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  • richardmitnick 10:42 am on March 23, 2017 Permalink | Reply
    Tags: , , , phys.org, , Scientists switch on 'artificial sun' in German lab   

    From DLR via phys.org: “Scientists switch on ‘artificial sun’ in German lab” 

    DLR Bloc

    German Aerospace Center

    phys.org

    March 23, 2017

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    In this March 21, 2017 photo engineer Volkmar Dohmen stands in front of xenon short-arc lamps in the DLR German national aeronautics and space research center in Juelich, western Germany. The lights are part of an artificial sun that will be used for research purposes. (Caroline Seidel/dpa via AP)

    Scientists in Germany are flipping the switch on what’s being described as “the world’s largest artificial sun,” hoping it will help shed light on new ways of making climate-friendly fuel.

    The “Synlight” experiment in Juelich, about 30 kilometers (19 miles) west of Cologne, consists of 149 giant spotlights normally used for film projectors.

    Starting Thursday, scientists from the German Aerospace Center will start experimenting with this dazzling array to try to find ways of tapping the enormous amount of energy that reaches Earth in the form of light from the sun.

    One area of research will focus on how to efficiently produce hydrogen, a first step toward making artificial fuel for airplanes.

    The experiment uses as much electricity in four hours as a four-person household would in a year.

    2
    n this March 21, 2017 photo engineer Volkmar Dohmen stands in front of xenon short-arc lamps in the DLR German national aeronautics and space research center in Juelich, western Germany. The lights are part of an artificial sun that will be used for research purposes. (Caroline Seidel/dpa via AP)

    See the full article here .

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    DLR Center

    DLR is the national aeronautics and space research centre of the Federal Republic of Germany. Its extensive research and development work in aeronautics, space, energy, transport and security is integrated into national and international cooperative ventures. In addition to its own research, as Germany’s space agency, DLR has been given responsibility by the federal government for the planning and implementation of the German space programme. DLR is also the umbrella organisation for the nation’s largest project management agency.

    DLR has approximately 8000 employees at 16 locations in Germany: Cologne (headquarters), Augsburg, Berlin, Bonn, Braunschweig, Bremen, Goettingen, Hamburg, Juelich, Lampoldshausen, Neustrelitz, Oberpfaffenhofen, Stade, Stuttgart, Trauen, and Weilheim. DLR also has offices in Brussels, Paris, Tokyo and Washington D.C.

     
  • richardmitnick 8:48 am on March 20, 2017 Permalink | Reply
    Tags: Anderson limit, , How small can superconductors be?, , P.W. Anderson, Parity effect, phys.org, , Richardson-Gaudin models   

    From phys.org: “How small can superconductors be?” 

    physdotorg
    phys.org

    March 20, 2017
    Lisa Zyga

    1
    Topographic image of a lead nanocrystal used in the study. Scale bar: 10 nm. Credit: Vlaic et al. Nature Communications

    For the first time, physicists have experimentally validated a 1959 conjecture that places limits on how small superconductors can be. Understanding superconductivity (or the lack thereof) on the nanoscale is expected to be important for designing future quantum computers, among other applications.

    In 1959, physicist P.W. Anderson conjectured that superconductivity can exist only in objects that are large enough to meet certain criteria. Namely, the object’s superconducting gap energy must be larger than its electronic energy level spacing—and this spacing increases as size decreases. The cutoff point (where the two values are equal) corresponds to a volume of about 100 nm3. Until now it has not been possible to experimentally test the Anderson limit due to the challenges in observing superconducting effects at this scale.

    In the new study published in Nature Communications, Sergio Vlaic and coauthors at the University Paris Sciences et Lettres and French National Centre for Scientific Research (CNRS) designed a nanosystem that allowed them to experimentally investigate the Anderson limit for the first time.

    The Anderson limit arises because, at very small scales, the mechanisms underlying superconductivity essentially stop working. In general, superconductivity occurs when electrons bind together to form Cooper pairs. Cooper pairs have a slightly lower energy than individual electrons, and this difference in energy is the superconducting gap energy. The Cooper pairs’ lower energy inhibits electron collisions that normally create resistance. If the superconducting gap energy gets too small and vanishes—which can occur, for example, when the temperature increases—then the electron collisions resume and the object stops being a superconductor.

    The Anderson limit shows that small size is another way that an object may stop being a superconductor. However, unlike the effects of increasing the temperature, this is not because smaller objects have a smaller superconducting gap energy. Instead, it arises because smaller crystals have fewer electrons, and therefore fewer electron energy levels, than larger crystals do. Since the total possible electron energy of an element stays the same, regardless of size, smaller crystals have larger spacings between their electron energy levels than larger crystals do.

    According to Anderson, this large electronic energy level spacing should pose a problem, and he expected superconductivity to disappear when the spacing becomes larger than the superconducting gap energy. The reason for this, generally speaking, is that one consequence of increased spacing is a decrease in potential energy, which interferes with the competition between kinetic and potential energy that is necessary for superconductivity to occur.

    To investigate what happens to the superconductivity of objects around the Anderson limit, the scientists in the new study prepared large quantities of isolated lead nanocrystals ranging in volume from 20 to 800 nm3.

    Although they could not directly measure the superconductivity of such tiny objects, the researchers could measure something called the parity effect, which results from superconductivity. When an electron is added to a superconductor, the additional energy is partly affected by whether there is an even or odd number of electrons (the parity), which is due to the electrons forming Cooper pairs. If the electrons don’t form Cooper pairs, there is no parity effect, indicating no superconductivity.

    Although the parity effect has previously been observed in large superconductors, this study is the first time that it has been observed in small nanocrystals approaching the Anderson limit. In accordance with Anderson’s predictions from more than 50 years ago, the researchers observed the parity effect for larger nanocrystals, but not for the smallest nanocrystals below approximately 100 nm3.

    The results not only validate the Anderson conjecture, but also extend to a more general area, the Richardson-Gaudin models. These models are equivalent to the conventional theory of superconductivity, the Bardeen Cooper Schrieffer theory, for very small objects.

    “Our experimental demonstration of the Anderson conjecture is also a demonstration of the validity of the Richardson-Gaudin models,” coauthor Hervé Aubin at the University Paris Sciences et Lettres and CNRS told Phys.org. “The Richardson-Gaudin models are an important piece of theoretical works because they can be solved exactly and apply to a wide range of systems; not only to superconducting nanocrystals but also to atomic nuclei and cold fermionic atomic gas, where protons and neutrons, which are fermions like electrons, can also form Cooper pairs.”

    On the more practical side, the researchers expect the results to have applications in future quantum computers.

    “One of the most interesting applications of superconducting islands is their use as Cooper pair boxes employed in quantum bits, the elemental unit of a hypothetical quantum computer,” Aubin said. “So far, Cooper pair boxes used in qubits are much larger than the Anderson limit. Upon reducing the size of the Cooper pair box, quantum computer engineers will eventually have to cope with superconductivity at the Anderson limit.”

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 9:57 am on March 14, 2017 Permalink | Reply
    Tags: , , , , phys.org,   

    From phys.org: “Astronomers discover 16 new high-redshift quasars” 

    physdotorg
    phys.org

    March 14, 2017
    Tomasz Nowakowski

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    The color track of quasar at z = 5 to 6 (red dots and line) with a step of ∆z = 0.1, generated by calculating the mean colors of simulated quasars at each redshift bin. The contours show the locus of M dwarfs, from early type to late type. The cyan contours denote M1-M3 dwarfs, the orange contours denote M4-M6 dwarfs and the purple contours denote M7-M9 dwarfs. Clearly, z ∼ 5.5 quasars are serious contaminated by late type M dwarfs. Credit: Yang et al., 2017.

    Using a new color selection technique, astronomers have detected 16 new luminous, high-redshift quasars. The discovery could be very important for understanding of the early universe, as such high-redshift, quasi-stellar objects provide essential clues on the evolution of the intergalactic medium, quasar evolution and early super-massive black hole growth. The findings were presented in a paper published Mar. 10 on the arXiv pre-print repository.

    High-redshift quasars (at redshift higher than 5.0) are very difficult to find using conventional color selections. This is due to their low spatial density and high contaminants from cool dwarfs. Among more than 300,000 quasars discovered to date, only 290 of them are at redshift higher than 5.0. The scientific community is especially interested in high-redshift quasars at redshift between 5.3 and 5.7, due to their optical colors, which are similar to those of late-type stars. Only about 30 such objects have been found so far.

    With the aim of filling this gap of known quasars at redshift ranging from 5.3 to 5.7, a team of astronomers led by Jinyi Yang of the Peking University in Beijing, China, has developed a new optical/infrared color selection technique. The method is based on optical, near-infrared and mid-infrared photometric data from Sloan Digital Sky Survey (SDSS), UKIRT InfraRed Deep Sky Surveys – Large Area Survey (ULAS), VISTA Hemisphere Survey (VHS) and NASA’s Wide field Infrared Survey Explorer (WISE).


    SDSS Telescope at Apache Point Observatory, NM, USA


    UKIRT, located on Mauna Kea, Hawai’i, USA as part of Mauna Kea Observatory


    NASA/WISE Telescope

    The method has proved its worth as the researchers were able to find 16 new luminous, high-redshift quasars at redshift within the desired range. The observations were carried out between October 2014 and November 2015.

    “In this paper, we report initial results from a new search that focuses on the selection of z ~ 5.5 quasars,” the team wrote.

    Among the newly discovered quasi-stellar objects, J113414.23+082853.3 is the one with the highest redshift – at 5.69. This quasar also showcases strong Lyman-alpha emission and strong intergalactic medium absorption blueward of Lyman-alpha line.

    Another interesting new quasar found by the researchers is J152712.86+064121.9 (at 5.57). It is a weak line quasar with a very weak Lyman-alpha emission line and no other obvious emission features. However, the team revealed that its redshift was measured by matching the continuum to template; thus, its redshift uncertainty is a little larger than others.

    The scientists underline the importance of their research, noting that it could help us better understand the evolution of quasars at redshift from 5.0 to 6.0, over the post-reionization epoch.

    “The physical conditions of the post-reionization intergalactic medium, at z ~ 5-6, provides the basic boundary conditions of models of reionization, such as the evolution of intergalactic temperature, photon mean free path, metallicity and the impact of helium reionization. They place strong constraints on reionization topology as well as on the sources of reionization and chemical feedback by early galaxy population,” the paper reads.

    The team now plans to publish another paper in which a broader sample of high-redshift quasars will be presented. This study will also include the data from the UKIRT Hemisphere Survey (UHS), Pan-STARRS PS1 Survey and the VLT Survey Telescope (VST) ATLAS.


    Pan-STARRS1 located on Haleakala, Maui, HI, USA


    ESO VST telescope, at ESO’s Paranal Observatory

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page. set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 4:58 pm on March 8, 2017 Permalink | Reply
    Tags: , , , BRITE (BRight Target Explorer) Constellation project, , Iota Orionis: Pulsating beacon of a constellation, nanosats, phys.org, Ritter Observatory   

    From phys.org: “Iota Orionis: Pulsating beacon of a constellation” 

    physdotorg
    phys.org

    March 8, 2017

    1
    Iota Orionis is a binary star system and is easily visible with the naked eye, being the brightest star in the constellation Orion’s sword. Credit: Danielle Futselaar

    Astronomers from the BRITE (BRight Target Explorer) Constellation project and Ritter Observatory have discovered a repeating one-per-cent spike in the light of a very massive star which could change our understanding of such stars. Iota Orionis is a binary star system and is easily visible with the naked eye, being the brightest star in the constellation Orion’s sword. Its unique variability, reported in the journal Monthly Notices of the Royal Astronomical Society, was discovered using the world’s smallest astronomical space satellites, referred to as “nanosats”. “As the first functional nanosatellite astronomy mission, the BRITE-Constellation is at the vanguard of this coming space revolution,” said Canadian BRITE-Constellation principal investigator Gregg Wade, of Royal Military College of Canada, Ont.

    The light from Iota Orionis is relatively stable 90 per cent of the time but then dips rapidly followed by a large spike. “The variations look strikingly similar to an electrocardiogram showing the sinus rhythms of the heart, and are known as heartbeat systems,” said Herbert Pablo, the project’s principal investigator, a post-doctoral researcher at Université de Montréal and member of the Centre for Research in Astrophysics of Quebec (CRAQ). This unusual variation is the result of the interaction of two stars in a highly elliptical 30-day orbit around each other.

    While the two stars spend the majority of their time far apart, they do come nearly eight times closer together for a short time once every orbit. At that point the gravitational force between the two stars becomes so strong that it rapidly distorts their shapes, like pulling on the end of a balloon, causing the unusual changes in light. Iota Orionis represents the first time this effect has been seen in such a massive system (35 times the mass of the Sun), an order of magnitude larger than any in previously known systems, and allows for direct determination of the masses and radii of the components.

    A shaking star is like an open book

    Even more interesting is that these systems allow us to peer inside the stars themselves. “The intense gravitational force between the stars as they move closer together triggers quakes in the star, allowing us to probe the star’s inner workings, just as we do for the Earth’s interior during Earthquakes,” said Pablo. The phenomenon of quakes is very rare in massive stars in general and this is the first time induced quakes have ever been seen in a star this massive, let alone one whose mass and radius are known. These unprecedented quakes have also led to the first real clues to how such stars will evolve.

    Astronomers are hopeful that this discovery will provide the initiative to search for other such systems, creating a fundamental shift in how we study the evolution of massive stars. This is important, since massive stars are laboratories of elements essential to human life.

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 3:50 pm on March 7, 2017 Permalink | Reply
    Tags: , Carbon storage in trees, , EucFACE facility, Hawkesbury Institute for the Environment, phys.org, Western Sydney University   

    From phys.org: “Trees’ ability to store carbon in doubt after groundbreaking Australian study” 

    physdotorg
    phys.org

    March 7, 2017
    Mark Smith

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    Credit: Notneb82, Wikimedia Commons

    The ability of trees to offset carbon emissions has been questioned after a Western Sydney University study found common Australian trees are unable to store as much carbon as previously thought.

    1

    Published in the Nature Climate Change journal, the research found that Australia’s iconic Eucalyptus forests are likely to need additional soil nutrients in order to grow and take advantage of extra carbon dioxide in the atmosphere.

    The findings have significant implications for models used by international climate agencies, many of which assume that rising carbon dioxide will fertilise trees and result in more growth and capture of CO2 from the air.

    “The world pays a lot of attention to climate change modelling, including predictions on the amount of carbon that will be stored in trees,” explains lead scientist, Professor David Ellsworth, from the University’s Hawkesbury Institute for the Environment.

    “These reports are based on models and data taken largely from temperate forests where nutrients are in adequate supply, meaning that estimates on carbon absorption do not account for nutrient shortages on forest productivity.

    “Since many of the world’s sub-tropical and tropical forested regions exist on low-nutrient soils, our results indicate that global estimates of carbon storage in forests could be too high.”

    The research was conducted at Western Sydney University’s Hawkesbury Institute for the Environment, at the world’s only Free Air CO2 Experiment in native woodland, the innovative EucFACE facility.

    The EucFACE climate experiment exposes large tracts of remnant native eucalypt forest to treatments of elevated CO2 at 550ppm, which is around 150ppm more than the air that is breathed today.

    The research is in stark contrast to similar experiments in the United States and Europe, where researchers added extra CO2 to plots in temperate forests and found that trees increased their growth by around 23 per cent.

    At EucFACE, however, the researchers found that while photosynthesis levels increased consistently by 19 per cent under elevated CO2, it did not translate into increases in wood, stems and leaves over the three-year measurement.

    When the researchers added phosphorus to trees under elevated CO2, they found a consistent increase in tree growth of 35 per cent, demonstrating how Australian eucalypts would probably store more carbon from the air if they had access to enough nutrients.

    Because CO2 levels are gradually rising, scientists believe that within thirty to fifty years the air will contain 550ppm or more of CO2, resulting in potentially massive changes to the climate and the ecosystems that support life on Earth.

    “Many greenhouse crops such as tomatoes, cut flowers and cucumbers are given added CO2 to make them grow bigger, faster and yield more fruit,” says Professor Ellsworth.

    “Yet out in Australia’s native forests, conditions for plants are not quite so ideal. Australia’s soils are very old and weathered by millions of years of sun and rain, meaning soils are very low in nutrients, and most of the available nutrients are tied up inside wood, leaves and roots.

    “It means that our soils simply lack the available nutrients that would let trees take advantage of the extra CO2 they find in the air.”

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 3:33 pm on March 7, 2017 Permalink | Reply
    Tags: , , MIcroscope technology, phys.org, Scanning tunneling microscope   

    From phys.org: “New microscope technique offers a better way to measure magnetic field of individual atoms” 

    physdotorg
    phys.org

    March 7, 2017
    Bob Yirka

    1
    Credit: CC0 Public Domain

    A team of researchers at IBM has developed a new way to measure the magnetic field of individual atoms that offers 1000 times the energy resolution of conventional techniques. In their paper published in the journal Nature Nanotechnology, the team describes their approach, how well it works and their hope that they will be able to modify it in such a way as to allow others with less specialized hardware to use it.

    Scientists are eager to better measure the magnetic fields of individual atoms because they believe it will lead to a better understanding of material and biological interactions—most particularly those involving weak magnetic interactions. Current methods rely on using defects in diamonds, though the team at IBM notes that prior work at their lab shows that it is possible to measure weak interactions in another way, an approach described as challenging. In this new effort, the team has come up with a way to get the job done that is relatively simple, though, they note, it requires special hardware.

    In the new approach, an atom called a sensor is placed near a target atom inside of a scanning tunneling microscope—a magnetic field is then applied to the microscope followed by a jolt of electricity to the tunnel junction. From there on, the frequency of the atom is monitored—when it matches the spin of the precess (the axis of rotation around a magnetic field that reflects its degree of magnetism), it reveals the measure of the magnetic field. The change in orientation is measured by moving the sensor atom to the microscope’s sensor tip.

    The researchers found their approach to be far more accurate and easier to read than other methods, pointing out that the signal they got from the technique was both stronger and more robust. They note also that few other labs likely have the combination of equipment (such as the high frequency cabling added to the microscope) required to replicate their technique, so they plan to continue the work in hopes of achieving the same results under more relaxed conditions.

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 9:35 pm on March 3, 2017 Permalink | Reply
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    From NC State via phys.org: “Calculations show close Ia supernova should be neutrino detectable offering possibility of identifying explosion type” 

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    North Carolina State University

    phys.org

    phys.org

    1
    Density contour plots including deflagration (white) and detonation (green) surfaces. Credit: arXiv:1609.07403 [astro-ph.HE]

    A team of researchers at North Carolina State University has found that current and future neutrino detectors placed around the world should be capable of detecting neutrinos emitted from a relatively close supernova. They also suggest that measuring such neutrinos would allow them to explain what goes on inside of a star during such an explosion—if the measurements match one of two models that the team has built to describe the inner workings of a supernova.

    Supernovae have been classified into different types depending on what causes them to occur—one type, called a la supernova, occurs when a white dwarf pulls in enough material from a companion, eventually triggering carbon fusion, which leads to a massive explosion. Researchers here on Earth can see evidence of a supernova by the light that is emitted. But astrophysicists would really like to know more about the companion and the actual process that occurs inside the white dwarf leading up to the explosion—and they believe that might be possible by studying the neutrinos that are emitted.

    In this new effort, a team led by Warren Wright calculated that neutrinos from a relatively nearby supernova should be detectable by current sensors already installed and working around the planet and by those that are in the works. Wright also headed two teams that have each written a paper describing one of two types of models that the team has built to describe the process that occurs in the white dwarf leading up to the explosion—both teams have published their work in the journal Physical Review Letters.

    The first model is called the deflagration-to-detonation transition; the second, the gravitationally confined detonation. Both are based on theory regarding interactions inside of the star and differ mostly in how spherically symmetric they are. The two types would also emit different kinds and amounts of neutrinos, which is why the team is hoping that the detectors capable of measuring them will begin to do so. That would allow the teams to compare their models against real measurable data, and in so doing, perhaps finally offer some real evidence of what occurs when stars explode.

    See the full article here .

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    NC State campus

    NC State was founded with a purpose: to create economic, societal and intellectual prosperity for the people of North Carolina and the country. We began as a land-grant institution teaching the agricultural and mechanical arts. Today, we’re a pre-eminent research enterprise that excels in science, technology, engineering, math, design, the humanities and social sciences, textiles and veterinary medicine.

    NC State students, faculty and staff take problems in hand and work with industry, government and nonprofit partners to solve them. Our 34,000-plus high-performing students apply what they learn in the real world by conducting research, working in internships and co-ops, and performing acts of world-changing service. That experiential education ensures they leave here ready to lead the workforce, confident in the knowledge that NC State consistently rates as one of the best values in higher education.

     
  • richardmitnick 9:02 am on February 23, 2017 Permalink | Reply
    Tags: , , , Light-driven reaction converts carbon dioxide into fuel, phys.org, , Rhodium nanoparticles   

    From Duke via phys.org: “Light-driven reaction converts carbon dioxide into fuel” 

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    Duke Crest

    Duke University

    phys.org

    phys.org

    February 23, 2017

    1
    Duke University researchers have engineered rhodium nanoparticles (blue) that can harness the energy in ultraviolet light and use it to catalyze the conversion of carbon dioxide to methane, a key building block for many types of fuels. Credit: Chad Scales

    Duke University researchers have developed tiny nanoparticles that help convert carbon dioxide into methane using only ultraviolet light as an energy source.

    Having found a catalyst that can do this important chemistry using ultraviolet light, the team now hopes to develop a version that would run on natural sunlight, a potential boon to alternative energy.

    Chemists have long sought an efficient, light-driven catalyst to power this reaction, which could help reduce the growing levels of carbon dioxide in our atmosphere by converting it into methane, a key building block for many types of fuels.

    Not only are the rhodium nanoparticles made more efficient when illuminated by light, they have the advantage of strongly favoring the formation of methane rather than an equal mix of methane and undesirable side-products like carbon monoxide. This strong “selectivity” of the light-driven catalysis may also extend to other important chemical reactions, the researchers say.

    “The fact that you can use light to influence a specific reaction pathway is very exciting,” said Jie Liu, the George B. Geller professor of chemistry at Duke University. “This discovery will really advance the understanding of catalysis.”

    The paper appears online Feb. 23 in Nature Communications.

    Despite being one of the rarest elements on Earth, rhodium plays a surprisingly important role in our everyday lives. Small amounts of the silvery grey metal are used to speed up or “catalyze” a number of key industrial processes, including those that make drugs, detergents and nitrogen fertilizer, and they even play a major role breaking down toxic pollutants in the catalytic converters of our cars.

    Rhodium accelerates these reactions with an added boost of energy, which usually comes in the form of heat because it is easily produced and absorbed. However, high temperatures also cause problems, like shortened catalyst lifetimes and the unwanted synthesis of undesired products.

    2
    Rhodium nanocubes were observed under a transmission electron microscope. Credit: Xiao Zhang

    In the past two decades, scientists have explored new and useful ways that light can be used to add energy to bits of metal shrunk down to the nanoscale, a field called plasmonics.

    “Effectively, plasmonic metal nanoparticles act like little antennas that absorb visible or ultraviolet light very efficiently and can do a number of things like generate strong electric fields,” said Henry Everitt, an adjunct professor of physics at Duke and senior research scientist at the Army’s Aviation and Missile RD&E Center at Redstone Arsenal, AL. “For the last few years there has been a recognition that this property might be applied to catalysis.”

    Xiao Zhang, a graduate student in Jie Liu’s lab, synthesized rhodium nanocubes that were the optimal size for absorbing near-ultraviolet light. He then placed small amounts of the charcoal-colored nanoparticles into a reaction chamber and passed mixtures of carbon dioxide and hydrogen through the powdery material.

    When Zhang heated the nanoparticles to 300 degrees Celsius, the reaction generated an equal mix of methane and carbon monoxide, a poisonous gas. When he turned off the heat and instead illuminated them with a high-powered ultraviolet LED lamp, Zhang was not only surprised to find that carbon dioxide and hydrogen reacted at room temperature, but that the reaction almost exclusively produced methane.

    “We discovered that when we shine light on rhodium nanostructures, we can force the chemical reaction to go in one direction more than another,” Everitt said. “So we get to choose how the reaction goes with light in a way that we can’t do with heat.”

    This selectivity—the ability to control the chemical reaction so that it generates the desired product with little or no side-products—is an important factor in determining the cost and feasibility of industrial-scale reactions, Zhang says.

    “If the reaction has only 50 percent selectivity, then the cost will be double what it would be if the selectively is nearly 100 percent,” Zhang said. “And if the selectivity is very high, you can also save time and energy by not having to purify the product.”

    Now the team plans to test whether their light-powered technique might drive other reactions that are currently catalyzed with heated rhodium metal. By tweaking the size of the rhodium nanoparticles, they also hope to develop a version of the catalyst that is powered by sunlight, creating a solar-powered reaction that could be integrated into renewable energy systems.

    “Our discovery of the unique way light can efficiently, selectively influence catalysis came as a result of an on-going collaboration between experimentalists and theorists,” Liu said. “Professor Weitao Yang’s group in the Duke chemistry department provided critical theoretical insights that helped us understand what was happening. This sort of analysis can be applied to many important chemical reactions, and we have only just begun to explore this exciting new approach to catalysis.”

    Read more at: https://phys.org/news/2017-02-light-driven-reaction-carbon-dioxide-fuel.html#jCp

    See the full article here .

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    Duke Campus

    Younger than most other prestigious U.S. research universities, Duke University consistently ranks among the very best. Duke’s graduate and professional schools — in business, divinity, engineering, the environment, law, medicine, nursing and public policy — are among the leaders in their fields. Duke’s home campus is situated on nearly 9,000 acres in Durham, N.C, a city of more than 200,000 people. Duke also is active internationally through the Duke-NUS Graduate Medical School in Singapore, Duke Kunshan University in China and numerous research and education programs across the globe. More than 75 percent of Duke students pursue service-learning opportunities in Durham and around the world through DukeEngage and other programs that advance the university’s mission of “knowledge in service to society.”

     
  • richardmitnick 1:58 pm on February 18, 2017 Permalink | Reply
    Tags: , , , , phys.org, Radial acceleration relation exists in nearby high-mass elliptical and low-mass spheroidal galaxies, The growing proof of the relation or natural law requires new thinking about dark matter and gravity   

    From phys.org: “Research team finds radial acceleration relation in all common types of galaxies” 

    physdotorg
    phys.org

    February 16, 2017

    1
    The giant elliptical galaxy NGC 4472. Credit: Courtesy of David W. Hogg, Michael R. Blanton, and the Sloan Digital Sky Survey Collaboration

    SDSS Telescope at Apache Point Observatory, NM, USA
    SDSS Telescope at Apache Point Observatory, NM, USA

    The distribution of normal matter precisely determines gravitational acceleration in all common types of galaxies, a team led by Case Western Reserve University researchers reports.

    The team has shown this radial acceleration relation exists in nearby high-mass elliptical and low-mass spheroidal galaxies, building on last year’s discovery of this relation in spiral and irregular galaxies. This provides further support that the relation is tantamount to a new natural law, the researchers say.

    “This demonstrates that we truly have a universal law for galactic systems,” said Federico Lelli, formerly an astronomy postdoctoral fellow at Case Western Reserve University and currently a fellow at the European Southern Observatory.

    “This is similar to the Kepler law for planetary systems, which does not care about the specific properties of the planet. Whether the planet is rocky like Earth or gaseous like Jupiter, the law applies,” said Lelli, who led this investigation.

    In this case, the observed acceleration tightly correlates with the gravitational acceleration from the visible mass, no matter the type of galaxy. In other words, if astronomers measure the distribution of normal matter, they know the rotation curve, and vice versa.

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey
    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    “But it is still unclear what this relation means and what is its fundamental origin,” Lelli said.

    The study is published online in Astrophysical Journal today. Co-authors are Stacy McGaugh, chair of the Department of Astronomy at Case Western Reserve, James Schombert, astronomy professor at the University of Oregon, and Marcel Pawlowski, former astronomy postdoctoral researcher at Case Western Reserve and current Hubble fellow at the University of California, Irvine.

    The researchers found that in 153 spiral and irregular galaxies, 25 ellipticals and lenticulars, and 62 dwarf spheroidals, the observed acceleration tightly correlates with the gravitational acceleration expected from visible mass.

    Observed deviations from this correlation are not related to any specific galaxy property but completely random and consistent with measurement errors, the team found.

    The tightness of this relation is difficult to understand in terms of dark matter as it’s currently understood, the researchers said.

    It also challenges the current understanding of galaxy formation and evolution, in which many random processes such as galaxy mergers and interactions, inflows and outflows of gas, star formation and supernovas, occur at the same time.

    “Regularity must somehow emerge from this chaos,” Lelli said.

    To make their discovery, researchers combined different tracers of the centripetal acceleration found in different types of galaxies, from which they made 1-to-1 comparisons.

    The kinematical tracers were cold gas in spiral and irregular galaxies, stars or hot gas in ellipticals and lenticulars, and individual giant stars in dwarf spheroidals.

    The investigation included so-called ultra-faint dwarf spheroidal galaxies, but due to their lack of light—which makes them hard to study—the researchers can’t confidently offer a clear interpretation of the radial acceleration relation in these.

    Nevertheless, the growing proof of the relation, or natural law, requires new thinking about dark matter and gravity, the researchers said.

    “Within the standard dark-matter paradigm, this law implies that the visible matter and the dark matter must be tightly coupled in galaxies at a local level and independently on global properties. They must know about each other,” Lelli said. “Within alternative models like modified gravity, this law represents a key empirical constraint and may guide theoretical physicists to build some appropriate mathematical extension of Einstein’s General Relativity.”

    The team’s research so far has focused on galaxies in the nearby universe. Lelli and his colleagues plan to test the relation in more distant galaxies, just a few billion years after the big bang. They are hoping to learn whether the same relation holds during the lifetime of the Universe.

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 10:57 am on February 15, 2017 Permalink | Reply
    Tags: Faint polarized flares detected from the variable star UV Ceti, , or Luyten 726-8B, phys.org, , UV Ceti   

    From U Sidney via phys.org: “Faint, polarized flares detected from the variable star UV Ceti” 

    U Sidney bloc

    University of Sidney

    phys.org

    phys.org

    February 15, 2017
    Tomasz Nowakowski

    1
    Faraday dispersion function of UV Ceti at 154 MHz during the off and on period of the Dec. 11, 2015 flare. Credit: Lynch et al., 2017.

    Astronomers have detected four faint, polarized flares at 154 MHz from the nearby variable star UV Ceti. The newly observed flares are much fainter than most flares found at these frequencies. The findings were presented February 10 in a paper published online on the arXiv pre-print server.

    Located just about 8.7 light years away, UV Ceti, or Luyten 726-8B, belongs to a nearby binary star system Luyten 726-8.

    3
    Luyten 726-8 AB / UV Ceti http://www.solstation.com/stars/luy726-8.htm

    It is a variable red dwarf of spectral type M, just like its companion star BL Ceti (Luyten 726-8A). Due to its proximity, this star system is a treasure trove for astronomers studying flaring events of magnetically active stellar systems.

    That is why a team of researchers led by Christene Lynch of the University of Sydney in Australia selected UV Ceti as a target of radio astronomy observations in December 2015. They used the Murchison Widefield Array (MWA) in Australia to confirm previous bright flare detections in the system at 100 to 200 MHz.

    SKA Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO), 800 kilometres north of Perth
    SKA Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO), 800 kilometres north of Perth

    The array allowed the scientist to get a glimpse of low-level flares fainter than expected.

    “We have detected four flares from UV Ceti at 154 MHz using the Murchison Widefield Array,” the paper reads.

    The observation sessions, which used a 30.72 MHz bandwidth centered at 154 MHz with 40 kHz channels and 0.5-second integrations, allowed the team to observe flare emission in the polarized images. In each epoch, they detected a single right-handed circularly polarized flare, finding also a left-handed flare immediately following the right-handed one. Moreover, they detected linear polarization during the brightest flare, what indicates that the flares are elliptically polarized. The researchers noted that these results highlight the importance of polarization images in such studies.

    “These dim flares are only detected in polarized images, which have an order of magnitude better sensitivity than the total intensity images. This highlights the utility of using polarization images to detect low level emission in confusion limited images,” the team wrote in the paper.

    The study also revealed that the newly detected flares have flux densities between 10 to 65 mJy. This means that they are about 100 times fainter than most flares observed so far at similar frequencies. Notably, three of the four flares described in the paper have flux densities below 15 mJy, while the one observed on Dec. 11, 2015 reached nearly 65 mJy.

    The researchers emphasize that their study provides first flare rate measurements for low-intensity (below 100 mJy) flares at 100 to 200 MHz. However, they note that there is still much to accomplish in the field of flare emission research and recommend further observations. Future studies would improve our understanding of physical parameters of the stellar magnetospheric plasma.

    “To better characterize M dwarf flares at meter wavelengths requires more observational time on individual sources to constrain flare rates. More sensitive observations are also needed to investigate the fine time-frequency structure of the flares. Simultaneous multi-wavelength observations would also add to this analysis,” the team concluded.

    See the full article here .

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    U Sidney campus

    Our founding principle as Australia’s first university was that we would be a modern and progressive institution. It’s an ideal we still hold dear today.

    When Charles William Wentworth proposed the idea of Australia’s first university in 1850, he imagined “the opportunity for the child of every class to become great and useful in the destinies of this country”.

    We’ve stayed true to that original value and purpose by promoting inclusion and diversity for the past 160 years.

    It’s the reason that, as early as 1881, we admitted women on an equal footing to male students. Oxford University didn’t follow suit until 30 years later, and Jesus College at Cambridge University did not begin admitting female students until 1974.

    It’s also why, from the very start, talented students of all backgrounds were given the chance to access further education through bursaries and scholarships.

    Today we offer hundreds of scholarships to support and encourage talented students, and a range of grants and bursaries to those who need a financial helping hand.

     
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