Hot off the presses! Mar 04 Nature

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Latest Articles Include:

• Do scientists really need a PhD?
  - Nature 464(7285):7 (2010)
  Young scientists at a Chinese genomics institute are foregoing conventional postgraduate training for the chance to be part of major scientific initiatives. Is this the way of the future?
• The ratings game
  - Nature 464(7285):7 (2010)
  International university rankings need to be improved — and interpreted more wisely.
• The bigger picture
  - Nature 464(7285):8 (2010)
  General science meetings are good opportunities for researchers to broaden their horizons.
• Biology: Secret code
  - Nature 464(7285):10 (2010)
  
• Genetics: Gene guards
  - Nature 464(7285):10 (2010)
  
• Nanotechnology: Light DNA machine
  - Nature 464(7285):10 (2010)
  
• Electronics: Caught on film
  - Nature 464(7285):10 (2010)
  
• Biology: Stayin' alive
  - Nature 464(7285):10 (2010)
  
• Astrophysics: Old stars call out
  - Nature 464(7285):10 (2010)
  
• Chemical biology: With added sugar
  - Nature 464(7285):11 (2010)
  
• Applied physics: Sound lasers hum along
  - Nature 464(7285):11 (2010)
  
• Wildlife biology: Lizard back burden
  - Nature 464(7285):11 (2010)
  
• Neuroscience: Use it or lose it
  - Nature 464(7285):11 (2010)
  
• Journal club
  - Nature 464(7285):11 (2010)
  
• News briefing: 4 March 2010
  - Nature 464(7285):12 (2010)
  The week in science This article is best viewed as a PDF. Research|Policy|Events|Business|Business watch|People|The week ahead|Number crunch|Sound bites The UK Met Office has asked the World Meteorological Organization (WMO) to create a new data set of global land-surface air temperatures. By reanalysing existing temperature measurements from meteorological stations, the "robust and transparent" data set would provide daily or perhaps even more frequent figures. At present, only monthly averages are offered by the three existing global data sets (maintained by the Met Office, NASA's Goddard Institute for Space Studies and the US National Climatic Data Center). A WMO spokesman says that the concept will require three years of work and several million euros. A neutrino beam fired across the width of Japan has found its target. On 25 February, physicists with the T2K (Tokai-to-Kamioka) multinational collaboration said the Super-Kamiokande detector in Hida, Japan, had spotted a neutrino generated at the Japan Proton Accelerator Research Complex some 295 kilometres away. The T2K is looking at how neutrinos — almost mass-less fundamental particles — oscillate between different types, or flavours, as they travel. British scientists seem to have won key concessions from the UK government over a draft set of principles outlining how it treats independent science advice. A specific reference to the "academic freedom" of advisers is likely to be inserted into the principles, and a controversial clause suggesting that science advisers and ministers should work to "reach a shared position" will be removed. Science minister Paul Drayson told a Parliamentary science and technology committee hearing about the changes on 24 February. The principles were called for after the sacking of drugs adviser David Nutt. See go.nature.com/gUh9AX for more. The United Nations (UN) will ask a group of scientists to independently investigate the work of the UN Intergovernmental Panel on Climate Change, following criticism of the body's fourth assessment report. The unexpected action was called for by ministers at a UN Environment Programme forum in Bali, Indonesia, on 26 February. Full details of the review, and its scope, are expected by 5 March. An initiative between two US agencies aims to strengthen links between biomedical research and regulatory science. The National Institutes of Health (NIH) and the Food and Drug Administration (FDA) announced their collaboration on 24 February. The latest science needs to be integrated into methods used to evaluate drugs and medical devices, the agencies said. The partnership is led by a joint NIH–FDA leadership council, and will start with a grants programme for work in regulatory science, funded with US$6.75 million over three years. Space exploration and clean energy received boosts in India's 2010–11 budget plans, announced on 26 February. Finance minister Pranab Mukherjee proposed a levy — of 50 rupees (US$1.1) a tonne — on domestic and imported coal to pay for a national clean-energy research fund. He also increased the renewable-energy ministry's project-spending power by 61% to $220 million; the space department received a total budget increase of 39%, to $1.25 billion, and the science and technology ministry saw its budget raised 25% to $1.05 billion. Companies were also permitted larger tax deductions on investment in research and development. N. YOUNG/ACE/CRC A giant 78-kilometre-long iceberg has calved off from East Antarctica's Mertz Glacier after being rammed by an even larger iceberg. The 97-kilometre-long assailant itself broke off from the continent's Ross Ice Shelf in 1987. Pre-existing fractures in the Mertz Glacier's tongue had left the northern extremity dangling like a 'loose tooth' before it detached some time between 10 and 13 February. A joint French–Australian research group began studying the glacier in 2007, during the International Polar Year. These European Space Agency satellite images showing the glacier before (above) and after the iceberg broke free were released on 26 February. On 2 March the European Commission authorized commercial cultivation of a genetically modified (GM) potato, called Amflora, in Europe. It is the first time the commission has cleared a GM crop for cultivation in 12 years. German chemicals company BASF, which developed the potato as a way to yield higher-quality starch, says that it plans to start commercial cultivation this year. The commission also allowed three GM maize (corn) varieties made by biotech giant Monsanto in St Louis, Missouri, to be sold — but not grown — in Europe. German chemical and drug-maker Merck KGaA of Darmstadt will buy Millipore, the US manufacturer of life-science laboratory supplies, in a transaction valued at US$7.2 billion including debts. Millipore shareholders must still approve the deal, which was announced on 28 February. Three pharmaceutical powerhouses will create a publicly available genomic database of two cancers common in Asia. On 23 February, Eli Lilly, Merck and Pfizer launched the Asian Cancer Research Group — a not-for-profit company that aims to analyse 2,000 tissue samples collected from Asian patients with lung and stomach cancer. The firms have not stated how much they will invest in the venture. J. SULLIVAN/GETTY IMAGES Bloom Energy, a private start-up company based in Sunnyvale, California, unveiled its proprietary solid-oxide fuel cell in a glitzy event on 24 February at eBay's headquarters in San Jose, California. The cells are being tested by companies including Google, Wal-Mart and Coca Cola. Bloom's co-founder and chief executive, K. R. Sridhar (pictured with California governor Arnold Schwarzenegger) — a former NASA researcher — revealed few technical details at the launch, which generated huge publicity. Lower prices for crystalline-silicon solar cells are threatening the commercial viability of companies that make thin-film photovoltaic cells. Thin-film cells, micrometres or nanometres thick and made of materials such as cadmium telluride, are supposed to be cheaper — although less efficient — than conventional silicon units. But, in 2009, prices of crystalline silicon modules plummeted by 50% from their 2008 peak, converging on those offered by the leading thin-film supplier First Solar, based in Tempe, Arizona (see chart). "The global photovoltaic module market flipped from under-supply to over-supply before any thin-film players, except First Solar, managed to get to scale manufacturing," says Jenny Chase, a solar-energy analyst at consultants Bloomberg New Energy Finance (NEF). She expects the price of crystalline silicon modules to dip below US$1.50 per watt this year. First Solar, whose chairman sold more than 40% of his holding in the company last week, should cope despite the lower silicon price, says Chase, because of its established sales channels and lower costs than competitors. But only a handful of the 285 companies known by Bloomberg NEF to be working on thin-film photovoltaic technology will be able to establish the high-volume manufacturing needed to push down costs and compete with cheap crystalline-silicon modules, says Chase. Benoît Battistelli has been elected president of the European Patent Office (EPO) after four acrimonious rounds of voting among its 36 member states. Currently head of France's national intellectual property office, Battistelli takes over from Britain's Alison Brimelow in July for a five-year term. His major challenges include tackling tensions over devolving work from the EPO to national offices; dealing with challenges to patents on biological entities — such as stem cells — that appeal to the EPO's ambiguous 'morality' clause; and collaborating on a single European patent to confer continent-wide protection. The prestigious Karolinska Institute near Stockholm has dismissed biochemist Karl Tryggvason from the post of dean of research for exerting "undue influence" over the allocation of funds to scientists. In a 2 March statement the institute said that Tryggvason had e-mailed an independent evaluation committee to advocate for particular professors to receive funds. "I take such unethical conduct very, very seriously," said Harriet Wallberg-Henriksson, the institute's president. Additional action might be necessary pending further investigation, the institute added. The European Space Agency's Mars Express probe makes its two closest approaches to Mars's largest moon, Phobos. → go.nature.com/wjEfAS The fifth annual MIT Energy Conference (organized by the Massachusetts Institute of Technology) takes place in Boston, Massachusetts. → go.nature.com/ZqUH44 The European office of the World Health Organization holds its Fifth Ministerial Conference on Environment and Health in Parma, Italy. It promises to set the European agenda on emerging environmental health challenges, particularly those affecting children. → go.nature.com/rLoXCZ The area planted with genetically modified crops worldwide in 2009, a 7% rise from 2008. Proportion of the 14 million biotech-crop planters who were resource-poor farmers in developing countries. Source: International Service for the Acquisition of Agri-biotech Applications, 23 February Yasuo Sekita, an official at Japan's Meteorological Agency, apologizes for over-zealous tsunami forecasts after the 27 February Chile earthquake. For more on tsunami responses, see page 14. Source: The Wall Street Journal There are currently no comments. This is a public forum. Please keep to our Community Guidelines. You can be controversial, but please don't get personal or offensive and do keep it brief. Remember our threads are for feedback and discussion - not for publishing papers, press releases or advertisements.
• Model response to Chile quake?
  - Nature 464(7285):14 (2010)
  Experts debate how much emergency-response planners should rely on tsunami forecasts. Waves caused by a magnitude-8.8 earthquake flattened coastal regions in Chile.R. Candia/AP/Press Association Images Moments after a magnitude-8.8 earthquake rocked Chile this weekend, a tsunami began to sweep across the Pacific Ocean at hundreds of kilometres per hour. And within 2 hours, scientists had determined that coastal communities beyond Chile probably had little to fear. Yet around the Pacific, from Hawaii to Japan, authorities ordered extensive evacuations. To some tsunami experts the response was no more than prudent. Others think that it was a costly overreaction. "The warning system worked well in terms of trustworthiness of forecast, but its implementation had large loopholes," says Costas Synolakis, a tsunami expert at the University of Southern California, Los Angeles. Events in Chile, where the earthquake has claimed more than 700 lives, showed the value of a timely tsunami warning. Despite the enormity of the quake — the fifth-strongest since 1900 — the Chilean Navy, responsible for tsunami warnings, failed to issue an immediate alert. Within 34 minutes, destructive waves had hit the coastal city of Valparaíso, sweeping away buildings and people. The number of casualties there is unknown — but the Chilean minister of defence, Francisco Vidal, says that without warnings issued by local authorities and harbour officials acting on their own, many more lives would have been lost. Tsunami forecasters were already trying to work out what would happen next. Burak Uslu, a tsunami modeller with the Pacific Marine and Environmental Laboratory (PMEL) in Seattle, Washington, used a mathematical model called Method of Splitting Tsunami, developed with Synolakis and Vasily Titov of the PMEL, to forecast when waves would arrive, how high they would be and how much dry land would be flooded. It was the first time that the model had been applied to a big tsunami in the Pacific. Click for larger image About 2 hours after the quake, the tsunami passed the first of the Pacific's network of monitoring buoys, which recorded a wave one-quarter of the height of the 2004 Indian Ocean tsunami. When Uslu used the buoy data to refine the model's predictions (see 'Catching a wave'), he found that most of the tsunami energy would pass between Tahiti and Hawaii and continue on to Japan, and that Hawaiian beaches could be flooded up to a height of 1.2 metres. Around the same time, however, the US Pacific Tsunami Warning Center (PTWC) in Ewa Beach, Hawaii, issued an ocean-wide tsunami warning. Synolakis contends that the PTWC was divided on how to respond to the forecasts — after all, a tsunami triggered by the largest-ever recorded earthquake, which struck Chile in 1960, had killed 61 people in Hilo, Hawaii. But this is denied by Charles McCreery, director of the PTWC: "I heard no dissent in our office." The PTWC decided that tsunami alerts should be kept in place despite the forecasts of relatively little impact outside Chile. Many thousands of people were evacuated from beaches and low-lying land in Hawaii and parts of Japan, and Californian beach-goers and communities were held on standby. "We were not going to gamble with people's lives," says McCreery. He maintains that Hawaii had a good chance of sustaining damage and points out that the Marquesas Islands in the south Pacific were hit by waves that were 4 metres from crest to trough. In time, the model's predictions would be vindicated by events around the Pacific. When the waves arrived in Hawaii, they were little higher than the normal surf, whereas coastal communities in northern Japan, 17,000 kilometres from the earthquake zone, faced modest flooding — the worst impact outside Chile. Scientists think that this week's tsunami was milder than the Indian Ocean event because the fault that slipped lay beneath a relatively shallow part of the ocean, and therefore displaced a smaller volume of water. The geometry of the fault and the way it ruptured probably also helped to limit the severity of the tsunami. "Had the ground ruptured a bit further north, Hawaii would had been severely hit," says Synolakis. ADVERTISEMENT McCreery admits that the PTWC took a conservative approach to what the model was telling them. "We'll be looking at this very hard over the next few months, and longer, to see what improvements can be made," he says. As confidence grows in the model, experts may be more prepared to cancel tsunami warnings earlier, he adds. Although serial false alarms can make people complacent about the threat of a tsunami, McCreery says that occasional evacuations can actually increase people's confidence that the system is working. Jörn Lauterjung, a tsunami expert at the German Research Centre for Geosciences in Potsdam who oversees the German–Indonesian tsunami early-warning system, agrees that the PTWC made the right decision. If an earthquake of similar magnitude strikes the Indian Ocean region, he says, authorities should take the same action. But Synolakis argues that the increasing reliability of tsunami forecasts allows emergency planners to order evacuation only when necessary. "The authorities in charge need to listen to science," says Synolakis. "Every ounce of extra prevention is counterproductive as it reduces the overall credibility of the system." This is a public forum. Please keep to our Community Guidelines. You can be controversial, but please don't get personal or offensive and do keep it brief. Remember our threads are for feedback and discussion - not for publishing papers, press releases or advertisements.
• Unmanned planes take wing for science
  - Nature 464(7285):14 (2010)
  Drones will measure ozone and aerosols in the atmosphere. Nose for science: the Global Hawk will gather data during 30-hour flights.T. LANDIS/NASA PHOTO Later this month a remote-controlled aircraft is scheduled to take off from the Mojave Desert in California and veer west over the Pacific Ocean. The Global Hawk, a slim-winged, high-flying jet, was designed for military reconnaissance and tested in both Iraq and Afghanistan. But this time the plane will fly for science. Guided by pilots at NASA's Dryden Research Center, north of Los Angeles, the plane will measure concentrations of ozone, aerosols and various trace gases along a 15,000-kilometre loop around Hawaii. At the same time, atmospheric scientists hope that the drone's flight will usher in an era of unmanned scientific aircraft that can probe parts of the sky normally inaccessible to manned planes. During the past two decades, several teams have developed and tested remote-controlled science planes, and NASA already flies the smaller Predator B — also of military origin — over western US wildfires. Drones never caught on as serious research tools, in part because they could carry so little compared with manned planes. But the Global Hawk is larger and much more capable than its predecessors, lifting a payload of around 900 kilograms to a height of nearly 20,000 metres and covering a distance of some 20,000 kilometres. That combination "can't even be approached with any other aircraft", says David Fahey, a principal investigator with the drone project at the National Oceanic and Atmospheric Administration (NOAA) in Boulder, Colorado. "Scientists don't really know how to use a platform like this, because we've never had one. You kind of have to let your imagination be unbridled for a bit, and then you rein it back in." In particular, the Global Hawk will give scientists the ability to stay in the stratosphere for hours, collecting samples in this key region where ozone is being destroyed. The manned ER-2 can tap the lower stratosphere, but it can't fly as far as the Global Hawk or remain up for as long, says Paul Newman, the scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who is leading this month's mission with Fahey. "Whenever you use these planes it always seems as if the thing that you really want to sample is about 1,000 miles farther than you can go." Flying instruments on the Global Hawk isn't cheap or easy. NASA charges the same price — US$3,500 per hour — to use the Global Hawk as for various manned aircraft. And although staying in the air for long periods offers many advantages, Fahey says that the team has had to figure out the logistics of rotating crews of scientists to monitor equipment during a 30-hour flight. Chris Naftel, who manages the programme for NASA, saw the potential of the military reconnaissance drones in 2005, when the Air Force was decommissioning seven Global Hawk prototypes. Naftel secured two of the prototypes in 2007 and a third last year for free. The agency signed an agreement with the plane's producer, Northrop Grumman in Los Angeles, to help convert the aircraft, install new communications equipment, train employees and build an operations centre. During the summer, a team of NASA scientists will deploy the Global Hawk to monitor Atlantic storms, hoping to peer inside them as some develop from tropical disturbances into hurricanes. Multiple teams are developing other research missions, and NASA is now working on a mobile communications centre that will give the aircraft truly global coverage. With Global Hawk about to start its science runs, support is growing for unmanned research planes. A report from the US National Research Council last month called unmanned vehicles an "extremely exciting complement" to NASA's current aerial fleet. And NOAA is pondering whether to develop its own fleet of science drones. ADVERTISEMENT David Parrish, a colleague of Fahey's at NOAA who conducts intensive atmospheric research campaigns with a converted passenger aircraft, the P3, emphasizes that manned missions are unlikely to end any time soon. His team loads a P3 with so much instrumentation that the plane, which is designed to hold 80–90 passengers, can seat just five or six scientists. "It's very difficult to develop instruments with the needed precision and accuracy, yet small enough to fly on these unmanned platforms," Parrish says. He adds, however, that "the atmosphere is so big and so complex" that there is certainly room for both types of aircraft. There are currently no comments. This is a public forum. Please keep to our Community Guidelines. You can be controversial, but please don't get personal or offensive and do keep it brief. Remember our threads are for feedback and discussion - not for publishing papers, press releases or advertisements.
• University rankings smarten up
  - Nature 464(7285):16 (2010)
  Systems for ranking the world's higher-education and research institutions are about to become more sophisticated, says Declan Butler. Improved university rankings may help students, researchers and policy-makers to make better choices.S. JARRATT/CORBIS Every autumn, politicians, university administrators, funding offices and countless students wait impatiently for the World University Rankings produced by Britain's Times Higher Education (THE) magazine. A position in the upper echelons of the THE ranking can influence policy-makers' higher-education investments, determine which institutions attract the best researchers or students, and prompt universities to try to boost their ratings. But academics and universities have long criticized what they describe as the outsized influence of the THE and other university rankings, saying that their methodology and data are problematic (see Nature 447, 514–515; 2007). Many universities see wild swings in their rankings from year to year, for example, which cannot reflect real changes in quality; and many French universities' ratings suffer because their researchers' publications often list affiliations with national research agencies as well as the university itself, diluting the benefit for the university. Now, universities and other stakeholders are developing their own rankings to tackle these shortcomings. "Rankings have outgrown the expectations of those who started them," says Kazimierz Bilanow, managing director of the IREG Observatory on Academic Rankings and Excellence, a Warsaw-based ranking quality-assurance body created in October 2009. "What were often exercises intended to boost newspaper circulation have come to have enormous influence on policy-making and funding of institutions and governments." Several approaches to university rankings now being developed are switching the emphasis away from crude league tables and towards more nuanced assessments that could provide better guidance for policy-makers, funding bodies, researchers and students alike. They promise to rank universities on a much wider range of criteria, and assess more intangible qualities, such as educational excellence. And the THE ranking list is trying to remake itself in the face of the criticism. One complaint is that the THE's rankings rely heavily on reputational surveys, which involve polling academics about which universities they think are the best in a given field. Some argue that these assessments often use too few academics, who may not be well informed about all the universities they are being asked to judge, and that there is a bias towards English-speaking countries. In November 2009, the THE announced that the data for its rankings would no longer be supplied by QS, a London-based higher-education media company. "We are very much aware that national policy and multimillion-pound decisions are influenced by these rankings," said THE editor Ann Mroz at the time. "We are also acutely aware of the criticisms made of the methodology. Therefore, we feel we have a duty to improve how we compile them." League-table turnabout The THE will in future draw its ranking data from the Global Institutional Profiles Project, which was launched by data provider Thomson Reuters in January. The project aims to create a comprehensive database on thousands of the world's universities, including details of research funding, numbers of researchers and PhDs awarded, and measures of educational performance. The company will also use its internal citation and publication data to generate multiple indicators of institutions' research performance, and will build in auditing procedures to guard against misinformation provided by universities. Thomson Reuters plans to continue reputational surveys, but aims to have at least 25,000 reviewers, compared with the 4,000 used by QS for the THE 2009 rankings. It has partnered with UK pollster Ipsos MORI to try to ensure the survey is representative. "We are not doing this randomly, but putting a lot of thought behind it," says Simon Pratt, project manager for institutional research at Thomson Reuters. "We want a more balanced view across all subject areas." The THE will continue to rank all universities in the form of a league table, which critics say offers a false precision that exaggerates differences between institutions. But the new rankings will be more nuanced and detailed, according to Pratt, including data that enable institutions to compare themselves on various indicators with peers having similar institutional profiles. Comparing like with like is the cornerstone of a European Commission effort to create a global database of universities — the Multi-dimensional Global ranking of Universities (U-Multirank). A pilot project involving 150 universities will be launched in the coming months by a group of German, Dutch, Belgian and French research centres that specialize in research and education metrics, known as the Consortium for Higher Education and Research Performance Assessment. U-Multirank hopes to focus its comparisons on institutions that have similar activities and missions. Existing league tables lump together all types of universities, but comparing a large multidisciplinary university with a regional university focused on teaching, for example, makes little sense, says Frans van Vught, one of U-Multirank's project leaders and former president and rector of the University of Twente in Enschede, the Netherlands. To identify universities with similar profiles, the project will draw on a sister European Union project, U-Map, in which van Vught is also involved. U-Map is building a classification of universities based on their level of research activity, the types of degrees and student programmes offered, as well as the extent of other important roles such as their regional and industrial engagement and international orientation. U-Multirank will develop indicators of performance on each of these aspects. After completion of the pilots, the two projects will seek philanthropic funding to become operational services, says van Vught. U-Multirank also hopes to overcome one of the major criticisms of many existing ranking systems: that they focus excessively on research output, neglecting the many other crucial roles that universities have, not least teaching. Indeed, the Academic Ranking of World Universities, compiled by Shanghai Jiao Tong University in China and generally known as the Shanghai index, focuses exclusively on research output and citation impact, including variables such as numbers of Nobel prizewinners and publications in Nature and Science (see 'Top marks'). Rankings that use citation counts do not usually take into account the widely different citation rates among disciplines. This biases rankings in favour of biomedical research institutions, penalizing those that publish mainly in the social sciences or in other fields with lower citation rates. By contrast, both the Thomson Reuters and U-Multirank initiatives will use a variety of normalized bibliometric indicators that take this, and other pitfalls, into account. In place of league tables, U-Multirank will give an overall grade of institutional performance on each of the various indicators it considers, allowing students, scientists and policy-makers to access and combine the indicators most relevant to them, so making their own à la carte rankings. "They will be able to look at the data through their own spectacles," says van Vught. But as everyone in the field acknowledges, educational aspects of universities are particularly difficult to compare. Research is an international activity, and reasonable indicators exist for comparing institutions. Education, by contrast, is largely organized nationally and reflects different cultures and traditions. "It's a much tougher problem," says Pratt. University dropout rates in France, for example, cannot be compared directly with those in other countries because all students who pass the baccalauréat automatically acquire a place at a French university. Selection takes place at the end of the first undergraduate year, and not immediately after leaving high school, pushing up the dropout rate. Similarly, the length and content of degrees often vary greatly between countries. Measuring ideas That's a gap in assessment that the Organisation for Economic Co-operation and Development (OECD) is trying to fill. Last month, it launched a US$12.5-million pilot project, the Assessment of Higher Education Learning Outcomes (AHELO), to develop new metrics for assessing teaching and learning outcomes. The project, which does not intend to produce rankings, will try to measure complex aspects of university life — such as the ability of students to think critically and come up with original ideas — across different cultures and languages. Although few details are yet available, it says it intends to launch a pilot involving 200 students in a dozen or so universities in six countries, including the United States and Japan. "We will be watching the development of the AHELO exercise very closely," says Ben Sowter, QS's head of research. QS intends to continue developing its university ranking despite losing its link to the THE. "We will continue improving the methodology and response levels to the surveys," says Sowter, adding that he welcomes the new competition. Other experts say that having more rankings will be beneficial, as it will reduce the undue influence of any one ranking. ADVERTISEMENT And now it is the rankings' turn to be assessed. The European University Association, which represents more than 800 universities, plans to publish annual reviews of all international rankings, assessing their methodologies and scrutinizing why institutions rise or fall in the rankings. The effort will be loosely modelled on an existing overview of ranking systems produced by the Swiss State Secretariat for Education and Research and the Rectors' Conference of the Swiss Universities. The reviews should help users to decide on which ranking data can best answer key questions about universities' performance. "Any ranking exercise, however sophisticated, is being irresponsible if it projects itself as the right answer to a question, whereas the only right answer is in the hands of the person asking it," says Sowter. There are currently no comments. This is a public forum. Please keep to our Community Guidelines. You can be controversial, but please don't get personal or offensive and do keep it brief. Remember our threads are for feedback and discussion - not for publishing papers, press releases or advertisements.
• Fat rats skew research results
  - Nature 464(7285):19 (2010)
  Overfed lab animals make poor subjects for experiments. Failure to recognize that many laboratory animals live unhealthy lives may be leading researchers to misinterpret their findings, potentially misdirecting efforts to develop theraputic drugs. The problem, reports a group at the US National Institute on Aging in Bethesda, Maryland, is that many rats and mice used in experiments are so overweight that they are glucose intolerant and heading for an early death (B. Martin et al. Proc. Natl Acad. Sci. USA doi:10.1073/pnas.0912955107; 2010). As a result, data from the animals — about, for example, the effects of an anti-cancer drug — may not apply to normal-weight animals. "The vast majority of investigators who use rats and mice don't recognize that their normal conditions are relatively unhealthy," says Mark Mattson, chief of the National Institute on Aging's Laboratory of Neurosciences and a co-author on the paper. "The most logical way to extrapolate is to say any data we obtain in the animal model would be more relevant to overweight, sedentary humans than normal-weight, active individuals." Mattson and his colleagues note that the standard lab practice of allowing rats and mice continuous access to food without much opportunity to exercise can cause some to balloon in weight to up to 1 kilogram. Beneficial effects of a potential drug or behaviour could simply result from its effect on the consequences of an animal's unhealthy lifestyle, they say, and studies showing that caloric restriction can extend lifespan may have to be reinterpreted. "A major reason the lifespan of rats and mice is extended by caloric restriction is they started from an unhealthy baseline," argues Mattson. He and his co-workers identify areas as diverse as immune function, cancer and neurological disorders that could be affected by the problem. Mattson says that including running wheels in cages and feeding only on alternate days could solve the 'fat rat' problem, adding that the institutional committees that oversee and approve such experiments should encourage researchers to tackle the problem. ADVERTISEMENT The fat-rat hypothesis is certainly credible, says Robin Franklin, a neuroscientist and director of research at the Department of Veterinary Medicine, University of Cambridge, UK. "But I suspect it's one of many factors that are responsible for the difference between animal models and human diseases," he says, adding that the problem has not been apparent in his research. Still, Mattson and his colleagues have penned "hundreds of papers using rodent models and are widely known in their field", says Christian Newcomer, executive director of the Association for Assessment and Accreditation of Laboratory Animal Care, a non-profit organization based in Frederick, Maryland, that accredits animal use in many laboratories, including those of the US National Institutes of Health. "I think [the paper] is going to carry a lot of weight." There are currently no comments. This is a public forum. Please keep to our Community Guidelines. You can be controversial, but please don't get personal or offensive and do keep it brief. Remember our threads are for feedback and discussion - not for publishing papers, press releases or advertisements.
• The labours of Fotis Kafatos
  - Nature 464(7285):20 (2010)
  Launching the European Research Council was a Herculean effort, says its outgoing president. Having battled the red tape of the European Commission, Fotis Kafatos will now focus on his research.F. BARON Amid the bustle of the life-sciences department at Imperial College London, Fotis Kafatos looks spent. For the past four years, he has nursed the European Research Council (ERC) to life, delivering the first pan-European initiative to fund cutting-edge basic research judged solely on excellence. The struggle has left him satisfied but exhausted. So on 1 March — a year earlier than his term was due to end — Kafatos handed over his presidency of the ERC to Helga Nowotny, a social scientist at the Vienna Science and Technology Fund, and one of the ERC's two vice-presidents. Kafatos plans to devote more time to his research on malaria, which he says has come practically to a standstill. "I don't begrudge the time I spent on the ERC, but I would be foolish not to step down now — it was consuming me," he tells Nature in an exclusive interview. "If I knew how much time it would take out of my life when I started I might not have done it. But I am happy I did." Kafatos, together with the other 21 members of the ERC's scientific council, helped to secure the ERC a 7-year €7.5-billion (US$10.2-billion) budget, which has funded more than 1,000 projects worth a total of €1.7 billion. Like many of the world's best research agencies, including the US National Science Foundation in Arlington, Virginia, the ERC selects winners solely on scientific merit. "We delivered to Europe what we promised," Kafatos declares. Colour begins to creep back into Kafatos's face as he tells of the ERC's other achievements. For instance, it has attracted more than 3,000 distinguished scientists from across the world to review applications. The review panels are "the backbone of our operations. We are very proud of it," he says. The council has also spurred individual nations to spend more money on research. "Ten countries or regions, including Switzerland and Spain, have injected additional national funds for runner-up candidates who were deemed excellent but could not be funded," says Kafatos. Busting bureaucracy However, the ERC has had its share of problems. Its first call for proposals from young researchers, in 2007, attracted more than 9,000 applicants, several times more than it expected — it had enough money to fund just 299 projects. "This huge interest could have been a disaster because the success rate was so low. But credit to young researchers, they were not put off," Kafatos recalls. "I would be foolish not to step down now." But it was not so much the teething troubles of the young ERC that wore Kafatos down, as the bureaucracy of the European Commission, which is responsible for ensuring that funding from the European Union pot — including the ERC's budget — is spent properly. An overly strict control culture permeates the commission, Kafatos says. "We continuously had to spend energy, time and effort on busting bureaucracy roadblocks that kept appearing in our way," says Kafatos. "At best, this costs us precious energy and resources. At worst it may hamper our zeal to inspire and continuously improve the ERC strategy, it can damage the morale of our staff and discourage the top talented researchers from applying to or reviewing for the ERC." For example, the commission insists that winners of ERC funding, who already have to provide detailed research proposals, describe the milestones they aim to reach and how, so that their projects can be audited. How successful researchers are in reaching those goals could affect their chances of winning funding in the future. Kafatos says that this rule hampers the freedom of researchers to change their plans in the light of new science after their proposal has been accepted. "This is nonsensical. If you could a priori describe what your success will be, you would not have to do the experiments," says Kafatos. "I am convinced that proper and secure use of public funds can be achieved in a much less domineering system," he adds. He is not alone. A review led by the former president of Latvia, Vaira Vīķe-Freiberga, and published in July last year, recommended that the commission make "immediate corrections" to the running of the ERC or risk inflicting a "deadly blow" on the funding body. Kafatos says that a pressing challenge for his successor is to ensure that the commission follows up on the report's recommendations and agrees to a further review in 2011 to consider whether more reforms are needed. ADVERTISEMENT Kafatos also calls for new legislation to establish the ERC as a permanent institution. The ERC currently has a temporary status, raising the prospect, albeit unlikely, that it might not be funded in Europe's next research initiative — the eighth Framework programme, set to begin in 2013. Kafatos hopes instead that the Framework programme will include a "major expansion" of the ERC budget, which would allow the council to launch new funding initiatives, including supporting PhD programmes and institutes of advanced study, similar to the one in Princeton, New Jersey, at which researchers are free to pursue speculative ideas. Most of all, Kafatos wants the agency he laboured to build to have the freedom to choose how it operates and how it is governed. "We need to build our institution to fit the needs of the mission and not vice versa," he says. There are currently no comments. This is a public forum. Please keep to our Community Guidelines. You can be controversial, but please don't get personal or offensive and do keep it brief. Remember our threads are for feedback and discussion - not for publishing papers, press releases or advertisements.
• Weapons labs to thrive as Obama trims nukes
  - Nature 464(7285):21 (2010)
  President takes first steps towards goal of disarmament. The administration of US President Barack Obama is nearing the completion of a much-anticipated policy that could restrict the role of the nation's nuclear arsenal while strengthening the weapons-research infrastructure at the Department of Energy laboratories. Initially scheduled for release late last year, and then again for 1 March, the Nuclear Posture Review will lay out the administration's justifications and strategy for maintaining a nuclear arsenal. It will also be the president's first opportunity to make good on his promise, made in Prague last April, to take "concrete steps" towards nuclear disarmament and to reduce the role of nuclear weapons in the US security strategy. The policy is likely to affirm the Obama administration's decision not to pursue new weapon designs, although many expect there to be wiggle room for scientists at the weapons labs to modify existing systems in the name of safety and security. Officials are still debating how to frame the US nuclear strategy in the review, which is now expected sometime in the coming weeks. Some politicians and non-proliferation advocates have urged the president to promise that nuclear weapons will be used only to deter a nuclear attack, whereas others advocate a less restrictive phrasing. "I personally expect to be disappointed," says Matthew Bunn, a nuclear expert at Harvard University in Cambridge, Massachusetts. "I think it will have some positive-sounding language, but I think the overall changes will be modest." The document will help to guide work throughout the energy department, including at the primary weapons laboratories, Los Alamos National Laboratory in New Mexico and Lawrence Livermore National Laboratory in California, as the administration works on a new treaty with Russia that could see the weapons stockpile reduced. An expanded role for the labs was already clear from the administration's proposed fiscal budget for 2011, released last month. ADVERTISEMENT In the budget, the National Nuclear Security Administration, based in Washington DC, which manages the weapons programme and non-proliferation activities within the Department of Energy, would receive a 13.4% increase to US$11.2 billion, including more than $7 billion to manage the nuclear stockpile. Of that, $1.6 billion would go towards science, technology and engineering programmes, which include advanced computer simulations, research into the ageing of nuclear materials, and fusion experiments at the Livermore lab's National Ignition Facilty. The goal is to ensure that ageing, untested weapons would work as designed. There are currently no comments. This is a public forum. Please keep to our Community Guidelines. You can be controversial, but please don't get personal or offensive and do keep it brief. Remember our threads are for feedback and discussion - not for publishing papers, press releases or advertisements.
• Chinese bioscience: The sequence factory
  - Nature 464(7285):22 (2010)
  In 2006, Li Yingrui left Peking University for the BGI, China's premier genome-sequencing institute. Now, freckled and fresh-faced at 23 years old, he baulks at the way a senior BGI colleague characterized his college career — saying Li was wasting time playing video games and sleeping during class. There are currently no comments.
• Non-proliferation: Borderline detection
  - Nature 464(7285):26 (2010)
  The radiation alarm started wailing and flashing its red strobe light on an otherwise ordinary day last August as a car tried to pass through the Sadakhlo border crossing. The alarm itself wasn't unusual. There are currently no comments.
• World view: Curing climate backlash
  - Nature 464(7285):28 (2010)
  A volatile mix of science and politics has ignited a backlash against climate science in the United States and United Kingdom. The exposure of e-mails from the University of East Anglia's Climatic Research Unit (CRU) in Norwich, UK, last November, and the subsequent discovery of errors and distortions in the 2007 report of the Intergovernmental Panel on Climate Change (IPCC), may have little bearing on the overall weight of scientific evidence about anthropogenic climate change. There are currently no comments.
• South Africa: telescopes raise the nation's sights
  - Nature 464(7285):30 (2010)
  In your Editorial and News Feature on South African science (Nature463, 709; Nature463, 726–728; 2010), you are critical of the country's bid to host the Square Kilometre Array (SKA) radio telescope. But from an astronomer's viewpoint, there is every reason to be optimistic.
• South Africa: aiming to be premier global astronomy hub
  - Nature 464(7285):30 (2010)
  As director-general of science and technology in South Africa during the period when the major programmes reviewed in your News Feature were initiated (Nature 463, 726–728; 2010), I strongly believe that we should still be championing big science projects such as the Square Kilometre Array (SKA) radio telescope.When the African National Congress government began reshaping South African science after apartheid, we asked ourselves what resources we had that might attract good scientists from abroad.
• South Africa: big science should stay on the agenda
  - Nature 464(7285):30 (2010)
  Your News Feature on South African science (Nature 463, 726–728; 2010) suggests that without financial support from abroad, research endeavours would all but collapse. But there are positive developments.
• Myth-busting about first mass-produced human cell line
  - Nature 464(7285):30 (2010)
  In Steve Silberman's Book Review of The Immortal Life of Henrietta Lacks (Nature 463, 610; 2010), two myths about HeLa cells are perpetuated.Your lead-in claims that the death of Henrietta Lacks "led to the first immortal cell line", but that distinction belongs to the L929 cell line, which was derived from mouse connective tissue and described almost a decade earlier (W. Earle J. Natl Cancer Inst. 4, 165–212; 1943
• Spring awakening planned for Mars rover Spirit
  - Nature 464(7285):31 (2010)
  Your ill-timed 'obituary', in News, for the Mars rover Spirit (Nature 463, 600; 2010) brings to mind Mark Twain's saying that reports of his death had been exaggerated.
• Esaki diode is still a radio star, half a century on
  - Nature 464(7285):31 (2010)
  An FM transistor radio owned by one of us (L. E.
• Foundations could allocate money more productively
  - Nature 464(7285):31 (2010)
  Could the huge grant-giving community in the United States be made more effective? This question needs addressing now, while both the economy and grant giving are down.
• Stop laser uranium enrichment
  - Nature 464(7285):32 (2010)
  The US Congress should discourage efforts to advance the technology to make fuel for nuclear reactors, say Francis Slakey and Linda R. Cohen — the risks outweigh the benefits.
• Is there anybody out there?
  - Nature 464(7285):34 (2010)
  Paul Davies's latest book argues that the search for intelligent life beyond Earth should be expanded. Chris McKay considers why we should look closer to home — perhaps even in our DNA.
• Why you shouldn't always follow the crowd
  - Nature 464(7285):35 (2010)
  A school of fish dives and darts to avoid a predator. The motions of each fish appear chaotic, yet as a group they are effective — the school seems intelligent.
• Autism and animal insight
  - Nature 464(7285):35 (2010)
  "I'm not like other people," declares actress Claire Danes as animal-behaviour expert Temple Grandin in director Mick Jackson's latest film. Unable to speak until age four, Grandin was diagnosed as autistic.
• Q&A: Joanna Cole on writing science books for kids
  - Nature 464(7285):36 (2010)
  Joanna Cole has authored more than 100 science books for children, including the best-selling Magic School Bus series, the latest edition of which tackles the topic of climate change. In the last of our series of interviews with authors who write science books for different audiences, Cole reveals how clarity and colour can introduce even very young children to science.
• Behavioural neurobiology: The treacherous scent of a human
  - Nature 464(7285):37 (2010)
  Mosquitoes' odorant receptors help the insects to find humans and, inadvertently, to transmit malaria. The identification of the odorants that bind to these receptors opens up ways of reducing mosquito biting.
• Microscopy: When mica and water meet
  - Nature 464(7285):38 (2010)
  A neat mode of operation of the atomic force microscope has been used to probe the interface between mica and water. The results help to settle a long-standing debate about the nature of this interface.
• 50 & 100 years ago
  - Nature 464(7285):39 (2010)
  'Tizard and the Science of War' — His flair for setting the cat among the official pigeons, and for ignoring the normal channels, made him not always popular with the upper hierarchy. His sharp incisive wit was often exercised at the expense of the complacent, the pompous and the incompetent ... but I never heard of it being used at the expense of the young, the vigorous or the keen.
• Materials science: Hydrocarbon superconductors
  - Nature 464(7285):39 (2010)
  Superconductivity has been discovered in the materials that form when alkali metals react with a solid hydrocarbon. This is the first new class of organic, high-temperature superconductor in a decade.
• Clinical immunology: Culprits with evolutionary ties
  - Nature 464(7285):41 (2010)
  The cellular organelles we know as mitochondria are thought to have originated as symbiotic bacteria. Indeed, the two use common mechanisms to trigger innate immune responses to injury and infection, respectively.
• Materials science: Mind the helical crack
  - Nature 464(7285):42 (2010)
  Catastrophic breakage of brittle materials such as ceramics is usually triggered by the rapid spreading of cracks. Computer simulations have now cracked the three-dimensional details of this process.
• Developmental genetics: Time for teeth
  - Nature 464(7285):43 (2010)
  The age at which babies cut their first tooth very much depends on the age at which their parents did. But what genes — or general genome-wide differences, for that matter — mediate variations in this trait?
• Obituary: Marshall Nirenberg (1927–2010)
  - Nature 464(7285):44 (2010)
  A humble, gentle and visionary giant of molecular biology.
• Quantum computers
  - Nature 464(7285):45 (2010)
  Over the past several decades, quantum information science has emerged to seek answers to the question: can we gain some advantage by storing, transmitting and processing information encoded in systems that exhibit unique quantum properties? Today it is understood that the answer is yes, and many research groups around the world are working towards the highly ambitious technological goal of building a quantum computer, which would dramatically improve computational power for particular tasks. A number of physical systems, spanning much of modern physics, are being developed for quantum computation. However, it remains unclear which technology, if any, will ultimately prove successful. Here we describe the latest developments for each of the leading approaches and explain the major challenges for the future.
• Remarkably ancient balanced polymorphisms in a multi-locus gene network
  Hittinger CT Gonçalves P Sampaio JP Dover J Johnston M Rokas A - Nature 464(7285):54 (2010)
  Local adaptations within species are often governed by several interacting genes scattered throughout the genome. Single-locus models of selection cannot explain the maintenance of such complex variation because recombination separates co-adapted alleles. Here we report a previously unrecognized type of intraspecific multi-locus genetic variation that has been maintained over a vast period. The galactose (GAL) utilization gene network of Saccharomyces kudriavzevii, a relative of brewer's yeast, exists in two distinct states: a functional gene network in Portuguese strains and, in Japanese strains, a non-functional gene network of allelic pseudogenes. Genome sequencing of all available S. kudriavzevii strains revealed that none of the functional GAL genes were acquired from other species. Rather, these polymorphisms have been maintained for nearly the entire history of the species, despite more recent gene flow genome-wide. Experimental evidence suggests that inactiva! tion of the GAL3 and GAL80 regulatory genes facilitated the origin and long-term maintenance of the two gene network states. This striking example of a balanced unlinked gene network polymorphism introduces a remarkable type of intraspecific variation that may be widespread.
• A human gut microbial gene catalogue established by metagenomic sequencing
  - Nature 464(7285):59 (2010)
  To understand the impact of gut microbes on human health and well-being it is crucial to assess their genetic potential. Here we describe the Illumina-based metagenomic sequencing, assembly and characterization of 3.3 million non-redundant microbial genes, derived from 576.7 gigabases of sequence, from faecal samples of 124 European individuals. The gene set, ~150 times larger than the human gene complement, contains an overwhelming majority of the prevalent (more frequent) microbial genes of the cohort and probably includes a large proportion of the prevalent human intestinal microbial genes. The genes are largely shared among individuals of the cohort. Over 99% of the genes are bacterial, indicating that the entire cohort harbours between 1,000 and 1,150 prevalent bacterial species and each individual at least 160 such species, which are also largely shared. We define and describe the minimal gut metagenome and the minimal gut bacterial genome in terms of functions p! resent in all individuals and most bacteria, respectively.
• Odorant reception in the malaria mosquito Anopheles gambiae
  Carey AF Wang G Su CY Zwiebel LJ Carlson JR - Nature 464(7285):66 (2010)
  The mosquito Anopheles gambiae is the major vector of malaria in sub-Saharan Africa. It locates its human hosts primarily through olfaction, but little is known about the molecular basis of this process. Here we functionally characterize the Anopheles gambiae odorant receptor (AgOr) repertoire. We identify receptors that respond strongly to components of human odour and that may act in the process of human recognition. Some of these receptors are narrowly tuned, and some salient odorants elicit strong responses from only one or a few receptors, suggesting a central role for specific transmission channels in human host-seeking behaviour. This analysis of the Anopheles gambiae receptors permits a comparison with the corresponding Drosophila melanogaster odorant receptor repertoire. We find that odorants are differentially encoded by the two species in ways consistent with their ecological needs. Our analysis of the Anopheles gambiae repertoire identifies receptors that m! ay be useful targets for controlling the transmission of malaria.
• Linking dwarf galaxies to halo building blocks with the most metal-poor star in Sculptor
  - Nature 464(7285):72 (2010)
  Current cosmological models1, 2 indicate that the Milky Way's stellar halo was assembled from many smaller systems. On the basis of the apparent absence of the most metal-poor stars in present-day dwarf galaxies, recent studies3 claimed that the true Galactic building blocks must have been vastly different from the surviving dwarfs. The discovery of an extremely iron-poor star (S1020549) in the Sculptor dwarf galaxy based on a medium-resolution spectrum4 cast some doubt on this conclusion. Verification of the iron-deficiency, however, and measurements of additional elements, such as the α-element Mg, are necessary to demonstrate that the same type of stars produced the metals found in dwarf galaxies and the Galactic halo. Only then can dwarf galaxy stars be conclusively linked to early stellar halo assembly. Here we report high-resolution spectroscopic abundances for 11 elements in S1020549, confirming its iron abundance of less than 1/4,000th that of the Sun, and s! howing that the overall abundance pattern follows that seen in low-metallicity halo stars, including the α-elements. Such chemical similarity indicates that the systems destroyed to form the halo billions of years ago were not fundamentally different from the progenitors of present-day dwarfs, and suggests that the early chemical enrichment of all galaxies may be nearly identical.
• Superconductivity in alkali-metal-doped picene
  - Nature 464(7285):76 (2010)
  Efforts to identify and develop new superconducting materials continue apace, motivated by both fundamental science and the prospects for application. For example, several new superconducting material systems have been developed in the recent past, including calcium-intercalated graphite compounds1, boron-doped diamond2 and—most prominently—iron arsenides such as LaO1–xFxFeAs (ref. 3). In the case of organic superconductors, however, no new material system with a high superconducting transition temperature (Tc) has been discovered in the past decade. Here we report that intercalating an alkali metal into picene, a wide-bandgap semiconducting solid hydrocarbon, produces metallic behaviour and superconductivity. Solid potassium-intercalated picene (Kxpicene) shows Tc values of 7 K and 18 K, depending on the metal content. The drop of magnetization in Kxpicene solids at the transition temperature is sharp (<2 K), similar to the behaviour of Ca-intercalated gra! phite1. The Tc of 18 K is comparable to that of K-intercalated C60 (ref. 4). This discovery of superconductivity in Kxpicene shows that organic hydrocarbons are promising candidates for improved Tc values.
• Reinventing germanium avalanche photodetector for nanophotonic on-chip optical interconnects
  - Nature 464(7285):80 (2010)
  Integration of optical communication circuits directly into high-performance microprocessor chips can enable extremely powerful computer systems1. A germanium photodetector that can be monolithically integrated with silicon transistor technology2, 3, 4, 5, 6, 7, 8 is viewed as a key element in connecting chip components with infrared optical signals. Such a device should have the capability to detect very-low-power optical signals at very high speed. Although germanium avalanche photodetectors9, 10 (APD) using charge amplification close to avalanche breakdown can achieve high gain and thus detect low-power optical signals, they are universally considered to suffer from an intolerably high amplification noise characteristic of germanium11. High gain with low excess noise has been demonstrated using a germanium layer only for detection of light signals, with amplification taking place in a separate silicon layer12. However, the relatively thick semiconductor layers that ! are required in such structures limit APD speeds to about 10 GHz, and require excessively high bias voltages of around 25 V (ref. 12). Here we show how nanophotonic and nanoelectronic engineering aimed at shaping optical and electrical fields on the nanometre scale within a germanium amplification layer can overcome the otherwise intrinsically poor noise characteristics, achieving a dramatic reduction of amplification noise by over 70 per cent. By generating strongly non-uniform electric fields, the region of impact ionization in germanium is reduced to just 30 nm, allowing the device to benefit from the noise reduction effects13, 14, 15 that arise at these small distances. Furthermore, the smallness of the APDs means that a bias voltage of only 1.5 V is required to achieve an avalanche gain of over 10 dB with operational speeds exceeding 30 GHz. Monolithic integration of such a device into computer chips might enable applications beyond computer optical interco! nnects1—in telecommunications16, secure quantum key distribu! tion17, and subthreshold ultralow-power transistors18.
• Helical crack-front instability in mixed-mode fracture
  - Nature 464(7285):85 (2010)
  Planar crack propagation under pure tension loading (mode I) is generally stable. However, it becomes universally unstable with the superposition of a shear stress parallel to the crack front (mode III). Under this mixed-mode (I + III) loading configuration, an initially flat parent crack segments into an array of daughter cracks that rotate towards a direction of maximum tensile stress1. This segmentation produces stepped fracture surfaces with characteristic 'lance-shaped' markings observed in a wide range of engineering2, 3, 4, 5, 6, 7 and geological materials1, 8. The origin of this instability remains poorly understood and a theory with which to predict the surface roughness scale is lacking. Here we perform large-scale simulations of mixed-mode I + III brittle fracture using a continuum phase-field method9, 10, 11 that describes the complete three-dimensional crack-front evolution. The simulations reveal that planar crack propagation is linearly unsta! ble against helical deformations of the crack front, which evolve nonlinearly into a segmented array of finger-shaped daughter cracks. Furthermore, during their evolution, facets gradually coarsen owing to the growth competition of daughter cracks in striking analogy with the coarsening of finger patterns observed in nonequilibrium growth phenomena12, 13, 14. We show that the dynamically preferred unstable wavelength is governed by the balance of the destabilizing effect of far-field stresses and the stabilizing effect of cohesive forces on the process zone scale, and we derive a theoretical estimate for this scale using a new propagation law for curved cracks in three dimensions. The rotation angles of coarsened facets are also compared to theoretical predictions and available experimental data.
• Metabolic streamlining in an open-ocean nitrogen-fixing cyanobacterium
  Tripp HJ Bench SR Turk KA Foster RA Desany BA Niazi F Affourtit JP Zehr JP - Nature 464(7285):90 (2010)
  Nitrogen (N2)-fixing marine cyanobacteria are an important source of fixed inorganic nitrogen that supports oceanic primary productivity and carbon dioxide removal from the atmosphere1. A globally distributed2, 3, periodically abundant4 N2-fixing5 marine cyanobacterium, UCYN-A, was recently found to lack the oxygen-producing photosystem II complex6 of the photosynthetic apparatus, indicating a novel metabolism, but remains uncultivated. Here we show, from metabolic reconstructions inferred from the assembly of the complete UCYN-A genome using massively parallel pyrosequencing of paired-end reads, that UCYN-A has a photofermentative metabolism and is dependent on other organisms for essential compounds. We found that UCYN-A lacks a number of major metabolic pathways including the tricarboxylic acid cycle, but retains sufficient electron transport capacity to generate energy and reducing power from light. Unexpectedly, UCYN-A has a reduced genome (1.44 megabases) tha! t is structurally similar to many chloroplasts and some bacteria, in that it contains inverted repeats of ribosomal RNA operons7. The lack of biosynthetic pathways for several amino acids and purines suggests that this organism depends on other organisms, either in close association or in symbiosis, for critical nutrients. However, size fractionation experiments using natural populations have so far not provided evidence of a symbiotic association with another microorganism. The UCYN-A cyanobacterium is a paradox in evolution and adaptation to the marine environment, and is an example of the tight metabolic coupling between microorganisms in oligotrophic oceanic microbial communities.
• Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira
  - Nature 464(7285):95 (2010)
  The early evolutionary history of Ornithodira (avian-line archosaurs) has hitherto been documented by incomplete (Lagerpeton1) or unusually specialized forms (pterosaurs and Silesaurus2). Recently, a variety of Silesaurus-like taxa have been reported from the Triassic period of both Gondwana and Laurasia, but their relationships to each other and to dinosaurs remain a subject of debate3, 4, 5. Here we report on a new avian-line archosaur from the early Middle Triassic (Anisian) of Tanzania. Phylogenetic analysis places Asilisaurus kongwe gen. et sp. nov. as an avian-line archosaur and a member of the Silesauridae, which is here considered the sister taxon to Dinosauria. Silesaurids were diverse and had a wide distribution by the Late Triassic, with a novel ornithodiran bauplan including leaf-shaped teeth, a beak-like lower jaw, long, gracile limbs, and a quadrupedal stance. Our analysis suggests that the dentition and diet of silesaurids, ornithischians and sauropodomo! rphs evolved independently from a plesiomorphic carnivorous form. As the oldest avian-line archosaur, Asilisaurus demonstrates the antiquity of both Ornithodira and the dinosaurian lineage. The initial diversification of Archosauria, previously documented by crocodilian-line archosaurs in the Anisian6, can now be shown to include a contemporaneous avian-line radiation. The unparalleled taxonomic diversity of the Manda archosaur assemblage indicates that archosaur diversification was well underway by the Middle Triassic or earlier.
• Changes in Hox genes' structure and function during the evolution of the squamate body plan
  - Nature 464(7285):99 (2010)
  Hox genes are central to the specification of structures along the anterior–posterior body axis1, 2, and modifications in their expression have paralleled the emergence of diversity in vertebrate body plans3, 4. Here we describe the genomic organization of Hox clusters in different reptiles and show that squamates have accumulated unusually large numbers of transposable elements at these loci5, reflecting extensive genomic rearrangements of coding and non-coding regulatory regions. Comparative expression analyses between two species showing different axial skeletons, the corn snake and the whiptail lizard, revealed major alterations in Hox13 and Hox10 expression features during snake somitogenesis, in line with the expansion of both caudal and thoracic regions. Variations in both protein sequences and regulatory modalities of posterior Hox genes suggest how this genetic system has dealt with its intrinsic collinear constraint to accompany the substantial morphologica! l radiation observed in this group.
• Circulating mitochondrial DAMPs cause inflammatory responses to injury
  - Nature 464(7285):104 (2010)
  Injury causes a systemic inflammatory response syndrome (SIRS) that is clinically much like sepsis1. Microbial pathogen-associated molecular patterns (PAMPs) activate innate immunocytes through pattern recognition receptors2. Similarly, cellular injury can release endogenous 'damage'-associated molecular patterns (DAMPs) that activate innate immunity3. Mitochondria are evolutionary endosymbionts that were derived from bacteria4 and so might bear bacterial molecular motifs. Here we show that injury releases mitochondrial DAMPs (MTDs) into the circulation with functionally important immune consequences. MTDs include formyl peptides and mitochondrial DNA. These activate human polymorphonuclear neutrophils (PMNs) through formyl peptide receptor-1 and Toll-like receptor (TLR) 9, respectively. MTDs promote PMN Ca2+ flux and phosphorylation of mitogen-activated protein (MAP) kinases, thus leading to PMN migration and degranulation in vitro and in vivo. Circulating MTDs ca! n elicit neutrophil-mediated organ injury. Cellular disruption by trauma releases mitochondrial DAMPs with evolutionarily conserved similarities to bacterial PAMPs into the circulation. These signal through innate immune pathways identical to those activated in sepsis to create a sepsis-like state. The release of such mitochondrial 'enemies within' by cellular injury is a key link between trauma, inflammation and SIRS.
• Haematopoietic stem cells derive directly from aortic endothelium during development
  Bertrand JY Chi NC Santoso B Teng S Stainier DY Traver D - Nature 464(7285):108 (2010)
  A major goal of regenerative medicine is to instruct formation of multipotent, tissue-specific stem cells from induced pluripotent stem cells (iPSCs) for cell replacement therapies. Generation of haematopoietic stem cells (HSCs) from iPSCs or embryonic stem cells (ESCs) is not currently possible, however, necessitating a better understanding of how HSCs normally arise during embryonic development. We previously showed that haematopoiesis occurs through four distinct waves during zebrafish development, with HSCs arising in the final wave in close association with the dorsal aorta. Recent reports have suggested that murine HSCs derive from haemogenic endothelial cells (ECs) lining the aortic floor1, 2. Additional in vitro studies have similarly indicated that the haematopoietic progeny of ESCs arise through intermediates with endothelial potential3, 4. Here we have used the unique strengths of the zebrafish embryo to image directly the generation of HSCs from the ventral! wall of the dorsal aorta. Using combinations of fluorescent reporter transgenes, confocal time-lapse microscopy and flow cytometry, we have identified and isolated the stepwise intermediates as aortic haemogenic endothelium transitions to nascent HSCs. Finally, using a permanent lineage tracing strategy, we demonstrate that the HSCs generated from haemogenic endothelium are the lineal founders of the adult haematopoietic system.
• Blood stem cells emerge from aortic endothelium by a novel type of cell transition
  Kissa K Herbomel P - Nature 464(7285):112 (2010)
  The ontogeny of haematopoietic stem cells (HSCs) during embryonic development is still highly debated, especially their possible lineage relationship to vascular endothelial cells1, 2. The first anatomical site from which cells with long-term HSC potential have been isolated is the aorta-gonad-mesonephros (AGM), more specifically the vicinity of the dorsal aortic floor3. But although some authors have presented evidence that HSCs may arise directly from the aortic floor into the dorsal aortic lumen4, others support the notion that HSCs first emerge within the underlying mesenchyme5. Here we show by non-invasive, high-resolution imaging of live zebrafish embryos, that HSCs emerge directly from the aortic floor, through a stereotyped process that does not involve cell division but a strong bending then egress of single endothelial cells from the aortic ventral wall into the sub-aortic space, and their concomitant transformation into haematopoietic cells. The process is p! olarized not only in the dorso-ventral but also in the rostro-caudal versus medio-lateral direction, and depends on Runx1 expression: in Runx1-deficient embryos, the exit events are initially similar, but much rarer, and abort into violent death of the exiting cell. These results demonstrate that the aortic floor is haemogenic and that HSCs emerge from it into the sub-aortic space, not by asymmetric cell division but through a new type of cell behaviour, which we call an endothelial haematopoietic transition.
• In vivo imaging of haematopoietic cells emerging from the mouse aortic endothelium
  Boisset JC van Cappellen W Andrieu-Soler C Galjart N Dzierzak E Robin C - Nature 464(7285):116 (2010)
  Haematopoietic stem cells (HSCs), responsible for blood production in the adult mouse, are first detected in the dorsal aorta starting at embryonic day 10.5 (E10.5)1, 2, 3. Immunohistological analysis of fixed embryo sections has revealed the presence of haematopoietic cell clusters attached to the aortic endothelium where HSCs might localize4, 5, 6. The origin of HSCs has long been controversial and several candidates of the direct HSC precursors have been proposed (for review see ref. 7), including a specialized endothelial cell population with a haemogenic potential. Such cells have been described both in vitro in the embryonic stem cell (ESC) culture system8, 9 and retrospectively in vivo by endothelial lineage tracing5, 10 and conditional deletion experiments11. Whether the transition from haemogenic endothelium to HSC actually occurs in the mouse embryonic aorta is still unclear and requires direct and real-time in vivo observation. To address this issue we used ! time-lapse confocal imaging and a new dissection procedure to visualize the deeply located aorta. Here we show the dynamic de novo emergence of phenotypically defined HSCs (Sca1+, c-kit+, CD41+) directly from ventral aortic haemogenic endothelial cells.
• SIRT3 regulates mitochondrial fatty-acid oxidation by reversible enzyme deacetylation
  - Nature 464(7285):121 (2010)
  Sirtuins are NAD+-dependent protein deacetylases. They mediate adaptive responses to a variety of stresses, including calorie restriction and metabolic stress. Sirtuin 3 (SIRT3) is localized in the mitochondrial matrix, where it regulates the acetylation levels of metabolic enzymes, including acetyl coenzyme A synthetase 2 (refs 1, 2). Mice lacking both Sirt3 alleles appear phenotypically normal under basal conditions, but show marked hyperacetylation of several mitochondrial proteins3. Here we report that SIRT3 expression is upregulated during fasting in liver and brown adipose tissues. During fasting, livers from mice lacking SIRT3 had higher levels of fatty-acid oxidation intermediate products and triglycerides, associated with decreased levels of fatty-acid oxidation, compared to livers from wild-type mice. Mass spectrometry of mitochondrial proteins shows that long-chain acyl coenzyme A dehydrogenase (LCAD) is hyperacetylated at lysine 42 in the absence of SIRT3. ! LCAD is deacetylated in wild-type mice under fasted conditions and by SIRT3 in vitro and in vivo; and hyperacetylation of LCAD reduces its enzymatic activity. Mice lacking SIRT3 exhibit hallmarks of fatty-acid oxidation disorders during fasting, including reduced ATP levels and intolerance to cold exposure. These findings identify acetylation as a novel regulatory mechanism for mitochondrial fatty-acid oxidation and demonstrate that SIRT3 modulates mitochondrial intermediary metabolism and fatty-acid use during fasting.
• Opposing microRNA families regulate self-renewal in mouse embryonic stem cells
  - Nature 464(7285):126 (2010)
  Nature 463, 621–626 (2010) In Figure 3B of this Article, the labels for the two far right columns were inadvertently swapped. The corrected Figure 3B is shown below.
• Transitions
  - Nature 464(7285):132 (2010)
  Different business models for difficult times.