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  • richardmitnick 2:31 pm on April 21, 2020 Permalink | Reply
    Tags: , ALPINE SURVEY-"ALMA Large Program to Investigate C+ at Early Times", , , , Caltech, , , , , ,   

    From Caltech: “Rotating Galaxies Galore” 

    Caltech Logo

    From Caltech

    April 21, 2020
    Whitney Clavin
    (626) 395‑1944
    wclavin@caltech.edu

    New results from an ambitious sky survey program, called ALPINE, reveal that rotating disk-shaped galaxies may have existed in large numbers earlier in the universe than previously thought.

    The ALPINE program, formally named “ALMA Large Program to Investigate C+ at Early Times,” uses data obtained from 70 hours of sky observations with the ALMA observatory (Atacama Large Millimeter/submillimeter Array) in Chile, in combination with data from previous observations by a host of other telescopes, including the W. M. Keck Observatory in Hawaii and NASA’s Hubble and Spitzer space telescopes. Specifically, the survey looked at a patch of sky containing dozens of remote galaxies.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Keck Observatory, operated by Caltech and the University of California, Maunakea Hawaii USA, 4,207 m (13,802 ft)

    NASA/ESA Hubble Telescope

    NASA/Spitzer Infrared Telescope. No longer in service.

    “This is the first multi-wavelength study from ultraviolet to radio waves of distant galaxies that existed between 1 billion and 1.5 billion years after the Big Bang,” says Andreas Faisst, a staff scientist at IPAC, an astronomy center at Caltech, and a principal investigator of the ALPINE program, which includes scientists across the globe.

    One of ALPINE’s key functions is using ALMA to observe the signature of an ion known as C+, which is a positively charged form of carbon. When ultraviolet light from newborn stars hits clouds of dust, it creates the C+ atoms. By measuring the signature of this atom, or “emission line,” in galaxies, astronomers can see how the galaxies are rotating; as the gas containing C+ in the galaxies spins toward us, its light signature shifts to bluer wavelengths, and as it spins away, the light shifts to redder wavelengths. This is similar to a police car’s siren increasing in pitch as it races toward you and decreasing as it moves away.

    The ALPINE team made the C+ measurements on 118 remote galaxies to create a catalog of not only their rotation speeds but also other features such as gas density and the number of stars that are formed.

    The survey revealed rotating mangled galaxies that were in the process of merging, in addition to seemingly perfectly smooth spiral-shaped galaxies. About 15 percent of the galaxies observed had a smooth, ordered rotation that is expected for spiral galaxies. However, the authors note, the galaxies may not be spirals but rotating disks with clumps of material. Future observations with the next generation of space-based telescopes will pinpoint the detailed structure of these galaxies.

    “We are finding nicely ordered rotating galaxies at this very early and quite turbulent stage of our universe,” says Faisst. “That means they must have formed by a smooth process of gathering gas and haven’t collided with other galaxies yet, as many of the other galaxies have.”

    By combining the ALMA data with measurements from other telescopes, including the now-retired Spitzer, which specifically helped measure the masses of the galaxies, the scientists are better able to study how these young galaxies evolve over time.

    “How do galaxies grow so much so fast? What are the internal processes that let them grow so quickly? These are questions that ALPINE is helping us answer,” says Faisst. “And with the upcoming launch of NASA’s James Webb Space Telescope, we will be able to follow-up on these galaxies to learn even more.”

    The study, led by Faisst, titled, “The ALPINE-ALMA [CII] Survey: Multi-Wavelength Ancillary Data and Basic Physical Measurements,” [The Astrophysical Journal Supplement Series] was funded by NASA and the European Southern Observatory.

    A brief overview of the survey, produced by a team led by Olivier LeFèvre of the Laboratoire d’Astrophysique de Marseille (LAM), is at https://ui.adsabs.harvard.edu/abs/2019arXiv191009517L/abstract; the ALMA data is detailed in another paper by a team led by Matthieu Béthermin of LAM, available at https://ui.adsabs.harvard.edu/abs/2020arXiv200200962B/abstract.

    ALMA is a partnership of ESO (representing its Member States), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (South Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. More information about ALMA is at
    https://www.almaobservatory.org/.

    1
    A collage of 21 galaxies imaged by the ALPINE survey. The images are based on light emitted by singly ionized carbon, or C+. These data show the variety of different galaxy structures already in place less than 1.5 billion years after the Big Bang (our universe is 13.8 billion years old). Some of the images actually contain merging galaxies; for example, the object in the top row, second from left, is actually three galaxies that are merging. Other galaxies appear to be more smoothly ordered and may be spirals; a clear example is in the second row, first galaxy from the left. Our Milky Way galaxy is shown to scale to help visualize the small sizes of these infant galaxies. Credit: Michele Ginolfi (ALPINE collaboration); ALMA(ESO/NAOJ/NRAO); NASA/JPL-Caltech/R. Hurt (IPAC)

    2
    Using ALMA, scientists can measure the rotation of galaxies in the early universe with a precision of several 10 kilometers per second. This is made possible by observing light emitted by singly ionized carbon in the galaxies, also known as C+. The C+ emission from gas clouds rotating toward us is shifted to bluer, shorter wavelengths, while the clouds rotating away from us emit light shifted to longer, redder wavelengths. By measuring this shift in light, astronomers can determine how fast the galaxies are rotating.
    Credit: Andreas Faisst (ALPINE collaboration)

    3
    The object pictured above is DC-818760, which consists of three galaxies that are likely on collision course. Like all the galaxies in the ALPINE survey, it has been imaged by different telescopes. This “multi-wavelength” approach allows astronomers to study in detail the structure of these galaxies. NASA’s Hubble Space Telescope (blue) reveals regions of active star formation not obscured by dust; NASA’s now-retired Spitzer Space Telescope (green) shows the location of older stars that are used to measure the stellar mass of galaxies; and ALMA (red) traces gas and dust, allowing the amount of star formation hidden by dust to be measured. The picture at the top of the image combines light from all three telescopes. The velocity map on the bottom shows gas in the rotating galaxies approaching us (blue) or receding (red).
    Credit: Gareth Jones & Andreas Faisst (ALPINE collaboration); ALMA(ESO/NAOJ/NRAO); NASA/STScI; JPL-Caltech/IPAC (R. Hurt)

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 9:59 am on April 9, 2020 Permalink | Reply
    Tags: "Black Hole Bends Light Back on Itself", A black hole that is orbited by a sun-like star; together the pair is called XTE J1550-564., , , , , Caltech,   

    From Caltech : “Black Hole Bends Light Back on Itself” 

    Caltech Logo

    From Caltech

    April 08, 2020

    Whitney Clavin
    (626) 395‑1944
    wclavin@caltech.edu

    New study proves a theory first predicted more than 40 years ago.

    1
    This illustration shows how some of the light coming from a disk around a black hole is bent back onto the disk itself due to the gravity of the hefty black hole. The light is then reflected back off the disk. Astronomers using data from NASA’s now-defunct Rossi X-ray Timing Explorer (RXTE) mission were able to distinguish between light that came straight from the disk and light that was reflected. The bluish material coming off the black hole is an outflowing jet of energetic particles. Credit: NASA/JPL-Caltech/R. Hurt (IPAC)/R. Connors (Caltech)

    You may have heard that nothing escapes the gravitational grasp of a black hole, not even light. This is true in the immediate vicinity of a black hole, but a bit farther out—in disks of material that swirl around some black holes—light can escape. In fact, this is the reason actively growing black holes shine with brilliant X-rays.

    Now, a new study accepted for publication in The Astrophysical Journal offers evidence that, in fact, not all of the light streaming from a black hole’s surrounding disk easily escapes. Some of it gives in to the monstrous pull of the black hole, turns back, and then ultimately bounces off the disk and escapes.

    “We observed light coming from very close to the black hole that is trying to escape, but instead is pulled right back by the black hole like a boomerang,” says Riley Connors, lead author of the new study and a postdoctoral scholar at Caltech. “This is something that was predicted in the 1970s, but hadn’t been shown until now.”

    The new findings were made possible by combing through archival observations from NASA’s now-defunct Rossi X-ray Timing Explorer (RXTE) mission, which came to an end in 2012.

    NASA/ROSSI

    The researchers specifically looked at a black hole that is orbited by a sun-like star; together, the pair is called XTE J1550-564. The black hole “feeds” off this star, pulling material onto a flat structure around it called an accretion disk. By looking closely at the X-ray light coming from the disk as the light spirals toward the black hole, the team found imprints indicating that the light had been bent back toward the disk and reflected off.

    “The disk is essentially illuminating itself,” says co-author Javier Garcia, a research assistant professor of physics at Caltech. “Theorists had predicted what fraction of the light would bend back on the disk, and now, for the first time, we have confirmed those predictions.”

    The scientists say that the new results offer another indirect confirmation of Albert Einstein’s general theory of relativity, and also will help in future measurements of the spin rates of black holes, something that is still poorly understood.

    “Since black holes can potentially spin very fast, they not only bend the light but twist it,” says Connors. “These recent observations are another piece in the puzzle of trying to figure out how fast black holes spin.”

    The new study, titled, “Evidence for Returning Disk Radiation in the Black Hole X-ray Binary XTEJ1550-564,” was funded by NASA, the Alexander von Humboldt Foundation, and the Margarete von Wrangell Fellowship. Other co-authors are Thomas Dauser, Stefan Licklederer, and Jörn Wilms of The University of Erlangen-Nüremberg in Germany; Victoria Grinberg of the Universität Tübingen in Germany; James Steiner of the MIT Kavli Institute for Astrophysics and Space Research and Harvard University; Navin Sridhar of Columbia University; John Tomsick of UC Berkeley; and Fiona Harrison, the Harold A. Rosen Professor of Physics at Caltech and the Kent and Joyce Kresa Leadership Chair of the Division of Physics, Mathematics and Astronomy.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 12:13 pm on March 5, 2020 Permalink | Reply
    Tags: "Microstructures Self-Assemble into New Materials", A team of engineers at Caltech and ETH Zürich have developed a material that is designed at the nanoscale but assembles itself—with no need for the precision laser assembly., , Caltech, , , Nanoarchitected material at the cubic-centimeter scale.,   

    From Caltech: “Microstructures Self-Assemble into New Materials” 

    Caltech Logo

    From Caltech

    March 02, 2020
    Robert Perkins
    (626) 395‑1862
    rperkins@caltech.edu

    1
    Caltech

    A new process developed at Caltech makes it possible for the first time to manufacture large quantities of materials whose structure is designed at a nanometer scale—the size of DNA’s double helix.

    Pioneered by Caltech materials scientist Julia R. Greer, “nanoarchitected materials” exhibit unusual, often surprising properties—for example, exceptionally lightweight ceramics that spring back to their original shape, like a sponge, after being compressed. These properties could be desirable for applications ranging from ultrasensitive tactile sensors to advanced batteries, but so far, engineers have only been able to create them in very limited amounts. To create a material whose structure is designed at such a small scale, they often have to be assembled nano-layer by nano-layer in a 3-D printing process that uses a high-precision laser and custom-synthesized chemicals. That painstaking process limits the overall amount of material that can be built.

    Now, a team of engineers at Caltech and ETH Zürich have developed a material that is designed at the nanoscale but assembles itself—with no need for the precision laser assembly. For the first time, they were able to create a sample of nanoarchitected material at the cubic-centimeter scale.

    “We couldn’t 3-D print this much nanoarchitected material even in a month; instead we’re able to grow it in a matter of hours,” says Carlos Portela, postdoctoral scholar at Caltech and lead author of a study on the new process that was published by the journal Proceedings of the National Academy of Sciences (PNAS) on March 2.

    At the nanoscale, the material looks like a sponge but is actually an assembly of interconnected curved shells. That’s the key to the material’s high stiffness- and strength-to-weight ratios: the smoothly curved thin shells, like those of an egg, are free of corners or junctions, which are usually weak points leading to failure in other similar materials. This provides unique mechanical benefits with a minimum of material actually used. In testing, a sample of the material was able to achieve strength-to-density ratios comparable to some forms of steel, while thinner-walled configurations exhibit negligible damage and recovery after repeated compression.

    “This new fabrication route, supported by the experimental and numerical analysis that we’ve conducted, gets us one step closer to being able to produce nanoarchitected materials at a useful scale, with a marked ease of fabrication,” says Greer, the Ruben F. and Donna Mettler Professor of Materials Science, Mechanics, and Medical Engineering and coauthor of the PNAS paper.

    Though it is measurably more resilient than virtually all nanoarchitected materials with similar densities synthesized by the Greer group, what makes these so-called nano-labyrinthine materials particularly special is that they assemble themselves. This achievement, led by Caltech graduate student Daryl Yee, works like this: two materials that don’t dissolve into each other are mixed together, blending them to create a disordered state. Heating up the mixture polymerizes the materials so that the current geometry gets locked in place. One of the two materials is then removed, leaving nanoscale shells. The resulting porous template is subsequently coated, and then the second polymer is removed. What’s left is lightweight nano-shell network.

    The process requires extreme precision; if incorrectly heated, the microstructure will either melt together or collapse and will not lead to interconnected shells. But for the first time, the team sees the potential to scale up nanoarchitecture.

    “It is exciting to see our computationally designed optimal nanoscale architectures being realized experimentally in the lab,” says Dennis M. Kochmann, corresponding author of the PNAS paper and professor of mechanics and materials at ETH Zürich and a visiting associate in aerospace at Caltech. His team, including former Caltech graduate student A. Vidyasagar and Sebastian Krödel and Tamara Weissenbach of ETH Zürich, predicted the versatile properties of the nano-labyrinthine materials through theory and simulations.

    Next, the team plans to expand the tunability and versatility of the process by exploring pathways to carefully control the microstructure, expand on the material options for the nano-shells, and push for the production of larger volumes of the material.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 11:49 am on February 20, 2020 Permalink | Reply
    Tags: "A Mingling of Computational and Economic Ideas", (CSIS)-Center for Social Information Sciences, Caltech, Coming up with solutions for computer-based economic problems., Computational advertising was born in startups at Caltech., One of the first projects tackled by SISL researchers in the early 2000s involved the practice of computational advertising., Today the work continues in areas such as power grids; kidney donor waiting lists; and cloud computing.   

    From Caltech: “A Mingling of Computational and Economic Ideas” 

    Caltech Logo

    From Caltech

    February 18, 2020
    Whitney Clavin
    (626) 395‑1944
    wclavin@caltech.edu

    1
    https://www.caltech.edu/

    The flourishing field of computational economics was born in the spaces between disciplines.

    By the early 2000s, it had become clear that markets—places where people have exchanged money and goods for thousands of years—were becoming increasingly complex. Computers had become an integral part of many types of markets, such as those related to website advertising, wireless spectrum auctions, electricity grids, and more. At that time, Caltech’s John Ledyard, the Allen and Lenabelle Davis Professor of Economics and Social Sciences, Emeritus, and others recognized the growing need for economists and computer scientists to share information so that they could together come up with solutions for computer-based economic problems.

    “We wanted to create a dialogue between economists and computer scientists,” says Ledyard, who, along with his colleagues, founded the Social and Information Sciences Lab (SISL) at Caltech for this purpose in the early 2000s. “Caltech was the perfect place to do this because it’s small, and we don’t have strong boundaries between the departments.”

    Years later, those efforts have exceeded expectations; SISL, which was recently renamed the Center for Social Information Sciences (CSIS) and is now funded by the Ronald and Maxine Linde Institute of Economic and Management Sciences, is thriving. The center enables an interdisciplinary network of professors, postdoctoral scholars, and students to perform cutting-edge research in the now-flourishing field of computational economics.

    “What is unique about CSIS is that these two groups work together seamlessly without walls,” says Laura Doval, an assistant professor of economics at Caltech and member of CSIS. Doval is a member of the Division of the Humanities and Social Sciences (HSS) while many of her computer-science colleagues are affiliated with the Division of Engineering and Applied Science (EAS). “The groups have different languages and approaches,” she says. “While economists tend to focus on designs carefully tailored to induce correct incentives on market participants, computer scientists are more willing to sacrifice exact incentives in favor of computational accuracy, which is very important in large-scale systems. More and more, these different approaches are coming together.”

    One of the first projects tackled by SISL researchers in the early 2000s involved the practice of computational advertising. Consider what happens almost every time you load a new website. Within microseconds, a high-speed, automated auction takes place, where advertisers are given the chance to bid on the prospect of posting an ad to your webpage. The advertisers’ computer programs have basic information about you and your likes and dislikes, and can decide how much they would be willing to pay to show you an ad.

    “This is a huge computational task,” says Adam Wierman, a professor of computing and mathematical sciences at Caltech and co-director of CSIS along with Federico Echenique, the Allen and Lenabelle Davis Professor of Economics. “But then it’s also an economics problem because you have to figure out how to price the ads.

    “Computational advertising was born in startups at Caltech,” says Wierman. Indeed, two Caltech startups in this field were later bought by Yahoo and Google.

    “What social scientists bring to the table is a deep understanding of incentives and how to get people to do what you want,” says Jean-Laurent Rosenthal, the Rea A. and Lela G. Axline Professor of Business Economics and the Ronald and Maxine Linde Leadership Chair of HSS. “Computer scientists, on the other hand, devise algorithms for large-scale market systems. With CSIS, all of this is intertwined.”

    In other projects, CSIS researchers studied pollution trading rights and the development of methods to preserve online privacy as well as different types of auctions including land auctions and spectrum auctions—where cell phone companies and other businesses that wirelessly relay large volumes of data bid for portions of the radio spectrum.

    Today, the work continues in areas such as power grids, kidney donor waiting lists, and cloud computing. Recently, Doval, Wierman, and Echenique completed a study of public school lotteries. As part of the study, they designed a new algorithm to match students to schools in the Pasadena Unified School District. With the algorithm, the study found, families were better matched to their top school choices, helping the district to retain families that might have previously left for private or charter schools.

    “This is what we call a dynamic matching problem,” says Doval. “Parents might receive public-school assignments but then they don’t know if they got into private schools yet, so they hold on to the public-school assignment they received and wait. This takes a public-school seat from somebody else, and both parties could end up leaving the system—the first because they finally received their private-school assignment, and the second because they did not know a seat would be freed up. We designed the system to avoid this problem, to be more dynamic, by allowing the system to constantly update the assignments based on who has taken a seat and who has left.”

    Another vital component of CSIS is the training of students and postdoctoral scholars, which has benefits for the program as a whole. When postdoctoral scholars, for example, work on projects that bridge social and computer sciences, their faculty advisors are also brought together.

    “We have seen more than 20 postdocs go on to become faculty members at top schools,” says Wierman. “They have taken this field that didn’t exist when the center was founded and carried it to new schools. We are sowing the seeds of a new field that are being spread around the U.S.”

    Other researchers once affiliated with CSIS are also bringing their knowledge into new arenas. Simon Wilkie, a former senior research associate at Caltech, served as both the senior economist at Microsoft and the chief economist of the Federal Communications Commission (FCC). He is now head of the Monash Business School in Australia. Former faculty member Preston McAfee served as the chief economist at Microsoft until 2018.

    “The center is doing exactly what we hoped for in the beginning: each group is better for being a part of the other,” says Ledyard. “Some of the greatest breakthroughs at Caltech and other places have come from the spaces between disciplines.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 4:17 pm on January 9, 2020 Permalink | Reply
    Tags: Caltech, New Quantum Algorithm, , Quantum imaginary time evolution, The Hamiltonian represents the energy of the system   

    From Caltech: “Caltech Researchers Develop New Quantum Algorithm” 

    Caltech Logo

    From Caltech

    December 18, 2019
    Emily Velasco
    626‑395‑6487
    evelasco@caltech.edu

    1

    Quantum computers, just like classical computers, are only as good as the instructions that we give them. And although quantum computing is one of the hottest topics in science these days, the instructions, or algorithms, for quantum computers still have a long way to go to become useful. Garnet Chan, Caltech’s Bren Professor of Chemistry, is tackling this problem. In a new paper [Nature Physics], he describes how he, together with Fernando Brandao, Bren Professor of Theoretical Physics, and Austin Minnich, professor of mechanical engineering and applied physics, developed an algorithm for quantum computers that will help them find use in simulations in the physical sciences.

    The algorithm is derived from one already in use in classical computing called imaginary time evolution. Chan’s new algorithm, tailored to run on quantum computers, has been fittingly dubbed quantum imaginary time evolution and allows a user to find the lowest energy of a given molecule or material.

    We sat down with Chan to talk about his research and what it means for quantum computing.

    In lay terms, what have you achieved with your new research?

    There has been a lot of interest in what kind of problems a quantum computer can potentially help to solve in the physical sciences. One problem that many people are interested in is how to simulate the ground states of molecules and materials. Our new paper proposes a way to calculate ground states of Hamiltonians that runs on near-term quantum computers with very few resources.

    What is a Hamiltonian, and why would you want to know its ground state?

    The Hamiltonian represents the energy of the system, and the ground state of the Hamiltonian is the most stable state of the problem. Most physical systems, under ordinary conditions, are not too excited, and thus live close to their ground states.

    For example, if we want to do a simulation of water, we could look at how water behaves after it has been blasted into a plasma—an electrically charged gas—but that’s not the state water is usually found in; it is not the ground state of water. Ground states are of special interest in understanding the world under ordinary conditions.
    Why is it challenging to perform these calculations on a quantum computer?

    Quantum devices currently decohere after a short period of time, which means that the computer needs to be recalibrated and cannot be used for calculations until it is set up again. That means we need to find a way to perform calculations on them very efficiently so we solve our problem before decoherence occurs.

    What does your algorithm do?

    There have been many proposals for how to obtain ground states on quantum computers. One of the first was by Alexei Kitaev [Caltech’s Ronald and Maxine Linde Professor of Theoretical Physics and Mathematics], but unfortunately that algorithm, known as phase estimation, requires too many instructions and cannot be implemented before current quantum computers decohere. Another way, called the variational approach, is very simple to implement but in practice turns out not to be so accurate. We wanted to find a way that could be potentially as accurate as phase estimation but which could also be practically programmed on today’s quantum computers.

    What does the development of this algorithm mean for quantum computing?

    Quantum computers are still very new, and we still need to learn what they will be useful for. Because we can barely use them right now, part of the answer lies in developing efficient programs that can be run on them in very little time. Our work provides a basis for assessing the capabilities of quantum computers as they are now, which will help tell us what we can expect in the future.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 7:05 pm on January 8, 2020 Permalink | Reply
    Tags: , , , Caltech, , , NOAO WIYN Telescope, The name NEID is derived from the word meaning "to see" in the native language of the Tohono O'odham on whose land Kitt Peak is located.   

    From Caltech: “Measuring the Minute Wobbles of Stars” 

    Caltech Logo

    From Caltech

    January 08, 2020

    Whitney Clavin
    (626) 395‑1944
    wclavin@caltech.edu

    1
    NEID– A new instrument aims to detect tiny stellar motions caused by the tug of Earth-mass planets. Caltech/Penn State

    NEID chamber for the WIYN telescope. Photos courtesy of NOAO WIYN and Washburn Labs-University of Wisconsin.

    Penn State NEID spectrographic instrument schematic for the WIYN telescope at Kitt Peak, AZ, USA Altitude 2,096 m 6,877 ft

    4
    First-light spectrum of the star 51 Pegasi as captured by NEID on the WIYN telescope with a blowup of a small section of the spectrum. The right panel shows the light from the star, highly dispersed by NEID, from short wavelengths (bluer colors) to long wavelengths (redder colors). The colors shown, which approximate the true color of the starlight at each part of image, are included for illustrative purposes only. The region in the small white box in the right panel, when expanded (left panel), shows the spectrum of the star (longer dashed lines) and the light from the wavelength calibration source (dots). Deficits of light (dark interruptions) in the stellar spectrum, are due to stellar absorption lines — “fingerprints” of the elements that are present in the atmosphere of the star. By measuring the subtle motion of these features, to bluer or redder wavelengths, astronomers can detect the “wobble” of the star produced in response to its orbiting planet.
    Credit: Guðmundur Kári Stefánsson/Princeton University/Penn State/NSF’s National Optical-Infrared Astronomy Research Laboratory/KPNO/AURA

    As the planets in our solar system go around the sun, they tug on it, causing it to wobble. Jupiter, our most massive planet, yanks on our sun to a significant degree, whereas Earth, which is tiny by comparison, exerts a much weaker tug.

    Other Earth-like planets circling stars in our galaxy would similarly cause minute wobbles in their stars, so planet hunters search for these wobbles using a technique called the radial velocity method. So far, they have not found any exoplanets like the Earth, but that may change with a new telescope instrument called NEID.

    “We may be able to find the first Earth-mass planets with NEID,” says Arpita Roy, a Caltech postdoctoral scholar who works with Professor of Astronomy Andrew Howard and who helped build NEID with a team led by researchers at Penn State. Roy says that the instrument can currently detect stellar motions of about 30 centimeters per second but that their ultimate goal is to try to get down to 10 centimeters per second on certain stars—the speed our sun moves due to Earth’s tug.

    NEID was recently installed on the 3.5-meter WIYN telescope at Kitt Peak National Observatory in Southern Arizona and made its first observations on December 13, 2019.

    NOAO WIYN Telescope, Kitt Peak National Observatory, Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers (55 mi) west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft)

    Kitt Peak National Observatory of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers 55 mi west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft)

    The instrument is being developed as part of a joint initiative between NASA and the National Science Foundation. The name NEID is derived from the word meaning “to see” in the native language of the Tohono O’odham, on whose land Kitt Peak is located.

    A news release about NEID’s “first light” observations, from NSF’s National Optical-Infrared Astronomy Research Laboratory, which operates the Kitt Peak National Observatory, is online at: https://www.nationalastro.org/news/neid-exoplanet-instrument-sees-first-light/.

    Roy is also the project scientist for an upcoming instrument similar to NEID, called the Keck Planet Finder, scheduled to be installed at the W. M. Keck Observatory on Maunakea, Hawaii, in 2021.

    Keck Observatory, operated by Caltech and the University of California, Maunakea Hawaii USA, 4,207 m (13,802 ft)

    Says Roy, “In many ways, NEID is paving the way for the Keck Planet Finder, which should be able to find Earth-mass planets even faster.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 11:20 am on December 26, 2019 Permalink | Reply
    Tags: 'edscottite', A rare form of iron-carbide mineral that's never been found in nature., Analyses have revealed traces of gold and iron along with rarer minerals such as kamacite; schreibersite; taenite; and troilite., , Caltech, Distinctive black-and-red rock, , Now we can add edscottite to that list., The Wedderburn meteorite   

    From Caltech via Science Alert: “Scientists Have Officially Found a Mineral Never Before Seen in Nature” 

    Caltech Logo

    From Caltech

    via

    ScienceAlert

    Science Alert

    25 DEC 2019
    PETER DOCKRILL

    1
    The Wedderburn meteorite. (Museums Victoria/CC BY 4.0)

    It was found along the side of a road in a remote Australian gold rush town. In the old days, Wedderburn was a hotspot for prospectors – it occasionally still is – but nobody there had ever seen a nugget quite like this one.

    The Wedderburn meteorite, found just north-east of the town in 1951, was a small 210-gram chunk of strange-looking space rock that fell out of the sky. For decades, scientists have been trying to decipher its secrets, and researchers just decoded another.

    In a study published in August [American Mineralogist] this year, led by Caltech mineralogist Chi Ma, scientists analysed the Wedderburn meteorite and verified the first natural occurrence of what they call ‘edscottite’: a rare form of iron-carbide mineral that’s never been found in nature.

    Since the Wedderburn meteorite’s spacey origins were first identified, the distinctive black-and-red rock has been examined by numerous research teams – to the extent that only about one-third of the original specimen still remains intact, held within the geological collection at Museums Victoria in Australia.

    The rest has been taken away in a series of slices, extracted to analyse what the meteorite is made from. Those analyses have revealed traces of gold and iron, along with rarer minerals such as kamacite, schreibersite, taenite, and troilite. Now we can add edscottite to that list.

    The edscottite discovery – named in honour of meteorite expert and cosmochemist Edward Scott from the University of Hawaii – is significant because never before have we confirmed that this distinct atomic formulation of iron carbide mineral occurs naturally.

    Such a confirmation is important, because it’s a pre-requisite for minerals to be officially recognised as such by the International Mineralogical Association (IMA).

    A synthetic version of the iron carbide mineral has been known about for decades – a phase produced during iron smelting.

    But thanks to the analysis by Chi Ma and UCLA geophysicist Alan Rubin, edscottite is now an official member of the IMA’s mineral club, which is more exclusive than you might think.

    “We have discovered 500,000 to 600,000 minerals in the lab, but fewer than 6,000 that nature’s done itself,” Museums Victoria senior curator of geosciences Stuart Mills, who wasn’t involved with the new study, told The Age.

    As for how this sliver of natural edscottite ended up just outside of rural Wedderburn can’t be known for sure, but according to planetary scientist Geoffrey Bonning from Australian National University, who wasn’t involved with the study, the mineral could have formed in the heated, pressurised core of an ancient planet.

    Long ago, this ill-fated, edscottite-producing planet could have suffered some kind of colossal cosmic collision – involving another planet, or a moon, or an asteroid – and been blasted apart, with the fragmented chunks of this destroyed world being flung across time and space, Bonning told The Age.

    Millions of years later, the thinking goes, one such fragment landed by chance just outside Wedderburn – and our understanding of the Universe is the richer for it.

    3
    Scanning electron microscopy image (colorized) showing edscottite in the polished Wedderburn section from the UCLA Meteorite Collection. Image credit: Ma & Rubin, doi: 10.2138/am-2019-7102.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 2:16 pm on December 21, 2019 Permalink | Reply
    Tags: "Scientists Identify Almost 2 Million Previously "Hidden" Earthquakes", , Caltech, , , , ,   

    From Caltech: “Scientists Identify Almost 2 Million Previously “Hidden” Earthquakes” 

    Caltech Logo

    From Caltech

    April 18, 2019 [Just found this is a search]
    Robert Perkins
    (626) 395‑1862
    rperkins@caltech.edu

    A closer look at seismic data from 2008–17 expands Southern California’s earthquake catalog by a factor of 10.

    1
    Seismic activity associated with the Cahuilla earthquake swarm in Southern California’s Anza Valley. Filling out the earthquake catalogue using template matching shows the swarm in greater detail. The color of each seismic event records its depth, and so the rainbow-like appearance of the swarm indicates the shallow-to-deep slant of the fault, not previously visible from earlier data.

    Pouring through 10 years’ worth of Southern California seismic data with the scientific equivalent of a fine-tooth comb, Caltech seismologists have identified nearly two million previously unidentified tiny earthquakes that occurred between 2008 and 2017.

    Their efforts, published online by the journal Science on April 18, expand the earthquake catalog for that region and period of time by a factor of 10—growing it from about 180,000 recorded earthquakes to more than 1.81 million. The new data reveal that there are about 495 earthquakes daily across Southern California occurring at an average of roughly three minutes apart. Previous earthquake cataloging had suggested that approximately 30 minutes would elapse between seismic events.

    This 10-fold increase in the number of recorded earthquakes represents the cataloging of tiny temblors, between negative magnitude 2.0 (-2.0) and 1.7, made possible by the broad application of a labor-intensive identification technique that is typically only employed on small scales. These quakes are so small that they can be difficult to spot amid the background noise that appears in seismic data, such as shaking from automobile traffic or building construction.

    “It’s not that we didn’t know these small earthquakes were occurring. The problem is that they can be very difficult to spot amid all of the noise,” says Zachary Ross, lead author of the study and postdoctoral scholar in geophysics, who will join the Caltech faculty in June as an assistant professor of geophysics. Ross collaborated with Egill Hauksson, research professor of geophysics at Caltech, as well as Daniel Trugman of Los Alamos National Laboratory and Peter Shearer of Scripps Institution of Oceanography at UC San Diego.

    To overcome the low signal-to-noise ratio, the team turned to a technique known as “template matching,” in which slightly larger and more easily identifiable earthquakes are used as templates to illustrate what an earthquake’s signal at a given location should, in general, look like. When a likely candidate with the matching waveform was identified, the researchers then scanned records from nearby seismometers to see whether the earthquake’s signal had been recorded elsewhere and could be independently verified.


    Using powerful computers and a technique called template matching, scientists at Caltech have identified millions of previously unidentified tiny earthquakes. The new data reveal that there are about 495 earthquakes daily across Southern California, occurring at an average of roughly three minutes apart. This graphic shows the earthquakes recorded near Cahuilla, California from 2016-2017.

    Template matching works best in regions with closely spaced seismometers, since events generally only cross-correlate well with other earthquakes within a radius of about 1 to 2 miles, according to the researchers. In addition, because the process is computationally intensive, it has been limited to much smaller data sets in the past. For the present work, the researchers relied on an array of 200 powerful graphics processing units (GPUs) that worked for weeks on end to scan the catalog, detect new earthquakes, and verify their findings.

    However, the findings were worth the effort, Hauksson says. “Seismicity along one fault affects faults and quakes around it, and this newly fleshed-out picture of seismicity in Southern California will give us new insights into how that works,” he says. The expanded earthquake catalog reveals previously undetected foreshocks that precede major earthquakes as well as the evolution of swarms of earthquakes. The richer data set will allow scientists to gain a clearer picture of how seismic events affect and move through the region, Ross says.

    “The advance Zach Ross and colleagues has made fundamentally changes the way we detect earthquakes within a dense seismic network like the one Caltech operates with the USGS. Zach has opened a new window allowing us to see millions of previously unseen earthquakes and this changes our ability to characterize what happens before and after large earthquakes,” said Michael Gurnis, Director of the Seismological Laboratory and John E. and Hazel S. Smits Professor of Geophysics

    See the full article here .

    Earthquake Alert

    1

    Earthquake Alert

    Earthquake Network projectEarthquake Network is a research project which aims at developing and maintaining a crowdsourced smartphone-based earthquake warning system at a global level. Smartphones made available by the population are used to detect the earthquake waves using the on-board accelerometers. When an earthquake is detected, an earthquake warning is issued in order to alert the population not yet reached by the damaging waves of the earthquake.

    The project started on January 1, 2013 with the release of the homonymous Android application Earthquake Network. The author of the research project and developer of the smartphone application is Francesco Finazzi of the University of Bergamo, Italy.

    Get the app in the Google Play store.

    3
    Smartphone network spatial distribution (green and red dots) on December 4, 2015

    Meet The Quake-Catcher Network

    QCN bloc

    Quake-Catcher Network

    The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

    After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

    The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

    The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

    There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

    Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

    USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

    If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

    BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

    Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

    Below, the QCN Quake Catcher Network map
    QCN Quake Catcher Network map

    ShakeAlert: An Earthquake Early Warning System for the West Coast of the United States

    The U. S. Geological Survey (USGS) along with a coalition of State and university partners is developing and testing an earthquake early warning (EEW) system called ShakeAlert for the west coast of the United States. Long term funding must be secured before the system can begin sending general public notifications, however, some limited pilot projects are active and more are being developed. The USGS has set the goal of beginning limited public notifications in 2018.

    Watch a video describing how ShakeAlert works in English or Spanish.

    The primary project partners include:

    United States Geological Survey
    California Governor’s Office of Emergency Services (CalOES)
    California Geological Survey
    California Institute of Technology
    University of California Berkeley
    University of Washington
    University of Oregon
    Gordon and Betty Moore Foundation

    The Earthquake Threat

    Earthquakes pose a national challenge because more than 143 million Americans live in areas of significant seismic risk across 39 states. Most of our Nation’s earthquake risk is concentrated on the West Coast of the United States. The Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $5.3 billion, with 77 percent of that figure ($4.1 billion) coming from California, Washington, and Oregon, and 66 percent ($3.5 billion) from California alone. In the next 30 years, California has a 99.7 percent chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10 percent chance of a magnitude 8 to 9 megathrust earthquake on the Cascadia subduction zone.

    Part of the Solution

    Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of the ShakeAlert system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage.

    Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds. ShakeAlert can give enough time to slow trains and taxiing planes, to prevent cars from entering bridges and tunnels, to move away from dangerous machines or chemicals in work environments and to take cover under a desk, or to automatically shut down and isolate industrial systems. Taking such actions before shaking starts can reduce damage and casualties during an earthquake. It can also prevent cascading failures in the aftermath of an event. For example, isolating utilities before shaking starts can reduce the number of fire initiations.

    System Goal

    The USGS will issue public warnings of potentially damaging earthquakes and provide warning parameter data to government agencies and private users on a region-by-region basis, as soon as the ShakeAlert system, its products, and its parametric data meet minimum quality and reliability standards in those geographic regions. The USGS has set the goal of beginning limited public notifications in 2018. Product availability will expand geographically via ANSS regional seismic networks, such that ShakeAlert products and warnings become available for all regions with dense seismic instrumentation.

    Current Status

    The West Coast ShakeAlert system is being developed by expanding and upgrading the infrastructure of regional seismic networks that are part of the Advanced National Seismic System (ANSS); the California Integrated Seismic Network (CISN) is made up of the Southern California Seismic Network, SCSN) and the Northern California Seismic System, NCSS and the Pacific Northwest Seismic Network (PNSN). This enables the USGS and ANSS to leverage their substantial investment in sensor networks, data telemetry systems, data processing centers, and software for earthquake monitoring activities residing in these network centers. The ShakeAlert system has been sending live alerts to “beta” users in California since January of 2012 and in the Pacific Northwest since February of 2015.

    In February of 2016 the USGS, along with its partners, rolled-out the next-generation ShakeAlert early warning test system in California joined by Oregon and Washington in April 2017. This West Coast-wide “production prototype” has been designed for redundant, reliable operations. The system includes geographically distributed servers, and allows for automatic fail-over if connection is lost.

    This next-generation system will not yet support public warnings but does allow selected early adopters to develop and deploy pilot implementations that take protective actions triggered by the ShakeAlert notifications in areas with sufficient sensor coverage.

    Authorities

    The USGS will develop and operate the ShakeAlert system, and issue public notifications under collaborative authorities with FEMA, as part of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.

    For More Information

    Robert de Groot, ShakeAlert National Coordinator for Communication, Education, and Outreach
    rdegroot@usgs.gov
    626-583-7225

    Learn more about EEW Research

    ShakeAlert Fact Sheet

    ShakeAlert Implementation Plan


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 12:41 pm on December 14, 2019 Permalink | Reply
    Tags: "How Electrons Break the Speed Limit", Caltech, Charge transport near room temperature cannot be explained by standard models., In fact it violates the Planckian limit., In some materials the strong interaction between electrons and phonons in turn creates a new quasiparticle known as a polaron., Individual vibrations can be thought of as quasiparticles called phonons., , This advance is crucial since many semiconductors and oxides of interest for future electronics and energy applications exhibit polaron effects.   

    From Caltech: “How Electrons Break the Speed Limit” 

    Caltech Logo

    From Caltech

    1

    December 09, 2019
    Robert Perkins
    (626) 395‑1862
    rperkins@caltech.edu

    New understanding of charge transport reveals an exotic quantum mechanical regime.

    In work that may have broad implications for the development of new materials for electronics, Caltech scientists for the first time have developed a way to predict how electrons interacting strongly with atomic motions will flow through a complex material. To do so, they relied only on principles from quantum mechanics and developed an accurate new computational method.

    Studying a material called strontium titanate, postdoctoral researcher Jin-Jian Zhou and Marco Bernardi, assistant professor of applied physics and materials science, showed that charge transport near room temperature cannot be explained by standard models. In fact, it violates the Planckian limit, a quantum speed limit for how fast electrons can dissipate energy while they flow through a material at a given temperature.

    Their work was published in the journal Physical Review Research on December 2.

    The standard picture of charge transport is simple: electrons flowing through a solid material do not move unimpeded but instead can be knocked off course by the thermal vibrations of atoms that make up the material’s crystalline lattice. As the temperature of a material changes, so too does the amount of vibration and the resulting effect of this vibration on charge transport.

    Individual vibrations can be thought of as quasiparticles called phonons, which are excitations in materials that behave like individual particles, moving and bouncing around like an object. Phonons behave like the waves in the ocean, while electrons are like a boat sailing across that ocean, jostled by the waves. In some materials, the strong interaction between electrons and phonons in turn creates a new quasiparticle known as a polaron.

    “The so-called polaron regime, in which electrons interact strongly with atomic motions, has been out of reach for first-principles calculations of charge transport because it requires going beyond simple perturbative approaches to treat the strong electron-phonon interaction,” says Bernardi. “Using a new method, we have been able to predict both the formation and the dynamics of polarons in strontium titanate. This advance is crucial since many semiconductors and oxides of interest for future electronics and energy applications exhibit polaron effects.”

    Strontium titanate is known as a complex material because at different temperatures its atomic structure changes dramatically, with the crystal lattice shifting from one shape to another, which in turn shifts the phonons that electrons have to navigate. Last year, Zhou and Bernardi showed in a Physical Review Letters paper that they can describe the phonons associated with these structural phase transitions and include them in their computational workflow to accurately predict the temperature dependence of the electron mobility in strontium titanate.

    Now, they have developed a new method that can describe the strong interactions between the electrons and phonons in strontium titanate. This allows them to explain the formation of polarons and accurately predict both the absolute value and the temperature dependence of the electron mobility, a key charge-transport property in materials.

    In doing so, they uncovered an exotic feature of strontium titanate: charge transport near room temperature cannot be explained with the simple standard picture of electrons scattering with atomic vibrations in the material. Rather, transport occurs in a subtle quantum mechanical regime in which the electrons carry electricity collectively rather than individually, allowing them to violate the theoretical limit for charge transport.

    “In strontium titanate, the usual mechanism of charge transport due to electrons scattering with phonons has been widely accepted for the last half century. However, the picture that emerges from our study is far more complicated,” says Zhou. “At room temperature, it’s as if roughly half of each electron contributes to charge transport through the usual phonon scattering mechanism, while the other half of the electron contributes to a collective form of transport that is not yet fully understood.”

    In addition to representing a fundamental advance in the understanding of charge transport, the new method by Zhou and Bernardi can be applied to many semiconductors as well as to materials such as oxides and perovskites, and to new quantum materials exhibiting polaron effects. Besides charge transport, Zhou and Bernardi plan to investigate materials with unconventional thermoelectricity (the generation of electricity from heat) and superconductivity (electric current without resistance). In these materials, existing calculations have not yet been able to take into account polaron effects.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 10:30 am on December 5, 2019 Permalink | Reply
    Tags: "Caltech Undergrads Build Robot for DARPA Challenge", Balto competed in the August 2019 tunnel-navigation section of the DARPA SubT Challenge., Balto is about half the size of the more powerful Huskies and costs an order of magnitude less., Balto-the robot truck, Caltech, , Like other teams CoSTAR has a diverse fleet of different types of robots including a hybrid rolling/flying robot; a tracked tank-like robot; and small flying drones that can navigate tunnels., Team CoSTAR, Truck-like robot will be a probe for exploring underground arenas.   

    From Caltech: “Caltech Undergrads Build Robot for DARPA Challenge” 

    Caltech Logo

    From Caltech

    December 02, 2019
    Robert Perkins
    (626) 395‑1862
    rperkins@caltech.edu

    Truck-like robot will be a probe for exploring underground arenas.

    1
    Caltech seniors Jake Ketchum and Alexandra (Sasha) Bodrova work on the superstructure that holds Balto’s critical custom components.

    A robot designed and built by undergraduate students at Caltech working with graduate students at Caltech and JPL, which Caltech manages for NASA, took to the field in the first phase of the Defense Advanced Research Projects Agency (DARPA) Subterranean (SubT) Challenge this summer, where the Caltech-JPL team took second place.

    The SubT Challenge is an international competition sponsored by DARPA to advance technologies to autonomously map, navigate, and search underground environments. Teams earn points by accurately identifying and mapping artifacts that represent items a first responder might find underground: items like a cell phone, backpack, or even a thermal manikin that simulates a survivor.

    The August competition, a tunnel-navigation task, was the first of three stages leading up to a final event in August 2021. In the second stage, to be held in Februrary 2020, the team will compete in an urban underground environment; in the third, in August 2020, they move to a cave. Teams that fail to perform well enough in any stage can be disqualified. For the final, the remaining teams will compete in an event that combines all three environments.

    3
    Balto competed in the August 2019 tunnel-navigation section of the DARPA SubT Challenge.

    In the tunnel competition, there were 11 teams, most made up of consortia of research institutions and private companies. Team CoSTAR (Collaborative SubTerranean Autonomous Resilient Robots), led by JPL Robotics Technologist Ali Agha, includes JPL, Caltech, MIT, the Korea Advanced Institute of Science and Technology (KAIST), and Sweden’s Lulea University of Technology.

    Like other teams, CoSTAR has a diverse fleet of different types of robots, including a hybrid rolling/flying robot, a tracked tank-like robot, and small flying drones that can navigate tunnels. The vehicles work together to perform assigned tasks: for example, a ground robot might begin exploration but come to an unnavigable roadblock, at which point a flying drone might be called in to explore beyond the roadblock. The backbone of the CoSTAR fleet is a group of simple, efficient, and reliable truck-like four-wheeled robots called the Huskies.

    The newest addition to the fleet, added this summer, looks like the runt of the Husky litter. Dubbed Balto after a famous rescue sled dog, the new robot was built atop a commercial radio control car. Caltech’s Joel Burdick, the Richard L. and Dorothy M. Hayman Professor of Mechanical Engineering and Bioengineering and JPL research scientist, and the leader of the Caltech section of the CoSTAR team, decided that using an off-the-shelf R/C as a base would fast track the development of Balto since the team was able to start with a vehicle that already had a sturdy suspension and powerful electric motor.

    Balto is about half the size of the more powerful Huskies, and costs an order of magnitude less. The final product is a vehicle that is about a meter long, weighs about 12 kilograms, and is capable of navigating slopes of up to 40 degrees. Because it is so light, it is also a good deal faster than the Huskies, and can reach speeds of 55 miles per hour.

    “The idea was to create a ground-based scout,” Burdick says. “The drones are our air-based scouts, and Balto is our eyes and ears on the ground. It’s light, cheap, and fast. It can get in, find out what’s going on, and help us to make decisions about how to proceed.” Balto can also fill in as a substitute in emergencies. For example, since wireless signals are often blocked in underground environments, SubT competitors have had to build ad hoc wireless networks by using robots stationed along the tunnel as wireless nodes so that the robots can communicate with one another. If one of the nodes fails, Balto is capable or quickly rushing in to fill in the gap.

    Initial work on Balto began in CS/EE/ME 75, Multidisciplinary Systems Engineering, a cross-discipline special projects undergraduate class at Caltech. This spring, a team of about a half-dozen undergraduate students began work on the off-the-shelf car that would become Balto. First, they stripped the body off of the vehicle’s chassis and began designing a removable superstructure that would house all of the equipment necessary to transform an R/C car into a self-guided robot explorer. The superstructure of Balto, which was built using milling machines and 3-D printers at Caltech, can be lifted as a single unit off of the chassis. Balto features a towering LIDAR unit (a detection and ranging technology in which the vehicle’s surroundings scanned with laser beams) that works in tandem with twin cameras to “see” its surroundings, a radio receiver that allows it to communicate with the rest of the fleet, and an on-board computer that contains the programming that makes the vehicle autonomous.

    “The chassis is largely stock, but Balto’s electrical and control systems have been entirely replaced,” says Jake Ketchum, now a Caltech senior, who led the CS/EE/ME 75 class team and continued to work on Balto through the Summer Undergraduate Research Fellowship (SURF) program.

    The team also swapped out the vehicle’s simple motor controller to an upgraded version that gives the autonomous guidance system more precise control over the vehicle’s speed, which allows them to more accurately place Balto where it is needed.

    “Balto was tested in the field and, in the fully autonomous mode, successfully navigated tunnels that were more than 100 meters long,” says Alexandra (Sasha) Bodrova, now a Caltech senior who also worked on Balto through the SURF program. “Balto detected and avoided obstacles such as rocks and rails, made sharp turns, and then returned to the starting line, in reverse.”

    4
    Alexandra Bodrova fabricates custom parts for Balto.

    At the beginning of the summer, the Balto team was expanded to include graduate student researchers Nikhilesh Alatur and Anushri Dixit, who were tasked with incorporating autonomous control to the vehicle and integrating it into CoSTAR’s fleet.

    Alatur and Dixit were among the CoSTAR team members who traveled to Pittsburgh for the first leg of the SubT Challenge, held at the National Institute for Occupational Safety and Health (NIOSH) Mining Program’s Safety Research Coal Mine and Experimental Mine, a federal site where mine-related safety and health research is conducted.

    The competition took place over the course of four days, with each team given one hour per day to complete specific tasks, most of which involved finding and engaging with objects of interest, like a backpack or a lever arm. While a small group of 10 engineers launched the robots at the mouth of the mine, most of the rest of the team, including Alatur and Dixit, watched the action via a livestream from the conference room near the mine.

    “Everyone worked in shifts, fixing robots during the night and watching the competition or sleeping during the day,” Dixit says.

    “Every day, up to 20 minutes before the start of our run, we weren’t even sure the team was going to get off of the line,” Burdick says, describing how the team would scramble to address software and hardware issues on its completely custom robots.

    Given the importance of the Huskies to the fleet, the first order of business was always to make sure they made it into the field. For the first three days of the competition, Balto mainly warmed the bench as the team deployed its other vehicles.

    Then, on the fourth and final day of competition, the decision was made to send in Balto.

    “It was pretty intense. There were five or six people gathered around the screen, and as soon as Balto went in, everyone started screaming and shouting and cheering,” says Alatur, graduate student at ETH Zurich who is spending a six-month stint on the CoSTAR team as a student researcher at JPL. “We were happy to see that Balto was sent in for the last few minutes of the competition and could make its debut in a DARPA challenge.” During the competition, Alatur and Dixit stayed in constant text contact with Ketchum and Bodrova, who watched the livesteam from Caltech and were equally excited to see the robot take to the field.

    Balto’s mission was limited; as Burdick puts it, the main goal was to see how the robot performed and to gather data that can be used to improve it for the next round of the competition. The original plan was that Balto would be tasked with positioning communication nodes—basically, wifi signal boosters that enable all of the robots in the tunnel to stay connected—but it turned out to be unnecessary. Instead, Balto drove 125 meters into the tunnel and stopped, just as directed, and acted as a wifi unit to relay signals as necessary. “In the end, we didn’t truly need it, but it did its job well,” Burdick says. “And more importantly, we gained data about Balto’s performance that will help us down the line.”

    Because of Balto’s speed, diminutive size, and ruggedness, Burdick predicts a growing role for the little robot in future competitions. This year’s CS/EE/ME 75 class will continue to refine Balto, as well as other new vehicles to be used in the next phases of the competition in February and August, 2020.

    “I think we’re going to be grateful to have a small, tough robots like Balto when we get to the final event in 2021,” he says.

    See the full article here .


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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

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