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    Retinal isomerization in bacteriorhodopsin captured by a femtosecond x-ray laser - Ultrafast isomerization of retinal is the primary step in photoresponsive biological functions including vision in humans and ion transport across bacterial membranes. We used an x-ray laser to study the subpicosecond structural dynamics of retinal isomerization in the light-driven proton pump bacteriorhodopsin. A series of structural snapshots with near-atomic spatial resolution and temporal resolution in the femtosecond regime show how the exc...
    Feed Source: science.sciencemag.org

    Neutrino emission from the direction of the blazar TXS 0506+056 prior to the IceCube-170922A alert - A high-energy neutrino event detected by IceCube on 22 September 2017 was coincident in direction and time with a gamma-ray flare from the blazar TXS 0506+056. Prompted by this association, we investigated 9.5 years of IceCube neutrino observations to search for excess emission at the position of the blazar. We found an excess of high-energy neutrino events, with respect to atmospheric backgrounds, at that position between September 2014 and Mar...
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    Metal-free three-dimensional perovskite ferroelectrics - Inorganic perovskite ferroelectrics are widely used in nonvolatile memory elements, capacitors, and sensors because of their excellent ferroelectric and other properties. Organic ferroelectrics are desirable for their mechanical flexibility, low weight, environmentally friendly processing, and low processing temperatures. Although almost a century has passed since the first ferroelectric, Rochelle salt, was discovered, examples of highly desirab...
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    Programming self-organizing multicellular structures with synthetic cell-cell signaling - A common theme in the self-organization of multicellular tissues is the use of cell-cell signaling networks to induce morphological changes. We used the modular synNotch juxtacrine signaling platform to engineer artificial genetic programs in which specific cell-cell contacts induced changes in cadherin cell adhesion. Despite their simplicity, these minimal intercellular programs were sufficient to yield assemblies with hallmarks of natural deve...
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    Phase transitions in a programmable quantum spin glass simulator - Understanding magnetic phases in quantum mechanical systems is one of the essential goals in condensed matter physics, and the advent of prototype quantum simulation hardware has provided new tools for experimentally probing such systems. We report on the experimental realization of a quantum simulation of interacting Ising spins on three-dimensional cubic lattices up to dimensions 8 x 8 x 8 on a D-Wave processor (D-Wave Systems, Burnaby, Canada...
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    The rise, collapse, and compaction of Mt. Mantap from the 3 September 2017 North Korean nuclear test - Surveillance of clandestine nuclear tests relies on a global seismic network, but the potential of spaceborne monitoring has been underexploited. We used satellite radar imagery to determine the complete surface displacement field of up to 3.5 meters of divergent horizontal motion with 0.5 meters of subsidence associated with North Korea’s largest underground nuclear test. Combining insight from geodetic and seismological remote sensing, w...
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    Deconstructive fluorination of cyclic amines by carbon-carbon cleavage - Deconstructive functionalizations involving scission of carbon-carbon double bonds are well established. In contrast, unstrained C(sp3)–C(sp3) bond cleavage and functionalization have less precedent. Here we report the use of deconstructive fluorination to access mono- and difluorinated amine derivatives by C(sp3)–C(sp3) bond cleavage in saturated nitrogen heterocycles such as piperidines and pyrrolidines. Silver-mediated ring-openin...
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    Late inception of a resiliently oxygenated upper ocean - Rising oceanic and atmospheric oxygen levels through time have been crucial to enhanced habitability of surface Earth environments. Few redox proxies can track secular variations in dissolved oxygen concentrations around threshold levels for metazoan survival in the upper ocean. We present an extensive compilation of iodine-to-calcium ratios (I/Ca) in marine carbonates. Our record supports a major rise in the partial pressure of oxygen in the at...
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    Sensitivity to "sunk costs" in mice, rats, and humans - Sunk costs are irrecoverable investments that should not influence decisions, because decisions should be made on the basis of expected future consequences. Both human and nonhuman animals can show sensitivity to sunk costs, but reports from across species are inconsistent. In a temporal context, a sensitivity to sunk costs arises when an individual resists ending an activity, even if it seems unproductive, because of the time already invested. ...
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    Ethylene-gibberellin signaling underlies adaptation of rice to periodic flooding - Most plants do poorly when flooded. Certain rice varieties, known as deepwater rice, survive periodic flooding and consequent oxygen deficiency by activating internode growth of stems to keep above the water. Here, we identify the gibberellin biosynthesis gene, SD1 (SEMIDWARF1), whose loss-of-function allele catapulted the rice Green Revolution, as being responsible for submergence-induced internode elongation. When submerged, plants carrying th...
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    Assessment of methane emissions from the U.S. oil and gas supply chain - Methane emissions from the U.S. oil and natural gas supply chain were estimated by using ground-based, facility-scale measurements and validated with aircraft observations in areas accounting for ~30% of U.S. gas production. When scaled up nationally, our facility-based estimate of 2015 supply chain emissions is 13 ± 2 teragrams per year, equivalent to 2.3% of gross U.S. gas production. This value is ~60% higher than the U.S. Environmenta...
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    Dual-spindle formation in zygotes keeps parental genomes apart in early mammalian embryos - At the beginning of mammalian life, the genetic material from each parent meets when the fertilized egg divides. It was previously thought that a single microtubule spindle is responsible for spatially combining the two genomes and then segregating them to create the two-cell embryo. We used light-sheet microscopy to show that two bipolar spindles form in the zygote and then independently congress the maternal and paternal genomes. These two spi...
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    Comment on "Designing river flows to improve food security futures in the Lower Mekong Basin" - Sabo et al. (Research Articles, 8 December 2017, p. 1270) use sophisticated analyses of flow and fishery data from the Lower Mekong Basin to design a "good" hydrograph that, if implemented by planned hydropower dams, would increase the catch by a factor of 3.7. However, the hydrograph is not implementable, and, if it were, it would devastate the fishery. Further, the analyses are questionable. ...
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    Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A - Previous detections of individual astrophysical sources of neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neutrinos remain unidentified. On 22 September 2017, we detected a high-energy neutrino, IceCube-170922A, with an energy of ~290 tera–electron volts. Its arrival direction was consistent with the location of a known -ray blazar, TXS 0506+056, observed to be in a f...
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    Response to Comments on "Designing river flows to improve food security futures in the Lower Mekong Basin" - Sabo et al. presented an empirically derived algorithm defining the socioecological response of the Tonle Sap Dai fishery in the Cambodian Mekong to basin-scale variation in hydrologic flow regime. Williams suggests that the analysis leading to the algorithm is flawed because of the large distance between the gauge used to measure water levels (hydrology) and the site of harvest for the fishery. Halls and Moyle argue that Sabo et al.’s fin...
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    Phylogenomics reveals multiple losses of nitrogen-fixing root nodule symbiosis - The root nodule symbiosis of plants with nitrogen-fixing bacteria affects global nitrogen cycles and food production but is restricted to a subset of genera within a single clade of flowering plants. To explore the genetic basis for this scattered occurrence, we sequenced the genomes of 10 plant species covering the diversity of nodule morphotypes, bacterial symbionts, and infection strategies. In a genome-wide comparative analysis of a total of...
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    Comment on "Designing river flows to improve food security futures in the Lower Mekong Basin" - The designer flow regime proposed by Sabo et al. (Research Articles, 8 December 2017, p. 1270) to support fisheries in the Lower Mekong Basin fails to account for important ecological, political, and economic dimensions. In doing so, they indicate that dam impacts can be easily mitigated. Such an action would serve to increase risks to food and livelihood futures in the basin. ...
    Feed Source: science.sciencemag.org

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