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SESAME and beyond

2017-05-25T10:24:10-07:00




News at a glance

2017-05-25T10:24:10-07:00




New Ebola outbreak rings alarm bells early

2017-05-25T10:24:10-07:00







A submillimeter building boom

2017-05-25T10:24:10-07:00







The strange case of the orange petunias

2017-05-25T10:24:10-07:00













Fossil power, guilt free

2017-05-25T10:24:10-07:00




Cleaning up coal--cost-effectively

2017-05-25T10:24:10-07:00




Do not publish

2017-05-25T10:24:10-07:00




Classical-quantum sensors keep better time

2017-05-25T10:24:10-07:00




How to fight corruption

2017-05-25T10:24:10-07:00




Turbines can use CO2 to cut CO2

2017-05-25T10:24:10-07:00










High fidelity

2017-05-25T10:24:10-07:00




Climate optimism gets a road map

2017-05-25T10:24:10-07:00







Editorial retraction

2017-05-25T10:24:10-07:00




Brazil's public universities in crisis

2017-05-25T10:24:10-07:00




Genomic databases: A WHO affair

2017-05-25T10:24:10-07:00




Comment on "Dissolved organic sulfur in the ocean: Biogeochemistry of a petagram inventory"

2017-05-25T10:24:10-07:00

Ksionzek et al. (Reports, 28 October 2016, p. 456) provide important data describing the distribution of dissolved organic sulfur (DOS) in the Atlantic Ocean. Here, we show that mixing between water masses is sufficient to explain the observed distribution of DOS, concluding that the turnover time of refractory DOS that Ksionzek et al. present cannot be deduced from their data.




Response to Comment on "Dissolved organic sulfur in the ocean: Biogeochemistry of a petagram inventory"

2017-05-25T10:24:10-07:00

Dittmar et al. proposed that mixing alone can explain our observed decrease in marine dissolved organic sulfur with age. However, their simple model lacks an explanation for the origin of sulfur-depleted organic matter in the deep ocean and cannot adequately reproduce our observed stoichiometric changes. Using radiocarbon age also implicitly models the preferential cycling of sulfur that they are disputing.







Neuroplasticity in learning to read

2017-05-25T10:24:10-07:00




Juno swoops around giant Jupiter

2017-05-25T10:24:10-07:00




Enhancing quantum sensing

2017-05-25T10:24:10-07:00




Sediments tell a tsunami story

2017-05-25T10:24:10-07:00




Representing direction in the fly

2017-05-25T10:24:10-07:00




Breaking down miRNAs

2017-05-25T10:24:10-07:00




A neuronal circuit for overeating

2017-05-25T10:24:10-07:00




Trapping RNA polymerase in the act

2017-05-25T10:24:10-07:00




No safe haven for metastases

2017-05-25T10:24:10-07:00







Mapping the proteome

2017-05-25T10:24:10-07:00




Flicking the Berry phase switch

2017-05-25T10:24:10-07:00




Who needs to know where species live?

2017-05-25T10:24:10-07:00




Unintended victims of fighting corruption

2017-05-25T10:24:10-07:00




Creating a weakness in prostate cancer

2017-05-25T10:24:10-07:00




Risks of reef erosion

2017-05-25T10:24:10-07:00




Roadmaps for building the neonatal brain

2017-05-25T10:24:10-07:00




Burn to run in the U.S.A.

2017-05-25T10:24:10-07:00




The NET effect of viral-triggered asthma

2017-05-25T10:24:10-07:00




Building a better mantle with BEAMS

2017-05-25T10:24:10-07:00




PPR a risk to Europe

2017-05-25T10:24:10-07:00




Perovskite ferroelectric bond-switching

2017-05-25T10:24:10-07:00




Jupiters interior and deep atmosphere: The initial pole-to-pole passes with the Juno spacecraft

2017-05-25T10:24:10-07:00

On 27 August 2016, the Juno spacecraft acquired science observations of Jupiter, passing less than 5000 kilometers above the equatorial cloud tops. Images of Jupiter’s poles show a chaotic scene, unlike Saturn’s poles. Microwave sounding reveals weather features at pressures deeper than 100 bars, dominated by an ammonia-rich, narrow low-latitude plume resembling a deeper, wider version of Earth’s Hadley cell. Near-infrared mapping reveals the relative humidity within prominent downwelling regions. Juno’s measured gravity field differs substantially from the last available estimate and is one order of magnitude more precise. This has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter’s core. The observed magnetic field exhibits smaller spatial variations than expected, indicative of a rich harmonic content.




Jupiters magnetosphere and aurorae observed by the Juno spacecraft during its first polar orbits

2017-05-25T10:24:10-07:00

The Juno spacecraft acquired direct observations of the jovian magnetosphere and auroral emissions from a vantage point above the poles. Juno’s capture orbit spanned the jovian magnetosphere from bow shock to the planet, providing magnetic field, charged particle, and wave phenomena context for Juno’s passage over the poles and traverse of Jupiter’s hazardous inner radiation belts. Juno’s energetic particle and plasma detectors measured electrons precipitating in the polar regions, exciting intense aurorae, observed simultaneously by the ultraviolet and infrared imaging spectrographs. Juno transited beneath the most intense parts of the radiation belts, passed about 4000 kilometers above the cloud tops at closest approach, well inside the jovian rings, and recorded the electrical signatures of high-velocity impacts with small particles as it traversed the equator.




Submillihertz magnetic spectroscopy performed with a nanoscale quantum sensor

2017-05-25T10:24:10-07:00

Precise timekeeping is critical to metrology, forming the basis by which standards of time, length, and fundamental constants are determined. Stable clocks are particularly valuable in spectroscopy because they define the ultimate frequency precision that can be reached. In quantum metrology, the qubit coherence time defines the clock stability, from which the spectral linewidth and frequency precision are determined. We demonstrate a quantum sensing protocol in which the spectral precision goes beyond the sensor coherence time and is limited by the stability of a classical clock. Using this technique, we observed a precision in frequency estimation scaling in time T as T–3/2 for classical oscillating fields. The narrow linewidth magnetometer based on single spins in diamond is used to sense nanoscale magnetic fields with an intrinsic frequency resolution of 607 microhertz, which is eight orders of magnitude narrower than the qubit coherence time.




Quantum sensing with arbitrary frequency resolution

2017-05-25T10:24:10-07:00

Quantum sensing takes advantage of well-controlled quantum systems for performing measurements with high sensitivity and precision. We have implemented a concept for quantum sensing with arbitrary frequency resolution, independent of the qubit probe and limited only by the stability of an external synchronization clock. Our concept makes use of quantum lock-in detection to continuously probe a signal of interest. Using the electronic spin of a single nitrogen-vacancy center in diamond, we demonstrate detection of oscillating magnetic fields with a frequency resolution of 70 microhertz over a megahertz bandwidth. The continuous sampling further guarantees an enhanced sensitivity, reaching a signal-to-noise ratio in excess of 104 for a 170-nanotesla test signal measured during a 1-hour interval. Our technique has applications in magnetic resonance spectroscopy, quantum simulation, and sensitive signal detection.




Release of mineral-bound water prior to subduction tied to shallow seismogenic slip off Sumatra

2017-05-25T10:24:10-07:00

Plate-boundary fault rupture during the 2004 Sumatra-Andaman subduction earthquake extended closer to the trench than expected, increasing earthquake and tsunami size. International Ocean Discovery Program Expedition 362 sampled incoming sediments offshore northern Sumatra, revealing recent release of fresh water within the deep sediments. Thermal modeling links this freshening to amorphous silica dehydration driven by rapid burial-induced temperature increases in the past 9 million years. Complete dehydration of silicates is expected before plate subduction, contrasting with prevailing models for subduction seismogenesis calling for fluid production during subduction. Shallow slip offshore Sumatra appears driven by diagenetic strengthening of deeply buried fault-forming sediments, contrasting with weakening proposed for the shallow Tohoku-Oki 2011 rupture, but our results are applicable to other thickly sedimented subduction zones including those with limited earthquake records.




An on/off Berry phase switch in circular graphene resonators

2017-05-25T10:24:10-07:00

The phase of a quantum state may not return to its original value after the system’s parameters cycle around a closed path; instead, the wave function may acquire a measurable phase difference called the Berry phase. Berry phases typically have been accessed through interference experiments. Here, we demonstrate an unusual Berry phase–induced spectroscopic feature: a sudden and large increase in the energy of angular-momentum states in circular graphene p-n junction resonators when a relatively small critical magnetic field is reached. This behavior results from turning on a Berry phase associated with the topological properties of Dirac fermions in graphene. The Berry phase can be switched on and off with small magnetic field changes on the order of 10 millitesla, potentially enabling a variety of optoelectronic graphene device applications.




Ring attractor dynamics in the Drosophila central brain

2017-05-25T10:24:10-07:00

Ring attractors are a class of recurrent networks hypothesized to underlie the representation of heading direction. Such network structures, schematized as a ring of neurons whose connectivity depends on their heading preferences, can sustain a bump-like activity pattern whose location can be updated by continuous shifts along either turn direction. We recently reported that a population of fly neurons represents the animal’s heading via bump-like activity dynamics. We combined two-photon calcium imaging in head-fixed flying flies with optogenetics to overwrite the existing population representation with an artificial one, which was then maintained by the circuit with naturalistic dynamics. A network with local excitation and global inhibition enforces this unique and persistent heading representation. Ring attractor networks have long been invoked in theoretical work; our study provides physiological evidence of their existence and functional architecture.




Rapid binge-like eating and body weight gain driven by zona incerta GABA neuron activation

2017-05-25T10:24:10-07:00

The neuronal substrate for binge eating, which can at times lead to obesity, is not clear. We find that optogenetic stimulation of mouse zona incerta (ZI) -aminobutyric acid (GABA) neurons or their axonal projections to paraventricular thalamus (PVT) excitatory neurons immediately (in 2 to 3 seconds) evoked binge-like eating. Minimal intermittent stimulation led to body weight gain; ZI GABA neuron ablation reduced weight. ZI stimulation generated 35% of normal 24-hour food intake in just 10 minutes. The ZI cells were excited by food deprivation and the gut hunger signal ghrelin. In contrast, stimulation of excitatory axons from the parasubthalamic nucleus to PVT or direct stimulation of PVT glutamate neurons reduced food intake. These data suggest an unexpected robust orexigenic potential for the ZI GABA neurons.




Tudor-SN-mediated endonucleolytic decay of human cell microRNAs promotes G1/S phase transition

2017-05-25T10:24:10-07:00

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression. The pathways that mediate mature miRNA decay are less well understood than those that mediate miRNA biogenesis. We found that functional miRNAs are degraded in human cells by the endonuclease Tudor-SN (TSN). In vitro, recombinant TSN initiated the decay of both protein-free and Argonaute 2–loaded miRNAs via endonucleolytic cleavage at CA and UA dinucleotides, preferentially at scissile bonds located more than five nucleotides away from miRNA ends. Cellular targets of TSN-mediated decay defined using microRNA sequencing followed this rule. Inhibiting TSN-mediated miRNA decay by CRISPR-Cas9 knockout of TSN inhibited cell cycle progression by up-regulating a cohort of miRNAs that down-regulates mRNAs that encode proteins critical for the G1-to-S phase transition. Our study indicates that targeting TSN nuclease activity could inhibit pathological cell proliferation.




RNA polymerase motions during promoter melting

2017-05-25T10:24:10-07:00

All cellular RNA polymerases (RNAPs), from those of bacteria to those of man, possess a clamp that can open and close, and it has been assumed that the open RNAP separates promoter DNA strands and then closes to establish a tight grip on the DNA template. Here, we resolve successive motions of the initiating bacterial RNAP by studying real-time signatures of fluorescent reporters placed on RNAP and DNA in the presence of ligands locking the clamp in distinct conformations. We report evidence for an unexpected and obligatory step early in the initiation involving a transient clamp closure as a prerequisite for DNA melting. We also present a 2.6-angstrom crystal structure of a late-initiation intermediate harboring a rotationally unconstrained downstream DNA duplex within the open RNAP active site cleft. Our findings explain how RNAP thermal motions control the promoter search and drive DNA melting in the absence of external energy sources.




New Products

2017-05-25T10:24:10-07:00




Stressing mental health

2017-05-25T10:24:10-07:00




A subcellular map of the human proteome

2017-05-25T10:24:10-07:00

Resolving the spatial distribution of the human proteome at a subcellular level can greatly increase our understanding of human biology and disease. Here we present a comprehensive image-based map of subcellular protein distribution, the Cell Atlas, built by integrating transcriptomics and antibody-based immunofluorescence microscopy with validation by mass spectrometry. Mapping the in situ localization of 12,003 human proteins at a single-cell level to 30 subcellular structures enabled the definition of the proteomes of 13 major organelles. Exploration of the proteomes revealed single-cell variations in abundance or spatial distribution and localization of about half of the proteins to multiple compartments. This subcellular map can be used to refine existing protein-protein interaction networks and provides an important resource to deconvolute the highly complex architecture of the human cell.




Ancestral alliances: Plant mutualistic symbioses with fungi and bacteria

2017-05-25T10:24:10-07:00

Within the plant microbiota, mutualistic fungal and bacterial symbionts are striking examples of microorganisms playing crucial roles in nutrient acquisition. They have coevolved with their hosts since initial plant adaptation to land. Despite the evolutionary distances that separate mycorrhizal and nitrogen-fixing symbioses, these associations share a number of highly conserved features, including specific plant symbiotic signaling pathways, root colonization strategies that circumvent plant immune responses, functional host-microbe interface formation, and the central role of phytohormones in symbiosis-associated root developmental pathways. We highlight recent and emerging areas of investigation relating to these evolutionarily conserved mechanisms, with an emphasis on the more ancestral mycorrhizal associations, and consider to what extent this knowledge can contribute to an understanding of plant-microbiota associations as a whole.