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Exoplanets

Nature - Wed, 09/17/2014 - 00:00

Exoplanets

Nature 513, 7518 (2014). doi:10.1038/513327a

Author: Leslie Sage

It is hard to imagine now, and the younger people in the field will not remember this, but there was a period when the search for exoplanets had rather a bad reputation, based on a number of high-profile claims that were subsequently disproved. Although there

Categories: Literature

Doppler spectroscopy as a path to the detection of Earth-like planets

Nature - Wed, 09/17/2014 - 00:00

Doppler spectroscopy as a path to the detection of Earth-like planets

Nature 513, 7518 (2014). doi:10.1038/nature13780

Authors: Michel Mayor, Christophe Lovis & Nuno C. Santos

Doppler spectroscopy was the first technique used to reveal the existence of extrasolar planetary systems hosted by solar-type stars. Radial-velocity surveys led to the detection of a rich population of super-Earths and Neptune-type planets. The numerous detected systems revealed a remarkable diversity. Combining Doppler measurements

Categories: Literature

Advances in exoplanet science from Kepler

Nature - Wed, 09/17/2014 - 00:00

Advances in exoplanet science from Kepler

Nature 513, 7518 (2014). doi:10.1038/nature13781

Authors: Jack J. Lissauer, Rebekah I. Dawson & Scott Tremaine

Numerous telescopes and techniques have been used to find and study extrasolar planets, but none has been more successful than NASA's Kepler space telescope. Kepler has discovered most of the known exoplanets, the smallest planets to orbit normal stars and the planets most likely to

Categories: Literature

Highlights in the study of exoplanet atmospheres

Nature - Wed, 09/17/2014 - 00:00

Highlights in the study of exoplanet atmospheres

Nature 513, 7518 (2014). doi:10.1038/nature13782

Author: Adam S. Burrows

Exoplanets are now being discovered in profusion. To understand their character, however, we require spectral models and data. These elements of remote sensing can yield temperatures, compositions and even weather patterns, but only if significant improvements in both the parameter retrieval process and measurements are

Categories: Literature

The role of space telescopes in the characterization of transiting exoplanets

Nature - Wed, 09/17/2014 - 00:00

The role of space telescopes in the characterization of transiting exoplanets

Nature 513, 7518 (2014). doi:10.1038/nature13783

Author: Artie P. Hatzes

Characterization studies now have a dominant role in the field of exoplanets. Such studies include the measurement of an exoplanet's bulk density, its brightness temperature and the chemical composition of its atmosphere. The use of space telescopes has played a key part in the characterization

Categories: Literature

Instrumentation for the detection and characterization of exoplanets

Nature - Wed, 09/17/2014 - 00:00

Instrumentation for the detection and characterization of exoplanets

Nature 513, 7518 (2014). doi:10.1038/nature13784

Authors: Francesco Pepe, David Ehrenreich & Michael R. Meyer

In no other field of astrophysics has the impact of new instrumentation been as substantial as in the domain of exoplanets. Before 1995 our knowledge of exoplanets was mainly based on philosophical and theoretical considerations. The years that followed have been marked, instead, by surprising

Categories: Literature

Extraction

Nature - Wed, 09/17/2014 - 00:00

Extraction

Nature 513, 7518 (2014). doi:10.1038/513454a

Author: Rebecca Roland

Total recall.

Categories: Literature

GATM gene variants and statin myopathy risk

Nature - Wed, 09/17/2014 - 00:00

GATM gene variants and statin myopathy risk

Nature 513, 7518 (2014). doi:10.1038/nature13628

Authors: D. F. Carr, A. Alfirevic, R. Johnson, H. Chinoy, T. van Staa & M. Pirmohamed

Arising from L. M. Mangravite et al. Nature502,377–380 (2013); doi:10.1038/nature12508Mangravite et al. identified six expression quantitative loci (eQTLs) that interacted with simvastatin exposure by using 480 lymphoblastoid cell lines exposed to β-hydroxy simvastatin acid in vitro. One of these SNPs (rs9806699) within the glycine amidinotransferase (GATM) gene was shown to have an association with statin-induced myopathy in two independent cohorts (n = 172 myopathy cases), conferring a protective effect (odds ratio = 0.61, 95% confidence interval = 0.39–0.95, P = 0.03). Our genotyping results from statin myopathy patients do not appear to replicate this finding. There is a Reply to this Brief Communication Arising by Mangravite, L. M. et al. Nature513,http://dx.doi.org/10.1038/nature13630 (2014).

Categories: Literature

GATM locus does not replicate in rhabdomyolysis study

Nature - Wed, 09/17/2014 - 00:00

GATM locus does not replicate in rhabdomyolysis study

Nature 513, 7518 (2014). doi:10.1038/nature13629

Authors: James S. Floyd, Joshua C. Bis, Jennifer A. Brody, Susan R. Heckbert, Kenneth Rice & Bruce M. Psaty

Arising from L. M. Mangravite et al. Nature502,377–380 (2013); doi:10.1038/nature12508All HMG-CoA reductase inhibitors (statins) can cause muscle injury ranging from asymptomatic elevations in creatine kinase levels to severe muscle breakdown (rhabdomyolysis) leading to kidney failure and death, and the genetic variants responsible for this uncommon adverse drug reaction remain largely undiscovered. Mangravite et al. reported a new locus in the gene GATM (rs9806699) that was associated with a decreased risk of muscle injury in two case-control studies of myopathy (odds ratio, 0.60). In a larger case-control study of statin-related rhabdomyolysis, a more severe form of muscle injury, we were unable to replicate this finding. This failure to replicate raises questions about the role of GATM in statin-related muscle injury. There is a Reply to this Brief Communication Arising by Mangravite, L. M. et al. Nature513,http://dx.doi.org/10.1038/nature13630 (2014).

Categories: Literature

Mangravite et al. reply

Nature - Wed, 09/17/2014 - 00:00

Mangravite et al. reply

Nature 513, 7518 (2014). doi:10.1038/nature13630

Authors: Lara M. Mangravite, Barbara E. Engelhardt, Matthew Stephens & Ronald M. Krauss

Replying to D. F. Carr et al.Nature513, http://dx.doi.org/10.1038/nature13628 (2014); J. S. Floyd et al.Nature513, http://dx.doi.org/10.1038/nature13629 (2014)Our study tested for associations of single-nucleotide polymorphisms (SNPs) at the GATM loci with statin-induced myopathy based on the finding that one of these SNPs (rs986699) was associated with statin-induced expression of GATM in a panel of human lymphoblastoid cell lines, and the fact that GATM encodes the enzyme responsible for synthesis of creatine, a major source of energy in skeletal muscle. Significant associations with incidence of myopathy were found for rs9806699 in statin users from the Marshfield Clinic cohort. Furthermore, significant association was reported in both the Marshfield cohort and in the SEARCH clinical trial of simvastatin treatment for two SNPs in linkage disequilibrium with the index SNP (rs1719247 and rs1346268, r2 > 0.7) that were genotyped in each of these groups. We have extended our meta-analysis to include the study data reported in the accompanying Comments by Carr et al. and Floyd et al., two studies that individually failed to replicate this association.

Categories: Literature

Corrections

Nature - Wed, 09/17/2014 - 00:00

Corrections

Nature 513, 7518 (2014). http://www.nature.com/doifinder/10.1038/513292b

The News Feature ‘Survival of the fittest’ (Nature513, 157–159; 2014) referred to the wrong Possession Island. The penguin work was done on the French Base d’Alfred Faure in the Crozet archipelago. The World View by Casparus J. Crous (Nature513,

Categories: Literature

Condensed-matter physics: Catching relativistic electrons

Nature - Wed, 09/17/2014 - 00:00

Condensed-matter physics: Catching relativistic electrons

Nature 513, 7518 (2014). doi:10.1038/513319a

Authors: Zhihuai Zhu & Jennifer E. Hoffman

Low-energy electrons have been found to mimic relativistic high-energy particles in cadmium arsenide. This defines the first stable '3D Dirac semimetal', which holds promise for fundamental-physics exploration and practical applications.

Categories: Literature

Animal behaviour: The evolutionary roots of lethal conflict

Nature - Wed, 09/17/2014 - 00:00

Animal behaviour: The evolutionary roots of lethal conflict

Nature 513, 7518 (2014). doi:10.1038/513321a

Authors: Joan B. Silk

A comprehensive analysis of lethal coalitionary aggression in chimpanzees convincingly demonstrates that such aggression is an adaptive behaviour, not one that has emerged in response to human impacts. See Letter p.414

Categories: Literature

Astrophysics: Giant black hole in a stripped galaxy

Nature - Wed, 09/17/2014 - 00:00

Astrophysics: Giant black hole in a stripped galaxy

Nature 513, 7518 (2014). doi:10.1038/513322a

Authors: Amy E. Reines

An oversized, supermassive black hole has been discovered at the centre of a densely packed conglomeration of stars. The finding suggests that the system is the stripped nucleus of a once-larger galaxy. See Letter p.398

Categories: Literature

50 & 100 Years Ago

Nature - Wed, 09/17/2014 - 00:00

50 & 100 Years Ago

Nature 513, 7518 (2014). doi:10.1038/513323a

50 Years AgoJourney to the Jade Sea. By John Hillaby — Books by writers who go to Africa in search of their souls are always interesting to us who went there in search of wages; this book is fascinating. “Essentially, I walked into

Categories: Literature

Organic chemistry: Reactivity tamed one bond at a time

Nature - Wed, 09/17/2014 - 00:00

Organic chemistry: Reactivity tamed one bond at a time

Nature 513, 7518 (2014). doi:10.1038/513324a

Authors: Matthew T. Villaume & Phil S. Baran

A catalyst that couples together three reactants to form just one compound out of several possibilities, as a single mirror-image isomer, should simplify the synthesis of biologically relevant molecules. See Article p.367

Categories: Literature

Multifunctional organoboron compounds for scalable natural product synthesis

Nature - Wed, 09/17/2014 - 00:00

Multifunctional organoboron compounds for scalable natural product synthesis

Nature 513, 7518 (2014). doi:10.1038/nature13735

Authors: Fanke Meng, Kevin P. McGrath & Amir H. Hoveyda

Efficient catalytic reactions that can generate C–C bonds enantioselectively, and ones that can produce trisubstituted alkenes diastereoselectively, are central to research in organic chemistry. Transformations that accomplish these two tasks simultaneously are in high demand, particularly if the catalysts, substrates and reagents are inexpensive and

Categories: Literature

A supermassive black hole in an ultra-compact dwarf galaxy

Nature - Wed, 09/17/2014 - 00:00

A supermassive black hole in an ultra-compact dwarf galaxy

Nature 513, 7518 (2014). doi:10.1038/nature13762

Authors: Anil C. Seth, Remco van den Bosch, Steffen Mieske, Holger Baumgardt, Mark den Brok, Jay Strader, Nadine Neumayer, Igor Chilingarian, Michael Hilker, Richard McDermid, Lee Spitler, Jean Brodie, Matthias J. Frank & Jonelle L. Walsh

Ultra-compact dwarf galaxies are among the densest stellar systems in the Universe. These systems have masses of up to 2 × 108 solar masses, but half-light radii of just 3–50 parsecs. Dynamical mass estimates show that many such dwarfs are more massive than expected from their luminosity. It remains unclear whether these high dynamical mass estimates arise because of the presence of supermassive black holes or result from a non-standard stellar initial mass function that causes the average stellar mass to be higher than expected. Here we report adaptive optics kinematic data of the ultra-compact dwarf galaxy M60-UCD1 that show a central velocity dispersion peak exceeding 100 kilometres per second and modest rotation. Dynamical modelling of these data reveals the presence of a supermassive black hole with a mass of 2.1 × 107 solar masses. This is 15 per cent of the object’s total mass. The high black hole mass and mass fraction suggest that M60-UCD1 is the stripped nucleus of a galaxy. Our analysis also shows that M60-UCD1’s stellar mass is consistent with its luminosity, implying a large population of previously unrecognized supermassive black holes in other ultra-compact dwarf galaxies.

Categories: Literature

Aridification of the Sahara desert caused by Tethys Sea shrinkage during the Late Miocene

Nature - Wed, 09/17/2014 - 00:00

Aridification of the Sahara desert caused by Tethys Sea shrinkage during the Late Miocene

Nature 513, 7518 (2014). doi:10.1038/nature13705

Authors: Zhongshi Zhang, Gilles Ramstein, Mathieu Schuster, Camille Li, Camille Contoux & Qing Yan

It is widely believed that the Sahara desert is no more than ∼2–3 million years (Myr) old, with geological evidence showing a remarkable aridification of north Africa at the onset of the Quaternary ice ages. Before that time, north African aridity was mainly controlled by the African summer monsoon (ASM), which oscillated with Earth’s orbital precession cycles. Afterwards, the Northern Hemisphere glaciation added an ice volume forcing on the ASM, which additionally oscillated with glacial–interglacial cycles. These findings led to the idea that the Sahara desert came into existence when the Northern Hemisphere glaciated ∼2–3 Myr ago. The later discovery, however, of aeolian dune deposits ∼7 Myr old suggested a much older age, although this interpretation is hotly challenged and there is no clear mechanism for aridification around this time. Here we use climate model simulations to identify the Tortonian stage (∼7–11 Myr ago) of the Late Miocene epoch as the pivotal period for triggering north African aridity and creating the Sahara desert. Through a set of experiments with the Norwegian Earth System Model and the Community Atmosphere Model, we demonstrate that the African summer monsoon was drastically weakened by the Tethys Sea shrinkage during the Tortonian, allowing arid, desert conditions to expand across north Africa. Not only did the Tethys shrinkage alter the mean climate of the region, it also enhanced the sensitivity of the African monsoon to orbital forcing, which subsequently became the major driver of Sahara extent fluctuations. These important climatic changes probably caused the shifts in Asian and African flora and fauna observed during the same period, with possible links to the emergence of early hominins in north Africa.

Categories: Literature

Spreading continents kick-started plate tectonics

Nature - Wed, 09/17/2014 - 00:00

Spreading continents kick-started plate tectonics

Nature 513, 7518 (2014). doi:10.1038/nature13728

Authors: Patrice F. Rey, Nicolas Coltice & Nicolas Flament

Stresses acting on cold, thick and negatively buoyant oceanic lithosphere are thought to be crucial to the initiation of subduction and the operation of plate tectonics, which characterizes the present-day geodynamics of the Earth. Because the Earth’s interior was hotter in the Archaean eon, the oceanic crust may have been thicker, thereby making the oceanic lithosphere more buoyant than at present, and whether subduction and plate tectonics occurred during this time is ambiguous, both in the geological record and in geodynamic models. Here we show that because the oceanic crust was thick and buoyant, early continents may have produced intra-lithospheric gravitational stresses large enough to drive their gravitational spreading, to initiate subduction at their margins and to trigger episodes of subduction. Our model predicts the co-occurrence of deep to progressively shallower mafic volcanics and arc magmatism within continents in a self-consistent geodynamic framework, explaining the enigmatic multimodal volcanism and tectonic record of Archaean cratons. Moreover, our model predicts a petrological stratification and tectonic structure of the sub-continental lithospheric mantle, two predictions that are consistent with xenolith and seismic studies, respectively, and consistent with the existence of a mid-lithospheric seismic discontinuity. The slow gravitational collapse of early continents could have kick-started transient episodes of plate tectonics until, as the Earth’s interior cooled and oceanic lithosphere became heavier, plate tectonics became self-sustaining.

Categories: Literature

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