquiring quantitative, high-resolution information about these magnetic fields. Their discovery, refined using FLASH simulations and real experimental results, opens new doors for understanding cosmic phenomena.

    “We chose to go after experiments motivated by astrophysics where magnetic fields were important,” said Lamb, the Robert A. Millikan Distinguished Service Professor Emeritus in Astronomy & Astrophysics and director of the Flash Center. “The creation of the code plus the need to try to figure out how to understand what magnetic fields are created caused us to build this software, that can for the first time quantitatively reconstruct the shape and strength of the magnetic field.”

    Skyrocketing experiments

    In proton radiography, energetic protons are shot through the magnetized plasma towards a detector on the other side. As the protons pass through the magnetic field, they are deflected from their path, forming a complex pattern on the detector. These patterns were difficult to interpret, and previous methods could only make general statements about the field’s properties.

    “Magnetic fields play important roles in essentially almost every astrophysical phenomena. If you aren’t able to actually look at what’s happening, or study them, you’re missing a key part of almost every astrophysical object or process that you’re interested in,” said Tzeferacos.

    By conducting simulated experiments with known magnetic fields, the Flash Center team constructed an algorithm that can reconstruct the field from the proton radiograph pattern. Once calibrated computationally, the method was applied to experimental data collected at laser facilities, revealing new insights about astrophysical events.

    The combination of the FLASH code, the development of the proton radiography diagnostic, and the ability to reconstruct magnetic fields from the experimental data, are revolutionizing laboratory plasma astrophysics and HEDP. “The availability of these tools has caused the number of HEDP experiments that study magnetic fields to skyrocket,” said Lamb.

    The new software for magnetic field reconstruction, called PRaLine, will be shared with the community both as part of the next FLASH code release and as a separate component available on GitHub. Lamb and Tzeferacos said they expect it to be used for studying many astrophysics topics, such as the annihilation of magnetic fields in the solar corona; astrophysical jets produced by young stellar objects, the Crab Nebula pulsar, and the supermassive black holes at the center of galaxies; and the amplification of magnetic fields and acceleration of cosmic rays by shocks in supernova remnants.

    “The types of experiments HEDP scientists perform now are very diverse,” said Tzeferacos. “FLASH contributed to this diversity, because it enables you to think outside the box, try different simulations of different configurations, and see what plasma conditions you are able to achieve.”

    The work was funded by grants from the U.S. Department of Energy and the National Science Foundation.

    See the full article here .

    Please help promote STEM in your local schools.

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    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 2:45 pm on January 3, 2018 Permalink | Reply
    Tags: "Scientists dig deep in soil for data to improve agriculture, , , , pollution, Soil sensors, Thoreau sensor network, U Chicago   

    From U Chicago: “Scientists dig deep in soil for data to improve agriculture, pollution” 

    U Chicago bloc

    University of Chicago

    January 2, 2018
    Louise Lerner

    1
    UChicago Facilities Services staff Todd Fechner (left) and Kyle Cherry bury a sensor at Stagg Field.

    For as long as humans have been farming, they’ve been trying to figure out what’s going on below ground. Soil is incredibly complex—full of organisms, microbes and chemicals that move and change constantly—and it all feeds into crop health and the Earth’s nutrient cycles in ways that aren’t fully understood. But getting data was a problem, since this generally required taking soil samples and then analyzing them in the lab, which is slow and often expensive.

    Recent advances in wireless data communications and the growing revolution of portable, cheap sensors have made it possible for UChicago scientists, including Profs. Monisha Ghosh and Supratik Guha, both affiliated with the Institute for Molecular Engineering, to start a pilot program to take real-time soil measurements—and they started in their own campus.

    Their project, called the Thoreau sensor network, buried more than 30 sensing boxes in a variety of different locations around the UChicago campus.

    5
    The sensor boxes are buried with the tip of the antenna six to eight inches underground, with sensors extending farther down. Photo by William Kent.

    Each one is a cube about five inches square, containing four sensors that measure the soil’s water content, salt, temperature and water potential, the measure of how readily the soil holds or drains moisture. Twice an hour, a tiny radio transmitter and antenna—fully buried underground—sends a burst of data to the receiver, located atop the William Eckhardt Research Center.

    For the hardware, they used commercial sensors that already exist. But there were a lot of questions about how the sensors might behave underground: Can the signals make it to the receivers above ground? Does the battery die faster? What happens to the machinery during freeze-thaw cycles?

    “This test run provides us extremely helpful real-world data on how one could actually run a sensor network like this,” Ghosh said. “For example, the Chicago winter gave us some very helpful information.” (A few of the sensors didn’t survive last winter.)

    There were also questions about whether the radio signals would be able to be transmitted from below the ground. The research team found that they could successfully transmit over distances of one and a half miles, even though the antennas were buried six to eight inches below the surface of the ground.

    Wet soil appears to inhibit the signal, they said, but the biggest issue so far is battery life. The group of undergraduate students working on the project have been a big help, Ghosh said. “They’ve come up with some really excellent ideas for saving battery life,” including a low-power timer that puts the sensor to sleep in between its 30-minute wake-up calls.

    Seasons of change

    2
    Arturo Ortiz of UChicago Facilities Services buries a sensor in another location; flowerbeds offer a different soil structure and composition from other soil. Photo by William Kent.

    The land that is now the University of Chicago campus was once sand, marsh and prairie at the edge of Lake Michigan. Now it’s home to a network of streets, century-old buildings, quadrangles, athletic fields, flowerbeds and libraries. Each use has different impacts on the soil below—and these differences show up in the data.

    The study is just underway, but Ghosh said they’ve seen some interesting trends and questions in their data. “For example, we believe we’re seeing patterns in how water leaves different types of soil after a rainfall,” she said, as well as moisture differences in the growing season versus the winter.

    As a materials scientist, Guha is interested in the sensor hardware. He heads the Center for Nanoscale Materials at Argonne National Laboratory, where research on developing new capabilities for sensors is underway.

    “For example, what we would really love to do is to make a sensor that can measure soil nitrates,” he said. This would provide a way to measure how much of the fertilizer that farmers apply to their soil gets to the plants. It’s thought that less than half of the nitrogen goes to plants; the rest of it likely washes off and pollutes rivers, lakes and oceans.

    “There’s a lot we’d like to do,” Ghosh said. “Can we hook sprinklers up to receive input from our sensors? How far down is the right depth for the best data? How much can we extend the range of how far a sensor can be from the receiver? Can we boost the signal to reach from beneath paved areas or sidewalks?”

    A complementary project is ongoing in India, testing the water quality of the Godavari River in southern India and how it reacts to weather, pollution, fishing and general use. In this case, a boat carries a mobile sensing platform equipped with GPS along the river every few days, enabling scientists to map the river chemistry.

    “Those results have been spectacular,” Guha said. “We’re seeing that dynamic mapping of river water quality can accurately help pinpoint and assess pollution sources.”

    Students get hands-on experience

    4
    Summer interns Cayla Hamann (background) and Cheng Chang (foreground) help install a water sensor on UChicago campus. Photo by Xufeng Zhang.

    The researchers discussed the results at a Nov. 1-2 workshop at UChicago for the emerging field of soil sensing, funded by the National Science Foundation. The goal was to share knowledge on the pursuit of better subterranean sensing networks by gathering experts from fields including microelectronics, machine learning and modeling, together with those who study the microbes and physics of soil directly.

    The UChicago students who have worked on the Thoreau project said they were getting hands-on experience with sensors as well as programming.

    Undergraduate students William Kent and Jacob Gold worked on the site’s website, including different ways for users to download the data. “We were given a ton of freedom and flexibility to plan out how we would convey that data,” said Gold, a third-year computer science major.

    Kent, a second-year and molecular engineering major, agreed. “They tell us the user needs to be able to do this, and we figure out how to make it work. I don’t think a lot of our peers really get that creative license in their research projects,” he said. “I feel like we’re really creating something.”

    Undergraduate student Arseniy Andreyev also designed and built much of the initial hardware, working with postdoctoral scientist Xufeng Zhang, Guha said.

    See the full article here .

    Please help promote STEM in your local schools.

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    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 2:02 pm on January 2, 2018 Permalink | Reply
    Tags: , , , , Scientists describe how solar system could have formed in bubble around giant star, U Chicago   

    From U Chicago: “Scientists describe how solar system could have formed in bubble around giant star” 

    U Chicago bloc

    University of Chicago

    December 22, 2017
    Louise Lerner

    1
    This simulation shows how bubbles form over the course of 4.7 million years from the intense stellar winds off a massive star. UChicago scientists postulated how our own solar system could have formed in the dense shell of such a bubble. Courtesy of V. Dwarkadas & D. Rosenberg.

    Despite the many impressive discoveries humans have made about the universe, scientists are still unsure about the birth story of our solar system.

    Scientists with the University of Chicago have laid out a comprehensive theory for how our solar system could have formed in the wind-blown bubbles around a giant, long-dead star. Published Dec. 22 in The Astrophysical Journal, the study addresses a nagging cosmic mystery about the abundance of two elements in our solar system compared to the rest of the galaxy.

    The general prevailing theory is that our solar system formed billions of years ago near a supernova. But the new scenario instead begins with a giant type of star called a Wolf-Rayet star, which is more than 40 to 50 times the size of our own sun. They burn the hottest of all stars, producing tons of elements which are flung off the surface in an intense stellar wind. As the Wolf-Rayet star sheds its mass, the stellar wind plows through the material that was around it, forming a bubble structure with a dense shell.

    “The shell of such a bubble is a good place to produce stars,” because dust and gas become trapped inside where they can condense into stars, said coauthor Nicolas Dauphas, professor in the Department of Geophysical Sciences. The authors estimate that 1 percent to 16 percent of all sun-like stars could be formed in such stellar nurseries.

    This setup differs from the supernova hypothesis in order to make sense of two isotopes that occur in strange proportions in the early solar system, compared to the rest of the galaxy. Meteorites left over from the early solar system tell us there was a lot of aluminium-26. In addition, studies, including a 2015 one by Dauphas [The Astrophysical Journal] and a former student, increasingly suggest we had less of the isotope iron-60.

    This brings scientists up short, because supernovae produce both isotopes. “It begs the question of why one was injected into the solar system and the other was not,” said coauthor Vikram Dwarkadas, a research associate professor in Astronomy and Astrophysics.

    This brought them to Wolf-Rayet stars, which release lots of aluminium-26, but no iron-60.

    “The idea is that aluminum-26 flung from the Wolf-Rayet star is carried outwards on grains of dust formed around the star. These grains have enough momentum to punch through one side of the shell, where they are mostly destroyed—trapping the aluminum inside the shell,” Dwarkadas said. Eventually, part of the shell collapses inward due to gravity, forming our solar system.

    3
    Slices of a simulation showing how bubbles around a massive star evolve over the course of millions of years (moving clockwise from top left). Courtesy of V. Dwarkadas & D. Rosenberg

    As for the fate of the giant Wolf-Rayet star that sheltered us: Its life ended long ago, likely in a supernova explosion or a direct collapse to a black hole. A direct collapse to a black hole would produce little iron-60; if it was a supernova, the iron-60 created in the explosion may not have penetrated the bubble walls, or was distributed unequally.

    Other authors on the paper included UChicago undergraduate student Peter Boyajian and Michael Bojazi and Brad Meyer of Clemson University.

    Funding: NASA

    See the full article here .

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    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 1:35 pm on September 22, 2017 Permalink | Reply
    Tags: Dauphas and his team looked at titanium in the shales over time, , Geologists often look at a particular kind of rock called shales, , If you fertilize the ocean with phosphorus life will bloom, Plate techtonics is believed to be needed to create felsic rock, Study suggests significant tectonic action was already taking place 3.5 billion years ago—about half a billion years earlier than currently thought, The flood of oxygen came from a surge of photosynthetic microorganisms - cyanobacteria, The titanium timeline suggests that the primary trigger of the surge of phosphorus was the change in the makeup of mafic rock over time, Tracing the path of metallic element titanium through the Earth’s crust across time, U Chicago   

    From U Chicago: “Study suggests tectonic plates began moving half a billion years earlier than thought” 

    U Chicago bloc

    University of Chicago

    September 21, 2017
    Louise Lerner

    1
    While previous studies had argued that Earth’s crust 3.5 billion years ago looked like these Hawaiian lavas, a new study led by UChicago scientists suggests by then much of it had already been transformed into lighter-colored felsic rock by plate tectonics.
    Photo by Basil Greber

    The Earth’s history is written in its elements, but as the tectonic plates slip and slide over and under each other over time, they muddy that evidence—and with it the secrets of why Earth can sustain life.

    A new study led by UChicago geochemists rearranges the picture of the early Earth by tracing the path of metallic element titanium through the Earth’s crust across time. The research, published Sept. 22 in Science, suggests significant tectonic action was already taking place 3.5 billion years ago—about half a billion years earlier than currently thought.

    The crust was once made of uniformly dark, magnesium- and iron-rich mafic minerals. But today the crust looks very different between land and ocean: The crust on land is now a lighter-colored felsic, rich in silicon and aluminum. The point at which these two diverged is important, since the composition of minerals affects the flow of nutrients available to the fledgling life struggling to survive on Earth.

    “This question has been discussed since geologists first started thinking about rocks,” said lead author Nicolas Dauphas, the Louis Block Professor and head of the Origins Laboratory in the Department of the Geophysical Sciences and the Enrico Fermi Institute. “This result is a surprise and certainly an upheaval in that discussion.”

    To reconstruct the crust changing over time, geologists often look at a particular kind of rock called shales, made up of tiny bits of other rocks and minerals that are carried by water into mud deposits and compressed into rock. The only problem is that scientists have to adjust the numbers to account for different rates of weathering and transport. “There are many things that can foul you up,” Dauphas said.

    To avoid this issue, Dauphas and his team looked at titanium in the shales over time. This element doesn’t dissolve in water and isn’t taken up by plants in nutrient cycles, so they thought the data would have fewer biases with which to contend.

    They crushed samples of shale rocks of different ages from around the world and checked in what form its titanium appeared. The proportions of titanium isotopes present should shift as the rock changes from mafic to felsic. Instead, they saw little change over three and a half billion years, suggesting that the transition must have occurred before then.

    2
    These granite peaks are an example of felsic rock, created via plate tectonics. Photo by Basil Greber

    This also would mark the beginning of plate tectonics, since that process is believed to be needed to create felsic rock.

    “With a null response like that, seeing no change, it’s difficult to imagine an alternate explanation,” said Matouš Ptáček, a UChicago graduate student who co-authored the study.

    “Our results can also be used to track the average composition of the continental crust through time, allowing us to investigate the supply of nutrients to the oceans going back 3.5 billion years ago,” said Nicolas Greber, the first author of the paper, then a postdoctoral researcher at UChicago and now with the University of Geneva.

    Phosphorous leads to life

    The question about nutrients is important for our understanding of the circumstances around a mysterious but crucial turning point called the great oxygenation event. This is when oxygen started to emerge as an important constituent of Earth’s atmosphere, wreaking a massive change on the planet—and making it possible for multi-celled beings to evolve.

    The flood of oxygen came from a surge of photosynthetic microorganisms; and in turn their work was fostered by a surge of nutrients to the oceans, particularly phosphorus. “Phosphorus is the most important limiting nutrient in the modern ocean. If you fertilize the ocean with phosphorus, life will bloom,” Dauphas said.

    The titanium timeline suggests that the primary trigger of the surge of phosphorus was the change in the makeup of mafic rock over time. As the Earth cooled, the mafic rock coming out of volcanoes and underground melts became richer in phosphorus.

    “We’ve known for a long time that mafic rock changed over time, but what we didn’t know was that their contribution to the crust has stayed rather consistent,” Ptáček said.

    Other institutions on the study were the University of California-Riverside, University of Oregon-Eugene and the University of Johannesburg.

    See the full article here .

    Please help promote STEM in your local schools.

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    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 2:35 pm on August 30, 2017 Permalink | Reply
    Tags: , , , , Supernova 2012ca, Type Ia supernovas, U Chicago, UChicago scientists detect first X-rays from mystery supernovas   

    From U Chicago: “UChicago scientists detect first X-rays from mystery supernovas” 

    U Chicago bloc

    University of Chicago

    August 23, 2017
    Louise Lerner

    1
    Scientists have detected the first X-rays from what appears to be a type Ia supernova, located inside the spiral-shaped galaxy ESO 336-G009, about 260 million light-years from Earth. DSS.

    Exploding stars lit the way for our understanding of the universe, but researchers are still in the dark about many of their features.

    A team of scientists, including scholars from the University of Chicago, appear to have found the first X-rays coming from type Ia supernovas. Their findings are published online Aug. 23 in the Monthly Notices of the Royal Astronomical Society.

    Astronomers are fond of type Ia supernovas, created when a white dwarf star in a two-star system undergoes a thermonuclear explosion, because they burn at a specific brightness. This allows scientists to calculate how far away they are from Earth, and thus to map distances in the universe. But a few years ago, scientists began to find type Ia supernovas with a strange optical signature that suggested they carried a very dense cloak of circumstellar material surrounding them.

    2
    An image showing X-rays detected from the supernova 2012ca (inside the circle). Image has been smoothed and colorized.
    Photo by Vikram Dwarkadas/Chandra X-ray Observatory

    NASA/Chandra Telescope

    Such dense material is normally only seen from a different type of supernova called type II, and is created when massive stars start to lose mass. The ejected mass collects around the star; then, when the star collapses, the explosion sends a shockwave hurtling at supersonic speeds into this dense material, producing a shower of X-rays. Thus we regularly see X-rays from type II supernovas, but they have never been seen from type Ia supernovas.

    When the UChicago-led team studied the supernova 2012ca, recorded by the Chandra X-ray Observatory, however, they detected X-ray photons coming from the scene.

    “Although other type Ia’s with circumstellar material were thought to have similarly high densities based on their optical spectra, we have never before detected them with X-rays,” said study co-author Vikram Dwarkadas, research associate professor in the Department of Astronomy and Astrophysics.

    The amounts of X-rays they found were small—they counted 33 photons in the first observation a year and a half after the supernova exploded, and ten in another about 200 days later—but present.

    “This certainly appears to be a Ia supernova with substantial circumstellar material, and it looks as though it’s very dense,” he said. “What we saw suggests a density about a million times higher what we thought was the maximum around Ia’s.”

    It’s thought that white dwarfs don’t lose mass before they explode. The usual explanation for the circumstellar material is that it would have come from a companion star in the system, but the amount of mass suggested by this measurement was very large, Dwarkadas said—far larger than one could expect from most companion stars. “Even the most massive stars do not have such high mass-loss rates on a regular basis,” he said. “This once again raises the question of how exactly these strange supernovas form.”

    “If it’s truly a Ia, that’s a very interesting development because we have no idea why it would have so much circumstellar material around it,” he said.

    “It is surprising what you can learn from so few photons,” said lead author and Caltech graduate student Chris Bochenek; his work on the study formed his undergraduate thesis at UChicago. “With only tens of them, we were able to infer that the dense gas around the supernova is likely clumpy or in a disk.”

    More studies to look for X-rays, and even radio waves coming off these anomalies, could open a new window to understanding such supernovas and how they form, the authors said.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 10:15 am on August 12, 2017 Permalink | Reply
    Tags: , , , New program teaches data science for energy and environment research, U Chicago   

    From U Chicago: “New program teaches data science for energy and environment research” 

    U Chicago bloc

    University of Chicago

    August 11, 2017
    Rob Mitchum

    Innovative curriculum will arm graduate students with critical tools for modern science.

    1
    An interdisciplinary program will train graduate students in data science to tackle issues related to food, energy and water.

    For the future of the planet, there are few research subjects more important than the global supplies of food, water and energy. To comprehensively study, understand and inform policy around these complex systems, the next generation of researchers in the physical, social and biological sciences will need fluency with data analysis methods that transverse traditional academic boundaries.

    A new interdisciplinary curriculum will train graduate students from geosciences, economics, computer science, public policy and other programs in computational and data science techniques critical for modern science. With a $3 million award from the National Science Foundation, the new research traineeship grant will combine expertise from across UChicago and Argonne National Laboratory in computing, statistics, social science, climate and agriculture.

    “This program will equip graduate students with the tools needed to advance the study of issues related to food, energy and water,” said Elisabeth Moyer, associate professor of atmospheric science in the Department of the Geophysical Sciences. “Our vision is to produce students who have the computational skills and breadth of knowledge, from social to physical sciences, needed to tackle these critical research subjects in all their complexity.”

    As Earth’s population rises in the coming years, demand for food, energy and water is expected to soar. The global scale and interdependence of these sectors—where increased agriculture decreases freshwater supplies, while both are affected by the environmental impact of accelerating energy production—necessitates research collaboration across fields. Improved data collection and modeling on these topics creates promising opportunities for understanding their complexities, but only if analyzed with the right computational methods.

    The program will produce students with a foundation in a discipline such as geosciences, economics or public policy, as well as the computational skills and breadth of multidisciplinary knowledge to tackle complex questions in food, energy and water. A three-year curriculum including boot camps, retreats, new courses and practicum projects will give each student experience working with data science methods and scientists from fields other than their own.

    Additional training in scientific communication and professional development, as well as opportunities for international research experience with the Potsdam Institute for Climate Impact Research and the African Institute for Mathematical Sciences, will further prepare students for research careers in this area.

    “We want to extend education outside the boundaries of traditional silo-ed disciplinary programs,” said Ryan Kellogg, professor at the Harris School of Public Policy. “This program will provide students with the computational skills needed to exploit the growing torrent of relevant data, and give them experience both interacting across disciplines and translating results to non-academic audiences.”

    Campus as a laboratory

    As part of the curriculum, students will receive introductions to computing in the social sciences and geosciences, spatial statistics and imagery analysis, geographic information systems (GIS), data science fundamentals, time series analysis and environmental economics. A general course on the food/energy/water system, drawn from existing courses for interdisciplinary audiences taught by Moyer and Cristina Negri, environmental engineer at Argonne and fellow of the Institute for Molecular Engineering, will be followed by a data analysis practicum where groups of students work with real data and organizations in government and industry.

    The program will build upon successful UChicago training initiatives such as the Executive Program in Applied Data Analytics, the Computational Analysis and Public Policy curriculum at the Harris School of Public Policy and the Data Science for Social Good Summer Fellowship.

    nstruction and mentorship will be provided by several UChicago research groups, including the Center for Robust Decision-Making on Climate and Energy Policy (climate and agricultural modeling), Knowledge Lab (text mining), the Energy Policy Institute at UChicago (environmental and energy economics), the Center for Data Science and Public Policy (data analytics and project management) and the Center for Spatial Data Science (spatial analysis). High-performance computing resources and tutorials will be provided by the Research Computing Center.

    “All across the University of Chicago campus, we have researchers applying innovative data science techniques to important questions in energy and the environment,” said Michael Franklin, the Liew Family Chair of Computer Science. “With this new program, we can extend that strength to enrich our graduate education, making our campus a laboratory for training a new generation of interdisciplinary, computational-minded scientists.”

    The award is one of 17 given out by the National Science Foundation this month as part of their NSF Research Traineeship program. The foundation awarded a total of $51 million to “develop and implement bold, new, potentially transformative models for graduate education in science, technology, engineering and mathematics fields.”

    “Integration of research and education through interdisciplinary training will prepare a workforce that undertakes scientific challenges in innovative ways,” said Dean Evasius, director of the NSF Division of Graduate Education in a news release. “The NSF Research Traineeship awards will ensure that today’s graduate students are prepared to pursue cutting-edge research and solve the complex problems of tomorrow.”

    In addition to Moyer, Kellogg and Franklin, additional investigators on the award include Joshua Elliott, Computation Institute fellow and research scientist, and Ian Foster, the Arthur Holly Compton Distinguished Service Professor of Computer Science and Argonne Distinguished Fellow.

    The program will start in the 2018-19 academic year. Further information will be available in the upcoming academic year for those interested in applying.

    See the full article here .

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    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 12:57 pm on August 4, 2017 Permalink | Reply
    Tags: , Clever experiment documents multi-scale fluid dynamics, , Total helicity - or the measure of when two vortex rings intertwine, U Chicago   

    From U Chicago: “Clever experiment documents multi-scale fluid dynamics” 

    U Chicago bloc

    University of Chicago

    August 3, 2017
    Steve Koppes.

    1
    Courtesy of Martin Sheeler.

    University of Chicago physicists working in the nascent field of experimental vortex dynamics have, with unexpected help from a Sharpie marker, achieved the first measurements of an elusive but fundamental property of fluid flow.

    Until now, there had been no way in the laboratory to measure the total helicity, or the measure of when two vortex rings intertwine. In their experiments, the UChicago team created thin-core vortices—the kinds found in aircraft wakes and insect flight—by producing hydrofoils using a 3-D printer.

    As luck would have it, the red Sharpie marker used to label the hydrofoils contained rhodamine dye, which fluoresced when illuminated by laser light. When the hydrofoils were placed in a water tank, the dye began to diffuse, and when the hydrofoil was accelerated, the dye got sucked into the core of the newly created vortex—a process recorded via high-speed laser scanning tomography.

    The new findings, published Aug. 3 in Science, are the first to show that helicity maintains a constant value during the flow of viscous fluids. Vortex dynamics have important applications in everyday life; meteorologists, for example, view helicity as a factor that contributes to the formation of supercell tornadoes.

    “The fact that we have some measurements for the first time that show helicity can be preserved, especially in the presence of stretching, can translate directly to those efforts,” said William Irvine, an associate professor in physics, who published the findings along with four co-authors.

    Twists and turns

    In their latest research, the physicists studied three related forms of helicity: twisting, linking and writhing. The three forms are simply different ways to describe geometrically related forms that have been twisted or stretched. Each vortex tube can be visualized as a bundle of filaments, similar to those bound together in a twisted rope.

    “If you take a piece of rope or or a telephone cord and you coil it up, then we would say that the center of this rope or telephone cord is writhing,” Irvine said. “And if we then took this thing that we coiled up and we pulled it straight, you would see twisting along its length.”

    Simulating helicity in those flows has been difficult because of the widely separated yet interconnecting scales in which they operate. Previous work had been largely theoretical and involved hypothetical, simpler fluids totally lacking in viscosity. Calculations showed that helicity was conserved in these hypothetical fluids, but viscosity emerged as a significant factor in the flow of actual fluids.

    “One of the core problems is that you need to sample or measure features of the flow that exist on very different length scales,” said Martin Scheeler, the study’s lead author, who recently completed his doctorate in physics at UChicago. The scales range from the diameter of a vortex (approximately 30 centimeters or one foot) to the diameter of its thin core (approximately one milllimeter or three hundredths of an inch).

    “You need to measure the flow inside the core as well as the overall shape evolution of that vortex,” Irvine said. “That’s quite a separation.” He characterized Scheeler’s work in overcoming the experimental challenges— simultaneously tracking the fine details of the flow while still measuring the critical larger-scale dynamics—as “a tour de force.”

    ‘It’s the wackier stuff that works’

    Irvine’s group had previously used bubbles to conduct pioneering research on the dynamics of vortices in their water-tank experiments. The helicity measurements, however, required something different, which was provided serendipitously through the Sharpie.

    Dye has long been used in vortex experiments, but less precisely. In previous experiments, the dye was placed diffusely in the tank, and then the vortices would envelope them. But the Sharpie presented an opportunity to precisely position the dye at the center of the vortices, as Scheeler painstakingly painted dots onto the entire length of the hydrofoils.

    “We hadn’t really realized that that was a possibility until we saw dye bleeding off the hydrofoil,” said Scheeler, who valued the creativity and freedom involved in designing experiments for a nascent field of physics.

    “There really is no playbook, and that’s really exciting,” he said. “You get to try out all sorts of different things, and sometimes it’s the wackier stuff that works.”

    Funding: National Science Foundation and the Packard Foundation

    See the full article here .

    Please help promote STEM in your local schools.

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    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 9:38 am on August 3, 2017 Permalink | Reply
    Tags: , , , , , , U Chicago   

    From U Chicago: “Dark Energy Survey reveals most precise measure of universe’s structure” 

    U Chicago bloc

    University of Chicago

    August 3, 2017

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet


    The Dark Energy Survey’s primary instrument, the 570-megapixel Dark Energy Camera, is mounted on the Blanco Telescope in Chile. UChicago, Argonne and Fermilab scientists are members of international Dark Energy Survey collaboration.

    Imagine planting a single seed and, with great precision, being able to predict the exact height of the tree that grows from it. Now imagine traveling to the future and snapping photographic proof that you were right.

    If you think of the seed as the early universe, and the tree as the universe the way it looks now, you have an idea of what the international Dark Energy Survey collaboration has just done. Scientists unveiled their most accurate measurement of the present large-scale structure of the universe at a meeting Aug. 3 at the University of Chicago-affiliated Fermi National Accelerator Laboratory. UChicago, Argonne and Fermilab scientists are members of international Dark Energy Survey collaboration.

    These measurements of the amount and “clumpiness” (or distribution) of dark matter in the present-day cosmos were made with a precision that, for the first time, rivals that of inferences from the early universe by the European Space Agency’s orbiting Planck observatory. The new Dark Energy Survey result (the tree, in the above metaphor) is close to “forecasts” made from the Planck measurements of the distant past (the seed), allowing scientists to understand more about the ways the universe has evolved over 14 billion years.

    “This result is beyond exciting,” said Fermilab’s Scott Dodelson, a professor in the Department of Astronomy and Astrophysics at UChicago and one of the lead scientists on this result, which was announced at the American Physical Society Division of Particles and Fields meeting. “For the first time, we’re able to see the current structure of the universe with the same clarity that we can see its infancy, and we can follow the threads from one to the other, confirming many predictions along the way.”

    Most notably, this result supports the theory that 26 percent of the universe is in the form of mysterious dark matter and that space is filled with an also-unseen dark energy, which makes up 70 percent and is causing the accelerating expansion of the universe.

    1
    A map of dark matter covering about one-thirtieth of the entire sky and spanning several billion light years—red regions have more dark matter than average, blue regions less dark matter. (Courtesy of Chihway Chang, the DES collaboration)

    Paradoxically, it is easier to measure the large-scale clumpiness of the universe in the distant past than it is to measure it today. In the first 400,000 years following the Big Bang, the universe was filled with a glowing gas, the light from which survives to this day. The Planck observatory’s map of this cosmic microwave background radiation gives us a snapshot of the universe at that very early time. Since then, the gravity of dark matter has pulled mass together and made the universe clumpier over time. But dark energy has been fighting back, pushing matter apart. Using the Planck map as a start, cosmologists can calculate precisely how this battle plays out over 14 billion years.

    “These first major cosmology results are a tribute to the many people who have worked on the project since it began 14 years ago,” said Dark Energy Survey Director Josh Frieman, a scientist at Fermilab and a professor in the Department of Astronomy and Astrophysics at UChicago. “It was an exciting moment when we unveiled the results to ourselves just last month, after carrying out a ‘blind’ analysis to avoid being influenced by our prejudices.”

    The Dark Energy Survey is a collaboration of more than 400 scientists from 26 institutions in seven countries. Its primary instrument is the 570-megapixel Dark Energy Camera, one of the most powerful in existence, which is able to capture digital images of light from galaxies eight billion light years from Earth. The camera was built and tested at Fermilab, the lead laboratory on the Dark Energy Survey, and is mounted on the National Science Foundation’s four-meter Blanco telescope, part of the Cerro Tololo Inter-American Observatory in Chile. The DES data are processed at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign.

    Scientists are using the camera to map an eighth of the sky in unprecedented detail over five years. The fifth year of observation will begin this month. The new results draw only from data collected during the survey’s first year, which covers one-thirtieth of the sky.

    Scientists used two methods to measure dark matter. First, they created maps of galaxy positions as tracers, and second, they precisely measured the shapes of 26 million galaxies to directly map the patterns of dark matter over billions of light years, using a technique called gravitational lensing.

    Gravitational Lensing NASA/ESA

    To make these ultra-precise measurements, the team developed new ways to detect the tiny lensing distortions of galaxy images—an effect not even visible to the eye, enabling revolutionary advances in understanding these cosmic signals. In the process, they created the largest guide to spotting dark matter in the cosmos ever drawn. The new dark matter map is ten times the size of the one that the Dark Energy Survey released in 2015 and will eventually be three times larger than it is now.

    “The Dark Energy Survey has already delivered some remarkable discoveries and measurements, and they have barely scratched the surface of their data,” said Fermilab Director Nigel Lockyer. “Today’s world-leading results point forward to the great strides DES will make toward understanding dark energy in the coming years.”

    See the full article here .

    Please help promote STEM in your local schools.

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    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 12:42 pm on June 25, 2017 Permalink | Reply
    Tags: , Efimov molecules, How the first complex molecules formed in the early universe and how complex materials came into being, Prof. Cheng Chin, Quantum objects, U Chicago   

    From U Chicago: “UChicago physicists settle debate over how exotic quantum particles form” 

    U Chicago bloc

    University of Chicago

    June 22, 2017
    Carla Reiter

    New research by physicists at the University of Chicago settles a longstanding disagreement over the formation of exotic quantum particles known as Efimov molecules.

    The findings, published last month in Nature Physics, address differences between how theorists say Efimov molecules should form and the way researchers say they did form in experiments. The study found that the simple picture scientists formulated based on almost 10 years of experimentation had it wrong—a result that has implications for understanding how the first complex molecules formed in the early universe and how complex materials came into being.

    1
    Prof. Cheng Chin. No image credit.

    Efimov molecules are quantum objects formed by three particles that bind together when two particles are unable to do so. The same three particles can make molecules in an infinite range of sizes, depending on the strength of the interactions between them.

    Experiments had shown the size of an Efimov molecule was roughly proportional to the size of the atoms that comprise it—a property physicists call universality.

    “This hypothesis has been checked and rechecked multiple times in the past 10 years, and almost all the experiments suggested that this is indeed the case,” said Cheng Chin, a professor of physics at UChicago, who leads the lab where the new findings were made. “But some theorists say the real world is more complicated than this simple formula. There should be some other factors that will break this universality.“

    The new findings come down somewhere between the previous experimental findings and predictions of theorists. They contradict both and do away with the idea of universality.

    “I have to say that I am surprised,” Chin said. “This was an experiment where I did not anticipate the result before we got the data.”

    The data came from extremely sensitive experiments done with cesium and lithium atoms using techniques devised by Jacob Johansen, previously a graduate student in Chin’s lab who is now a postdoctoral fellow at Northwestern University. Krutik Patel, a graduate student at UChicago, and Brian DeSalvo, a postdoctoral researcher at UChicago, also contributed to the work.

    “We wanted to be able to say once and for all that if we didn’t see any dependence on these other properties, then there’s really something seriously wrong with the theory,” Johansen said. “If we did see dependence, then we’re seeing the breakdown of this universality. It always feels good, as a scientist, to resolve these sorts of questions.”

    Developing new techniques

    2
    Here “3” symbolizes an Efimov molecule comprised of three atoms. While all “3”s look about the same, research from the Chin group observed a tiny “3” that is clearly different. Courtesy of Cheng Chin.

    Efimov molecules are held together by quantum forces rather than by the chemical bonds that bind together familiar molecules such as H2O. The atoms are so weakly connected that the molecules can’t exist under normal conditions. Heat in a room providing enough energy to shatter their bonds.

    The Efimov molecule experiments were done at extremely low temperatures—50 billionths of a degree above absolute zero—and under the influence of a strong magnetic field, which is used to control the interaction of the atoms. When the field strength is in a particular, narrow range, the interaction between atoms intensifies and molecules form. By analyzing the precise conditions in which formation occurs, scientists can infer the size of the molecules.

    But controlling the magnetic field precisely enough to make the measurements Johansen sought is extremely difficult. Even heat generated by the electric current used to create the field was enough to change that field, making it hard to reproduce in experiments. The field could fluctuate at a level of only one part in a million—a thousand times weaker than the Earth’s magnetic field—and Johansen had to stabilize it and monitor how it changed over time.

    The key was a technique he developed to probe the field using microwave electronics and the atoms themselves.

    “I consider what Jacob did a tour de force,” Chin said. “He can control the field with such high accuracy and perform very precise measurements on the size of these Efimov molecules and for the first time the data really confirm that there is a significant deviation of the universality.”

    The new findings have important implications for understanding the development of complexity in materials. Normal materials have diverse properties, which could not have arisen if their behavior at the quantum level was identical. The three-body Efimov system puts scientists right at the point at which universal behavior disappears.

    “Any quantum system made with three or more particles is a very, very difficult problem,” Chin said. “Only recently do we really have the capability to test the theory and understand the nature of such molecules. We are making progress toward understanding these small quantum clusters. This will be a building block for understanding more complex material.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
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