News this Week

Science  21 Oct 2011:
Vol. 334, Issue 6054, pp. 294
  1. Around the World

    1 - London
    Royal Society: Plan Ahead For Nuclear Power
    2 - Sriharikota, India
    Monsoon Satellite Promises Data Deluge
    3 - Indian Ocean
    Tsunami Warning System Passes Critical Test
    4 - Moscow
    Russian Scientists Rally to Protest Funding Freeze
    5 - Klong Luang, Pathum Thani, Thailand
    Thai Floods Spare Research Park
    6 - Washington, D.C.
    House Panel Lays Out Spending Preferences

    London

    Royal Society: Plan Ahead For Nuclear Power

    Despite projections of low nuclear power growth in Europe and the United States, a renaissance of nuclear power construction in China, Southeast Asia, and Russia is likely, Britain's Royal Society notes in a report released 12 October. As a result, the report says, governments and international bodies need to develop long-term policies to account not only for safety but also for security, proliferation risk, and fuel cycle management.

    “Spent fuel can no longer be an after-thought and governments worldwide need to face up to this issue,” Roger Cashmore, head of the U.K. Atomic Energy Authority and chair of the Royal Society working group that drafted the report, said in a statement.

    The panel recommends that countries place their civil nuclear programs under international safeguards run by the International Atomic Energy Agency (IAEA), so that spent fuel cannot be diverted for weapons use. Countries that already have nuclear weapons should separate their civil and military nuclear programs. It also suggests setting up a World Nuclear Forum, made up of CEOs and government leaders, to discuss nuclear developments and responsibilities. http://scim.ag/nuclearUK

    Sriharikota, India

    Monsoon Satellite Promises Data Deluge

    The Indo-French satellite Megha Tropiques, tasked with helping scientists understand the water and energy balance that controls monsoons, launched successfully 12 October from the Indian space port Sriharikota on the Bay of Bengal.

    CREDIT: CNES

    The $125 million mission will study the dynamics of cloud formation over the tropics, and how climate change could be affecting the monsoon. As it circles Earth near the equator, Megha Tropiques will revisit the same regions more than a dozen times each day, simultaneously measuring water vapor, clouds, precipitation, and radiation. These multiple measurements, mission scientists say, will give unique insights into the minutiae of how clouds are born and die during the monsoon.

    India and France have agreed to make scientific data from the satellite freely available—a welcome prospect for atmospheric scientists, says Christian Kummerow at Colorado State University, Fort Collins. “It is a very exciting mission and we do look forward to receiving the data from its instruments.”

    Indian Ocean

    Tsunami Warning System Passes Critical Test

    Deluged.

    Damage in Phuket, Thailand, following the 2004 tsunami.

    CREDIT: REUTERS

    Twenty-three Indian Ocean nations came together on 12 October to test a new warning communications network that might save lives the next time the region is pummeled by a tsunami. The $100 million Indian Ocean Tsunami Warning and Mitigation System performed well, though not flawlessly, during a simulation modeled on the devastating tsunami of 26 December 2004 that killed over 230,000 people in 14 countries. Several countries also conducted dry runs of their own emergency response plans. India, Kenya, and Malaysia conducted evacuation drills. An actual warning will depend on rapidly analyzing data from numerous seismic stations, instrumented buoys, and sea-floor pressure sensors deployed over the past 6 years, and spreading the word through the networks tested last week.

    The Intergovernmental Oceanographic Commission, a part of the United Nations Educational, Scientific and Cultural Organization, which coordinated development of the system, declared the test a success. Australia, India, and Indonesia will now take responsibility for issuing warnings to the region. The Japan Meteorological Agency and the United States' Pacific Tsunami Warning Center have issued regional warnings since 2005.

    Moscow

    Russian Scientists Rally to Protest Funding Freeze

    Hundreds of researchers, many in lab coats, rallied in Moscow's Pushkin Square 13 October to protest a funding freeze at Russia's two grant organizations and on procurement regulations that they call major obstacles to research. The rally was organized by the trade union of the Russian Academy of Sciences (RAS) and the Young Scientists Council, together with associations of Moscow State University students, and young scientists.

    The Russian government recently froze the budgets for Russia's two funding agencies, the Russian Foundation for Basic Research (RFBR) and the Russian Foundation for Humanities (RFH), leaving only $200 million for both agencies. Protestors urged the government to restore the old rule, under which RFBR received 6% of the overall budget for civilian science and RFH 1%. The protestors also demanded radical reform of laws governing public procurement, which severely limit grantees' freedom to spend the money as they see fit.

    “This rally is a warning,” says Evgeny Onishchenko of the RAS Institute of Physics, one of the organizers. “We want to make it clear that if nothing is done to meet our demands, there will be much more serious rallies of researchers all over the country.”

    Klong Luang, Pathum Thani, Thailand

    Thai Floods Spare Research Park

    Flood waters creeping toward Thailand's biggest research park forced the evacuation of dozens of public and private labs last week. The Thailand Science Park, 30 kilometers north of Bangkok, is home to 2700 employees working in four national research institutes under the National Science and Technology Development Agency as well as in the labs of 60 private companies.

    The campus closed 13 October; although the science park was still dry on Monday, it remained closed through 19 October due to high water in surrounding areas. The flooding, the worst in 50 years, has already claimed more than 300 lives and, according to a Businessweek report, caused over $5.1 billion in damage.

    Washington, D.C.

    House Panel Lays Out Spending Preferences

    A climate-science satellite, some technology commercialization efforts, and a chemical risk assessment program are all among the federal R&D programs that Republican leaders of the House of Representatives Committee on Science, Space, and Technology would cut to rein in the U.S. budget deficit. The ideas, which also include protecting the core budgets of the National Science Foundation (NSF) and the Department of Energy's (DOE's) Office of Science, were highlighted in an unusually detailed 14-page letter that the lawmakers sent on 14 October to Congress's bipartisan Joint Select Committee on Deficit Reduction, which must devise a plan to trim at least $1.2 trillion from the deficit over 10 years.

    In general, the Republican lawmakers took a back-to-basics approach, arguing for protecting traditional science programs while trimming many newer efforts championed by the Obama Administration. They took an especially dim view of climate-related research; taxpayers could save $149 million over 5 years, for instance, by axing NASA's Orbiting Carbon Observatory-2, designed to map greenhouse gas emissions. They would phase out DOE's Advanced Research Projects Agency–Energy (ARPA-E), saving $180 million. All told, they proposed cuts totaling $1.5 billion.

    The panel's ranking Democrat, meanwhile, penned a less specific plea for sparing the knife and fattening the federal purse. When it comes to funding science, it is “critically important” for the committee to “include serious revenue enhancements in its set of recommendations,” wrote Representative Eddie Bernice Johnson (D–TX). Neither letter is likely to have a major impact on the deficit committee, which faces a 23 November deadline for delivering its plan.

  2. Random Sample

    They Said It

    “If I'm going to take money from a citizen to put into education then I'm going to take that money to create jobs. So I want that money to go to degrees where people can get jobs in this state. Is it a vital interest of the state to have more anthropologists? I don't think so.”

    —Florida Governor Rick Scott (R) to the Sarasota Herald-Tribune on 10 October.

    Making the Invisible Visible

    CREDIT: © NANCY KEDERSHA

    For her colorful microscopy images that reveal the once-hidden secrets of cells, biochemist Nancy Kedersha has won the Lennart Nilsson Award for scientific and medical photography, presented annually in honor of Swedish photographer Lennart Nilsson. The award comes with a cash prize of SEK 100,000 (about $15,500). Kedersha will receive the award at a ceremony 8 November at the Berwald Hall in Stockholm, Sweden.

    “Nancy Kedersha's colour images open our eyes to the smallest components of life,” the award selection panel stated in a press release 14 October. “With the aid of a confocal microscope, she has turned biological data into an artistic experience.”

    Kedersha is a researcher at Harvard Medical School and director of the confocal microscopy core at Brigham and Women's Hospital in Boston. While working in the lab of biochemist and cell biologist Leonard Rome at the University of California, Los Angeles, in the 1980s, Kedersha developed a technique to stain and photograph cells to reveal their inner workings. Using this technique, she co-discovered a mysterious organelle called a vault that exists in everything from humans to slime molds. She has continued to develop techniques to identify different cell functions, distinguish healthy cells from cancerous ones, and observe cells dividing.

    Nearly Intact Dino Fossil Found in Germany

    CREDIT: © MINERALIENTAGE MÜNCHEN

    An exceptionally well-preserved baby dinosaur, with traces of skin and protofeathers, will be the main attraction at a fossil and gem show next week in Munich. The juvenile theropod, which lived between 145 million and 150 million years ago and was probably less than a year old when it died, is 98% intact. That makes it the most nearly complete dinosaur ever found in Europe, says Oliver Rauhut, curator at the Bavarian State Collection for Palaeontology and Geology in Munich, who led the first examinations of the fossil.

    The fossil's hairlike protofeathers may help researchers understand how and when feathers evolved. The roughly 70-cm specimen, not yet fully classified or named, was unearthed near the Bavarian town of Kelheim and has been registered as a German cultural artifact, which means that it can't leave the country. The mineral show will display the fossil for 4 days starting 27 October; a spokesperson for the show has said the unnamed owner plans to lend the fossil to a museum.

    By the Numbers

    1 billion tons — Amount of extra food that that could be grown on agricultural lands now devoted to animal feed and biofuel production, according to an analysis in this week's Nature.

    200,000 amps — Maximum power generated by a new airplane industry–sponsored lab at Cardiff University that studies the effects of lightning on materials. An average lightning strike generates 10,000 to 30,000 amps.

    The Story Is Dead. Long Live the Story.

    CREDIT: COURTESY JONATHON KEATS

    Artist and self-styled experimental philosopher Jonathon Keats is hoping to persuade the art world to join scientists in the Copernican Revolution—nearly 5 centuries late. In 1543, Nicolaus Copernicus made the humbling observation that the Earth revolves around the sun. Modern physicists often cite the “Copernican principle” that, as nature's rules are the same everywhere, the human viewpoint isn't unique.

    But the art world, Keats says, is still stubbornly Ptolemaic, in that it emphasizes the “exceptionalism” of humans and centers on stories about ourselves. So, in “The First Copernican Art Manifesto,” an exhibit that opened Thursday at the Modernism gallery in San Francisco, California, Keats will feature art that reflects banal, average truths about the universe.

    The pieces don't assume a human audience or viewpoint—and they don't aim to appeal to us, either. One canvas is painted a bland tan, the average color of the starlight of all stars measured by astronomers. Hydrogen gas released from glassware suspended above otherwise empty pedestals assumes a form invisible to human eyes. A quarter of the notes in a once-orderly Bach composition are rearranged—reflecting the increasing entropy of the universe since its tidy, pre–big bang singularity.

    Although not for humans, the exhibition is aimed at a particular demographic, in a way. “Were the aliens to land and see our show, they wouldn't say, ‘Now I understand humanity,’” Keats says. “They'd say, ‘Now I have a better understanding of the universe.’” The exhibit runs through the end of November.

  3. Newsmakers

    Dances With Titanium

    Fifty-five scientists around the world moonlighted as choreographers for Science's fourth annual “Dance Your Ph.D.” contest—and the results are in. This year's winning dances were based on protein x-ray crystallography, fruit-fly sex, and pigeon courtship, each scooping $500 prizes.

    CREDIT: JOEL MILLER

    The grand winner, announced 20 October, is Joel Miller, a biomedical engineer at the University of Western Australia in Perth. Miller's dance, which won the physics category, depicts his work with lasers to create titanium alloys strong and flexible enough for long-lasting hip replacements. “We didn't have a video camera,” says Miller. So he and his friends converted 2200 still photographs of the dance into stop-motion animation. In his winning entry, “Microstructure-Property relationships in Ti2448 components produced by Selective Laser Melting,” Miller, 32, flies in silvery spandex and a cape as he dances with women representing titanium's alpha and beta crystalline forms. He receives $1000 and a trip to Belgium to be crowned the winner on 22 November at TEDxBrussels.

    Category winners include “X-ray Crystal Structure of Human Protein Phosphatase,” by FoSheng Hsu of Cornell University (Chemistry); “Smell-Mediated Response to Relatedness of Potential Mates,” by Cedric Tan of the University of Oxford in the United Kingdom (Biology); and “A Study of Social Interactivity Using Pigeon Courtship,” by Emma Ware of Queen's University in Canada (Social Science). Videos of this year's 55 Ph.D. dances are at www.gonzolabs.org/dance.

  4. Particle Physics

    The Sterile Neutrino: Fertile Concept or Dead End?

    1. Adrian Cho

    Dozens of physicists gathered recently to debate whether the phantom particle exists and if it's worth hunting it.

    Mystery machine.

    The guts of the LSND detector, which may have seen sterile neutrinos.

    CREDIT: LOS ALAMOS NATIONAL LABORATORY

    BLACKSBURG, VIRGINIA—Unlike old soldiers, some scientific concepts seem never to fade away. Take the hypothetical subatomic particle called the “sterile neutrino,” which would be about the oddest bit of matter imaginable. For 15 years, researchers have accumulated hints from particle physics, nuclear physics, astrophysics, and cosmology that the particle—a more-elusive cousin of the nearly undetectable neutrinos—might be out there. But most physicists have found the evidence unconvincing, as most of the results pointing toward sterile neutrinos are of marginal statistical significance.

    Recently, however, the case for sterile neutrinos has grown stronger, bolstered by a new analysis of data from nuclear reactors. So last month 60 physicists from around the world gathered here* to hash out the arguments for and against the existence of sterile neutrinos and to try to decide whether it's worth staging a dedicated experiment to settle the matter.

    Performing such an experiment won't be easy. The hypothetical neutrinos are called sterile because they do not interact at all with known particles. “You're trying to prove the existence of something with no interactions,” says Patrick Huber, a theorist here at Virginia Polytechnic Institute and State University (Virginia Tech). “It's like trying to prove the existence of God.” Still, he says, it's time to figure out what it will take to discover or rule out sterile neutrinos once and for all. “I'm afraid we'll have the same workshop 15 years from now and will just have more [inconclusive] results that don't make the situation any clearer.”

    Some researchers say the case for a sterile neutrino is still half-baked. “I'm quite skeptical,” says Yves Déclais, a neutrino physicist at the University of Lyon in France. “Each piece of evidence itself is not completely self-consistent,” he says. “So I'm really concerned that there should be more work to understand each anomaly itself instead of trying to put together a dedicated experiment to look for sterile neutrinos.”

    Abundant in theory

    Ordinary neutrinos are already weird. Nearly massless and hardly interacting with other matter, they are born in “weak” nuclear decays and interactions. For example, a neutron decays into a proton by emitting an electron and an antineutrino. A neutrino can emerge when a nucleus of the isotope beryllium-7 turns into lithium-7 by capturing an electron and releasing a neutrino. Trillions of neutrinos stream through each of us every second.

    Weirder still, neutrinos come in three “flavors”—electron neutrinos, muon neutrinos, and tau neutrinos—that can morph into one another. For example, when cosmic rays strike the atmosphere, they create particles called muons that decay much as neutrons do, to produce muon neutrinos. The muon neutrinos can then “oscillate” or “mix” into other flavors before reaching Earth, as observed in 1998 by physicists using a giant subterranean detector called Super-Kamiokande in Japan. Electron neutrinos from the sun also change flavor, as physicists at the Sudbury Neutrino Observatory in Canada showed in 2001.

    A sterile neutrino would be even more elusive than an ordinary neutrino. It would not participate in weak interactions and would arise only from ordinary neutrinos oscillating into a sterile form. As sterile neutrinos would not interact themselves, physicists could detect them only indirectly, by observing ordinary neutrinos disappearing or appearing where they are not expected.

    Theorists have been thinking about sterile neutrinos since the late 1960s, when they first suspected that neutrinos from the sun oscillated. The morphing meant that neutrinos were not massless, and sterile neutrinos would help explain how the wispy particles put on weight.

    Flavor-changing oscillations prove that neutrinos have mass because a massless particle must travel at light speed, and, according to Einstein's theory of relativity, at light speed time stands still, making change impossible. The standard model of particle physics assumes that neutrinos are massless, but most extensions of the theory that fix that problem include sterile neutrinos, says Paul Langacker, a theorist at the Institute for Advanced Study in Princeton, New Jersey. “The sterile neutrino is not something bizarre or exotic,” he says.

    The details involve another key fact: As far as physicists know, all neutrinos spiral to the left, like footballs thrown by left-handed quarterbacks, and all antineutrinos spiral to the right. That would be fine if neutrinos traveled at unobtainable light speed. But as neutrinos have mass and travel slower, it's possible in principle for an observer to overtake a left-handed neutrino. The neutrino would then appear to travel the opposite way, as a right-handed neutrino—a particle not found in nature.

    Far out!

    Cosmic microwave background (top) and the map of the galaxies hint at an extra neutrino.

    CREDIT: NASA/WMAP SCIENCE TEAM; M. BLANTON AND THE SLOAN DIGITAL SKY SURVEY (SDSS) COLLABORATION, HTTP://WWW.SDSS.ORG

    Theorists have found two ways around this problem. First, when overtaken, an ordinary left-handed neutrino could appear instead as a heavy right-handed sterile neutrino. Or second, the overtaken neutrino could appear as a right-handed antineutrino. Even then, a theoretical “seesaw mechanism” would require heavy sterile neutrinos to explain why ordinary neutrinos are so light.

    That's plenty of reason to think sterile neutrinos are out there. However, most theories assume that sterile neutrinos are far heavier than ordinary neutrinos. For that reason and others, theory doesn't generally allow an ordinary neutrino to just morph into a sterile neutrino in the way some experiments indicate, Langacker says. So it's not clear that theorists and experimenters are stalking the same beast.

    Evidence of all sorts

    The strongest experimental evidence for sterile neutrinos comes from the Liquid Scintillator Neutrino Detector (LSND), which ran at Los Alamos National Laboratory in New Mexico from 1993 through 1998. Using a particle accelerator, physicists generated muon antineutrinos that streamed through a detector filled with 167 tons of mineral oil.

    Those low-energy muon antineutrinos should have passed right through. However, an electron antineutrino could interact with the detector by merging with a proton to create a positron and a neutron—essentially, the weak decay of the neutron run backward. Thus, physicists could spot electron antineutrinos appearing in a beam of muon antineutrinos. And they spotted 88 of them, give or take 23. “Lo and behold, we saw an excess of events,” says Los Alamos's William Louis.

    Reported in 1996 and 2001, the LSND results might seem to show muon antineutrinos mixing into electron antineutrinos. But it couldn't be that simple, Louis says. Different flavors of neutrinos mix at a rate that depends on the difference in their masses: The bigger the mass difference, the faster the mixing. Studies of atmospheric and solar neutrinos had placed limits on the mass differences among the three neutrino flavors, and the values were too low to explain the lickety-split mixing that LSND saw as the particles flew just 30 meters, Louis says.

    LSND researchers could explain their results, however, if muon antineutrinos oscillated first into sterile antineutrinos and then into electron antineutrinos. The sterile neutrinos would have to be heavier than ordinary neutrinos by 1 electron volt—about 100 times the differences among ordinary neutrinos.

    Hints of extra neutrinos also come from the heavens. For example, cosmologists think the universe burst into existence in the big bang as an ultrahot, ultradense soup of particles. Tiny fluctuations in the density of the soup then stretched to immense proportions during a faster-than-light growth spurt known as inflation and seeded the formation of galaxies. The fluctuations also limit the number of neutrino types, theorist Kevork Abazajian of the University of California, Irvine, said at the meeting.

    The density fluctuations can be thought of as waves of various wavelengths randomly piled on one another. The fluctuations' intensity and gravitational pull grow stronger as their wavelengths decreases; then the intensity peaks at a certain wavelength and starts to fall again. The position of that peak in a graph of intensity versus wavelength depends on the relative amounts of radiation and matter in the early universe. And because lightweight neutrinos acted like an additional form of radiation, the position of the peak also reveals the number of types of light neutrinos.

    To deduce the distribution and the peak in it, scientists measure tiny variations in the afterglow of the big bang—the cosmic microwave background radiation—across the sky, as NASA's space-borne Wilkinson Microwave Anisotropy Probe did from 2001 to 2010. Scientists also measure the distribution of the galaxies, as the Sloan Digital Sky Survey has done using a telescope at the Apache Point Observatory in New Mexico. The results suggest a fourth neutrino, Abazajian says. “There's a 1-in-20 chance that it's a statistical fluctuation, and those sorts of things go away all the time,” he says. “Still, it's intriguing that the data's converging to that value” of four types of neutrinos.

    The newest bit of evidence comes from nuclear reactors. Earlier this year, a team of theorists argued that reactors are putting out more electron antineutrinos than detectors tens of meters away show. The result suggests that some antineutrinos escape detection by morphing into sterile antineutrinos.

    Within a nuclear reactor, nuclei of the isotopes uranium-235, uranium-238, plutonium-239, and plutonium-241 split randomly to make myriad smaller nuclei that release copious antineutrinos. For example, a uranium-235 nucleus can split to make a nucleus of krypton-89. Krypton-89 then changes identity to rubidium-89, strontium-89, and yttrium-89, as one neutron after another in the nucleus spits out an electron and an antineutrino and turns into a proton. Thousands of other chains or “branches” of decays also occur.

    David Lhuillier of France's Alternative Energies and Atomic Energy Commission in Saclay and colleagues kept track of all those branches in a new calculation. Previous calculations showed that a score of reactor measurements taken over decades observed 97.6%, give or take 2.4%, of the expected antineutrino flux—fine agreement with the prediction. With the new calculation, the measurements average 94.3%, plus or minus 2.3%—a significant difference that suggests neutrinos are disappearing. “Before, all the experiments were in agreement with the prediction,” Lhuillier says. “Now everybody is below the prediction.” Physicists say this single result triggered the workshop.

    The disparate hints are tantalizing, says Joseph Formaggio of the Massachusetts Institute of Technology in Cambridge. “What's nice is that these anomalies come from different directions,” he says.

    Signs of discord

    Each clue comes with caveats, however. For example, starting in 2002, physicists tested the LSND result with the Mini-Booster Neutrino Experiment (MiniBooNE) at Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois. First, they fired muon neutrinos—instead of LSND's muon antineutrinos—450 meters into a detector filled with 800 tons of mineral oil. In 2007, they saw signs of electron neutrinos appearing in the muon neutrino beam, but with the wrong energy to mirror the process seen in LSND with antineutrinos. The result dampened enthusiasm for sterile neutrinos.

    MIA.

    New calculations suggest that nuclear reactors put out more neutrinos than are observed.

    CREDIT: ARMEL BRUCELLE/SYGMA/CORBIS

    But last year, the researchers reported that using muon antineutrinos, they see electron antineutrinos appearing as LSND did, albeit at lower statistical significance. “The excess in the MiniBooNE antineutrino data agrees beautifully with what you would expect from LSND,” says Louis, who also works on MiniBooNE. But it also makes matters more complicated. To explain why the effect appears only for antineutrinos, physicists need to add two sterile neutrinos to their theory.

    The cosmological evidence for sterile neutrinos also comes with qualifications, says Yvonne Wong of RWTH Aachen University in Germany. The unknown particles scientists might be glimpsing in cosmic radiation are significantly lighter than the sterile neutrinos hinted at by LSND and MiniBooNE. They aren't even necessarily true neutrinos, Wong says, but could be any feebly interacting particle.

    Even the newfound “reactor anomaly” has not bowled skeptics over. Petr Vogel, a theorist at the California Institute of Technology in Pasadena, who worked on the original reactor calculations 30 years ago, says the new calculations are undoubtedly more thorough and realistic than the old ones. However, they still leave out important details that might make the falloff in neutrinos less impressive, Vogel says. “I think what has been done is state of the art, and the shift [in the prediction] looks reasonable to me,” Vogel says. “But whether the error is really 2.3% remains to be seen.”

    Finally, the signs of sterile neutrinos may not agree with one another, says Thomas Schwetz-Mangold of the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, who presented a “global fit” to all the data. In particular, if ordinary neutrinos quickly oscillate into sterile neutrinos, then experiments that send muon neutrinos to distant detectors should see a decrease in the total number of neutrinos reaching their detectors. But experiments such as Fermilab's Main Injector Neutrino Oscillation Search, which fires neutrinos 735 kilometers to a detector in Minnesota, see no such loss. “If I take everything at face value, then the probability is less than a percent that it all fits together,” Schwetz-Mangold says.

    The killer experiment

    In spite of the odds, some experimenters are still eager to hunt sterile neutrinos. Plans vary widely, but physicists generally agree on what a killer experiment must do. If ordinary neutrinos morph into sterile neutrinos and back, then the number of ordinary neutrinos in a beam should go up and down as the neutrinos fly away from their source. So scientists would have to spot that spatial oscillation over tens of meters.

    The easiest way would be to add a second detector to the MiniBooNE experiment closer to the neutrino source or to move the existing detector. The rate at which electron antineutrinos appear should then change. Building a second detector 200 meters from the source would cost $10 million, Geoffrey Mills, a MiniBooNE team member from Los Alamos, said at the conference. Alternatively, researchers could move the current detector for about $5 million, he reported.

    Adding the second detector to MiniBooNE is a must-do, some researchers say. But Roxanne Guenette of Yale University warned that a definitive measurement would likely take two more-expensive new detectors.

    Others want to look for the oscillation of electron neutrinos by putting an intense radioactive source inside a jumbo detector. The number of electron neutrino detections should go up and down as the distance within the detector from the source increases. Virginia Tech's Jonathan Link proposes placing a chromium-51 source in the center of the Sudbury Neutrino Observatory, which is a sphere filled with 1000 tons of heavy water.

    The source should cost less than $3 million, Link says. “I do believe that this is the cheapest option that has some chance of making some sort of statement about the LSND-type sterile neutrino,” he says. Gioacchino Ranucci of Italy's National Institute of Nuclear Physics in Milan presented a proposal to place a source under the 270-ton Borexino detector in Italy's subterranean Gran Sasso National Laboratory.

    Hanging over all of this is the question of money, as the United States particle physics budget has been stuck at $800 million for years. Virginia Tech's Ramaswamy Raghavan is developing the Low Energy Solar Neutrino Spectrometer detector, which would study solar neutrinos and, with a radioactive source, could look for sterile neutrinos. It would cost $50 million to $75 million. “Can you predict in the current fiscal situation in the U.S. that this is going to happen?” Raghavan says.

    To help make the case for funding, conference attendees plan to write a white paper laying out the options. There's some urgency, says Huber, the Virginia Tech theorist who helped organize the meeting. “I don't want to do sterile neutrinos my whole career,” he says. He doesn't say whether the ephemeral beast will continue to entice him if no definitive answer is quick in coming.

    • * Sterile Neutrinos at the Crossroads, 26–28 September.

  5. Human Subject Research

    Social Science for Pennies

    1. John Bohannon

    Social scientists are turning to online retail giant Amazon.com to cheaply recruit people around the world for research studies

    Global pool.

    This map shows a 10% sample of workers (red) available on Amazon.com's Mechanical Turk.

    CREDIT: PANOS IPEIROTIS & DAHN TAMIR, NEW YORK UNIVERSITY/GOOGLE FUSION TABLES

    It's a problem that all social scientists face. You have a brilliant idea for a study. You have the experimental design all worked out, and your university's review board has approved it. But you still have to recruit hundreds of people as subjects for the experiment.

    Gabriel Lenz, a political scientist at the University of California, Berkeley, faced this problem last year when he and collaborators wanted to follow up on another group's study of voting behavior (Science, 10 June 2005, p. 1623). For that study, Americans were shown photographs of past U.S. congressional candidates and asked to rate the politicians on various characteristics, such as competence and attractiveness. Even though the study subjects had no information beyond an image of the candidates' faces, their snap judgments were a significant predictor of who actually won the races. Lenz wanted to see if that surprising result collapsed when those evaluating the photos come from cultures different from those of the candidates. But how to recruit people living in multiple countries?

    Lenz and his research assistant Michael Myers had an idea: Why not order research subjects through Amazon.com? The company runs an online marketplace called Mechanical Turk for people across the world available to do work on computers. (The name is a reference to an 18th century chess-playing “machine” that actually worked by virtue of a man hidden inside.) For tiny sums, anyone can hire people to perform almost any kind of simple task, such as tagging items in images. Lenz's experiment required people to look at photographs of Brazilian political candidates and fill in a data sheet.

    But first, he and his colleagues had to decide on how much they would pay each participant. Those offering a job through MTurk, known as requestors, compete with each other to recruit Turkers, the 500,000 people currently registered with the MTurk site as available for work. The task of rating the political candidate photos required about 4 minutes. “We played around with various payment rates,” Lenz says. For Turkers based in India, the researchers started low, offering 15 cents. In just 4 days, they received data from 100 people. Then for a control group, they recruited more than 300 Americans for between 20 and 50 cents each. The total cost? About $160, and that includes the 10% fee Amazon charges.

    In just a few weeks, Lenz had all the data his group needed. In spite of the cultural differences, the snap-judgment effect persisted: American and Indian subjects predicted the winners of Brazilian political races based on nothing more than a mug shot, the researchers reported last year in the social science journal World Politics.

    As others follow Lenz's lead, many more social science papers using MTurk will appear in the coming years, predicts Adam Berinsky, a political scientist at the Massachusetts Institute of Technology in Cambridge. “Everyone I know is using it,” he says. For example, social scientists used 10,000 Turkers to create a tool for tracking the emotional content of Twitter messages (Science, 30 September, p. 1814).

    For now, most researchers are using MTurk for pilot studies, quickly and cheaply testing online versions of experiments that they then perform with subjects face to face. But the use of MTurk subjects will eventually become mainstream, Berinsky says. The obvious advantage is the speed and cost. “Generally, we pay $8 for a 15- to 20-minute experiment in a lab. We can run the same study on MTurk for 75 cents to a dollar.”

    There are other advantages. “Turkers are amazingly focused research subjects,” Berinsky says. Unlike the typical university undergraduates used for social science studies, Turkers get paid only if they generate usable data. This is necessary to eliminate not only people who don't understand the task but also “spammers,” people who try to exploit MTurk by skimming through the jobs and giving random responses wherever possible to accelerate the process.

    For example, Lenz had to reject about 20% of his American and 50% of his Indian Turkers for those reasons. But that is a manageable problem, Berinsky says. A counterintuitive solution is to keep the price low. “If you offer more than a dollar, you attract the spammers who sort jobs by level of pay,” he says. “You have to find the sweet spot where the payment is not too high but still attractive enough for most Turkers.” So far, that sweet spot seems to be between 15 and 50 cents for a 10-minute job.

    Even if MTurk is cheap and fast, doubts will linger about interpreting data from research subjects whom you never meet. To address those concerns, Berinsky and Lenz are teaming up with Gregory Huber, a political scientist at Yale University, to study the Turker population. And of course, they are using MTurk to do so. They recently replicated two classic survey experiments and a political science experiment. In each case, the data obtained with MTurk were consistent with published studies that tested people in laboratories.

    The scientists have found some differences, too. Turkers “are younger and more ideologically liberal than the U.S. public,” Berinsky says. However, they are more representative of the U.S. population than a typical cohort of university undergraduates.

    There is one long-term concern: the “super-Turkers,” people who are essentially professional workers on MTurk, some of them logging more than 20 hours per week. Many social science experiments rely on the subjects not knowing the researchers' intentions. Berinsky says super-Turkers could potentially skew experiments if they try too hard to please researchers. There is incentive to do that because MTurk uses a reputation system. If a Turker does not have at least a 95% positive approval rating from their requestors, they'll often go unhired.

    “Mechanical Turk seems like the proverbial goose that lays the golden eggs,” Berinsky says. “But I worry that in the rush for cheap research subjects, we're going to trample the goose to death.”

  6. Network Science

    Open-Source Ecology Takes Root Across the World

    1. Erik Stokstad

    A new collaboration of volunteer research sites is running simple yet powerful experiments to shed light on global change in grasslands.

    Standardized.

    Researchers worldwide add nutrients and measure plots the same way.

    CREDIT: JOSLIN MOORE; CHENGJIN CHU; SCOTT COLLINS; YANN HAUTIER; PETER ADLER; T. MICHAEL ANDERSON

    In 2005, a handful of young researchers in Santa Barbara, California, were fed up with their inability to answer a major ecological question by reviewing the literature. So they decided to take matters into their own hands and created a network of small experiments. In the past 6 years, the network has spread to six continents and is now poised to make substantial contributions to ecology. “We're on the edge of something big,” says John Orrock of the University of Wisconsin, Madison, a network co-founder.

    The half-dozen Ph.D. students and postdocs were part of a workshop at the National Center for Ecological Analysis and Synthesis (NCEAS) in Santa Barbara. The group was investigating fundamental influences on the structure of grasslands, such as herbivory and nutrients. Trying to analyze data from far-flung places, the group was stymied by a common obstacle. “It's really frustrating because everyone does their studies differently,” says Elizabeth Borer, who is now at the University of Minnesota, Twin Cities.

    Diversity.

    NutNet sites include 1747 plant taxa in many ecosystems, such as (see photos, left to right) subalpine grassland, alpine meadow, desert, pasture, sagebrush steppe, and savanna.

    CREDIT: ELIZABETH BORER

    During a coffee break at NCEAS, Borer and a few others hatched a plan: They would each set up a small research plot, use the same methods, then pool their data. The vision was a network of sites that would be quick and cheap to set up without the need for major grants, enabling simple experiments around the world. “It's like big science on a shoestring,” says Scott Collins of the University of New Mexico, Albuquerque, who later joined the network.

    The collaboration, called the Nutrient Network—now known as NutNet—has grown far beyond initial expectations, with scientists volunteering at 68 sites in 12 countries. In part, it's popular because the simple experiments are designed to answer a broad set of questions about how grasslands respond to global change—without disproportionate effort by any one individual. “It's not a brand-new idea, but it's novel that they've pulled it off,” says Alan Townsend of the University of Colorado, Boulder, who is not involved. The network also provides an easy way for young faculty members, postdocs, and grad students to get involved in a large collaboration and contribute to high-profile papers.

    So far, the effort has been funded with just a single $322,000 grant from the U.S. National Science Foundation (NSF) for coordinating data and analysis, yet already the first few papers have been published over the past year. The most recent, which appeared in Science last month (23 September, p. 1750), challenged a long-standing idea in ecology about plant diversity and productivity. Dozens more papers are in the works, and ecologists enthuse about the network's potential for cost-effective, rapid results. “NutNet has tremendously improved on the way we've done things,” says Alan Knapp of Colorado State University, Fort Collins, another ecologist who is not involved. “I've been incredibly impressed.”

    Keep it simple

    Research networks aren't new to ecology, of course. The Long Term Ecological Research (LTER) network, for example, is composed of 26 research sites and stations, almost all in the United States, that have been collecting data for 30 years. And construction began this fall on some of the 20 U.S. observatories that will make up the $434 million National Ecological Observatory Network. These hefty networks require a fair amount of money to operate, because staff members collect hundreds of types of data, often year-round.

    During the NCEAS workshop, NutNet's founder s quickly sketched an alternative vision: Each researcher would conduct the same few experiments in several plots of 25 square meters. They would add combinations of three crucial plant nutrients—nitrogen, phosphorus, and potassium—and they would fence part of the plots to exclude deer, zebras, kangaroos, and other herbivores.

    By measuring changes in biomass and species composition, they would try to tease apart the relative impact of herbivores and nutrients on the structure of the community. “Ecologists have been fascinated by this question for a long time,” Orrock says. Moreover, the experiments simulate the impacts of anthropogenic global change. Nutrient levels have been boosted dramatically by fertilizers and pollution from fossil fuels. At the same time, humans have altered the density of herbivores in many places through farming or indirectly by hunting of predators.

    “We're out to change the culture.”

    —ELIZABETH BORER, UNIVERSITY OF MINNESOTA, TWIN CITIES

    CREDIT: TIM RUMMELHOFF

    Several attendees at the NCEAS workshop immediately volunteered to participate. One of the first was Helmut Hillebrand of the Carl von Ossietzky University of Oldenburg in Germany, who set up a NutNet site, even though he's a plankton ecologist. “I think it's the next generation of ecological experiments,” he says. The site he started is located in an old field 5 minutes from his parents' house, so he drops by to collect data while visiting.

    Borer and the others also invited a few colleagues to join, and the idea began to spread by word of mouth. Sensing potential, the group sent an e-mail in November 2006 to just about every grassland ecologist they knew. By the time data started arriving the next year, there were 51 sites.

    Members of the network agree to submit data immediately to a central database. All participants—now about 100, including a dozen or so graduate students—have access to the data. Simply by contributing data, they can be an author on high-profile papers that address the project's big questions. The network is already making a mark: Last month's paper in Science showed that a textbook idea about the relationship between plant productivity and species richness in fact occurs rarely. Other key papers, based on the experimental results of adding nutrients and excluding herbivores, are still being written.

    NutNet participants must propose papers on additional ideas to the whole group. The goal is to avoid duplication and allow other members to contribute to analysis or writing the manuscript. Jennifer Firn of the Queensland University of Technology in Brisbane, Australia, for example, wanted to look at invasive species in the plots. “The process of turning this idea into a paper was the best learning experience I have ever had,” says Firn, who became an assistant professor in February. “I had more than 30 authors and co-authors, so it meant so much advice and expertise were available.” Published in Ecology Letters in March, the paper showed that non-native plants, some invasive, don't all spread like the worst weeds. Instead, most species in the NutNet plots were about as common in their new environment as in their native range. That suggests that regulators of plant imports might want to focus on screening out plants that are highly abundant overseas.

    Network members decide among themselves what kinds of additional data to gather. “This is like an indie garage band, a cooperative without all the top-down headaches,” says co-founder W. Stanley Harpole, an assistant professor at Iowa State University in Ames. (Others make analogies to the development of open-source software or start-up companies.) Eighteen members are analyzing regular deliveries from other participants, who collect everything from soil microbes to arthropods and leaf litter. “It is simple, mail-order sampling,” says co-founder Eric Seabloom of the University of Minnesota, Twin Cities. “The person in the field doesn't have to do that much.”

    “This is like an indie garage band.”

    —STAN HARPOLE, IOWA STATE UNIVERSITY

    CREDIT: COURTESY OF STAN HARPOLE

    Facing the future

    An all-volunteer approach may have its limitations, however. So far, the majority of sites are in the United States. Peter Adler of Utah State University in Logan, a co-founder, says the group tried to recruit scientists in South America without much success. “Maybe it's just [bad] luck,” he says. Townsend expects that more researchers in less developed countries will eventually sign up, as word spreads about the network and its publications. Earlier this month, several sites in India agreed to provide observational data, and a few more will also conduct experiments.

    A larger question is how long a volunteer effort can be sustained. “In absence of external funding, I fear that the good will of those individuals and their institutions may not persist,” says Michael Willig of the University of Connecticut, Storrs, who is not a participant in the network. But co-founder Melinda Smith of Yale University predicts that interest will remain high as long as the network produces high-impact papers. Harpole points out that each plot has space reserved for experiments not yet planned. “We're banking for the future,” he says.

    The looming danger is the expiration of the NSF grant in January 2013. These funds pay for collaboration meetings and for a postdoc, Eric Lind of the University of Minnesota, Twin Cities, who runs the central database. “The death of the Nutrient Network will be when the funding for that postdoc position runs out,” Adler says. The steering committee hopes to cover those expenses with future research grants for more ambitious analyses.

    Even if the NutNet peters out, the founders hope it will be a model. To Borer, the success so far shows that individual scientists at any stage of their career can help answer big questions even if they haven't landed a major grant. “We're out to change the culture,” she says. “The success of this model could empower other groups to address equally important ecological problems at a global scale.”

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