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  • richardmitnick 5:18 pm on December 22, 2014 Permalink | Reply
    Tags: , Bioengineering,   

    From Brown: “New technology makes tissues, someday maybe organs” 

    Brown University
    Brown University

    December 22, 2014
    David Orenstein 401-863-1862

    A new instrument could someday build replacement human organs the way electronics are assembled today: with precise picking and placing of parts.

    Building large tissues
    A new device allows perfusion of bioengineered structures built from smaller pieces of tissue prepared in the lab. It is a first step toward someday building whole organs. Video: Mike Cohea/Brown University

    In this case, the parts are not resistors and capacitors, but 3-D microtissues containing thousands to millions of living cells that need a constant stream of fluid to bring them nutrients and to remove waste. The new device is called “BioP3” for pick, place, and perfuse. A team of researchers led by Jeffrey Morgan, a Brown University bioengineer, and Dr. Andrew Blakely, a surgery fellow at Rhode Island Hospital and the Warren Alpert Medical School, introduces BioP3 in a new paper in the journal Tissue Engineering Part C.

    Because it allows assembly of larger structures from small living microtissue components, Morgan said, future versions of BioP3 may finally make possible the manufacture of whole organs such as livers, pancreases, or kidneys.

    Honeycombs of bioengineered tissue, top, can be stacked and arranged to build larger living structures.

    “For us it’s exciting because it’s a new approach to building tissues, potentially organs, layer by layer with large, complex living parts,” said Morgan, professor of molecular pharmacology, physiology and Biotechnology. “In contrast to 3-D bioprinting that prints one small drop at a time, our approach is much faster because it uses pre-assembled living building parts with functional shapes and a thousand times more cells per part.”

    Morgan’s research has long focused on making individual microtissues in various shapes such as spheres, long rods, donut rings and honeycomb slabs. He uses a novel micromolding technique to direct the cells to self-assemble and form these complex shapes. He is a founder of the Providence startup company MicroTissues Inc., which sells such culture-making technology.

    Now, the new paper shows, there is a device to build even bigger tissues by combining those living components.

    “This project was particularly interesting to me since it is a novel approach to large-scale tissue engineering that hasn’t been previously described,” Blakely said.

    The BioP3 prototype

    The BioP3, made mostly from parts available at Home Depot for less than $200, seems at first glance to be a small, clear plastic box with two chambers: one side for storing the living building parts and one side where a larger structure can be built with them. It’s what rests just above the box that really matters: a nozzle connected to some tubes and a microscope-like stage that allows an operator using knobs to precisely move it up, down, left, right, out and in.

    The plumbing in those tubes allows a peristaltic pump to create fluid suction through the nozzle’s finely perforated membrane. That suction allows the nozzle to pick up, carry and release the living microtissues without doing any damage to them, as shown in the paper.

    Once a living component has been picked, the operator can then move the head from the picking side to the placing side to deposit it precisely. In the paper, the team shows several different structures Blakely made including a stack of 16 donut rings and a stack of four honeycombs. Because these are living components, the stacked microtissues naturally fuse with each other to form a cohesive whole after a short time.

    Because each honeycomb slab had about 250,000 cells, the stack of four achieved a proof-of-concept, million-cell structure more than 2 millimeters thick.

    That’s not nearly enough cells to make an organ such as a liver (an adult’s has about 100 billion cells), Morgan said, but the stack did have a density of cells consistent with that of human organs. In 2011, Morgan’s lab reported that it could make honeycomb slabs 2 centimeters wide, with 6 million cells each. Complex stacks with many more cells are certainly attainable, Morgan said.

    If properly nurtured, stacks of these larger structures could hypothetically continue to grow, Morgan said. That’s why the BioP3 keeps a steady flow of nutrient fluid through the holes of the honeycomb slabs to perfuse nutrients and remove waste. So far, the researchers have shown that stacks survive for days.

    In the paper the team made structures with a variety of cell types including H35 liver cells, KGN ovarian cells, and even MCF-7 breast cancer cells (building large tumors could have applications for testing of chemotherapeutic drugs or radiation treatments). Different cell types can also be combined in the microtissue building parts. In 2010, for example, Morgan collaborated on the creation of an artificial human ovary unifying three cell types into a single tissue.

    Improvements underway

    Because version 1.0 of the BioP3 is manually operated, it took Blakely about 60 minutes to stack the 16 donut rings around a thin post, but he and Morgan have no intention of keeping it that way.

    In September, Morgan received a $1.4-million, three-year grant from the National Science Foundation in part to make major improvements, including automating the movement of the nozzle to speed up production.

    “Since we now have the NSF grant, the Bio-P3 will be able to be automated and updated into a complete, independent system to precisely assemble large-scale, high-density tissues,” Blakely said.

    In addition, the grant will fund more research into living building parts — how large they can be made and how they will behave in the device over longer periods of time. Those studies include how their shape will evolve and how they function as a stack.

    “We are just at the beginning of understanding what kinds of living parts we can make and how they can be used to design vascular networks within the structures,” Morgan said. “Building an organ is a grand challenge of biomedical engineering. This is a significant step in that direction.”

    Brown has sought a patent on the BioP3.

    In addition to Blakely and Morgan, the paper’s other authors are biology graduate student Kali Manning and Anubhav Tripathi, professor of engineering, who co-directs Brown’s Center for Biomedical Engineering with Morgan.

    National Institutes of Health (grant T32 GM065085-09) and the NSF (grant CBET-1428092) have supported the research.

    See the full article here.

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    Welcome to Brown

    Rhode Island Hall: Rhode Island Hall’s classical exterior was recently renovated with a modern interiorRhode Island Hall: Rhode Island Hall’s classical exterior was recently renovated with a modern interior

    Located in historic Providence, Rhode Island and founded in 1764, Brown University is the seventh-oldest college in the United States. Brown is an independent, coeducational Ivy League institution comprising undergraduate and graduate programs, plus the Alpert Medical School, School of Public Health, School of Engineering, and the School of Professional Studies.

    With its talented and motivated student body and accomplished faculty, Brown is a leading research university that maintains a particular commitment to exceptional undergraduate instruction.

    Brown’s vibrant, diverse community consists of 6,000 undergraduates, 2,000 graduate students, 400 medical school students, more than 5,000 summer, visiting and online students, and nearly 700 faculty members. Brown students come from all 50 states and more than 100 countries.

    Undergraduates pursue bachelor’s degrees in more than 70 concentrations, ranging from Egyptology to cognitive neuroscience. Anything’s possible at Brown—the university’s commitment to undergraduate freedom means students must take responsibility as architects of their courses of study.

  • richardmitnick 5:03 pm on December 22, 2014 Permalink | Reply
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    From LBL: “Piezoelectricity in a 2D Semiconductor” 

    Berkeley Logo

    Berkeley Lab

    December 22, 2014
    Lynn Yarris (510) 486-5375

    A door has been opened to low-power off/on switches in micro-electro-mechanical systems (MEMS) and nanoelectronic devices, as well as ultrasensitive bio-sensors, with the first observation of piezoelectricity in a free standing two-dimensional semiconductor by a team of researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab).

    Xiang Zhang, director of Berkeley Lab’s Materials Sciences Division and an international authority on nanoscale engineering, led a study in which piezoelectricity – the conversion of mechanical energy into electricity or vice versa – was demonstrated in a free standing single layer of molybdenum disulfide, a 2D semiconductor that is a potential successor to silicon for faster electronic devices in the future.

    “Piezoelectricity is a well-known effect in bulk crystals, but this is the first quantitative measurement of the piezoelectric effect in a single layer of molecules that has intrinsic in-plane dipoles,” Zhang says. “The discovery of piezoelectricity at the molecular level not only is fundamentally interesting, but also could lead to tunable piezo-materials and devices for extremely small force generation and sensing.”

    Xiang Zhang directs Berkeley Lab’s Materials Sciences Division (photo by Roy Kaltschmidt, Berkeley Lab)

    Zhang, who holds the Ernest S. Kuh Endowed Chair at the University of California (UC) Berkeley and is a member of the Kavli Energy NanoSciences Institute at Berkeley, is the corresponding author of a paper in Nature Nanotechnology describing this research. The paper is titled Observation of Piezoelectricity in Free-standing Monolayer MoS2. The co-lead authors are Hanyu Zhu and Yuan Wang, both members of Zhang’s UC Berkeley research group. (See below for a complete list of co-authors.)

    Since its discovery in 1880, the piezoelectric effect has found wide application in bulk materials, including actuators, sensors and energy harvesters. There is rising interest in using nanoscale piezoelectric materials to provide the lowest possible power consumption for on/off switches in MEMS and other types of electronic computing systems. However, when material thickness approaches a single molecular layer, the large surface energy can cause piezoelectric structures to be thermodynamically unstable.

    Over the past couple of years, Zhang and his group have been carrying out detailed studies of molybdenum disulfide, a 2D semiconductor that features high electrical conductance comparable to that of graphene, but, unlike graphene, has natural energy band-gaps, which means its conductance can be switched off.

    “Transition metal dichalcogenides such as molybdenum disulfide can retain their atomic structures down to the single layer limit without lattice reconstruction, even in ambient conditions,” Zhang says. “Recent calculations predicted the existence of piezoelectricity in these 2D crystals due to their broken inversion symmetry. To test this, we combined a laterally applied electric field with nano-indentation in an atomic force microscope for the measurement of piezoelectrically-generated membrane stress.”

    To maximize piezoelectric coupling, electrodes (yellow dashed lines) were defined parallel to the zigzag edges (white dashed lines) of the MoS2 monolayer. Green and red colors denote the intensity of reflection and photoluminescence respectively.

    Zhang and his group used a free-standing molybdenum disulfide single layer crystal to avoid any substrate effects, such as doping and parasitic charge, in their measurements of the intrinsic piezoelectricity. They recorded a piezoelectric coefficient of 2.9×10-10 C/m, which is comparable to many widely used materials such as zinc oxide and aluminum nitride.

    “Knowing the piezoelectric coefficient is important for designing atomically thin devices and estimating their performance,” says Nature paper co-lead author Zhu. “The piezoelectric coefficient we found in molybdenum disulfide is sufficient for use in low-power logic switches and biological sensors that are sensitive to molecular mass limits.”

    Zhang, Zhu and their co-authors also discovered that if several single layers of molybdenum disulfide crystal were stacked on top of one another, piezoelectricity was only present in the odd number of layers (1,3,5, etc.)

    “This discovery is interesting from a physics perspective since no other material has shown similar layer-number sensitivity,” Zhu says. “The phenomenon might also prove useful for applications in which we want devices consisting of as few as possible material types, where some areas of the device need to be non-piezoelectric.”

    In addition to logic switches and biological sensors, piezoelectricity in molybdenum disulfide crystals might also find use in the potential new route to quantum computing and ultrafast data-processing called “valleytronics.” In valleytronics, information is encoded in the spin and momentum of an electron moving through a crystal lattice as a wave with energy peaks and valleys.

    “Some types of valleytronic devices depend on absolute crystal orientation, and piezoelectric anisotropy can be employed to determine this,’ says Nature paper co-lead author Wang. “We are also investigating the possibility of using piezoelectricity to directly control valleytronic properties such as circular dichroism in molybdenum disulfide.”

    In addition to Zhang, Zhu and Wang, other co-authors of the Nature paper were Jun Xiao, Ming Liu, Shaomin Xiong, Zi Jing Wong, Ziliang Ye, Yu Ye and Xiaobo Yin.

    This research was supported by Light-Material Interactions in Energy Conversion, an Energy Frontier Research Center led by the California Institute of Technology, in which Berkeley Lab is a major partner. The Energy Frontier Research Center program is supported by DOE’s Office of Science.

    See the full article here.

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  • richardmitnick 4:12 pm on December 22, 2014 Permalink | Reply
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    From U Hawaii: “Correction: Tonight isn’t the longest night in Earth’s history” 

    U Hawaii

    University of Hawaii

    Dec 21, 2014
    Joseph Stromberg

    This article originally said that, due to the rotation of the Earth gradually slowing down over time, this winter solstice would feature the longest night ever.

    I got this wrong. The Earth’s rotation is gradually slowing on an extremely long timescale, but on a shorter year-to-year basis, geologic factors can alter the speed as well.

    Data indicates that the rotation speed has actually sped up slightly over the past forty years (likely due to melting of ice at the poles and the resulting redistribution of the Earth’s mass), and before that, the trend was up-and-down for most of the 20th century — so, as far as we know, the longest night in Earth’s history likely occurred in 1912. I apologize for the error. Thanks to Steve Allen and Ryan Hardy for pointing it out.

    Today, you might already know, is the winter solstice. That means for people living in the Northern Hemisphere, it’s the longest night of the year.

    However, as science blogger Colin Schultz points out, tonight will also be the longest night ever.

    At any location in the Northern Hemisphere, in other words, tonight’s period of darkness will be slightly longer than any other, ever — at least, since the planet started spinning right around the time it was first formed some 4.5 billion years ago.

    Why this night will be the longest ever

    The reason is that the rotation of the Earth is slowing over time. Every year, scientists estimate, the length of a day increases by about 15 to 25 millionths of a second.

    It may be a truly tiny amount (and it means that even in your entire lifetime, the length of a day will only expand by about two milliseconds), but it forces official timekeepers to add a leap second every few years.

    The main reason Earth’s rotation slowing down is the moon. Shortly after the formation of Earth, it was impacted by a planet-sized object. This enormous collision threw off the material that would eventually coalesce into the moon, and also sent Earth spinning quite rapidly.

    In the four-plus billion years since, that spinning has slowed down pretty significantly (with an Earth day going from about six hours to 24 hours as a result) because of the moon’s gravity.

    The moon’s gravity pulls ocean water slightly toward and away from it, causing tides. But because of the alignment of the two bodies, the resulting bulge of water is slightly ahead of the spot on Earth that’s directly under the moon.

    As a result, the Earth encounters just a bit of friction from this bulge of water as it rotates, slowing it down slightly.

    The phenomenon — called tidal acceleration — also allows the moon to drift slightly farther away from Earth over time. (It’s also what’s led the same face of the moon to always faces Earth as it rotates around us, and eventually, if things went on long enough, the same face of Earth would always face the moon as well, a phenomenon called tidal locking.)

    There are a few other things that contribute to Earth’s slowing down, but their contributions are minor. One is that the moon’s gravity similarly causes Earth’s crust to flex, like its water, leading to some friction as well.

    Why winter solstice is the longest night of the year

    This one is much simpler. The Earth orbits around the sun on a tilted axis, so sometimes, the Northern Hemisphere gets more exposure to sunlight over the course of a day, and sometimes, the Southern Hemisphere does. This is what accounts for the changing of the seasons.

    Every year, on December 21 or 22, this tilt means that locations in the Northern Hemisphere get the shortest duration of sunlight they’ll get all year, so they experience the shortest day and longest night. On June 21 or 22, they get the longest days and shortest nights.

    Meanwhile, everything is reversed for locations in the Southern Hemisphere — they have their longest days in December, and longest nights in June.

    See the full article here.

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    The University of Hawai‘i System includes 10 campuses and dozens of educational, training and research centers across the Hawaiian Islands. As the public system of higher education in Hawai‘i, UH offers opportunities as unique and diverse as our Island home.

    The 10 UH campuses and educational centers on six Hawaiian Islands provide unique opportunities for both learning and recreation.

    UH is the State’s leading engine for economic growth and diversification, stimulating the local economy with jobs, research and skilled workers.

  • richardmitnick 3:53 pm on December 22, 2014 Permalink | Reply
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    From astrobio.net: “Barren Deserts Can Host Complex Ecosystems in Their Soils” 

    Astrobiology Magazine

    Astrobiology Magazine

    Dec 22, 2014
    Adam Hadhazy

    Biological soil crusts” don’t look like much. In fact, people often trample right over these dark, or green-tinted, sometimes raised patches in the desert soil. But these scruffy stretches can house delicate ecosystems as varied and complexly interwoven as that of a lush, tropical rainforest.

    Life forms including bacteria, algae, fungi and lichens, as well as plants such as mosses and liverworts, can band together to create biological soil crusts in dry, nutrient-starved environments. Scientists are just beginning to document the diversity of species that call biological soil crusts home.

    “These are incredibly diverse microbial communities with hundreds of different organisms,” said Jason Raymond, assistant professor in the School of Earth and Space Exploration at Arizona State University. “If you were counting animals in the Amazon, you wouldn’t come close to the diversity of these biological soil crusts.”

    Raymond is the senior author of three new papers in the scientific journal Genome Association, which shed light on the microbes that commonly set up shop in biological soil crusts in Utah’s Moab Desert. The papers present a genome of three different bacteria. These genomes contain genes known to enable certain biological forms and functions. Identifying these genes therefore speaks to the interplay of these bacteria as they eke out a living in their shared, severe environment.

    Figuring out how life thrives in biological soil crusts, in conditions that would fell most other life on the planet, will help in gauging the habitability of other worlds.

    “Biological soil crusts are an outstanding example of nature coping with a really challenging set of environmental conditions,” said Raymond. “We’re pushing as close as we can to extreme environments on other planets.”

    Starved in the desert

    Although the Moab Desert is hot and dry, the biggest challenge for life in its biological soil crusts, as in other such places, is obtaining nutrients — food, essentially. The new studies reveal the array of adaptive tools the microbes possess for ensnaring scarce, vital nutrients and preventing them from leaching away into the environment.

    A picture of Canyonlands National Park near the city of Moab, Utah. Credit: NOAA/NGDC, John Lockridge, Longmont, Colorado

    On a basic level, humans, like all other life, do not need hot dogs to eat or ice tea to drink to survive. When it comes to food and beverage, it boils down to chemical elements. The most basic set of chemical elements life typically needs is summed up by the acronym CHNOPS, made up of the letter signifiers of the elements carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. (Complex life, like humans, need a whole bunch of other elements as well, such as selenium and iodine.)

    In the Moab Desert, carbon and nitrogen are two particularly dear elements. In more hospitable habitats, like a grassland in a temperate climate, carbon — organic matter — is readily available from fallen leaves, dead plants and animals, and so on. Nitrogen is “fixed,” or nabbed from the atmosphere by numerous microbes and taken up by plants for subsequent dissemination in the environment. In the Moab, in contrast, not enough plants or animals can survive to keep these two elements widely available for use by other organisms.

    “If you’ve been there or seen pictures, you know how barren that landscape is,” said Raymond. “In terms of fundamental nutrient availability of carbon and nitrogen, these things are tough to get your hands on when you’re in a biological soil crust.”

    Living on the edge

    To get a bead on understanding how the Moab Desert’s microbial critters make do, Raymond and his Arizona State University colleagues obtained samples of biological soil crusts found there. Three microbes grew readily in a growth medium in the lab. The medium, however, was not exactly a smorgasbord. To get by on the available nutrients, the microbes still had to be resourceful and obtain nutrients from the air, such as carbon via carbon dioxide gas, or use one of a small handful of compounds the team supplied in the media.

    A Bacillus species with evident flagella, the whiplike tails many microbes use to move around. Credit: CDC/Dr. William A. Clark/Wikipedia

    “It was a very minimal media,” said Raymond. “If something’s growing on there, you know it’s able to fix carbon and nitrogen out of the atmosphere, or using one of the specifically chosen carbon and nitrogen compounds we add to the media. Either way, these organisms are very efficient recyclers of organic material.”

    After growing the cultures, the scientists sequenced the genes of the organisms present. Three different species in the Microvirga, Bacillus and Massilia genera stood out. The three species are alike in some ways. For instance, all have genes for making structures such as flagella —whiplike tails — to allow them to get closer to areas with favorable nutrient availability. Once there, all three microbes have genes for producing “biofilms,” a tactic of binding together to remain in place.

    Significant differences in their genetic toolkits exist as well. Each bacterium tries to occupy a niche in the biological soil crust community, in partnership or perhaps even at the occasional expense of its neighbors. The Bacillus strain, for instance, has genes for pumping out what are known as siderophores. These molecules bind readily to iron, for instance, another chemical element that many organisms need to survive.

    The Microvirga bacterial strain identified by Raymond and colleagues has genes for sucking up siderophores from the environment, but not for making them. It seems that the Microvirga benefits from the Bacillus going to the trouble of sending out siderophores.

    “The interesting thing is that the Bacillus sends out these little shuttles to hopefully get ahold of iron and bring it back, but there is no guarantee,” said Raymond.

    The Microvirga, in this instance, might well be freeloaders.

    Letting nothing go to waste

    In other ways, the three species coexist peacefully, particularly when there’s no speakable limit to the resource. All three benefit from the general ability to obtain nutrients from the air, which is certainly a “more the merrier” type of situation in a biological soil crust.

    A moss species, called hairless twisted moss, growing as part of a biological soil crust in Utah. The member species of biological soil crusts each play important roles in maintaining the health of the overall community. Credit: NPS/Neal Herbert

    “There is an incredible efficiency in recycling organic matter so that it doesn’t go back into the environment,” noted Raymond.

    On an individual basis, the bacteria can complement each other. The Massilia, for example, fills a niche by apparently being able to survive in oxygen-free, “anaerobic” conditions. That ability suggests it contributes to the overall community’s wellbeing by still retaining nutrients in the shared environment in internal or underground locations sealed off from the outside air.

    “Each microbe has a specialty and they are complementary,” said Raymond.

    Characterizing all three microbes, Raymond said: “They’re sort of the trash compactors of this community. They’ll literally grab ahold of any nutrient-rich sources in the environment and try to metabolize it. That’s a testament to how limited this environment is.”

    The new studies suggest the high degree to which species living in biological soil crusts rely on their neighbors to play respective parts in nutrient fixation, processing, dead member decomposition, and more.

    “Nearly every organism in this community is dependent on some other organism’s waste product or byproduct,” said Raymond.

    Delicate, yet steadfast

    Interdependence at such a high level does leave biological soil crusts vulnerable. Human activity in particular, such as four-wheeling in remote desert environs caked by biological soil crusts, can devastate whole mini-ecosystems, which might take centuries to recover.

    “Any perturbation has the potential to have catastrophic consequences,” said Raymond.

    On the other hand, the ties that bind in biological soil crusts do point, more positively, to how organisms can cooperate to turn a wasteland into an oasis. Environments that scientists would expect to be sterile often astonish us with the lengths to which their denizens go to survive. And as in the case of biological soil crusts, surprising complexity can arise in some of the harshest places.

    An artist’s impression of sunset on an austere exoplanetary landscape, in this case of the super-Earth Gliese 667 Cc. The exoplanet resides in a triple star system and the three suns are visible in the sky. Credit: ESO/L. Calçada

    The same paradigm probably holds true for other worlds with conditions that look abjectly dismal for life.

    “One of the things that constantly surprises me is, wherever people seem to go on the planet, there’s life,” said Raymond. “Anywhere we go on Earth, life has figured out a way to penetrate that niche and take advantage of some aspect of that environment.”

    Accordingly, Raymond thinks that because defining habitability is proving so slippery, astrobiologists might want to take the opposite approach in setting out the parameters of clear inhabitability.

    “We’re trying to find examples of the most extreme environments we can on Earth,” said Raymond. “We’re trying to get into places where biology runs headlong into the inorganic part of the Earth, where any nutrient you want to pick up you’ve got to get from a rock or the atmosphere.”

    Essentially, if life can make it there, in these places on Earth, it might just make it anywhere.

    See the full article here.

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  • richardmitnick 3:28 pm on December 22, 2014 Permalink | Reply
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    From IceCube: “Gamma-ray bursts are not main contributors to the astrophysical neutrino flux in IceCube” 

    IceCube South Pole Neutrino Observatory

    22 Dec 2014
    Silvia Bravo

    Gamma-ray bursts (GRBs) were once the most promising candidate source of ultra-high-energy cosmic rays (UHECRs). They release extremely large amounts of energy in short periods of time, so if they could accelerate protons as they do electrons, then GRBs could account for most of the observed UHECRs.

    But along comes IceCube, the first gigaton neutrino detector ever built, ready to dig into the origin of UHECRs using neutrinos. There’s a whole universe in which to look for a signal but, to test GRBs as possible sources, they started with a search for neutrinos in coincidence with observed GBRs. Previous results, published by the IceCube Collaboration in 2012 in Nature, found no such coincidence. This cast doubt on GRBs as the main source of UHECRs. In a follow-up study submitted today to the Astrophysical Journal Letters, the collaboration shows that the contribution of GRBs to the observed astrophysical neutrino flux cannot be larger than about 1%.

    The study also sets the most stringent limits yet on GRB neutrino production, excluding much of the parameter space for the most popular models. The collaboration is now also providing a tool to set limits on other GRB models using IceCube data.

    The jet from a gamma-ray burst emerging at nearly light speed. Image credit: NASA / Swift / Cruz deWilde.

    NASA SWIFT Telescope

    One may wonder how observing neutrinos in Antarctic ice tells us anything about cosmic rays and GRBs. The answer is simple, if you ask a physicist: neutrinos are an unambiguous signature of proton acceleration. And cosmic rays are, in their vast majority, very high energy protons.

    That cosmic rays exist at energies up to 10^20 eV is a fact; we have observed them with all sort of detectors since their discovery by Victor [Francis] Hess back in 1912. Physicists have developed several models that could explain how and where cosmic rays can be accelerated to such extreme energies. All of these models also tell us that any cosmic proton accelerator that we can imagine would also be a very high energy neutrino generator. While cosmic rays are scrambled by intergalactic magnetic fields, neutrinos travel in straight paths, potentially allowing us to identify their sources. For this reason, the search for the sources of cosmic rays has also become the search for very high energy neutrinos.

    IceCube, the first detector to measure a very high energy neutrino flux, is now squeezing every bit of information out of its data, to learn more about the origins of those neutrinos and thus of cosmic rays. In the current research, IceCube has looked for a neutrino signature in coincidence with over 500 GRBs observed during the data-taking period from April 2008 to May 2012. A single low-significance neutrino was found, confirming previous results by the collaboration. However, this data sample was much larger, including the first data from the completed detector and allowing still more stringent limits on GRB neutrino production.

    GRBs were once very promising candidates for the source of UHECRs. Corresponding author Michael Richman from University of Maryland notes that “using data taken from one year of operation of the completed detector, IceCube has already cast doubt on that hypothesis.” IceCube’s recent observation of an astrophysical neutrino flux marks a new era of neutrino astronomy. This flux is compatible with the expectation from cosmic ray production. While GRBs are excluded as dominant sources of either UHECRs or the diffuse astrophysical neutrinos, ongoing analyses will shed new light on these mysterious signals.

    + Info Search for Prompt Neutrino Emission from Gamma-Ray Bursts with IceCube, IceCube Collaboration: M.G. Aartsen et al. Submitted to Astrophysical Journal Letters, arxiv.org/abs/1412.6510

    See the full article here.

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    ICECUBE neutrino detector
    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma ray bursts, and cataclysmic phenomena involving black holes and neutron stars. The IceCube telescope is a powerful tool to search for dark matter, and could reveal the new physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

  • richardmitnick 2:58 pm on December 22, 2014 Permalink | Reply
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    From JPL: “Sun Sizzles in High-Energy X-Rays” 


    December 22, 2014
    Whitney Clavin
    Jet Propulsion Laboratory, Pasadena, Calif.

    For the first time, a mission designed to set its eyes on black holes and other objects far from our solar system has turned its gaze back closer to home, capturing images of our sun. NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has taken its first picture of the sun, producing the most sensitive solar portrait ever taken in high-energy X-rays.


    “NuSTAR will give us a unique look at the sun, from the deepest to the highest parts of its atmosphere,” said David Smith, a solar physicist and member of the NuSTAR team at University of California, Santa Cruz.

    Solar scientists first thought of using NuSTAR to study the sun about seven years ago, after the space telescope’s design and construction was already underway (the telescope launched into space in 2012). Smith had contacted the principal investigator, Fiona Harrison of the California Institute of Technology in Pasadena, who mulled it over and became excited by the idea.

    “At first I thought the whole idea was crazy,” says Harrison. “Why would we have the most sensitive high energy X-ray telescope ever built, designed to peer deep into the universe, look at something in our own back yard?” Smith eventually convinced Harrison, explaining that faint X-ray flashes predicted by theorists could only be seen by NuSTAR.

    While the sun is too bright for other telescopes such as NASA’s Chandra X-ray Observatory, NuSTAR can safely look at it without the risk of damaging its detectors. The sun is not as bright in the higher-energy X-rays detected by NuSTAR, a factor that depends on the temperature of the sun’s atmosphere.

    NASA Chandra Telescope
    NASA Chandra schematic
    Chandra X-ray space observatory

    X-rays stream off the sun in this image showing observations from by NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, overlaid on a picture taken by NASA’s Solar Dynamics Observatory (SDO) .Image credit: NASA/JPL-Caltech/GSFC

    NASA Solar Dynamics Observatory
    NASA Solar Dynamics Observatory schematic

    This first solar image from NuSTAR demonstrates that the telescope can in fact gather data about sun. And it gives insight into questions about the remarkably high temperatures that are found above sunspots — cool, dark patches on the sun. Future images will provide even better data as the sun winds down in its solar cycle.

    “We will come into our own when the sun gets quiet,” said Smith, explaining that the sun’s activity will dwindle over the next few years.

    With NuSTAR’s high-energy views, it has the potential to capture hypothesized nanoflares — smaller versions of the sun’s giant flares that erupt with charged particles and high-energy radiation. Nanoflares, should they exist, may explain why the sun’s outer atmosphere, called the corona, is sizzling hot, a mystery called the “coronal heating problem.” The corona is, on average, 1.8 million degrees Fahrenheit (1 million degrees Celsius), while the surface of the sun is relatively cooler at 10,800 Fahrenheit (6,000 degrees Celsius). It is like a flame coming out of an ice cube. Nanoflares, in combination with flares, may be sources of the intense heat.

    If NuSTAR can catch nanoflares in action, it may help solve this decades-old puzzle.

    “NuSTAR will be exquisitely sensitive to the faintest X-ray activity happening in the solar atmosphere, and that includes possible nanoflares,” said Smith.

    What’s more, the X-ray observatory can search for hypothesized dark matter particles called axions. Dark matter is five times more abundant than regular matter in the universe. Everyday matter familiar to us, for example in tables and chairs, planets and stars, is only a sliver of what’s out there. While dark matter has been indirectly detected through its gravitational pull, its composition remains unknown.

    It’s a long shot, say scientists, but NuSTAR may be able spot axions, one of the leading candidates for dark matter, should they exist. The axions would appear as a spot of X-rays in the center of the sun.

    Meanwhile, as the sun awaits future NuSTAR observations, the telescope is continuing with its galactic pursuits, probing black holes, supernova remnants and other extreme objects beyond our solar system.

    NuSTAR is a Small Explorer mission led by Caltech and managed by NASA’s Jet Propulsion Laboratory, also in Pasadena, for NASA’s Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Virginia. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA’s Goddard Space Flight Center, Greenbelt, Maryland; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, California; ATK Aerospace Systems, Goleta, California; and with support from the Italian Space Agency (ASI) Science Data Center.

    NuSTAR’s mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Rohnert Park, California. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

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    NASA JPL Campus

    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge [1], on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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  • richardmitnick 2:24 pm on December 22, 2014 Permalink | Reply
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    From New Scientist: “Europa’s geysers disappear in a cloud of mystery” 


    New Scientist

    19 December 2014
    Adam Mann

    Now you see it, now you don’t. Now you see it, now you don’t. Now you see it, now you don’t. Europa’s 200-kilometre-high water jets may have been downgraded from major discovery to major mystery. Follow-up searches have yet to see the geysers again, while older observations don’t seem to support their existence. Some people are now wondering if the jets are far rarer than expected – or if they were ever there to begin with.


    “It’s a real puzzle now,” said Donald Shemansky of the University of Southern California in Los Angeles, who presented the analysis of spacecraft data at the American Geophysical Union conference in San Francisco on 18 December that contradicted the idea of regularly erupting plumes.

    We already suspected that Jupiter’s icy moon Europa had a vast ocean of water beneath its frozen crust. But excitement surged last year when a team led by Lorenz Roth of the Southwest Research Institute in San Antonio, Texas, announced that the Hubble Space Telescope had spotted a small bump of water coming from Europa’s south pole, meaning the moon was shooting its insides out into space.

    NASA Hubble Telescope
    NASA Hubble schematic
    NAS/ESA Hubble

    This made the moon an ideal target for orbital probes to attempt to fly through the jets and detect the presence of life.

    Shy geysers

    But the geysers have yet to reappear. That doesn’t necessarily mean they don’t exist, says Roth – but they “are more transient than we would have hoped”.

    Shemansky’s results further muddle the spouting waters. His team looked at data from NASA’s Cassini spacecraft, which flew by Jupiter in 2001 on its way to Saturn.

    NASA Cassini Spacecraft

    Another moon of Jupiter, Io, is extremely active, with constant volcanic eruptions on its surface that shoot charged particles of sulphur and oxygen out into space. These ions get swept up in Jupiter’s strong magnetic field, forming a ring of plasma around the gas giant.


    If Europa’s plumes had been active in 2001, some of their water molecules should have been split by Jupiter’s radiation and dumped hydrogen atoms into space. For a short time, these hydrogen atoms would have joined Jupiter’s plasma torus, cooling the other charged particles.

    Thin air

    But when Shemansky and his team looked at the Cassini data, they saw nothing like that. Furthermore, they argue that Europa’s atmosphere is about two orders of magnitude thinner than previously believed, which seems impossible if it is regularly being replenished with water from the inside.

    Not so fast, says Kurt Retherford, also of the Southwest Research Institute and another of the plume’s original discoverers. Cassini zipped by Jupiter at a significant distance, making hydrogen atoms difficult to detect even if they were present.

    “We would say using their technique, they couldn’t possibly find water,” he said.

    Retherford, Roth and their colleagues are now preparing a paper to rebut Shemansky’s analysis. Their main worry is about how Shemansky was modelling the plasma around Jupiter.

    “It contradicts everything that’s been done before in Europa’s environment,” said Roth.

    At the limits

    The original detection of plumes was at the limit of Hubble’s capabilities, and finding them again may be difficult for many reasons. Until a definitive repeat observation is made, many in the field are hedging their bets.

    “The Hubble observation was so borderline that maybe they were fooled, or they got lucky and caught an event that’s not so common,” said Robert Pappalardo of NASA’s Jet Propulsion Laboratory in Pasadena, California.

    NASA is expected to decide next year whether to send a robotic mission to the frozen moon, so knowing if the jets are real will be crucial in guiding how researchers design instruments to either try to confirm their existence or sample their contents.

    Whether the geysers exist or not, Pappalardo still sees Europa as a great scientific destination. “Either way, the plumes certainly kicked Europa up in the public consciousness.” 200-kilometre-high water jets may have been downgraded from major discovery to major mystery. Follow-up searches have yet to see the geysers again, while older observations don’t seem to support their existence. Some people are now wondering if the jets are far rarer than expected – or if they were ever there to begin with.

    “It’s a real puzzle now,” said Donald Shemansky of the University of Southern California in Los Angeles, who presented the analysis of spacecraft data at the American Geophysical Union conference in San Francisco on 18 December that contradicted the idea of regularly erupting plumes.

    We already suspected that Jupiter’s icy moon Europa had a vast ocean of water beneath its frozen crust. But excitement surged last year when a team led by Lorenz Roth of the Southwest Research Institute in San Antonio, Texas, announced that the Hubble Space Telescope had spotted a small bump of water coming from Europa’s south pole, meaning the moon was shooting its insides out into space.

    This made the moon an ideal target for orbital probes to attempt to fly through the jets and detect the presence of life.

    Whether the geysers exist or not, Pappalardo still sees Europa as a great scientific destination. “Either way, the plumes certainly kicked Europa up in the public consciousness.”

    See the full article here.

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  • richardmitnick 2:02 pm on December 22, 2014 Permalink | Reply
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    From livescience: “Medieval City’s Underground Ruins Discovered in England” 


    December 16, 2014
    Kelly Dickerson

    Archaeologists have uncovered the network of a medieval city in England that dates back to the late 11th century.

    The settlement, which includes a cathedral and a castle, is located at the historic site of Old Sarum, near Salisbury. In its heyday, the city thrived for about 300 years, but eventually declined in the 13th century, with the Roman conquest and the rise of New Sarum, the researchers said. Archaeologists have long known that the medieval city existed in Old Sarum, but this is the first detailed layout of the city ever created.

    Archaeologists have uncovered the layout of a medieval city near Salisbury, England.
    Credit: English Heritage

    Model of Castle and Cathedral of Old Sarum as they would have appeared in the latter part of the 12th century, by John B. Thorp, London, 1927. View from West. Scale of 32 feet to an inch. Exhibited in the cloister of Salisbury Cathedral.
    Date 22 May 2013

    “Our survey shows where individual buildings are located and from this we can piece together a detailed picture of the urban plan within the city walls,” Kristian Strutt, an archaeologist from the University of Southampton who is working on the site, said in a statement.

    Strutt and the team discovered a series of huge structures that line the southern edge of the city’s outer wall. The archaeologists think the structures are remnants of large defensive buildings that were designed to protect the city.

    The team also found evidence of residential homes clustered in the southeastern and southwestern corners, between the outer and inner city walls. Old mineral deposits scattered throughout the site may be remnants of kilns or furnaces. Some evidence suggests the city may have been lived in again for a brief period after the 1300s.

    The Old Sarum site belongs to English Heritage, an organization that advises the English government on historical sites. Because English Heritage wants to preserve the site, Strutt and the team of researchers didn’t rely on traditional, Indiana Jones-style excavation tools. Instead, the researchers scanned the site using a series of noninvasive, high-tech survey techniques.

    Archaeology tools have grown increasingly more sophisticated, and archaeologists are even using 3D-printed drones to explore sites now. For the Old Sarum survey, the team started by using magnetometry, a method that measures patterns in magnetic field strength. Magnetometry can create a map of features lying just below the Earth’s surface, since every material has a unique magnetic property that leaves its own distinct signature on a magnet reader. The researchers also used ground-penetrating radar (GPR), which fires Earth-penetrating microwaves at the ground and measures signals that reflect off structures lying below the surface.

    The team also used a method called electrical resistivity tomography (ERT) . ERT is a noninvasive way to get a picture of structures that might be buried deeper than magnetometers or GPR can detect. The method involves strands of electrodes lowered into deep boreholes. The electrodes can pick up the electrical resistance of currents that pass through materials buried below the surface.

    See the full article here.

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  • richardmitnick 6:15 am on December 22, 2014 Permalink | Reply
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    From MIT: “Trapping light with a twister” 

    MIT News

    December 22, 2014
    David L. Chandler | MIT News Office

    New understanding of how to halt photons could lead to miniature particle accelerators, improved data transmission.

    Researchers at MIT who succeeded last year in creating a material that could trap light and stop it in its tracks have now developed a more fundamental understanding of the process. The new work — which could help explain some basic physical mechanisms — reveals that this behavior is connected to a wide range of other seemingly unrelated phenomena.

    Plot of radiative quality factor as a function of wave vector for a photonic crystal slab. At five positions, this factor diverges to infinity, corresponding to special solutions of Maxwell equations called bound states in the continuum. These states have enough energy to escape to infinity but remain spatially localized. Courtesy of the researchers

    The findings are reported in a paper in the journal Physical Review Letters, co-authored by MIT physics professor Marin Soljačić; postdocs Bo Zhen, Chia Wei Hsu, and Ling Lu; and Douglas Stone, a professor of applied physics at Yale University.

    Light can usually be confined only with mirrors, or with specialized materials such as photonic crystals. Both of these approaches block light beams; last year’s finding demonstrated a new method in which the waves cancel out their own radiation fields. The new work shows that this light-trapping process, which involves twisting the polarization direction of the light, is based on a kind of vortex — the same phenomenon behind everything from tornadoes to water swirling down a drain.

    In addition to revealing the mechanism responsible for trapping the light, the new analysis shows that this trapped state is much more stable than had been thought, making it easier to produce and harder to disturb.

    “People think of this [trapped state] as very delicate,” Zhen says, “and almost impossible to realize. But it turns out it can exist in a robust way.”

    In most natural light, the direction of polarization — which can be thought of as the direction in which the light waves vibrate — remains fixed. That’s the principle that allows polarizing sunglasses to work: Light reflected from a surface is selectively polarized in one direction; that reflected light can then be blocked by polarizing filters oriented at right angles to it.

    But in the case of these light-trapping crystals, light that enters the material becomes polarized in a way that forms a vortex, Zhen says, with the direction of polarization changing depending on the beam’s direction.

    Because the polarization is different at every point in this vortex, it produces a singularity — also called a topological defect, Zhen says — at its center, trapping the light at that point.

    Hsu says the phenomenon makes it possible to produce something called a vector beam, a special kind of laser beam that could potentially create small-scale particle accelerators. Such devices could use these vector beams to accelerate particles and smash them into each other — perhaps allowing future tabletop devices to carry out the kinds of high-energy experiments that today require miles-wide circular tunnels.

    The finding, Soljačić says, could also enable easy implementation of super-resolution imaging (using a method called stimulated emission depletion microscopy) and could allow the sending of far more channels of data through a single optical fiber.

    “This work is a great example of how supposedly well-studied physical systems can contain rich and undiscovered phenomena, which can be unearthed if you dig in the right spot,” says Yidong Chong, an assistant professor of physics and applied physics at Nanyang Technological University in Singapore who was not involved in this research.

    Chong says it is remarkable that such surprising findings have come from relatively well-studied materials. “It deals with photonic crystal slabs of the sort that have been extensively analyzed, both theoretically and experimentally, since the 1990s,” he says. “The fact that the system is so unexotic, together with the robustness associated with topological phenomena, should give us confidence that these modes will not simply be theoretical curiosities, but can be exploited in technologies such as microlasers.”

    The research was partly supported by the U.S. Army Research Office through MIT’s Institute for Soldier Nanotechnologies, and by the Department of Energy and the National Science Foundation.

    See the full article here.

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  • richardmitnick 5:32 am on December 22, 2014 Permalink | Reply
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    From RAS: “The Milky Way’s new neighbour” 

    Royal Astronomical Society

    Royal Astronomical Society

    19 December 2014
    Media contact
    Robert Massey
    Royal Astronomical Society
    Mob: +44 (0)794 124 8035

    Science contact
    Prof Dimitry Makarov
    Special Astrophysical Observatory
    Nizhniy Arkhyz
    Tel: +7 87822 93404

    The Milky Way, the galaxy we live in, is part of a cluster of more than 50 galaxies that make up the ‘Local Group’, a collection that includes the famous Andromeda galaxy and many other far smaller objects. Now a Russian-American team have added to the canon, finding a tiny and isolated dwarf galaxy almost 7 million light years away. Their results appear in Monthly Notices of the Royal Astronomical Society.

    Local Group

    The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years away in the constellation Andromeda. The image also shows Messier Objects 32 and 110, as well as NGC 206 (a bright star cloud in the Andromeda Galaxy) and the star Nu Andromedae. This image was taken using a hydrogen-alpha filter.
    Adam Evans

    The team, led by Prof Igor Karachentsev of the Special Astrophysical Observatory in Karachai-Cherkessia, Russia, found the new galaxy, named KKs3, using the Hubble Space Telescope Advanced Camera for Surveys (ACS) in August 2014. Kks3 is located in the southern sky in the direction of the constellation of Hydrus and its stars have only one ten-thousandth of the mass of the Milky Way.

    NASA Hubble Telescope
    NASA Hubble schematic

    NASA Hubble ACS
    HUbble ACS

    The core of the galaxy is the right hand dark object at the top centre of the image, with its stars spreading out over a large section around it. (The left hand of the two dark objects is a much nearer globular star cluster.) Credit: D. Makarov. Kks3 is a ‘dwarf spheroidal or dSph galaxy’ , lacking features like the spiral arms found in our own galaxy. These systems also have an absence of the raw materials (gas and dust) needed for new generations of stars to form, leaving behind older and fainter relics. In almost every case, this raw material seems to have been stripped out by nearby massive galaxies like Andromeda, so the vast majority of dSph objects are found near much bigger companions.

    Isolated objects must have formed in a different way, with one possibility being that they had an early burst of star formation that used up the available gas resources. Astronomers are particularly interested in finding dSph objects to understand galaxy formation in the universe in general, as even HST struggles to see them beyond the Local Group. The absence of clouds of hydrogen gas in nebulae also makes them harder to pick out in surveys, so scientists instead try to find them by picking out individual stars.

    For that reason, only one other isolated dwarf spheroidal, KKR 25, has been found in the Local Group, a discovery made by the same group back in 1999.

    Team member Prof Dimitry Makarov, also of the Special Astrophysical Observatory, commented: “Finding objects like Kks3 is painstaking work, even with observatories like the Hubble Space Telescope. But with persistence, we’re slowly building up a map of our local neighbourhood, which turns out to be less empty than we thought. It may be that are a huge number of dwarf spheroidal galaxies out there, something that would have profound consequences for our ideas about the evolution of the cosmos.”

    The team will continue to look for more dSph galaxies, a task that will become a little easier in the next few years, once instruments like the James Webb Space Telescope and the European Extremely Large Telescope begin service.

    See the full article here.

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    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

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