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Fundamental shift in vitamin B12 eco-physiology of a model alga demonstrated by experimental evolution

ISME - Tue, 05/19/2015 - 00:00

Fundamental shift in vitamin B12 eco-physiology of a model alga demonstrated by experimental evolution

The ISME Journal 9, 1446 (June 2015). doi:10.1038/ismej.2014.230

Authors: Katherine E Helliwell, Sinéad Collins, Elena Kazamia, Saul Purton, Glen L Wheeler & Alison G Smith

Categories: Literature

Aerobic and anaerobic nitrogen transformation processes in N2-fixing cyanobacterial aggregates

ISME - Tue, 05/19/2015 - 00:00

Aerobic and anaerobic nitrogen transformation processes in N2-fixing cyanobacterial aggregates

The ISME Journal 9, 1456 (June 2015). doi:10.1038/ismej.2014.232

Authors: Isabell Klawonn, Stefano Bonaglia, Volker Brüchert & Helle Ploug

Categories: Literature

Validated predictive modelling of the environmental resistome

ISME - Tue, 05/19/2015 - 00:00

Validated predictive modelling of the environmental resistome

The ISME Journal 9, 1467 (June 2015). doi:10.1038/ismej.2014.237

Authors: Gregory CA Amos, Emma Gozzard, Charlotte E Carter, Andrew Mead, Mike J Bowes, Peter M Hawkey, Lihong Zhang, Andrew C Singer, William H Gaze & Elizabeth M H Wellington

Categories: Literature

Linking soil bacterial biodiversity and soil carbon stability

ISME - Tue, 05/19/2015 - 00:00

Linking soil bacterial biodiversity and soil carbon stability

The ISME Journal 9, 1477 (June 2015). doi:10.1038/ismej.2014.205

Authors: Rebecca L Mau, Cindy M Liu, Maliha Aziz, Egbert Schwartz, Paul Dijkstra, Jane C Marks, Lance B Price, Paul Keim & Bruce A Hungate

Categories: Literature

Low Snowpack Raising Drought Concerns in Oregon and Washington

Yale Environment 360 - Mon, 05/18/2015 - 11:09

While drought conditions in California and the southwestern U.S. have been dominating news headlines, Oregon and

Enlarge

Snowpack in May 2015 Washington could also soon be facing dangerously dry conditions due to low snowpack levels, as these photos show. Although the region has seen several months with average or just-below average precipitation, unusually warm temperatures on land and offshore led to most of that moisture arriving in the form of rain rather than snow. Like many parts of the western U.S. and Canada, the Pacific Northwest depends on mountain snowpack to melt and fill streams and rivers through warmer, drier summer months. According to state officials, snowpack in Washington was just 16 percent of normal as of May 15, and yearly runoff is predicted to be at its lowest in 64 years. Average snowpack in Oregon stood at just 11 percent of normal, its lowest level since 1992.

Categories: Environmental News

The Big Waste: Why Do We Throw Away So Much Food?

Yale Environment 360 - Mon, 05/18/2015 - 07:30

BY KARIM CHROBOG

Categories: Environmental News

Engineered yeast paves way for home-brew heroin

Nature - Mon, 05/18/2015 - 00:00

Engineered yeast paves way for home-brew heroin

Nature 521, 7552 (2015). http://www.nature.com/doifinder/10.1038/251267a

Author: Rachel Ehrenberg

Advance holds potential for better opiate painkillers — but raises concerns about illicit use.

Categories: Literature

Drugs: Regulate 'home-brew' opiates

Nature - Mon, 05/18/2015 - 00:00

Drugs: Regulate 'home-brew' opiates

Nature 521, 7552 (2015). doi:10.1038/521281a

Authors: Kenneth A. Oye, J. Chappell H. Lawson & Tania Bubela

The research community and the public require a fast, flexible response to the synthesis of morphine by engineered yeasts, urge Kenneth Oye, Tania Bubela and J. Chappell H. Lawson.

Categories: Literature

Indonesia Extends Major Logging Moratorium, Which Critics Decry as Weak

Yale Environment 360 - Fri, 05/15/2015 - 10:38

Indonesia has extended a major logging moratorium aimed at preserving the archipelago's vast swathes

Deforestation for a palm oil plantation in Indonesia. of tropical rainforest, but environmentalists say the logging ban does not go nearly far enough. The country, home to some of the world's most biodiverse rain forests and endangered species such as tigers and elephants, first enacted the moratorium in 2011, banning new logging permits for primary and virgin forests and peatlands. The moratorium was first extended until 2015, and now has been extended again, to 2017. Environmental groups have criticized the moratorium, however, saying that it still allows deforestation for ventures deemed in the national interest, such as infrastructure projects and agricultural plantations. Indonesia is the largest economy in Southeast Asia and third-largest carbon emitter in the world. Huge swathes of its forests have been chopped down by palm oil, mining, and timber companies.

Categories: Environmental News

Biologically Inspired Coating Will Improve Solar Panels, Researchers Say

Yale Environment 360 - Thu, 05/14/2015 - 10:58

Key characteristics of moths’ eyes, which are anti-reflective, and lotus leaves, which are water-repellant, inspired a new type of glass coating that could significantly improve the efficiency of solar panels, say researchers at Oak Ridge National Laboratory. The extremely durable coating can be customized to be fog-resistant, anti-reflective, and superhydrophobic — meaning it repels water drops so efficiently that they barely make contact with the solar panel surface, literally bouncing off and carrying away dirt and dust that hamper performance. The key component is a nanostructured layer of glass film that, under a microscope, has a porous texture resembling coral, which helps the solar cells absorb more light, the researchers say. Reflecting less sunlight means a 3 to 6 percent increase in light-to-electricity conversion efficiency and power output, studies show. The coating can be fabricated using standard industry techniques, the researchers say, making it easy and inexpensive to scale up and incorporate in current products.

Categories: Environmental News

A Remarkable Recovery for the Oysters of Chesapeake Bay

Yale Environment 360 - Thu, 05/14/2015 - 07:31

In the past century, more than 90 percent of the world’s oyster beds have been lost to pollution, overharvesting, disease, and

Wild oysters harvested from the Chesapeake Bay coastal development. The renowned oysters of the Chesapeake Bay experienced a similar decline, with production nearly disappearing a decade ago. Now, however, Chesapeake Bay oysters are undergoing a remarkable recovery thanks to a brilliant oyster geneticist, improved state and federal management, the expansion of private hatchery operations, the cleanup of the bay, and some help in the form of average rain years and excellent reproductive oyster classes.
Read more.

Categories: Environmental News

Aid burst lifts people out of extreme poverty

Nature - Thu, 05/14/2015 - 00:00

Aid burst lifts people out of extreme poverty

Nature 521, 7552 (2015). http://www.nature.com/doifinder/10.1038/nature.2015.17560

Author: Declan Butler

Huge experiment across six nations shows lasting benefits from short-term support.

Categories: Literature

UK universities slow to publish reports of misconduct investigations

Nature - Thu, 05/14/2015 - 00:00

UK universities slow to publish reports of misconduct investigations

Nature 521, 7552 (2015). http://www.nature.com/doifinder/10.1038/nature.2015.17559

Author: Elizabeth Gibney

Few institutions have followed research integrity guidelines to the letter.

Categories: Literature

Neural dynamics for landmark orientation and angular path integration

Nature - Thu, 05/14/2015 - 00:00

Neural dynamics for landmark orientation and angular path integration

Nature 521, 7551 (2015). doi:10.1038/nature14446

Authors: Johannes D. Seelig & Vivek Jayaraman

Many animals navigate using a combination of visual landmarks and path integration. In mammalian brains, head direction cells integrate these two streams of information by representing an animal's heading relative to landmarks, yet maintaining their directional tuning in darkness based on self-motion cues. Here we

Categories: Literature

Strangulation as the primary mechanism for shutting down star formation in galaxies

Nature - Thu, 05/14/2015 - 00:00

Strangulation as the primary mechanism for shutting down star formation in galaxies

Nature 521, 7551 (2015). doi:10.1038/nature14439

Authors: Y. Peng, R. Maiolino & R. Cochrane

Local galaxies are broadly divided into two main classes, star-forming (gas-rich) and quiescent (passive and gas-poor). The primary mechanism responsible for quenching star formation in galaxies and transforming them into quiescent and passive systems is still unclear. Sudden removal of gas through outflows or stripping is one of the mechanisms often proposed. An alternative mechanism is so-called “strangulation”, in which the supply of cold gas to the galaxy is halted. Here we report an analysis of the stellar metallicity (the fraction of elements heavier than helium in stellar atmospheres) in local galaxies, from 26,000 spectra, that clearly reveals that strangulation is the primary mechanism responsible for quenching star formation, with a typical timescale of four billion years, at least for local galaxies with a stellar mass less than 1011 solar masses. This result is further supported independently by the stellar age difference between quiescent and star-forming galaxies, which indicates that quiescent galaxies of less than 1011 solar masses are on average observed four billion years after quenching due to strangulation.

Categories: Literature

Electron pairing without superconductivity

Nature - Thu, 05/14/2015 - 00:00

Electron pairing without superconductivity

Nature 521, 7551 (2015). doi:10.1038/nature14398

Authors: Guanglei Cheng, Michelle Tomczyk, Shicheng Lu, Joshua P. Veazey, Mengchen Huang, Patrick Irvin, Sangwoo Ryu, Hyungwoo Lee, Chang-Beom Eom, C. Stephen Hellberg & Jeremy Levy

Strontium titanate (SrTiO3) is the first and best known superconducting semiconductor. It exhibits an extremely low carrier density threshold for superconductivity, and possesses a phase diagram similar to that of high-temperature superconductors—two factors that suggest an unconventional pairing mechanism. Despite sustained interest for 50 years, direct experimental insight into the nature of electron pairing in SrTiO3 has remained elusive. Here we perform transport experiments with nanowire-based single-electron transistors at the interface between SrTiO3 and a thin layer of lanthanum aluminate, LaAlO3. Electrostatic gating reveals a series of two-electron conductance resonances—paired electron states—that bifurcate above a critical pairing field Bp of about 1–4 tesla, an order of magnitude larger than the superconducting critical magnetic field. For magnetic fields below Bp, these resonances are insensitive to the applied magnetic field; for fields in excess of Bp, the resonances exhibit a linear Zeeman-like energy splitting. Electron pairing is stable at temperatures as high as 900 millikelvin, well above the superconducting transition temperature (about 300 millikelvin). These experiments demonstrate the existence of a robust electronic phase in which electrons pair without forming a superconducting state. Key experimental signatures are captured by a model involving an attractive Hubbard interaction that describes real-space electron pairing as a precursor to superconductivity.

Categories: Literature

Quantum coherent optical phase modulation in an ultrafast transmission electron microscope

Nature - Thu, 05/14/2015 - 00:00

Quantum coherent optical phase modulation in an ultrafast transmission electron microscope

Nature 521, 7551 (2015). doi:10.1038/nature14463

Authors: Armin Feist, Katharina E. Echternkamp, Jakob Schauss, Sergey V. Yalunin, Sascha Schäfer & Claus Ropers

Coherent manipulation of quantum systems with light is expected to be a cornerstone of future information and communication technology, including quantum computation and cryptography. The transfer of an optical phase onto a quantum wavefunction is a defining aspect of coherent interactions and forms the basis of quantum state preparation, synchronization and metrology. Light-phase-modulated electron states near atoms and molecules are essential for the techniques of attosecond science, including the generation of extreme-ultraviolet pulses and orbital tomography. In contrast, the quantum-coherent phase-modulation of energetic free-electron beams has not been demonstrated, although it promises direct access to ultrafast imaging and spectroscopy with tailored electron pulses on the attosecond scale. Here we demonstrate the coherent quantum state manipulation of free-electron populations in an electron microscope beam. We employ the interaction of ultrashort electron pulses with optical near-fields to induce Rabi oscillations in the populations of electron momentum states, observed as a function of the optical driving field. Excellent agreement with the scaling of an equal-Rabi multilevel quantum ladder is obtained, representing the observation of a light-driven ‘quantum walk’ coherently reshaping electron density in momentum space. We note that, after the interaction, the optically generated superposition of momentum states evolves into a train of attosecond electron pulses. Our results reveal the potential of quantum control for the precision structuring of electron densities, with possible applications ranging from ultrafast electron spectroscopy and microscopy to accelerator science and free-electron lasers.

Categories: Literature

Global carbon export from the terrestrial biosphere controlled by erosion

Nature - Thu, 05/14/2015 - 00:00

Global carbon export from the terrestrial biosphere controlled by erosion

Nature 521, 7551 (2015). doi:10.1038/nature14400

Authors: Valier Galy, Bernhard Peucker-Ehrenbrink & Timothy Eglinton

Riverine export of particulate organic carbon (POC) to the ocean affects the atmospheric carbon inventory over a broad range of timescales. On geological timescales, the balance between sequestration of POC from the terrestrial biosphere and oxidation of rock-derived (petrogenic) organic carbon sets the magnitude of the atmospheric carbon and oxygen reservoirs. Over shorter timescales, variations in the rate of exchange between carbon reservoirs, such as soils and marine sediments, also modulate atmospheric carbon dioxide levels. The respective fluxes of biospheric and petrogenic organic carbon are poorly constrained, however, and mechanisms controlling POC export have remained elusive, limiting our ability to predict POC fluxes quantitatively as a result of climatic or tectonic changes. Here we estimate biospheric and petrogenic POC fluxes for a suite of river systems representative of the natural variability in catchment properties. We show that export yields of both biospheric and petrogenic POC are positively related to the yield of suspended sediment, revealing that POC export is mostly controlled by physical erosion. Using a global compilation of gauged suspended sediment flux, we derive separate estimates of global biospheric and petrogenic POC fluxes of and megatonnes of carbon per year, respectively. We find that biospheric POC export is primarily controlled by the capacity of rivers to mobilize and transport POC, and is largely insensitive to the magnitude of terrestrial primary production. Globally, physical erosion rates affect the rate of biospheric POC burial in marine sediments more strongly than carbon sequestration through silicate weathering. We conclude that burial of biospheric POC in marine sediments becomes the dominant long-term atmospheric carbon dioxide sink under enhanced physical erosion.

Categories: Literature

Electron cryomicroscopy observation of rotational states in a eukaryotic V-ATPase

Nature - Thu, 05/14/2015 - 00:00

Electron cryomicroscopy observation of rotational states in a eukaryotic V-ATPase

Nature 521, 7551 (2015). doi:10.1038/nature14365

Authors: Jianhua Zhao, Samir Benlekbir & John L. Rubinstein

Eukaryotic vacuolar H+-ATPases (V-ATPases) are rotary enzymes that use energy from hydrolysis of ATP to ADP to pump protons across membranes and control the pH of many intracellular compartments. ATP hydrolysis in the soluble catalytic region of the enzyme is coupled to proton translocation through the membrane-bound region by rotation of a central rotor subcomplex, with peripheral stalks preventing the entire membrane-bound region from turning with the rotor. The eukaryotic V-ATPase is the most complex rotary ATPase: it has three peripheral stalks, a hetero-oligomeric proton-conducting proteolipid ring, several subunits not found in other rotary ATPases, and is regulated by reversible dissociation of its catalytic and proton-conducting regions. Studies of ATP synthases, V-ATPases, and bacterial/archaeal V/A-ATPases have suggested that flexibility is necessary for the catalytic mechanism of rotary ATPases, but the structures of different rotational states have never been observed experimentally. Here we use electron cryomicroscopy to obtain structures for three rotational states of the V-ATPase from the yeast Saccharomyces cerevisiae. The resulting series of structures shows ten proteolipid subunits in the c-ring, setting the ATP:H+ ratio for proton pumping by the V-ATPase at 3:10, and reveals long and highly tilted transmembrane α-helices in the a-subunit that interact with the c-ring. The three different maps reveal the conformational changes that occur to couple rotation in the symmetry-mismatched soluble catalytic region to the membrane-bound proton-translocating region. Almost all of the subunits of the enzyme undergo conformational changes during the transitions between these three rotational states. The structures of these states provide direct evidence that deformation during rotation enables the smooth transmission of power through rotary ATPases.

Categories: Literature

Erratum: Entanglement with negative Wigner function of almost 3,000 atoms heralded by one photon

Nature - Thu, 05/14/2015 - 00:00

Erratum: Entanglement with negative Wigner function of almost 3,000 atoms heralded by one photon

Nature 521, 7551 (2015). doi:10.1038/nature14470

Authors: Robert McConnell, Hao Zhang, Jiazhong Hu, Senka Ćuk & Vladan Vuletić

Nature519, 439–442 (2015); doi:10.1038/nature14293In Fig. 2a of this Letter, the solid blue line in the linear plot was inadvertently removed during the production process; this figure has now been corrected in the online versions of the manuscript.

Categories: Literature

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