Gastroenterology: Down the hatch

Nature 495, 7442 (2013). doi:10.1038/495446a

Author: David Katz

David Katz savours a guided tour of the ins and outs of the gastrointestinal tract.

Q&A: Knowledge liberator

Nature 495, 7442 (2013). doi:10.1038/495447a

Author: Robert Darnton

Robert Darnton heads the world's largest collection of academic publications, the Harvard University Library system. He is also a driver behind the new Digital Public Library of America. Ahead of its launch in April, he talks about Google, science journals and the open-access debate.

Research conduct: Online integrity training falls short

Nature 495, 7442 (2013). doi:10.1038/495449a

Author: Kenneth D. Pimple

Education in the responsible conduct of research (RCR) will receive a long-overdue critique at a conference discussing the work of the US Office of Research Integrity on 3–5 April in Baltimore, Maryland.The US National Institutes of Health has required recipients of training grants to

Research ethics: Too much reliance on anonymous tip-offs

Nature 495, 7442 (2013). doi:10.1038/495449b

Author: Gilberto Corbellini

Several scientific journals and ethics committees are deferring to anonymous judgment when it comes to charges of plagiarism and falsification of results in published research papers. As a bioethicist, I believe that this practice is risky, even when the tipster's views are valid: it could

Health metrics: Standardize records of place of death

Nature 495, 7442 (2013). doi:10.1038/495449c

Author: Barbara Gomes

We suggest that a record of the place of death should be incorporated into death-registration data as a useful additional health metric (Nature494, 281; 201310.1038/494281a).End-of-life care is a major public-health issue, given the rising number of deaths from

Radioactive dumping: Nuclear-waste site geology is paramount

Nature 495, 7442 (2013). doi:10.1038/495449d

Author: David Smythe

As a former geological adviser to the UK government on nuclear-waste repositories, I would like to clarify some points in your discussion of the quest for a British nuclear-waste disposal site (Nature494, 5–6; 201310.1038/494005b).Nirex was a

Robert Richardson (1937-2013)

Nature 495, 7442 (2013). doi:10.1038/495450a

Author: Douglas D. Osheroff

Discoverer of superfluidity in helium-3.

Publishing: Open to possibilities

Nature 495, 7442 (2013). doi:10.1038/nj7442-539a

Author: Stephen Pincock

Opting for open access means considering costs, journal prestige and career implications.

Turning point: Kate Rubins

Nature 495, 7442 (2013). doi:10.1038/nj7442-541a

Author: Virginia Gewin

Virologist decides to follow her dream and become an astronaut.

Sticky

Nature 495, 7442 (2013). doi:10.1038/495544a

Author: George Zebrowski

Go with the flow.

Is the ocean food provision index biased?

Nature 495, 7442 (2013). doi:10.1038/nature11974

Authors: Trevor A. Branch, Daniel J. Hively & Ray Hilborn

arising from B. S. Halpern et al.Nature488, 615–620 (2012)How close to maximum sustainable food provision is current seafood harvest from the world’s oceans? Halpern et al. suggest that the answer is 25% from a global index of food provision, part of their multifaceted index of ocean health. Rigorous methods used for management, however, demonstrate that their food provision index is uncorrelated with actual food provision, and that global ocean food provision is in the range of 71–95%. Their results stem from an uncertain method of estimating maximum sustainable yield (MSY), and we believe that this approach should be avoided as a measure of food provision. There is a Reply to this Brief Communication Arising by Halpern, B. S. et al. Nature495,http://dx.doi.org/10.1038/nature11975 (2013).

Halpern et al. reply

Nature 495, 7442 (2013). doi:10.1038/nature11975

Authors: Benjamin S. Halpern, Steven D. Gaines, Kristin Kleisner, Catherine Longo, Daniel Pauly, Andrew A. Rosenberg, Jameal F. Samhouri & Dirk Zeller

replying to T. A. Branch, D. J. Hively & R. Hilborn. Nature495, http://dx.doi.org/10.1038/nature11974 (2013)Branch et al. suggest that the fisheries component of our ocean health and benefits index is ‘biased’. We contend that our approach is no more biased than their alternative, and that our method improves on theirs in three fundamental ways: it provides a score for every country, accounts for thousands of data-poor stocks, and incorporates sustainability more comprehensively.

Correction

Nature 495, 7442 (2013). http://www.nature.com/doifinder/10.1038/495423a

The News Feature ‘Campus 2.0’ (Nature495, 160–163; 2013) wrongly said that Andrew Ng went public with Daphne Koller’s machine-learning course — it was his course. Both this course and a database course each attracted 100,000 students not 60,000 as stated.

Correction

Nature 495, 7442 (2013). http://www.nature.com/doifinder/10.1038/495449e

The Outlook article 'A many layered thing' (Nature492, S52–S54; 2012) contained an error in the graphic 'Caught in a loop'. The labels for the Th1 and Th17 cells were shown switched over.And in the Outlook article 'Mine,

Global health: Persuasive evidence on HIV policy

Nature 495, 7442 (2013). doi:10.1038/495452a

Authors: Grace John-Stewart

Antiretroviral therapy has revolutionized the fight against the HIV/AIDS pandemic. Surveillance analyses of a large population in rural South Africa make a compelling case that sustained support for this therapy is essential.

Materials science: Nanoparticle structures served up on a tray

Nature 495, 7442 (2013). doi:10.1038/495453a

Authors: Simon Billinge

A neat approach that involves laying an array of nanoparticles on a graphene sheet supported on an iridium substrate has allowed accurate measurement of the nanoparticles' atomic structure.

Earth science: How the ocean exhales

Nature 495, 7442 (2013). doi:10.1038/495454a

Authors: Elisabeth Sikes

A record of biogenic opal production in the subtropical Atlantic Ocean fuels the theory that ocean circulation, rather than winds, drove the release of carbon dioxide from deep marine waters at the end of the last ice age. See Letter p.495

X-ray crystallography: One size fits most

Nature 495, 7442 (2013). doi:10.1038/495456a

Authors: Pierre Stallforth & Jon Clardy

Crystalline 'sponges' offer a way to impose order on small molecules so that their structures can be solved by X-ray crystallography. This enables nanogram quantities of material to be analysed using the technique. See Article p.461

X-ray analysis on the nanogram to microgram scale using porous complexes

Nature 495, 7442 (2013). doi:10.1038/nature11990

Authors: Yasuhide Inokuma, Shota Yoshioka, Junko Ariyoshi, Tatsuhiko Arai, Yuki Hitora, Kentaro Takada, Shigeki Matsunaga, Kari Rissanen & Makoto Fujita

X-ray single-crystal diffraction (SCD) analysis has the intrinsic limitation that the target molecules must be obtained as single crystals. Here we report a protocol for SCD analysis that does not require the crystallization of the sample. In our method, tiny crystals of porous complexes are

Carbon monoxide in clouds at low metallicity in the dwarf irregular galaxy WLM

Nature 495, 7442 (2013). doi:10.1038/nature11933

Authors: Bruce G. Elmegreen, Monica Rubio, Deidre A. Hunter, Celia Verdugo, Elias Brinks & Andreas Schruba

Carbon monoxide (CO) is the primary tracer for interstellar clouds where stars form, but it has never been detected in galaxies in which the oxygen abundance relative to hydrogen is less than 20 per cent of that of the Sun, even though such ‘low-metallicity’ galaxies often form stars. This raises the question of whether stars can form in dense gas without molecules, cooling to the required near-zero temperatures by atomic transitions and dust radiation rather than by molecular line emission; and it highlights uncertainties about star formation in the early Universe, when the metallicity was generally low. Here we report the detection of CO in two regions of a local dwarf irregular galaxy, WLM, where the metallicity is 13 per cent of the solar value. We use new submillimetre observations and archival far-infrared observations to estimate the cloud masses, which are both slightly greater than 100,000 solar masses. The clouds have produced stars at a rate per molecule equal to 10 per cent of that in the local Orion nebula cloud. The CO fraction of the molecular gas is also low, about 3 per cent of the Milky Way value. These results suggest that in small galaxies both star-forming cores and CO molecules become increasingly rare in molecular hydrogen clouds as the metallicity decreases.