Published online 2 August 2011 | Nature 476, 18 (2011) | doi:10.1038/476018a

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Computing giants launch free science metrics

New Google and Microsoft services promise to democratize citation data.

Declan Butler

Mapping the landscape of science is about to get easier than ever before. Google and Microsoft are rolling out free tools that will enable researchers to analyse citation statistics, visualize research networks and track the hottest research fields.
The systems could be attractive for scientists and institutions that are unable — or unwilling — to pay for existing metrics platforms, such as Thomson Reuters' Web of Knowledge and Elsevier's Scopus database.
Launched in 2004 as a search engine for academic publications, Google Scholar last month added Google Scholar Citations (GSC), which lets a researcher create a personal profile showing all their articles in the Google Scholar database (go.nature.com/7wkpea). The profile also shows plots of the number of citations these papers have received over time, and other citation metrics including the popular h-index, which attempts to measure both the productivity of a scientist and the overall impact of their publications. The service is currently in invitation-only beta testing, but Google intends eventually to roll it out to all researchers.

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Meanwhile, Microsoft Academic Search (MAS), which launched in 2009 and has a tool similar to GSC, has over the past few months added a suite of nifty new tools based on its citation metrics (go.nature.com/u1ouut). These include visualizations of citation networks (see 'Mapping the structure of science'); publication trends; and rankings of the leading researchers in a field.
But although Microsoft's platform has many more features, Google Scholar has an enormous size advantage at present that makes its metrics far more accurate and reliable, say researchers. Google Scholar has indexed much more of the literature than has Microsoft, or indeed Web of Knowledge or Scopus. By contrast, MAS often turns up only a fraction of an author's true publications, which can result in its citation metrics having "absurdly low" values, says Péter Jacsó, an information scientist at the University of Hawaii in Honolulu.
"Microsoft Academic Search is still a nascent offering to the community," explains Lee Dirks, director of education and scholarly communication at Microsoft Research Connections, the academic-collaboration arm of Microsoft Research. MAS's content surged from 15.7 million to 27.1 million publications between March and June, and that pace will continue, says Dirks. Anne-Wil Harzing at the University of Melbourne, Australia, who develops tools to extract citation metrics from Google Scholar, says that MAS has "great potential".
Some researchers question whether purely computational approaches can ever generate reliable bibliographic databases and citation metrics without some human intervention to clean up and check the data. Jacsó points out that the text-mining software used by MAS and GCS can sometimes extract erroneous bibliographic information from publications, for example by misidentifying author names or affiliations (P. Jacsó Online Inform. Rev. 34, 175–191; 2010).
Anurag Acharya, the Google engineer behind Google Scholar and its new metrics system, counters that it has long since dealt with such issues, and that a stack of recent improvements means that his system is working "better and better". Harzing adds that critics often focus too much on such extreme bibliographic errors. She estimates that the overall level of errors in Google Scholar is so low that they do not greatly affect the accuracy of more robust metrics calculations such as the h-index.
Google Scholar also has an advantage over commercial providers in its extensive coverage of books — a significant research output in the social sciences and humanities — as well as conference proceedings, which are important outputs in the computing and engineering fields. Covering these is "crucial" to producing accurate metrics in these fields, says Ton van Raan, a bibliometrics expert at the Centre for Science and Technology Studies at Leiden University, the Netherlands. Joel Hammond, director of product development at Thomson Reuters, points out that the Web of Knowledge already indexes conference proceedings, and that it plans to launch a book-citation index this autumn. Scopus has similar plans.
Neither MAS nor GSC see themselves as direct competitors of Web of Knowledge or Scopus, however. "This is not about competition, this is about providing an open platform for academic research," says Dirks. Acharya, who was born in India, says that he is driven by a humanitarian goal: making available to everybody services that were previously accessible only to those at richer institutions. He says he finds it "satisfying" that Google Scholar's server logs reveal widespread use by researchers in poorer countries, where commercial services are often unavailable.

Hammond says that Thomson Reuters controls which publications it indexes more strictly than do the free services, and argues that this makes its metrics calculations more reliable. Scopus takes a similar line. But others say GSC and MAS might eventually become good enough for many users. "They have the major advantage of being freely available to anyone, and with continued development I think they have the potential to become serious competitors to the commercial products," says Carl Bergstrom, a biologist at the University of Washington, Seattle, who collaborates with both Microsoft Research and Thomson Reuters to analyse citation data.
Van Raan agrees. "It is clear that the commercial citation index producers will be more and more in competition with these free-access facilities," he says.

Published online 5 October 2011 | Nature | doi:10.1038/news.2011.572

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Impossible crystals snag chemistry Nobel

Daniel Shechtman takes award for doggedly pursuing quasicrystals.

Richard Van Noorden

Daniel ShechtmanAP Photo/Ariel Schalit

A materials scientist who discovered crystals with structures that many believed to be impossible — and who stubbornly held his ground against fierce opposition — has claimed this year's Nobel Prize in Chemistry.
Daniel Shechtman of the Technion Israel Institute of Technology in Haifa was awarded the prize for his 1982 discovery¹ of quasicrystals: materials with a mosaic-like, never-quite-repeating atomic structure that defied the textbooks of the time, existing only as mathematical curios. "It took an enormous amount of courage for Danny to stick to his claim," says Veit Elser, a physicist at Cornell University in Ithaca, New York.
It took two years for Shechtman to get his discovery published. His work was scorned by luminaries including double-Nobel-prizewinning chemist Linus Pauling, but after it was published, other examples of the crystals flooded in from around the globe. In 2009, researchers reported finding the quasicrystal structure in an alloy of aluminium, copper and iron, acquired by an Italian museum in 1990 but reported to have come from 200-million-year-old rocks in the Koryak Mountains in Russia².
"This is an award that we've been expecting for 25 years now — I've been sending a recommendation letter to the Nobel committee every year," says Jean-Marie Dubois, who studies complex metallic alloys at the University of Nancy, France.
It still isn't clear how atoms assemble into quasicrystal structures, and the discovery has so far found few real-world applications. But the quasicrystals do have unusual and potentially useful physical properties. Although many quasicrystals are metallic alloys, they do not behave like metals: thanks to the way their electrons are confined, they are poor at conducting heat and electricity, and have non-stick surfaces, so they might be useful in low-friction coatings for frying pans. They are also very hard, and can be used to improve the strength of materials such as steel. But it is not clear that materials incorporating quasicrystals will be more useful than others currently on the market, says Ronan McGrath, a surface scientist at the University of Liverpool, UK.
Instead, Shechtman's key contribution to chemistry was in opening scientists' eyes to the possibility of new forms of matter. "The discovery of quasicrystals has taught us humility," writes Sven Lidin, an inorganic chemist at Stockholm University and a member of the Nobel Committee for Chemistry.

Fearful symmetry

This atomic model of a silver-aluminium quasicrystal shows its mosaic pattern.Ames Laboratory

Thirty years ago, scientists thought that all crystalline materials were composed of atoms packed into regularly repeating three-dimensional lattices, similar to the hexagonal honeycomb of a beehive. This definition dictated that the basic repeating units could possess only particular symmetries: they could be rotated by one-half, one-quarter or one-sixth of a full circle and still look the same, but they could not possess pentagonal symmetry.
On 8 April 1982, Shechtman, who was on sabbatical at the US National Bureau of Standards (now the National Institute of Standards and Technology; NIST) in Gaithersburg, Maryland, found that an artificial alloy of aluminium and manganese disobeyed the rules.
When he shot electrons through the material, they created a regular diffraction pattern, proving that the material's atomic structure consisted of orderly repeating elements. But that pattern showed a forbidden pentagonal symmetry — it could be rotated by both one-tenth and one-fifth of a full circle and would still look the same. In his laboratory notebook for that day, Shechtman wrote: "10 Fold???"
"There can be no such creature," he is reported to have said. Others did their best to persuade him that his discovery was wrong. "I told everyone who was ready to listen that I had a material with pentagonal symmetry. People just laughed at me," Shechtman told Haaretz magazine in a profile earlier this year. He was asked to leave his research group, he says.
But Shechtman got his findings published in November 1984 in Physical Review Letters, with the help of Ilan Blech, a materials scientist at Technion, John Cahn, a physicist at NIST, and Denis Gratias, a crystallographer then at the Centre for Metallurgic Chemistry in Vitry, France. "All I did was present the wonderful work that he had done in a compelling way," Cahn says.
When the paper did come out, recalls Elser, "everybody was incredulous. This was what the textbooks had told them wasn't possible." Researchers around the world rushed to confirm the findings. Like Shechtman, they melted alloys of aluminium and manganese and put them onto a cold surface. The same diffraction pattern emerged.

"Given the relative simplicity of making these materials, it's certain that the five-fold patterns had been seen by numerous scientists before Shechtman, who dismissed them because they didn't fit the rigid rules of crystallography," says Elser.
Indeed, such 'aperiodic' five-fold structures had been described by mathematicians many decades before — most famously by British mathematician Roger Penrose. Related complex designs are found in Islamic art and architecture.
"Breaking the symmetry laws that we as crystallographers are educated on was difficult to accept," says Ada Yonath, a crystallographer based at the Weizmann Institute of Science in Rehovot, Israel, who won the Nobel Prize in Chemistry in 2009 for her work on the structure of the ribosome. "Though [Shechtman] is such a nice man I would work with him even if I disagreed with him." 

• References

  1. Shechtman, D., Blech, I., Gratias, D. & Cahn, J. W. Phys. Rev. Lett. 53, 1951-1953 (1984). | Article | ISI |
  2. Bindi, L., Steinhardt, P. J., Yao, N. & Lu, P. J. Science 324, 1306-1309 (2009). | Article | ISI | ChemPort |

Published online 5 October 2011 | Nature 478, 20 (2011) | doi:10.1038/478020a

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Experts question rankings of journals

F1000 scoring system could throw off results, say critics.

Declan Butler

Peer review may be a good way to assess research papers, but it can fall short in ranking the journals themselves. That's the reaction of some metrics experts to the first such journal rankings, launched this week by the Faculty of 1000 (F1000) in London. Critics question the method, which relies on scores awarded to individual papers by the F1000 'faculty' of 10,000 scientists and clinicians. Such scores, they claim, could be skewed by the interests and enthusiasms of individual reviewers.
Richard Grant, associate editor of F1000, says that the rankings give authors a valuable measure, complementary to journal league tables based on citation impact. He says that the first F1000 rankings will be refined, adding that F1000 is "constantly striving to improve coverage in all specialities".
Created in 2002, the F1000 aims to filter the literature by asking experts to select noteworthy papers and rate them as 6 (recommended), 8 (must read) or 10 (exceptional). Now, it has extended the concept by totting up the scores of all a journal's rated articles over a given period, and normalizing the totals — adjusting for the total number of articles that the journal published over that period, for example.
The results put the usual suspects at the top. In the rankings for 2010, the latest full year available, Nature leads in biology and the New England Journal of Medicine in medicine. But further down the lists, the F1000 often departs from impact factors. "We're aware the correlation with impact factors isn't exact, and we wouldn't expect it to be," says Grant. The Proceedings of the National Academy of Sciences (PNAS) "does particularly well by our ranking because there are a lot of papers in there that are obviously valuable to the community".
But some critics say that the limited number of papers reviewed — fewer than 20,000 per year, of more than one million published — could compromise the rankings. "The scores may tell us as much about the composition of the F1000 faculty as they do about the relative quality of various journals," says Carl Bergstrom, a biologist at the University of Washington, Seattle, and an F1000 faculty member who publishes a rival metric, the Eigenfactor.

Philip Davis, a scholarly-publishing expert at Cornell University in Ithaca, New York, says that "a single enthusiastic reviewer could propel a small, specialist journal into a high ranking simply by submitting more reviews". One journal seems to owe its surprisingly high ranking to a series of very positive evaluations of its articles by its own editor.
Grant says that such a competing interest should have been declared, and that the F1000 will look into the matter. In the interim, the journal in question has been withdrawn from the rankings. The F1000 will also make its code of conduct more explicit, says Grant. He notes that all evaluations and methodology are available on the F1000's website, making the ranking process transparent and allowing users to alert the F1000 to any concerns.