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  • richardmitnick 11:32 am on June 12, 2018 Permalink | Reply
    Tags: , , , , UCSB   

    From UC Santa Barbara: “Under the Sea” 

    UC Santa Barbara Name bloc
    From UC Santa Barbara

    June 5, 2018
    Jeff Mitchell

    Earth scientist Zach Eilon plumbs the depths of the Pacific Ocean to learn more about plate tectonics.

    5
    The Pacific ORCA science party on board the research vessel Kilo Moana; UCSB’s Zach Eilon is seventh from left. Photo Credit: Courtesy Zach Eilon

    2
    Watchstanders processing data in the vessel’s computer lab spot an underwater volcano that has never before been imaged. Photo Credit: Courtesy Zach Eilon

    3
    Preparing to deploy an Ocean Bottom Seismometer (OBS) at sunset. Photo Credit: Courtesy Zach Eilon

    4
    Preparing to test all the OBS communication devices, temporarily housed in the “rosette”, sitting beneath the A-frame; the yellow packages on deck are the OBS instruments, awaiting deployment. Photo Credit: Courtesy Zach Eilon

    Voyaging across a vast swath of the Pacific Ocean to learn more about how the Earth’s tectonic plates work, scientist Zach​​ Eilon was assisted along the way by friendly deep-sea denizen SpongeBob SquarePants.

    No, the beloved animated character wasn’t really there, but SpongeBob was the nickname Eilon, a UC Santa Barbara assistant professor of earth sciences, gave the sophisticated instrument that played a key role in his research.

    Otherwise known as ocean bottom seismometers, or OBS’s, these instruments are sensitive enough to detect earthquakes on the other side of the world.

    While the seismometers themselves sit on the seafloor, they are attached to a bright yellow flotation package — hence, the SpongeBob comparison — and are about a meter in width. The packages are affixed to a plastic base containing complex electronics.

    Eilon and collaborators carefully placed 30 of them on the ocean floor about 2,000 miles southeast of Hawaii during their recent Pacific ORCA (Pacific OBS Research into Convecting Asthenosphere) expedition aboard the U.S. Navy research vessel Kilo Moana.

    2
    U.S. Navy research vessel Kilo Moana

    The trip and the experiment were part of an ongoing and high-profile international effort, on which UCSB is one of three lead institutions in the U.S., to seismically instrument the Pacific Ocean.

    Oceanic plates make up 70 percent of the Earth’s surface and offer important windows into the Earth’s mantle, Eilon said, yet they are largely unexplored due to the obvious challenge of putting sensitive electronics three miles beneath the sea surface. The earth science community has identified several unanswered questions regarding the thermal structure of oceanic plates, the significance of volcanism in the middle of oceanic plates and how the convecting mantle beneath the plates controls their movements.

    Undulations in the gravity field and unexplained shallowing of the ocean floors hint that small-scale convection may be occurring beneath the oceanic plates, but this remains unconfirmed, according to Eilon. The new experiment could help prove it.

    “Our little instruments will sit on the ocean floor for approximately 15 months, recording earthquakes around the world,” he said. “When we return to retrieve them next year they’ll hold seismic data in their memory banks that could change the way in which we understand the oceanic plates. That understanding is pretty significant, considering that these plates make up about 70 percent of our planet’s surface.”

    When they are recovered in July 2019, the OBS units are expected to provide data that allows Eilon and his collaborators to make 3-D images of the oceanic tectonic plates – a bit like taking a CAT-scan of the Earth. Of particular interest is the mysterious asthenosphere, the zone of Earth’s mantle lying beneath the lithosphere (the tectonic plate) and believed to be much hotter and more fluid than rocks closer to the surface. The asthenosphere extends from about 60 miles to about 250 miles below Earth’s surface.

    Once ready for deployment, the weighted instrument packages are designed to carefully sink upright to the seafloor. When the science party returns to the site, the ship will send an acoustic signal down to the individual science packages, commanding them to release the weight holding them down, allowing the buoyant yellow “SpongeBob” portion of the device to slowly float them to the surface, he explained.

    Once on the surface, the ship’s crew will home in on the package (which has a light, flag, and radio so the scientists can locate it) and lift it from the sea. From there the science team will commence the process of downloading the seismic data which are detailed records of the ocean floor vibrations. Turning these wiggles into 3D images is the result of highly complex computer processing and mathematics.

    Eilon said that in addition to giving researchers a better idea of how the Earth’s tectonic plates work, the data is expected to provide important information about geologic hazards.

    “By improving our understanding of interactions between plates, the data we collect should improve our ability to forecast earthquakes and volcanic eruptions,” he said, “which I hope will help authorities save lives when these events occur.”

    Eilon, along with co-principal investigator Jim Gaherty of Columbia University, led the expedition’s diverse 14-member science team (drawn from 11 institutions across three continents). The $4-million research project is supported by the National Science Foundation.

    See the full article here .


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    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

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  • richardmitnick 3:00 pm on April 17, 2018 Permalink | Reply
    Tags: Application, Complexity, Fidelity, Hello DARKNESS, , , The most advanced camera in the world, UCSB   

    From UCSB: Science + Technology 

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    Complexity, Fidelity, Application
    UCSB/Google researchers in quantum computing professor John Martinis’ group outline their plan for quantum supremacy

    By Sonia Fernandez
    (805) 893-4765
    sonia.fernandez@ucsb.edu
    Thursday, April 12, 2018

    1
    The dilution refrigerator, a cryogenic device where the quantum happens. Photo Credit: Eric Lucero/Google, Inc.

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    This superconducting chip, with a total area of one square centimeter, consists of nine qubits in a 1D array. Microwave pusles are applied to control their states and their interaction, and consequently control the dynamics of the system. Such Josephson-junction based superconducting systems are a leading physical implementations for quantum computation and simulation processing. Photo Credit: Eric Lucero/Google, Inc.

    Things are getting real for researchers in the UC Santa Barbara John Martinis/Google group. They are making good on their intentions to claim supremacy in a tight global race to build the first quantum machine to outperform the world’s best classical supercomputers.

    But what is quantum supremacy in a field where horizons are being widened on a regular basis, in which teams of the brightest quantum computing minds in the world routinely up the ante on the number and type of quantum bits (“qubits”) they can build, each with their own range of qualities?

    “Let’s define that, because it’s kind of vague,” said Google researcher Charles Neill. Simply put, he continued, “we would like to perform an algorithm or computation that couldn’t be done otherwise. That’s what we actually mean.”

    Neill is lead author of the group’s new paper, “A blueprint for demonstrating quantum supremacy with superconducting qubits,” now published in the journal Science.

    Fortunately, nature offers up many such complex situations, in which the variables are so numerous and interdependent that classical computers can’t hold all the values and perform the operations. Think chemical reactions, fluid interactions, even quantum phase changes in solids and a host of other problems that have daunted researchers in the past. Something on the order of at least 49 qubits — roughly equivalent to a petabyte (one million gigabytes) of classical random access memory — could put a quantum computer on equal footing with the world’s supercomputers. Just recently, Neill’s Google/Martinis colleagues announced an effort toward quantum supremacy with a 72-qubit chip possessing a “bristlecone” architecture that has yet to be put through its paces.

    But according to Neill, it’s more than the number of qubits on hand.

    “You have to generate some sort of evolution in the system which leads you to use every state that has a name associated with it,” he said. The power of quantum computing lies in, among other things, the superpositioning of states. In classical computers, each bit can exist in one of two states — zero or one, off or on, true or false — but qubits can exist in a third state that is a superposition of both zero and one, raising exponentially the number of possible states a quantum system can explore.

    Additionally, say the researchers, fidelity is important, because massive processing power is not worth much if it’s not accurate. Decoherence is a major challenge for anyone building a quantum computer — perturb the system, the information changes. Wait a few hundredths of a second too long, the information changes again.

    “People might build 50 qubit systems, but you have to ask how well it computed what you wanted it to compute,” Neill said. “That’s a critical question. It’s the hardest part of the field.” Experiments with their superconducting qubits have demonstrated an error rate of one percent per qubit with three- and nine-qubit systems, which, they say, can be reduced as they scale up, via improvements in hardware, calibration, materials, architecture and machine learning.

    Building a qubit system complete with error correction components — the researchers estimate a range of 100,000 to a million qubits — is doable and part of the plan. And still years away. But that doesn’t mean their system isn’t already capable of doing some heavy lifting. Just recently it was deployed, with spectroscopy, on the issue of many-body localization in a quantum phase change — a quantum computer solving a quantum statistical mechanics problem. In that experiment, the nine-qubit system became a quantum simulator, using photons bouncing around in their array to map the evolution of electrons in a system of increasing, yet highly controlled, disorder.

    “A good reason why our fidelity was so high is because we’re able to reach complex states in very little time,” Neill explained. The more quickly a system can explore all possible states, the better the prediction of how a system will evolve, he said.

    If all goes smoothly, the world should be seeing a practicable UCSB/Google quantum computer soon. The researchers are eager to put it through its paces, gaining answers to questions that were once accessible only through theory, extrapolation and highly educated guessing — and opening up a whole new level of experiments and research.

    “It’s definitely very exciting,” said Google researcher Pedram Roushan, who led the many-body quantum simulation work published in Science in 2017. They expect their early work to stay close to home, such as research in condensed matter physics and quantum statistical mechanics, but they plan to branch out to other areas, including chemistry and materials, as the technology becomes more refined and accessible.

    “For instance, knowing whether or not a molecule would form a bond or react in some other way with another molecule for some new technology… there are some important problems that you can’t roughly estimate; they really depend on details and very strong computational power,” Roushan said, hinting that a few years down the line they may be able to provide wider access to this computing power. “So you can get an account, log in and explore the quantum world.”

    See the full article here .

    Hello DARKNESS

    UCSB physicists team up with Caltech astronomers to commission the most advanced camera in the world.

    April 16, 2018
    Julie Cohen
    (805) 893-7220
    julie.cohen@ucsb.edu

    3
    The world’s most advanced camera can detect planets around the nearest stars.
    Photo Credit: COURTESY PHOTO

    Somewhere in the vastness of the universe another habitable planet likely exists. And it may not be that far — astronomically speaking — from our own solar system.

    Distinguishing that planet’s light from its star, however, can be problematic. But an international team led by UC Santa Barbara physicist Benjamin Mazin has developed a new instrument to detect planets around the nearest stars. It is the world’s largest and most advanced superconducting camera. The team’s work appears in the journal Publications of the Astronomical Society of the Pacific.

    The group, which includes Dimitri Mawet of the California Institute of Technology and Eugene Serabyn of the Jet Propulsion Laboratory in Pasadena, California, created a device named DARKNESS (the DARK-speckle Near-infrared Energy-resolved Superconducting Spectrophotometer), the first 10,000-pixel integral field spectrograph designed to overcome the limitations of traditional semiconductor detectors. It employs Microwave Kinetic Inductance Detectors that, in conjunction with a large telescope and an adaptive optics system, enable direct imaging of planets around nearby stars.

    “Taking a picture of an exoplanet is extremely challenging because the star is much brighter than the planet, and the planet is very close to the star,” said Mazin, who holds the Worster Chair in Experimental Physics at UCSB.

    Funded by the National Science Foundation, DARKNESS is an attempt to overcome some of the technical barriers to detecting planets. It can take the equivalent of thousands of frames per second without any read noise or dark current, which are among the primary sources of error in other instruments. It also has the ability to determine the wavelength and arrival time of every photon. This time domain information is important for distinguishing a planet from scattered or refracted light called speckles.

    “This technology will lower the contrast floor so that we can detect fainter planets,” Mazin explained. “We hope to approach the photon noise limit, which will give us contrast ratios close to 10-8, allowing us to see planets 100 million times fainter than the star. At those contrast levels, we can see some planets in reflected light, which opens up a whole new domain of planets to explore. The really exciting thing is that this is a technology pathfinder for the next generation of telescopes.”

    Designed for the 200-inch Hale telescope at the Palomar Observatory near San Diego, California, DARKNESS acts as both the science camera and a focal-plane wave-front sensor, quickly measuring the light and then sending a signal back to a rubber mirror that can form into a new shape 2,000 times a second. This process cleans up the atmospheric distortion that causes stars to twinkle by suppressing the starlight and enabling higher contrast ratios between the star and the planet.

    During the past year and a half, the team has employed DARKNESS on four runs at Palomar to work out bugs. The researchers will return in May to take more data on certain planets and to demonstrate their progress in improving the contrast ratio.

    “Our hope is that one day we will be able to build an instrument for the Thirty Meter Telescope planned for Mauna Kea on the island of Hawaii or La Palma,” Mazin said. “With that, we’ll be able to take pictures of planets in the habitable zones of nearby low mass stars and look for life in their atmospheres. That’s the long-term goal and this is an important step toward that.”

    See the full article here .

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    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
  • richardmitnick 10:26 am on September 28, 2017 Permalink | Reply
    Tags: 2-D superlattice, , , Band Gaps Made to Order, Could usher a new generation of light-emitting devices for photonics applications, Each quantum dot acts as a quantum well where electron-hole activity occurs, In the quantum realm precision is even more important, , , , The quantum dot is theoretically an artificial “atom.”, UCSB   

    From UCSB: “Band Gaps, Made to Order” 

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    UC Santa Barbara

    September 25, 2017
    James Badham

    1
    This artist’s representation shows an electron beam (in purple) being used to create a 2D superlattice made up of quantum dots having extraordinary atomic-scale precision and placement.
    Photo Credit: PETER ALLEN

    Control is a constant challenge for materials scientists, who are always seeking the perfect material — and the perfect way of treating it — to induce exactly the right electronic or optical activity required for a given application.

    One key challenge to modulating activity in a semiconductor is controlling its band gap. When a material is excited with energy, say, a light pulse, the wider its band gap, the shorter the wavelength of the light it emits. The narrower the band gap, the longer the wavelength.

    As electronics and the devices that incorporate them — smartphones, laptops and the like — have become smaller and smaller, the semiconductor transistors that power them have shrunk to the point of being not much larger than an atom. They can’t get much smaller. To overcome this limitation, researchers are seeking ways to harness the unique characteristics of nanoscale atomic cluster arrays — known as quantum dot superlattices — for building next generation electronics such as large-scale quantum information systems. In the quantum realm, precision is even more important.

    New research conducted by UC Santa Barbara’s Department of Electrical and Computer Engineering reveals a major advance in precision superlattices materials. The findings by Professor Kaustav Banerjee, his Ph.D. students Xuejun Xie, Jiahao Kang and Wei Cao, postdoctoral fellow Jae Hwan Chu and collaborators at Rice University appear in the journal Nature Scientific Reports.

    Their team’s research uses a focused electron beam to fabricate a large-scale quantum dot superlattice on which each quantum dot has a specific pre-determined size positioned at a precise location on an atomically thin sheet of two-dimensional (2-D) semiconductor molybdenum disulphide (MoS2). When the focused electron beam interacts with the MoS2 monolayer, it turns that area — which is on the order of a nanometer in diameter — from semiconducting to metallic. The quantum dots can be placed less than four nanometers apart, so that they become an artificial crystal — essentially a new 2-D material where the band gap can be specified to order, from 1.8 to 1.4 electron volts (eV).

    This is the first time that scientists have created a large-area 2-D superlattice — nanoscale atomic clusters in an ordered grid — on an atomically thin material on which both the size and location of quantum dots are precisely controlled. The process not only creates several quantum dots, but can also be applied directly to large-scale fabrication of 2-D quantum dot superlattices. “We can, therefore, change the overall properties of the 2-D crystal,” Banerjee said.

    Each quantum dot acts as a quantum well, where electron-hole activity occurs, and all of the dots in the grid are close enough to each other to ensure interactions. The researchers can vary the spacing and size of the dots to vary the band gap, which determines the wavelength of light it emits.

    “Using this technique, we can engineer the band gap to match the application,” Banerjee said. Quantum dot superlattices have been widely investigated for creating materials with tunable band gaps but all were made using “bottom-up” methods in which atoms naturally and spontaneously combine to form a macro-object. But those methods make it inherently difficult to design the lattice structure as desired and, thus, to achieve optimal performance.

    As an example, depending on conditions, combining carbon atoms yields only two results in the bulk (or 3-D) form: graphite or diamond. These cannot be ‘tuned’ and so cannot make anything in between. But when atoms can be precisely positioned, the material can be designed with desired characteristics.

    “Our approach overcomes the problems of randomness and proximity, enabling control of the band gap and all the other characteristics you might want the material to have — with a high level of precision,” Xie said. “This is a new way to make materials, and it will have many uses, particularly in quantum computing and communication applications. The dots on the superlattice are so close to each other that the electrons are coupled, an important requirement for quantum computing.”

    The quantum dot is theoretically an artificial “atom.” The developed technique makes such design and “tuning” possible by enabling top-down control of the size and the position of the artificial atoms at large scale.

    To demonstrate the level of control achieved, the authors produced an image of “UCSB” spelled out in a grid of quantum dots. By using different doses from the electron beam, they were able to cause different areas of the university’s initials to light up at different wavelengths.

    “When you change the dose of the electron beam, you can change the size of the quantum dot in the local region, and once you do that, you can control the band gap of the 2-D material,” Banerjee explained. “If you say you want a band gap of 1.6 eV, I can give it to you. If you want 1.5 eV, I can do that, too, starting with the same material.”

    This demonstration of tunable direct band gap could usher a new generation of light-emitting devices for photonics applications.

    See the full article here .

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    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
  • richardmitnick 10:29 am on August 23, 2017 Permalink | Reply
    Tags: , NTSs-natural treatment systems, Recovering Runoff, Revolutionize the collection and management of stormwater, UCSB   

    From UCSB: “Recovering Runoff” 

    UC Santa Barbara Name bloc
    UC Santa Barbara

    August 17, 2017
    Shelly Leachman

    1
    Stormwater runoff. Photo Credit: iStock/Resavac

    2
    UCSB doctoral student Marina Feraud, center, is among the researchers involved in a multicampus project to investigate the use of stormwater to combat drought.
    Photo Credit: Matt Perko

    3
    UCSB participants in the project spanning five UC campuses are surveying existing natural treatment systems for possible study. Photo Credit: Matt Perko

    Dumping billions of gallons on California every year, rain is the state’s way out of drought — if only all that water could be captured instead of washing into drains and out to sea.

    An ambitious new collaboration spanning five University of California campuses, including UC Santa Barbara, hopes to do exactly that. The research partnership of UCSB, UC Irvine, UCLA, UC Riverside and UC San Diego aims to revolutionize the collection and management of stormwater — and demonstrate its potential for addressing drought and flood risk. A $1.9 million UC Multicampus Research Programs and Initiatives (MRPI) grant will help get it done.

    The project, “Fighting Drought with Stormwater,” is now underway. Work began in earnest in early August — which happens to be National Water Quality Month. The five Southern California UC campuses will serve as living laboratories for studying natural treatment systems, such as bioswales and biofilters, or rain gardens. The effort is meant to illuminate how well the systems are working now, and how they can be improved in form and function to boost stormwater recovery and bolster water resources.

    “Think about the winter rains in this region — the runoff mainly goes out to the ocean,” said UCSB’s Patricia Holden, a professor in the Bren School of Environmental Science & Management and co-investigator on the grant. “But UCSB and other campuses are increasingly instituting ‘green’ approaches, called natural treatment systems (NTSs), for stormwater management that slow down the runoff, capture it onsite, treat it so that it is less polluting to the ocean, and can recharge shallow groundwater.

    “Many campuses employ NTSs, but how well do they achieve co-benefits of advancing water neutrality, removing pollutants and delivering other ecosystem services?” she added. “How can knowledge — in biogeochemistry, hydrology, ecology and social sciences — assist optimizing designs and NTS management? What incentives are needed, so that stormwater runoff capture and beneficial reuse — at distributed, small scales — becomes more widespread?”

    For UCSB’s part in this multifaceted endeavor, Holden’s team members Dong Li, Marina Feraud and Mitchell Maier are spearheading an investigation into microbial communities in these systems and their impact on nitrogen cycling. By looking into accumulated pollutants in the soil media of NTSs and how they interact with microbes, they hope to ascertain if the level of pollution influences whether NTSs convert nitrate within the system into nitrogen, a harmless gas, or into nitrous oxide, a potent greenhouse gas.

    “The big idea behind the whole project is to advance research on stormwater treatment features that would allow us to capture and treat this water so it can be used as a resource,” said Feraud, a doctoral student. “We hope to increase knowledge of microbial communities in these systems — who’s there and what they’re doing — overlaying that with the level of pollution we might see in the soil media. Ultimately we want to increase overall understanding of these systems, and how design and maintenance choices affect their performance as measured by environmental metrics — in this case the potential to accumulate nitrate or release nitrous oxide. Making more informed choices in how we design and maintain these systems can promote their use and implementation, which we think is very important for treating water and improving water quality, while also allowing for beneficial reuse.”

    The UCSB group, by way of Li, is also bringing a novel line of inquiry to the project: the potential of these systems to reduce or remove disease-causing pathogens from stormwater runoff, through understanding and possibly enhancing natural predator-prey interactions.

    “Sometimes there are human pathogens in stormwater runoff,” said Li, a postdoctoral researcher. “NTSs use bioswales and biofilters to remove these pathogens so that the water can be reclaimed and reused. There are many different pollutants, but human pathogens are particularly important, and we definitely want to reduce their abundances via NTSs. The indigenous microbial ecology may be key to such removal.”

    The many other issues being addressed by this sweeping project include how to effect the removal of chemical pollutants from stormwater; the provision of ecosystem services — and potentially disservices — via these systems; understanding related socioeconomic benefits and drivers; and understanding water budgets in these systems toward achieving water neutrality on campuses and beyond.

    “This is a great demonstration of a collaborative, forward-looking approach to a critical water issue — of both quantity and quality — in Southern California, and one whose discoveries can be informative beyond the campuses,” Holden said. “We aim to use the campuses as testbeds, but produce understanding that can inform sites in surrounding communities.”

    The ultimate, long-range goal?

    Transform the infrastructure of such treatment systems from what today, the researchers say, is a major cause of environmental degradation into a “multifunctional green system that augments urban water supply, protects human and ecosystem health, minimizes flood risk and ensures public safety.”

    Said principal investigator and civil engineer Stanley Grant, of UC Irvine, when the grant was announced, “My hope is that by the end of our project, we will have set the southern UC campuses on a path toward becoming ‘stormwater-neutral,’ by which I mean all rain that falls on the campuses will be captured and used locally. It’s our chance to help the UC maintain its position as a global leader in environmental sustainability research and practice.”

    See the full article here .

    Please help promote STEM in your local schools.

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    UC Santa Barbara Seal
    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
  • richardmitnick 10:34 am on August 18, 2017 Permalink | Reply
    Tags: A Fleeting Blue Glow, , , , , LCO-Las Cumbres Observatory, , UCSB   

    From UCSB: “A Fleeting Blue Glow” 

    UC Santa Barbara Name bloc
    UC Santa Barbara

    August 14, 2017
    Julie Cohen

    Observations of a supernova colliding with a nearby companion star take UCSB astrophysicists by surprise.

    1
    Only 55 million lightyears away, this is one of the closest supernovae discovered in recent years.

    In the 2009 film “Star Trek,” a supernova hurtles through space and obliterates a planet unfortunate enough to be in its path. Fiction, of course, but it turns out the notion is not so farfetched.

    Using the nearby Las Cumbres Observatory (LCO), astrophysicists from UC Santa Barbara have observed something similar: an exploding star slamming into a nearby companion star.

    LCOGT Las Cumbres Observatory Global Telescope Network, Haleakala Hawaii, USA

    What’s more, they detected the fleeting blue glow from the interaction at an unprecedented level of detail. Their observations revealed surprising information about the mysterious companion star, a feat made possible by recent advances in linking telescopes into a robotic network. The team’s findings appear in the journal Astrophyiscal Journal Letters.

    The identity of this particular companion has been hotly debated for more than 50 years. Prevailing theory over the last few years has held that the supernovae happen when two white dwarfs spiral together and merge. This new study demonstrates that the supernova collided with the companion star that was not a white dwarf. White dwarf stars are the dead cores of what used to be normal stars like the sun.

    “We’ve been looking for this effect — a supernova crashing into its companion star — since it was predicted in 2010,” said lead author Griffin Hosseinzadeh, a UCSB graduate student. “Hints have been seen before, but this time the evidence is overwhelming.”

    The supernova in question is SN 2017cbv, a thermonuclear Type Ia, which astronomers use to measure the acceleration of the expansion of the universe. This kind of supernova is known to be the explosion of a white dwarf star, though it requires additional mass from a companion star to explode.

    The UCSB-led research implies that the white dwarf was stealing matter from a much larger companion star — approximately 20 times the radius of the sun — which caused the white dwarf to explode. The collision of the supernova and the companion star shocked the supernova material, heating it to a blue glow heavy in ultraviolet light. Such a shock could not have been produced if the companion were another white dwarf star.

    “The universe is crazier than science fiction authors have dared to imagine,” said Andy Howell, a staff scientist at LCO and Hosseinzadeh’s Ph.D. adviser. “Supernovae can wreck nearby stars, too, releasing unbelievable amounts of energy in the process.”

    Co-author David Sand, an associate professor at the University of Arizona, discovered the supernova on March 10, 2017, in the galaxy NGC 5643. Only 55 million lightyears away, SN 2017cbv was one of the closest supernovae discovered in recent years, found by the DLT40 survey using the Panchromatic Robotic Optical Monitoring and Polarimetry Telescope (PROMPT) in Chile, which monitors galaxies nightly at distances less than 40 megaparsecs (120 million light-years). This was one of the earliest catches ever — within a day, perhaps even hours, of its explosion. The DLT40 survey was created by Sand and study co-author Stefano Valenti, an assistant professor at UC Davis; both were previously postdoctoral researchers at LCO.

    Within minutes of discovery, Sand activated observations with LCO’s global network of 18 robotic telescopes, spaced around the Earth so that one is always on the night side. This allowed the team to take immediate and near-continuous observations.

    “With LCO’s ability to monitor the supernova every few hours, we were able to see the full extent of the rise and fall of the blue glow for the first time,” Hosseinzadeh said. “Conventional telescopes would have had only a data point or two and missed it.”

    Howell likened the event to gaining astronomical superpowers that give astronomers the ability to see the universe in new ways. “These capabilities were just a dream a few years ago,” he said. “But now we’re living the dream and unlocking the origins of supernovae in the process.”

    See the full article here .

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    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
  • richardmitnick 10:49 am on July 12, 2017 Permalink | Reply
    Tags: , , Tau can in a complex with RNA condense into a highly compact “droplet” while retaining its liquid properties, Tau protein, UCSB   

    From UCSB: “A Biophysical ‘Smoking Gun’ “ 

    UC Santa Barbara Name bloc
    UC Santa Barbara

    July 6, 2017
    Julie Cohen

    1
    Tau was found to belong to proteins that undergo liquid-liquid phase separation upon association with RNAs that establishes a new phase state. Photo Credit: Peter Allen.

    While much about Alzheimer’s disease remains a mystery, scientists do know that part of the disease’s progression involves a normal protein called tau, aggregating to form ropelike inclusions within brain cells that eventually strangle the neurons. Yet how this protein transitions from its soluble liquid state to solid fibers has remained unknown — until now.

    Discovering an unsuspected property of tau, UC Santa Barbara physical chemist Song-I Han and neurobiologist Kenneth S. Kosik have shed new light on the protein’s ability to morph from one state to another.

    Remarkably, tau can, in a complex with RNA, condense into a highly compact “droplet” while retaining its liquid properties. In a phenomenon called phase separation, tau and RNA hold together, without the benefit of a membrane, but remain separate from the surrounding milieu. This novel state highly concentrates tau and creates a set of conditions in which it becomes vulnerable to aggregation. Kosik and Han outline their discoveries in the journal PLOS Biology.

    “Our findings, along with related research in neurodegeneration, posit a biophysical ‘smoking gun’ on the path to tau pathology,” said Kosik, UCSB’s Harriman Professor of Neuroscience and co-director of the campus’s Neuroscience Research Institute. “The signposts on this path are the intrinsic ability of tau to fold into myriad shapes, to bind to RNA and to form compact reversible structures under physiologic conditions, such as the concentration, the temperature and the salinity.”

    The researchers found that, depending on the length and shape of the RNA, up to eight tau molecules bind to the RNA to form an extended fluidic assembly. Several other proteins like tau are known to irreversibly aggregate in other neurodegenerative diseases such as amyotrophic lateral sclerosis, more commonly known as Lou Gehrig’s disease.

    “There is an interesting relationship between intrinsically disordered proteins that are predisposed to become neurodegenerative — in this case tau — and this phase separation state,” said Han, a professor in UCSB’s Department of Chemistry and Biochemistry. “Is this droplet stage a reservoir that protects tau or an intermediate stage that helps transform tau into a disease state with fibrils or both at the same time? Figuring out the exact physiological role of these droplets is the next challenge.”

    Subsequent analysis will consist of an intensive search for the counterpart of tau droplets in living cells. In future work, the researchers also want to explore how and why a cell regulates the formation and dissolution of these droplets and whether this represents a potential inroad toward therapy.

    See the full article here .

    Please help promote STEM in your local schools.

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    UC Santa Barbara Seal
    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
  • richardmitnick 11:57 am on June 6, 2017 Permalink | Reply
    Tags: , antimicrobial therapy, , , , multidrug-resistant pathogens research, UCSB   

    From UCSB: “Why Antibiotics Fail” 

    UC Santa Barbara Name bloc
    UC Santa Barbara

    June 1, 2017
    Julie Cohen

    1
    Drug testing often excludes potent antibiotics for the treatment of microbial infections (blue plates). Drug testing under conditions that mimic natural infections succeeds in identifying effective antibiotics (red plates), even though these same antibiotics failed standard tests.
    Photo Credit: Peter Allen/Brian Long

    2
    Study authors (L): Michael Mahan, Lucien Barnes, Geneva Tripp and Douglas Heithoff. Photo Credit: Sonia Fernandez

    When a patient is prescribed the wrong antibiotic to treat a bacterial infection, it’s not necessarily the physician who is at fault. The current antibiotic assay — standardized in 1961 by the World Health Organization and used worldwide — is potentially flawed.

    So says UC Santa Barbara biologist Michael Mahan, whose lab has developed a new antimicrobial susceptibility test that could transform the way antibiotics are developed, tested and prescribed.

    The standard test specifies how well drugs kill bacteria on petri plates containing Mueller-Hinton Broth, a nutrient-rich laboratory medium that fails to reproduce most aspects of a natural infection. Now, Mahan and colleagues have used a mouse model to demonstrate that a variety of antibiotics work differently against various pathogens when inside the mammalian body. Their findings appear in the journal EBioMedicine.

    “The message is simple: Physicians may be relying on the wrong test for identifying antibiotics to treat infections,” said Mahan, a professor in UCSB’s Department of Molecular, Cellular and Developmental Biology. “By developing a test that mimics conditions in the body, we have identified antibiotics that effectively treat infections caused by diverse bacteria, including MRSA, the cause of deadly Staphylococcal infections. These drugs have been overlooked because they failed the standard tests, despite being inexpensive, nontoxic and available at local pharmacies.”

    The research has significant implications for public health. If a drug that passed the standard test doesn’t work, physicians can now choose a different drug immediately rather than increase the dose of the same drug when patients return — often in worse condition — after an ineffective first course of treatment.

    Reliance on the standard test may have contributed to the rise in multidrug-resistant bacteria, Mahan noted, due to the continued prescription of ineffective antibiotics. Further, he added, the standard test may also be slowing the discovery of new antibiotics. “These ‘wonder drugs’ may already exist but have been rejected by the standard test and are consequently not used in practice,” Mahan said.

    The scientists also report a way to “fix” the standard test to better predict how well antibiotics will treat infections: Simply add sodium bicarbonate. More commonly known as baking soda, this chemical is found in abundance in the body, where it helps to maintain precise blood pH. “Sodium bicarbonate makes the petri plates behave more like the body and increases the test’s accuracy for assigning the appropriate antibiotic to treat infections,” explained co-lead author Douglas Heithoff, a project scientist at UCSB’s Center for Nanomedicine.

    Mahan also points out that pharmaceutical companies could benefit from using the revised test to rescreen their collections of purified compounds that have failed the standard test. “There could be a treasure trove of compounds that have been shelved but could actually be quite effective against antibiotic-resistant strains,” he said.

    “Things aren’t as gloomy as we thought,” Mahan added. “We just have to be smart about it and change the way we’re using the drugs we already have while we continue to search for new ones.”

    See the full article here .

    Please help promote STEM in your local schools.

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    UC Santa Barbara Seal
    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
  • richardmitnick 12:34 pm on May 25, 2017 Permalink | Reply
    Tags: , , Plate attenuation, UCSB,   

    From UCSB: “The Birth and Death of a Tectonic Plate” 

    UC Santa Barbara Name bloc
    UC Santa Barbara

    May 24, 2017
    Julie Cohen

    Geophysicist Zachary Eilon developed a new technique to investigate the underwater volcanoes that produce Earth’s tectonic plates

    1
    Attenuation values recorded at ocean-bottom stations. Radial spokes show individual arrivals at their incoming azimuth; central circles show averages at each station

    2
    Geophysicist Zachary Eilon. Photo Credit: COURTESY IMAGE

    Several hundred miles off the Pacific Northwest coast, a small tectonic plate called the Juan de Fuca is slowly sliding under the North American continent. This subduction has created a collision zone with the potential to generate huge earthquakes and accompanying tsunamis, which happen when faulted rock abruptly shoves the ocean out of its way.

    In fact, this region represents the single greatest geophysical hazard to the continental United States; quakes centered here could register as hundreds of times more damaging than even a big temblor on the San Andreas Fault. Not surprisingly, scientists are interested in understanding as much as they can about the Juan de Fuca Plate.

    This microplate is “born” just 300 miles off the coast, at a long range of underwater volcanoes that produce new crust from melt generated deep below. Part of the global mid-ocean ridge system that encircles the planet, these regions generate 70 percent of the Earth’s tectonic plates. However, because the chains of volcanoes lie more than a mile beneath the sea surface, scientists know surprisingly little about them.

    UC Santa Barbara geophysicist Zachary Eilon and his co-author Geoff Abers at Cornell University have conducted new research — using a novel measurement technique — that has revealed a strong signal of seismic attenuation or energy loss at the mid-ocean ridge where the Juan de Fuca Plate is created. The researchers’ attenuation data imply that molten rock here is found even deeper within the Earth than scientists had previously thought. This in turn helps scientists understand the processes by which Earth’s tectonic plates are built, as well as the deep plumbing of volcanic systems. The results of the work appear in the journal Science Advances.

    “We’ve never had the ability to measure attenuation this way at a mid-ocean ridge before, and the magnitude of the signal tells us that it can’t be explained by shallow structure,” said Eilon, an assistant professor in UCSB’s Department of Earth Science. “Whatever is down there causing all this seismic energy to be lost extends really deep, at least 200 kilometers beneath the surface. That’s unexpected, because we think of the processes that give rise to this — particularly the effect of melting beneath the surface — as being shallow, confined to 60 km or less.”

    According to Eilon’s calculations, the narrow strip underneath the mid-ocean ridge, where hot rock wells up to generate the Juan de Fuca Plate, has very high attenuation. In fact, its levels are as high as scientists have seen anywhere on the planet. His findings also suggest that the plate is cooling faster than expected, which affects the friction at the collision zone and the resulting size of any potential megaquake.

    Seismic waves begin at an earthquake and radiate away from it. As they disperse, they lose energy. Some of that loss is simply due to spreading out, but another parameter also affects energy loss. Called the quality factor, it essentially describes how squishy the Earth is, Eilon said. He used the analogy of a bell to explain how the quality factor works.

    “If I were to give you a well-made bell and you were to strike it once, it would ring for a long time,” he explained. “That’s because very little of the energy is actually being lost with each oscillation as the bell rings. That’s very low attenuation, very high quality. But if I give you a poorly made bell and you strike it once, the oscillations will die out very quickly. That’s high attenuation, low quality.”

    Eilon looked at the way different frequencies of seismic waves attenuated at different rates. “We looked not only at how much energy is lost but also at the different amounts by which various frequencies are delayed,” he explained. “This new, more robust way of measuring attenuation is a breakthrough that can be applied in other systems around the world.

    “Attenuation is a very hard thing to measure, which is why a lot of people ignore it,” Eilon added. “But it gives us a huge amount of new information about the Earth’s interior that we wouldn’t have otherwise.”

    Next year, Eilon will be part of an international effort to instrument large unexplored swaths of the Pacific with ocean bottom seismometers. Once that data has been collected, he will apply the techniques he developed on the Juan de Fuca in the hope of learning more about what lies beneath the seafloor in the old oceans, where mysterious undulations in the Earth’s gravity field have been measured.

    “These new ocean bottom data, which are really coming out of technological advances in the instrumentation community, will give us new abilities to see through the ocean floor,” Eilon said. “This is huge because 70 percent of the Earth’s surface is covered by water and we’ve largely been blind to it — until now.

    “The Pacific Northwest project was an incredibly ambitious community experiment,” he said. “Just imagine the sort of things we’ll find out once we start to put these instruments in other places.”

    See the full article here .

    Please help promote STEM in your local schools.

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    UC Santa Barbara Seal
    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
  • richardmitnick 11:17 am on April 25, 2017 Permalink | Reply
    Tags: A Practical Approach to Conservation, , UCSB   

    From UCSB: “A Practical Approach to Conservation” 

    UC Santa Barbara Name bloc
    UC Santa Barbara

    April 24, 2017
    Julie Cohen

    1
    No image caption. No image credit

    2
    Kevin Lafferty and Hillary Young. Photo Credit: Sonia Fernandez

    Is conservation good for your health? Seems like a no-brainer, right?

    Not so much, according to a group of scientists who have collaborated on a new research volume that explores what turns out to be a very tough question.

    UC Santa Barbara ecologists teamed up with colleagues at Duke University and the University of Washington to present various perspectives on the subject for the journal Philosophical Transactions of the Royal Society B. Their special issue, Conservation, Biodiversity, and Infectious Disease, is a combination of theoretical work and case studies, all of which embrace a systems approach to infectious disease ecology.

    “I’m a firm believer that insights from ecology can help us manage disease and protect species,” said co-editor Kevin Lafferty, a senior ecologist with the U.S. Geological Survey and a principal investigator at UCSB’s Marine Science Institute. “But ecological systems are too complicated to expect one-size-fits-all solutions.”

    The biodiversity-disease relationship often has been framed as a simple synergy between conservation action and improved human health, yet the links between habitat disturbance and other factors that affect disease risk are complex. The editors sought authors from diverse perspectives and backgrounds to investigate how economics, climate change and biodiversity change affect infectious diseases.

    “What’s really unique about this issue is that we have gone all the way from theory articles that look at how biodiversity changes might affect disease to multiple field studies of various conservation interventions at different scales to an examination of the global drivers of biodiversity change,” said lead editor Hillary Young, an assistant professor in UCSB’s Department of Ecology, Evolution and Marine Biology (EEMB). “We wanted to present cases for viable and useful public health interventions.”

    Take schistosomiasis, a parasitic disease carried by fresh water snails. Found predominantly in tropical and subtropical climates, schistosomiasis infects 240 million people in as many as 78 countries, with a vast majority occurring in Africa. Schistosomiasis ranks second only to malaria as the most common parasitic disease.

    Susanne Sokolow, a researcher at UCSB’s Marine Science Institute and at Stanford University’s Hopkins Marine Station, presents her study of the disease in Senegal in one paper in the special issue. She found that when dams block the migration of snail-eating river prawns, snail abundance — and presumably schistosomiasis — increase.

    “This is a story that repeats itself in systems where river prawns are present, and one that has a simple solution,” said co-author Lafferty, who is an adjunct EEMB faculty member at UCSB. “This is a type of species that can be restored and that’s the kind of win-win we’re looking for. A third win occurs because river prawn fisheries create economic benefits. Restoring the river is too vague a solution; honing in on the specific lever in the system to which the disease is sensitive gets us there faster.”

    Young’s research in Kenya, also featured in this special issue, is different, but it tells a similar story: Details matter. The ecologists examined how different types of disturbances affected vector-borne diseases and found that agricultural disturbance and the removal of large wildlife caused strong and systematic increases in many pathogens. However, pastoral land use change had no general effect.

    “The type of land use change matters; you can’t just say conservation is good for disease,” Young said. “In fact, conservations are much more effective when scientists understand the nuances involved.

    “While the mechanisms involved in my system are entirely different from the schistosomiasis system, both underscore the importance of understanding the entire ecology of the system, finding win-win scenarios and acting on them rather than expecting generalities about conservation and disease,” she added.

    Discovering the specifics can be problematic because measurements of the environment, of biodiversity and of infectious diseases vary greatly. In another of the volume’s papers, Lafferty, Young and colleagues found a way to analyze global disease burden at two time points, which enabled them to examine the same things.

    “We analyzed what drives the world’s most important infectious diseases among countries and across decades,” Lafferty explained. “It’s the most comprehensive attempt yet to explain how conservation, climate and economics affect human health.”

    The researchers considered forestation, biodiversity, wealth, temperature, precipitation and urbanization. They found that any of those factors on their own could have a positive, negative or neutral effect, depending on the disease. By far the most consistent finding, though, was this: The wealthier the country, the less disease; and the more wealth increased, the lower the burden of infectious disease.

    Young noted that this research produced a better understanding of causality than most studies. “This paper has some good news that is rarely part of the story in our field,” Lafferty said. “Our analysis shows across the board — with just a couple of exceptions — that the burden of infectious diseases has diminished considerably over the last two decades and that is mostly due to increased wealth and urbanization.”

    “There is no one-size-fits-all lever, where improving access to healthcare is going to affect all infectious diseases,” Young added. “This body of work highlights the need to understand the nuances that make biodiversity and conservation effective levers.”

    The discourse begun in the special journal will continue at the 15th annual Ecology and Evolution of Infectious Diseases conference to be held June 24-27 at UCSB. Many authors will present their work. More information is available at https://eeid2017.eemb.ucsb.edu/

    See the full article here .

    Please help promote STEM in your local schools.

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    UC Santa Barbara Seal
    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
  • richardmitnick 12:53 pm on February 11, 2017 Permalink | Reply
    Tags: Drawn from the Deep, Earth’s mantle — a primordial soup even older than the moon., , High helium-3 relative to helium-4, UCSB   

    From UCSB: “Drawn from the Deep” 

    UC Santa Barbara Name bloc

    February 6, 2017
    Julie Cohen

    Geochemist Matt Jackson finds the hottest, most buoyant mantle plumes draw from a primordial reservoir deep in the Earth

    1
    Lead author Matthew Jackson samples Hawaiian lava with a rock hammer. Photo Credit: WHOI Geodynamics Program

    2
    Matthew Jackson. Photo Credit: Anna Maria Skuladottir

    The Earth’s mantle — the layer between the crust and the outer core — is home to a primordial soup even older than the moon. Among the main ingredients is helium-3 (He-3), a vestige of the Big Bang and nuclear fusion reactions in stars. And the mantle is its only terrestrial source.

    Scientists studying volcanic hotspots have strong evidence of this, finding high helium-3 relative to helium-4 in some plumes, the upwellings from the Earth’s deep mantle. Primordial reservoirs in the deep Earth, sampled by a small number of volcanic hotspots globally, have this ancient He-3/4 signature.

    Inspired by a 2012 paper that proposed a correlation between such hotspots and the velocity of seismic waves moving through the Earth’s interior, UC Santa Barbara geochemist Matthew Jackson teamed with the authors of the original paper — Thorsten Becker of the University of Texas at Austin and Jasper Konter of the University of Hawaii — to show that only the hottest hotspots with the slowest wave velocity draw from the primitive reservoir formed early in the planet’s history. Their findings appear in the journal Nature.

    “We used the seismology of the shallow mantle — the rate at which seismic waves travel through the Earth below its crust — to make inferences about the deeper mantle,” said Jackson, an assistant professor in UCSB’s Department of Earth Science. “At 200 km, the shallow mantle has the largest variability of seismic velocities — more than 6 percent, which is a lot. What’s more, that variability, which we hypothesize relates to temperature, correlates with He-3.”

    For their study, the researchers used the latest seismic models of the Earth’s velocity structure and 35 years of helium data. When they compared oceanic hotspots with high levels of He-3/4 to seismic wave velocities, they found that these represent the hottest hotspots, with seismic waves that move more slowly than they do in cooler areas. They also analyzed hotspot buoyancy flux, which can be used to measure how much melt a particular hotspot produces. In Hawaii, the Galapagos Islands, Samoa and Easter Island as well as in Iceland, hotspots had high buoyancy levels, confirming a basic rule of physics: the hotter, the more buoyant.

    “We found that the higher the hotspot buoyancy flux, the more melt a hotspot was producing and the more likely it was to have high He-3/4,” Jackson said. “Hotter plumes not only have slower seismic velocity and a higher hotspot buoyancy flux, they also are the ones with the highest He-3/4. This all ties together nicely and is the first time that He-3/4 has been correlated with shallow mantle velocities and hotspot buoyancy globally.”

    Becker noted that correlation does not imply causality, “but it is pretty nifty that we found two strong correlations, which both point to the same physically plausible mechanism: the primordial stuff gets picked up preferentially by the most buoyant thermochemical upwellings.”

    The authors also wanted to know why only the hottest, most buoyant plumes sample high He-3/4.

    “The explanation that we came up with — which people who do numerical simulations have been suggesting for a long time — is that whatever this reservoir is with primitive helium, it must be really dense so that only the hottest, most buoyant plumes can entrain some of it to the surface,” Jackson said. “That makes sense and it also explains how something so ancient could survive in the chaotically convecting mantle for 4.5 billion years. The density contrast makes it more likely that the ancient helium reservoir is preserved rather than mixed away.”

    “Since this correlation of geochemistry and seismology now holds from helium isotopes in this work to the compositions we examined in 2012, it appears that overall hotspot geochemical variations will need to be re-examined from the perspective of buoyancy,” Konter concluded.

    See the full article here .

    Please help promote STEM in your local schools.

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    UC Santa Barbara Seal
    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
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