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Journal Cover Science
  [SJR: 13.217]   [H-I: 915]   [3654 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 0036-8075 - ISSN (Online) 1095-9203
   Published by AAAS Homepage  [7 journals]
  • Comment on "The extent of forest in dryland biomes"
    • Authors: de la Cruz, M; Quintana-Ascencio, P. F, Cayuela, L, Espinosa, C. I, Escudero, A.
      Abstract: The study by Bastin et al. (Reports, 12 May 2017, p. 635) is based on an incomplete delimitation of dry forest distribution and on an old and incorrect definition of drylands. Its sampling design includes many plots located in humid ecosystems and ignores critical areas for the conservation of dry forests. Therefore, its results and conclusions may be unreliable.
      Keywords: Ecology, Online Only
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aao0369
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Topological or trivial'
    • Authors: Stajic J.
      Pages: 760
      Keywords: Physics
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-i
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Response to Comment on "The extent of forest in dryland biomes"
    • Authors: Bastin, J.- F; Mollicone, D, Grainger, A, Sparrow, B, Picard, N, Lowe, A, Castro, R.
      Abstract: De la Cruz et al. question the reliability of our results, claiming that we do not refer to the most appropriate spatial extent of drylands. In our response, we explain why we chose an existing and internationally recognized delineation of drylands among several options, and why our findings are due to a difference of remote sensing technique and not to the definition of drylands we have selected.
      Keywords: Ecology, Online Only
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aao2077
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Science for global understanding
    • Authors: Schlegel F.
      Pages: 699 - 699
      Keywords: Editorials
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aar3789
      Issue No: Vol. 358, No. 6364 (2017)
       
  • News at a glance
    • Pages: 700 - 702
      Keywords: Scientific Community
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.700
      Issue No: Vol. 358, No. 6364 (2017)
       
  • North Atlantic right whale faces extinction
    • Authors: Pennisi E.
      Pages: 703 - 704
      Keywords: Ecology, Science and Policy
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.703
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Giant radio telescope lends a hand in Puerto Rico relief
    • Authors: Clery D.
      Pages: 704 - 705
      Keywords: Astronomy, Scientific Community
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.704
      Issue No: Vol. 358, No. 6364 (2017)
       
  • New tools offer clues to how the human brain takes shape
    • Authors: Gibbons A.
      Pages: 705 - 706
      Keywords: Cell Biology, Development, Genetics, Neuroscience
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.705
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Genomes rewrite cholera's global story
    • Authors: Kupferschmidt K.
      Pages: 706 - 707
      Keywords: Epidemiology, Medicine, Diseases, Microbiology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.706
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Polarizing head of House science panel to retire
    • Authors: Mervis J.
      Pages: 708 - 708
      Keywords: Scientific Community, Science and Policy
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.708
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Medical centers spearhead China's pharma push
    • Authors: Normile D.
      Pages: 709 - 709
      Keywords: Asia/Pacific News, Medicine, Diseases, Pharmacology, Toxicology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.709
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Brain implant trials spur ethical discussions
    • Authors: Underwood E.
      Pages: 710 - 710
      Keywords: Neuroscience
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.710
      Issue No: Vol. 358, No. 6364 (2017)
       
  • The perfect wave
    • Authors: Cohen J.
      Pages: 711 - 713
      Keywords: Physics, Scientific Community
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.711
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Killer clones
    • Authors: Leslie M.
      Pages: 714 - 715
      Keywords: Genetics, Medicine, Diseases, Molecular Biology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.714
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Cell cycle proteins moonlight in multiciliogenesis
    • Authors: Levine, M; Holland, A.
      Pages: 716 - 718
      Keywords: Cell Biology, Development
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aaq0770
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Linking smell to metabolism and aging
    • Authors: Garrison, J. L; Knight, Z. A.
      Pages: 718 - 719
      Keywords: Neuroscience
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aao5474
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Tricks for noncovalent catalysis
    • Authors: Mattson A. E.
      Pages: 720 - 720
      Keywords: Chemistry
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aaq0680
      Issue No: Vol. 358, No. 6364 (2017)
       
  • A record of ice sheet demise
    • Authors: Marcott, S. A; Shakun, J. D.
      Pages: 721 - 722
      Keywords: Atmospheric Science
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aaq1179
      Issue No: Vol. 358, No. 6364 (2017)
       
  • The need to regulate replication fork speed
    • Authors: Gomez-Gonzalez, B; Aguilera, A.
      Pages: 722 - 723
      Keywords: Cell Biology, Molecular Biology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aaq0678
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Plant invasions in the Anthropocene
    • Authors: Kueffer C.
      Pages: 724 - 725
      Keywords: Planetary Science
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aao6371
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Small media, big impact
    • Authors: Gentzkow M.
      Pages: 726 - 727
      Keywords: Economics
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aar2579
      Issue No: Vol. 358, No. 6364 (2017)
       
  • A trove of biodiversity, at risk
    • Authors: Styles B.
      Pages: 728 - 728
      Keywords: Anatomy, Morphology, Biomechanics
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aaq1820
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Engineered emotions
    • Authors: Quinon P.
      Pages: 729 - 729
      Keywords: Engineering
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aao3113
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Canada fails to protect its caribou
    • Authors: Hebblewhite, M; Fortin, D.
      Pages: 730 - 731
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aar2464
      Issue No: Vol. 358, No. 6364 (2017)
       
  • North Atlantic right whales in danger
    • Authors: Taylor, S; Walker, T. R.
      Pages: 730 - 731
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aar2402
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Let experts judge research potential
    • Authors: Braaten D.
      Pages: 731 - 731
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aar2972
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Natural and engineered perovskites
    • Authors: Szuromi, P; Grocholski, B.
      Pages: 732 - 733
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.732
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Perovskite in Earths deep interior
    • Authors: Hirose, K; Sinmyo, R, Hernlund, J.
      Pages: 734 - 738
      Abstract: Silicate perovskite-type phases are the most abundant constituent inside our planet and are the predominant minerals in Earth’s lower mantle more than 660 kilometers below the surface. Magnesium-rich perovskite is a major lower mantle phase and undergoes a phase transition to post-perovskite near the bottom of the mantle. Calcium-rich perovskite is proportionally minor but may host numerous trace elements that record chemical differentiation events. The properties of mantle perovskites are the key to understanding the dynamic evolution of Earth, as they strongly influence the transport properties of lower mantle rocks. Perovskites are expected to be an important constituent of rocky planets larger than Mars and thus play a major role in modulating the evolution of terrestrial planets throughout the universe.
      Keywords: Materials Science
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aam8561
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Promises and challenges of perovskite solar cells
    • Authors: Correa-Baena, J.-P; Saliba, M, Buonassisi, T, Grätzel, M, Abate, A, Tress, W, Hagfeldt, A.
      Pages: 739 - 744
      Abstract: The efficiencies of perovskite solar cells have gone from single digits to a certified 22.1% in a few years’ time. At this stage of their development, the key issues concern how to achieve further improvements in efficiency and long-term stability. We review recent developments in the quest to improve the current state of the art. Because photocurrents are near the theoretical maximum, our focus is on efforts to increase open-circuit voltage by means of improving charge-selective contacts and charge carrier lifetimes in perovskites via processes such as ion tailoring. The challenges associated with long-term perovskite solar cell device stability include the role of testing protocols, ionic movement affecting performance metrics over extended periods of time, and determination of the best ways to counteract degradation mechanisms.
      Keywords: Materials Science
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aam6323
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Properties and potential optoelectronic applications of lead halide
           perovskite nanocrystals
    • Authors: Kovalenko, M. V; Protesescu, L, Bodnarchuk, M. I.
      Pages: 745 - 750
      Abstract: Semiconducting lead halide perovskites (LHPs) have not only become prominent thin-film absorber materials in photovoltaics but have also proven to be disruptive in the field of colloidal semiconductor nanocrystals (NCs). The most important feature of LHP NCs is their so-called defect-tolerance—the apparently benign nature of structural defects, highly abundant in these compounds, with respect to optical and electronic properties. Here, we review the important differences that exist in the chemistry and physics of LHP NCs as compared with more conventional, tetrahedrally bonded, elemental, and binary semiconductor NCs (such as silicon, germanium, cadmium selenide, gallium arsenide, and indium phosphide). We survey the prospects of LHP NCs for optoelectronic applications such as in television displays, light-emitting devices, and solar cells, emphasizing the practical hurdles that remain to be overcome.
      Keywords: Materials Science
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aam7093
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Perovskites in catalysis and electrocatalysis
    • Authors: Hwang, J; Rao, R. R, Giordano, L, Katayama, Y, Yu, Y, Shao-Horn, Y.
      Pages: 751 - 756
      Abstract: Catalysts for chemical and electrochemical reactions underpin many aspects of modern technology and industry, from energy storage and conversion to toxic emissions abatement to chemical and materials synthesis. This role necessitates the design of highly active, stable, yet earth-abundant heterogeneous catalysts. In this Review, we present the perovskite oxide family as a basis for developing such catalysts for (electro)chemical conversions spanning carbon, nitrogen, and oxygen chemistries. A framework for rationalizing activity trends and guiding perovskite oxide catalyst design is described, followed by illustrations of how a robust understanding of perovskite electronic structure provides fundamental insights into activity, stability, and mechanism in oxygen electrocatalysis. We conclude by outlining how these insights open experimental and computational opportunities to expand the compositional and chemical reaction space for next-generation perovskite catalysts.
      Keywords: Materials Science
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aam7092
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Wave upon wave of disease
    • Authors: Ash C.
      Pages: 758 - 758
      Keywords: Epidemiology, Microbiology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-a
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Disappearance of an ice sheet
    • Authors: Smith H. J.
      Pages: 758 - 758
      Keywords: Atmospheric Science
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-b
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Metabolic regulation of genome stability
    • Authors: Mao S.
      Pages: 758 - 758
      Keywords: Cell Biology, Molecular Biology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-c
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Measuring the impact of the media
    • Authors: Chin G.
      Pages: 758 - 758
      Keywords: Sociology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-d
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Evaluating author contribution statements
    • Authors: Clauset A.
      Pages: 758 - 759
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-e
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Scattered light, it is all the same
    • Authors: Osborne I. S.
      Pages: 758 - 759
      Keywords: Physics
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-f
      Issue No: Vol. 358, No. 6364 (2017)
       
  • De-stressing cancer with {beta}-blockers
    • Authors: Nusinovich Y.
      Pages: 758 - 759
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-g
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Fly brain inspires computing algorithm
    • Authors: Ray L. B.
      Pages: 758 - 759
      Keywords: Computers, Mathematics, Engineering
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-h
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Transporter layers improve stability
    • Authors: Szuromi P.
      Pages: 758 - 760
      Keywords: Physics, Applied
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-j
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Lewis acid catalysis tackled by tag team
    • Authors: Yeston J.
      Pages: 758 - 760
      Keywords: Chemistry
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-k
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Regulated lysosomal efflux of amino acids
    • Authors: Ray L. B.
      Pages: 758 - 760
      Keywords: Biochemistry
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-l
      Issue No: Vol. 358, No. 6364 (2017)
       
  • SAMTOR joins the family
    • Authors: Hurtley S. M.
      Pages: 758 - 760
      Keywords: Biochemistry, Cell Biology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-m
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Taming mitosis for differentiation
    • Authors: Hurtley S. M.
      Pages: 758 - 760
      Keywords: Cell Biology, Development
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-n
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Humans shape how plants invade
    • Authors: Fahrenkamp-Uppenbrink J.
      Pages: 758 - 760
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-o
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Connecting smell to metabolism
    • Authors: Alderton G.
      Pages: 758 - 760
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-p
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Balancing translation and Rac1 signaling
    • Authors: Ferrarelli L. K.
      Pages: 758 - 760
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-q
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Calibrating antifungal responses
    • Authors: Balasubramani A.
      Pages: 758 - 760
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.758-r
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Controlling cellular calcium concentration
    • Authors: Stern P.
      Pages: 759 - 759
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.759-a
      Issue No: Vol. 358, No. 6364 (2017)
       
  • A drug that fights both heart attack and cancer
    • Authors: Kelly P. N.
      Pages: 759 - 760
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.759-b
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Jail or bail' Machines versus judges
    • Authors: Wible B.
      Pages: 759 - 760
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.759-c
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Modeling human tumors--an imperfect art
    • Authors: Kiberstis P. A.
      Pages: 759 - 760
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.759-d
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Not all STEM teachers work in a classroom
    • Authors: McCartney M.
      Pages: 759 - 760
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.759-e
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Astrocytes regulating synaptogenesis
    • Authors: Hines P. J.
      Pages: 759 - 760
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.759-f
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Healing powers of dressing well
    • Authors: Lavine M. S.
      Pages: 759 - 760
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.759-g
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Lewis acid enhancement by hydrogen-bond donors for asymmetric catalysis
    • Authors: Banik, S. M; Levina, A, Hyde, A. M, Jacobsen, E. N.
      Pages: 761 - 764
      Abstract: Small-molecule dual hydrogen-bond (H-bond) donors such as ureas, thioureas, squaramides, and guanidinium ions enjoy widespread use as effective catalysts for promoting a variety of enantioselective reactions. However, these catalysts are only weakly acidic and therefore require highly reactive electrophilic substrates to be effective. We introduce here a mode of catalytic activity with chiral H-bond donors that enables enantioselective reactions of relatively unreactive electrophiles. Squaramides are shown to interact with silyl triflates by binding the triflate counterion to form a stable, yet highly Lewis acidic, complex. The silyl triflate-chiral squaramide combination promotes the generation of oxocarbenium intermediates from acetal substrates at low temperatures. Enantioselectivity in nucleophile additions to the cationic intermediates is then controlled through a network of noncovalent interactions between the squaramide catalyst and the oxocarbenium triflate.
      Keywords: Chemistry
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aao5894
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Observation of mean path length invariance in light-scattering media
    • Authors: Savo, R; Pierrat, R, Najar, U, Carminati, R, Rotter, S, Gigan, S.
      Pages: 765 - 768
      Abstract: The microstructure of a medium strongly influences how light propagates through it. The amount of disorder it contains determines whether the medium is transparent or opaque. Theory predicts that exciting such a medium homogeneously and isotropically makes some of its optical properties depend only on the medium’s outer geometry. Here, we report an optical experiment demonstrating that the mean path length of light is invariant with respect to the microstructure of the medium it scatters through. Using colloidal solutions with varying concentration and particle size, the invariance of the mean path length is observed over nearly two orders of magnitude in scattering strength. Our results can be extended to a wide range of systems—however ordered, correlated, or disordered—and apply to all wave-scattering problems.
      Keywords: Physics
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aan4054
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Perovskite solar cells with CuSCN hole extraction layers yield stabilized
           efficiencies greater than 20%
    • Authors: Arora, N; Dar, M. I, Hinderhofer, A, Pellet, N, Schreiber, F, Zakeeruddin, S. M, Grätzel, M.
      Pages: 768 - 771
      Abstract: Perovskite solar cells (PSCs) with efficiencies greater than 20% have been realized only with expensive organic hole-transporting materials. We demonstrate PSCs that achieve stabilized efficiencies exceeding 20% with copper(I) thiocyanate (CuSCN) as the hole extraction layer. A fast solvent removal method enabled the creation of compact, highly conformal CuSCN layers that facilitate rapid carrier extraction and collection. The PSCs showed high thermal stability under long-term heating, although their operational stability was poor. This instability originated from potential-induced degradation of the CuSCN/Au contact. The addition of a conductive reduced graphene oxide spacer layer between CuSCN and gold allowed PSCs to retain >95% of their initial efficiency after aging at a maximum power point for 1000 hours under full solar intensity at 60°C. Under both continuous full-sun illumination and thermal stress, CuSCN-based devices surpassed the stability of spiro-OMeTAD–based PSCs.
      Keywords: Physics, Applied
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aam5655
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Distinguishing a Majorana zero mode using spin-resolved measurements
    • Authors: Jeon, S; Xie, Y, Li, J, Wang, Z, Bernevig, B. A, Yazdani, A.
      Pages: 772 - 776
      Abstract: One-dimensional topological superconductors host Majorana zero modes (MZMs), the nonlocal property of which could be exploited for quantum computing applications. We use spin-polarized scanning tunneling microscopy to show that MZMs realized in self-assembled Fe chains on the surface of Pb have a spin polarization that exceeds that stemming from the magnetism of these chains. This feature, captured by our model calculations, is a direct consequence of the nonlocality of the Hilbert space of MZMs emerging from a topological band structure. Our study establishes spin-polarization measurements as a diagnostic tool to distinguish topological MZMs from trivial in-gap states of a superconductor.
      Keywords: Physics
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aan3670
      Issue No: Vol. 358, No. 6364 (2017)
       
  • How the news media activate public expression and influence national
           agendas
    • Authors: King, G; Schneer, B, White, A.
      Pages: 776 - 780
      Abstract: We demonstrate that exposure to the news media causes Americans to take public stands on specific issues, join national policy conversations, and express themselves publicly—all key components of democratic politics—more often than they would otherwise. After recruiting 48 mostly small media outlets, we chose groups of these outlets to write and publish articles on subjects we approved, on dates we randomly assigned. We estimated the causal effect on proximal measures, such as website pageviews and Twitter discussion of the articles’ specific subjects, and distal ones, such as national Twitter conversation in broad policy areas. Our intervention increased discussion in each broad policy area by ~62.7% (relative to a day’s volume), accounting for 13,166 additional posts over the treatment week, with similar effects across population subgroups.
      Keywords: Sociology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aao1100
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Cordilleran Ice Sheet mass loss preceded climate reversals near the
           Pleistocene Termination
    • Authors: Menounos, B; Goehring, B. M, Osborn, G, Margold, M, Ward, B, Bond, J, Clarke, G. K. C, Clague, J. J, Lakeman, T, Koch, J, Caffee, M. W, Gosse, J, Stroeven, A. P, Seguinot, J, Heyman, J.
      Pages: 781 - 784
      Abstract: The Cordilleran Ice Sheet (CIS) once covered an area comparable to that of Greenland. Previous geologic evidence and numerical models indicate that the ice sheet covered much of westernmost Canada as late as 12.5 thousand years ago (ka). New data indicate that substantial areas throughout westernmost Canada were ice free prior to 12.5 ka and some as early as 14.0 ka, with implications for climate dynamics and the timing of meltwater discharge to the Pacific and Arctic oceans. Early Bølling-Allerød warmth halved the mass of the CIS in as little as 500 years, causing 2.5 to 3.0 meters of sea-level rise. Dozens of cirque and valley glaciers, along with the southern margin of the CIS, advanced into recently deglaciated regions during the Bølling-Allerød and Younger Dryas.
      Keywords: Atmospheric Science
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aan3001
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Genomic history of the seventh pandemic of cholera in Africa
    • Authors: Weill, F.-X; Domman, D, Njamkepo, E, Tarr, C, Rauzier, J, Fawal, N, Keddy, K. H, Salje, H, Moore, S, Mukhopadhyay, A. K, Bercion, R, Luquero, F. J, Ngandjio, A, Dosso, M, Monakhova, E, Garin, B, Bouchier, C, Pazzani, C, Mutreja, A, Grunow, R, Sidikou, F, Bonte, L, Breurec, S, Damian, M, Njanpop-Lafourcade, B.-M, Sapriel, G, Page, A.-L, Hamze, M, Henkens, M, Chowdhury, G, Mengel, M, Koeck, J.-L, Fournier, J.-M, Dougan, G, Grimont, P. A. D, Parkhill, J, Holt, K. E, Piarroux, R, Ramamurthy, T, Quilici, M.-L, Thomson, N. R.
      Pages: 785 - 789
      Abstract: The seventh cholera pandemic has heavily affected Africa, although the origin and continental spread of the disease remain undefined. We used genomic data from 1070 Vibrio cholerae O1 isolates, across 45 African countries and over a 49-year period, to show that past epidemics were attributable to a single expanded lineage. This lineage was introduced at least 11 times since 1970, into two main regions, West Africa and East/Southern Africa, causing epidemics that lasted up to 28 years. The last five introductions into Africa, all from Asia, involved multidrug-resistant sublineages that replaced antibiotic-susceptible sublineages after 2000. This phylogenetic framework describes the periodicity of lineage introduction and the stable routes of cholera spread, which should inform the rational design of control measures for cholera in Africa.
      Keywords: Medicine, Diseases, Microbiology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aad5901
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Integrated view of Vibrio cholerae in the Americas
    • Authors: Domman, D; Quilici, M.-L, Dorman, M. J, Njamkepo, E, Mutreja, A, Mather, A. E, Delgado, G, Morales-Espinosa, R, Grimont, P. A. D, Lizarraga-Partida, M. L, Bouchier, C, Aanensen, D. M, Kuri-Morales, P, Tarr, C. L, Dougan, G, Parkhill, J, Campos, J, Cravioto, A, Weill, F.-X, Thomson, N. R.
      Pages: 789 - 793
      Abstract: Latin America has experienced two of the largest cholera epidemics in modern history; one in 1991 and the other in 2010. However, confusion still surrounds the relationships between globally circulating pandemic Vibrio cholerae clones and local bacterial populations. We used whole-genome sequencing to characterize cholera across the Americas over a 40-year time span. We found that both epidemics were the result of intercontinental introductions of seventh pandemic El Tor V. cholerae and that at least seven lineages local to the Americas are associated with disease that differs epidemiologically from epidemic cholera. Our results consolidate historical accounts of pandemic cholera with data to show the importance of local lineages, presenting an integrated view of cholera that is important to the design of future disease control strategies.
      Keywords: Epidemiology, Microbiology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aao2136
      Issue No: Vol. 358, No. 6364 (2017)
       
  • A neural algorithm for a fundamental computing problem
    • Authors: Dasgupta, S; Stevens, C. F, Navlakha, S.
      Pages: 793 - 796
      Abstract: Similarity search—for example, identifying similar images in a database or similar documents on the web—is a fundamental computing problem faced by large-scale information retrieval systems. We discovered that the fruit fly olfactory circuit solves this problem with a variant of a computer science algorithm (called locality-sensitive hashing). The fly circuit assigns similar neural activity patterns to similar odors, so that behaviors learned from one odor can be applied when a similar odor is experienced. The fly algorithm, however, uses three computational strategies that depart from traditional approaches. These strategies can be translated to improve the performance of computational similarity searches. This perspective helps illuminate the logic supporting an important sensory function and provides a conceptually new algorithm for solving a fundamental computational problem.
      Keywords: Computers, Mathematics, Engineering
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aam9868
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Redox-sensitive alteration of replisome architecture safeguards genome
           integrity
    • Authors: Somyajit, K; Gupta, R, Sedlackova, H, Neelsen, K. J, Ochs, F, Rask, M.-B, Choudhary, C, Lukas, J.
      Pages: 797 - 802
      Abstract: DNA replication requires coordination between replication fork progression and deoxynucleotide triphosphate (dNTP)–generating metabolic pathways. We find that perturbation of ribonucleotide reductase (RNR) in humans elevates reactive oxygen species (ROS) that are detected by peroxiredoxin 2 (PRDX2). In the oligomeric state, PRDX2 forms a replisome-associated ROS sensor, which binds the fork accelerator TIMELESS when exposed to low levels of ROS. Elevated ROS levels generated by RNR attenuation disrupt oligomerized PRDX2 to smaller subunits, whose dissociation from chromatin enforces the displacement of TIMELESS from the replisome. This process instantly slows replication fork progression, which mitigates pathological consequences of replication stress. Thus, redox signaling couples fluctuations of dNTP biogenesis with replisome activity to reduce stress during genome duplication. We propose that cancer cells exploit this pathway to increase their adaptability to adverse metabolic conditions.
      Keywords: Cell Biology, Molecular Biology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aao3172
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Calibrated mitotic oscillator drives motile ciliogenesis
    • Authors: Al Jord, A; Shihavuddin, A, Servignat dAout, R, Faucourt, M, Genovesio, A, Karaiskou, A, Sobczak-Thepot, J, Spassky, N, Meunier, A.
      Pages: 803 - 806
      Abstract: Cell division and differentiation depend on massive and rapid organelle remodeling. The mitotic oscillator, centered on the cyclin-dependent kinase 1–anaphase-promoting complex/cyclosome (CDK1-APC/C) axis, spatiotemporally coordinates this reorganization in dividing cells. Here we discovered that nondividing cells could also implement this mitotic clocklike regulatory circuit to orchestrate subcellular reorganization associated with differentiation. We probed centriole amplification in differentiating mouse-brain multiciliated cells. These postmitotic progenitors fine-tuned mitotic oscillator activity to drive the orderly progression of centriole production, maturation, and motile ciliation while avoiding the mitosis commitment threshold. Insufficient CDK1 activity hindered differentiation, whereas excessive activity accelerated differentiation yet drove postmitotic progenitors into mitosis. Thus, postmitotic cells can redeploy and calibrate the mitotic oscillator to uncouple cytoplasmic from nuclear dynamics for organelle remodeling associated with differentiation.
      Keywords: Cell Biology, Development
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aan8311
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Lysosomal metabolomics reveals V-ATPase- and mTOR-dependent regulation of
           amino acid efflux from lysosomes
    • Authors: Abu-Remaileh, M; Wyant, G. A, Kim, C, Laqtom, N. N, Abbasi, M, Chan, S. H, Freinkman, E, Sabatini, D. M.
      Pages: 807 - 813
      Abstract: The lysosome degrades and recycles macromolecules, signals to the cytosol and nucleus, and is implicated in many diseases. Here, we describe a method for the rapid isolation of mammalian lysosomes and use it to quantitatively profile lysosomal metabolites under various cell states. Under nutrient-replete conditions, many lysosomal amino acids are in rapid exchange with those in the cytosol. Loss of lysosomal acidification through inhibition of the vacuolar H+–adenosine triphosphatase (V-ATPase) increased the luminal concentrations of most metabolites but had no effect on those of the majority of essential amino acids. Instead, nutrient starvation regulates the lysosomal concentrations of these amino acids, an effect we traced to regulation of the mechanistic target of rapamycin (mTOR) pathway. Inhibition of mTOR strongly reduced the lysosomal efflux of most essential amino acids, converting the lysosome into a cellular depot for them. These results reveal the dynamic nature of lysosomal metabolites and that V-ATPase- and mTOR-dependent mechanisms exist for controlling lysosomal amino acid efflux.
      Keywords: Biochemistry
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aan6298
      Issue No: Vol. 358, No. 6364 (2017)
       
  • SAMTOR is an S-adenosylmethionine sensor for the mTORC1 pathway
    • Authors: Gu, X; Orozco, J. M, Saxton, R. A, Condon, K. J, Liu, G. Y, Krawczyk, P. A, Scaria, S. M, Harper, J. W, Gygi, S. P, Sabatini, D. M.
      Pages: 813 - 818
      Abstract: mTOR complex 1 (mTORC1) regulates cell growth and metabolism in response to multiple environmental cues. Nutrients signal via the Rag guanosine triphosphatases (GTPases) to promote the localization of mTORC1 to the lysosomal surface, its site of activation. We identified SAMTOR, a previously uncharacterized protein, which inhibits mTORC1 signaling by interacting with GATOR1, the GTPase activating protein (GAP) for RagA/B. We found that the methyl donor S-adenosylmethionine (SAM) disrupts the SAMTOR-GATOR1 complex by binding directly to SAMTOR with a dissociation constant of approximately 7 μM. In cells, methionine starvation reduces SAM levels below this dissociation constant and promotes the association of SAMTOR with GATOR1, thereby inhibiting mTORC1 signaling in a SAMTOR-dependent fashion. Methionine-induced activation of mTORC1 requires the SAM binding capacity of SAMTOR. Thus, SAMTOR is a SAM sensor that links methionine and one-carbon metabolism to mTORC1 signaling.
      Keywords: Biochemistry, Cell Biology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.aao3265
      Issue No: Vol. 358, No. 6364 (2017)
       
  • New Products
    • Pages: 819 - 819
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.819-a
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Webinar Deciphering cancer: Investigating cell death mechanisms
    • Authors: Strasser, A; Letai, A. G.
      Pages: 819 - 819
      Keywords: Biochemistry, Cell Biology, Development, Medicine, Diseases, Molecular Biology
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.819-b
      Issue No: Vol. 358, No. 6364 (2017)
       
  • Fighting for my Dream
    • Authors: Valdez-Ward E.
      Pages: 830 - 830
      PubDate: 2017-11-09T10:21:56-08:00
      DOI: 10.1126/science.358.6364.830
      Issue No: Vol. 358, No. 6364 (2017)
       
 
 
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