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Nature
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Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.
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MicroRNA-10b and breast cancer metastasis
Arising from: L. Ma, J. Teruya-Feldstein & R. A. Weinberg Nature449, 682?688 (2007); Ma et al.replyMicroRNAs regulate messenger RNA expression but are frequently dysregulated in tumours. Ma et al. report that overexpression of microRNA-10b (miR-10b) initiates invasion and metastasis in models of breast cancer and that its expression in primary breast carcinomas correlates with clinical progression. We tested this in patients with primary breast cancer, of whom 92 had nodal metastases at diagnosis and 127 were node-negative. We found no significant association between miR-10b levels and metastasis or prognosis. Although we concede that miR-10b may have a biological effect in a few cells at the growing edge of a tumour, we believe that it is unlikely to correlate in whole tumour samples with clinical progression.
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Ma et al. reply
Replying to: H. E. Gee, et al.Nature455, 10.1038/nature07362 (2008)Gee et al. contest that microRNA-10b is not a prognostic marker for metastasis risk in breast cancer. However, their observations do not bear on the pro-metastatic roles of microRNA-10b (miR-10b) as we described them, nor do they undermine our conclusions.
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Can light be stopped in realistic metamaterials?
Arising from: K. L. Tsakmakidis, A. D. Boardman & O. Hess Nature450, 397?401 (2007); Tsakmakidis et al.replyTsakmakidis et al. extend earlier work (for example, refs 2, 3) in proposing a novel metamaterial waveguide structure that can stop broadband light, producing so-called ?trapped rainbows?. The authors make the bold assumption that metamaterial loss can be ignored: but material loss, with dispersion, is an inherent feature of negative-index metamaterials (for example, refs 4, 5); any realistic model must include loss and dispersion to satisfy the fundamental principle of causality. Here we revisit the authors? predictions and show that even when an arbitrarily small metamaterial loss is introduced, it is impossible to stop the light; moreover, we find that all slow-light modes in such structures give impractically large propagation losses.
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Tsakmakidis et al. reply
Replying to: A. Reza, M. M. Dignam & S. Hughes Nature455, 10.1038/nature07359 (2008)Reza et al. have confirmed our calculations and results on storing light inside metamaterial waveguides. But they claim that losses constitute an ?inherent? feature of any ?realistic? negative-refraction metamaterial (NR-MM), and that light can never be stopped inside such a material in a practical way. We argue that both of these assertions are incorrect.
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Making the paper: Alexander Chervonsky
Gut bacteria may safeguard against a form of diabetes.
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Abstractions
First authorRoughly 2.4 billion years ago, enough molecular oxygen began being produced to support the evolution of oxygen-dependent 'aerobic' organisms. This period has been dubbed the Great Oxidation Event. But how the oxygen was produced remains a mystery. Traces of hydrocarbons in 2.7-billion-year-old shales
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From the blogosphere
The online world often feels like a foreign land, writes Timo Hannay, Nature.com's publishing director, at Nascent, Nature's blog on web technology (http://tinyurl.com/4jz8sc).Unfamiliar 'languages' such as patches in open-source software, links, online comments, votes and Facebook 'pokes' are the social currencies
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Getting personal
The commercialization of personal genomics is moving with dizzying speed and scientists need to find innovative ways of discussing the implications with consumers.
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A look within
A series of Essays examines what science has to say about being human.
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Fair trade?
Europe needs to find a responsible way out of its climate-regulation impasse.
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