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Science Advances

Robert M Cox, Stefanie A Krumm, Vidhi D Thakkar, Maximilian Sohn, Richard K Plemper
The paramyxovirus RNA-dependent RNA-polymerase (RdRp) complex loads onto the nucleocapsid protein (N)-encapsidated viral N:RNA genome for RNA synthesis. Binding of the RdRp of measles virus (MeV), a paramyxovirus archetype, is mediated through interaction with a molecular recognition element (MoRE) located near the end of the carboxyl-terminal Ntail domain. The structurally disordered central Ntail section is thought to add positional flexibility to MoRE, but the functional importance of this Ntail region for RNA polymerization is unclear...
February 2017: Science Advances
Frédéric Bouchard, Robert Fickler, Robert W Boyd, Ebrahim Karimi
Attempts at cloning a quantum system result in the introduction of imperfections in the state of the copies. This is a consequence of the no-cloning theorem, which is a fundamental law of quantum physics and the backbone of security for quantum communications. Although perfect copies are prohibited, a quantum state may be copied with maximal accuracy via various optimal cloning schemes. Optimal quantum cloning, which lies at the border of the physical limit imposed by the no-signaling theorem and the Heisenberg uncertainty principle, has been experimentally realized for low-dimensional photonic states...
February 2017: Science Advances
Matthew S Palsson, Mile Gu, Joseph Ho, Howard M Wiseman, Geoff J Pryde
Computer simulation of observable phenomena is an indispensable tool for engineering new technology, understanding the natural world, and studying human society. However, the most interesting systems are often so complex that simulating their future behavior demands storing immense amounts of information regarding how they have behaved in the past. For increasingly complex systems, simulation becomes increasingly difficult and is ultimately constrained by resources such as computer memory. Recent theoretical work shows that quantum theory can reduce this memory requirement beyond ultimate classical limits, as measured by a process' statistical complexity, C...
February 2017: Science Advances
Anna Zalineeva, Stève Baranton, Christophe Coutanceau, Gregory Jerkiewicz
We report new results for electrochemical H adsorption on and absorption in octahedral palladium nanoparticles (Pd-NPs) with an average tip-to-tip size of 7.8 nm and a narrow size distribution. They reveal a very high H loading of 0.90 that cannot be achieved using bulk Pd materials or larger NPs; this behavior is assigned to a combination of two factors: their small size and face morphology. Temperature-dependent cyclic voltammetry (CV) studies in the range of 296 to 333 K reveal unique features that are attributed to electrochemical H adsorption, H absorption, and H2 generation...
February 2017: Science Advances
Daniel O Brodsky, Mark E Barber, Jan A N Bruin, Rodolfo A Borzi, Santiago A Grigera, Robin S Perry, Andrew P Mackenzie, Clifford W Hicks
A major area of interest in condensed matter physics is the way electrons in correlated electron materials can self-organize into ordered states, and a particularly intriguing possibility is that they spontaneously choose a preferred direction of conduction. The correlated electron metal Sr3Ru2O7 has an anomalous phase at low temperatures that features strong susceptibility toward anisotropic transport. This susceptibility has been thought to indicate a spontaneous anisotropy, that is, electronic order that spontaneously breaks the point-group symmetry of the lattice, allowing weak external stimuli to select the orientation of the anisotropy...
February 2017: Science Advances
Xiaofei Hu, Zifan Li, Yaran Zhao, Jianchao Sun, Qing Zhao, Jianbin Wang, Zhanliang Tao, Jun Chen
Na-CO2 batteries using earth-abundant Na and greenhouse gas CO2 are promising tools for mobile and stationary energy storage, but they still pose safety risks from leakage of liquid electrolyte and instability of the Na metal anode. These issues result in extremely harsh operating conditions of Na-CO2 batteries and increase the difficulty of scaling up this technology. We report the development of quasi-solid state Na-CO2 batteries with high safety using composite polymer electrolyte (CPE) and reduced graphene oxide (rGO) Na anodes...
February 2017: Science Advances
Marlène Gamelon, Vidar Grøtan, Anna L K Nilsson, Steinar Engen, James W Hurrell, Kurt Jerstad, Adam S Phillips, Ole W Røstad, Tore Slagsvold, Bjørn Walseng, Nils C Stenseth, Bernt-Erik Sæther
Climate change will affect the population dynamics of many species, yet the consequences for the long-term persistence of populations are poorly understood. A major reason for this is that density-dependent feedback effects caused by fluctuations in population size are considered independent of stochastic variation in the environment. We show that an interplay between winter temperature and population density can influence the persistence of a small passerine population under global warming. Although warmer winters favor an increased mean population size, density-dependent feedback can cause the local population to be less buffered against occasional poor environmental conditions (cold winters)...
February 2017: Science Advances
Veronika Siska, Eppie Ruth Jones, Sungwon Jeon, Youngjune Bhak, Hak-Min Kim, Yun Sung Cho, Hyunho Kim, Kyusang Lee, Elizaveta Veselovskaya, Tatiana Balueva, Marcos Gallego-Llorente, Michael Hofreiter, Daniel G Bradley, Anders Eriksson, Ron Pinhasi, Jong Bhak, Andrea Manica
Ancient genomes have revolutionized our understanding of Holocene prehistory and, particularly, the Neolithic transition in western Eurasia. In contrast, East Asia has so far received little attention, despite representing a core region at which the Neolithic transition took place independently ~3 millennia after its onset in the Near East. We report genome-wide data from two hunter-gatherers from Devil's Gate, an early Neolithic cave site (dated to ~7.7 thousand years ago) located in East Asia, on the border between Russia and Korea...
February 2017: Science Advances
Todd J Braje, Torben C Rick, Paul Szpak, Seth D Newsome, Joseph M McCain, Emma A Elliott Smith, Michael Glassow, Scott L Hamilton
The intensive commercial exploitation of California sheephead (Semicossyphus pulcher) has become a complex, multimillion-dollar industry. The fishery is of concern because of high harvest levels and potential indirect impacts of sheephead removals on the structure and function of kelp forest ecosystems. California sheephead are protogynous hermaphrodites that, as predators of sea urchins and other invertebrates, are critical components of kelp forest ecosystems in the northeast Pacific. Overfishing can trigger trophic cascades and widespread ecological dysfunction when other urchin predators are also lost from the system...
February 2017: Science Advances
Bjoern Lekitsch, Sebastian Weidt, Austin G Fowler, Klaus Mølmer, Simon J Devitt, Christof Wunderlich, Winfried K Hensinger
The availability of a universal quantum computer may have a fundamental impact on a vast number of research fields and on society as a whole. An increasingly large scientific and industrial community is working toward the realization of such a device. An arbitrarily large quantum computer may best be constructed using a modular approach. We present a blueprint for a trapped ion-based scalable quantum computer module, making it possible to create a scalable quantum computer architecture based on long-wavelength radiation quantum gates...
February 2017: Science Advances
Thomas J Lapen, Minako Righter, Rasmus Andreasen, Anthony J Irving, Aaron M Satkoski, Brian L Beard, Kunihiko Nishiizumi, A J Timothy Jull, Marc W Caffee
The timing and nature of igneous activity recorded at a single Mars ejection site can be determined from the isotope analyses of Martian meteorites. Northwest Africa (NWA) 7635 has an Sm-Nd crystallization age of 2.403 ± 0.140 billion years, and isotope data indicate that it is derived from an incompatible trace element-depleted mantle source similar to that which produced a geochemically distinct group of 327- to 574-million-year-old "depleted" shergottites. Cosmogenic nuclide data demonstrate that NWA 7635 was ejected from Mars 1...
February 2017: Science Advances
Satyaprasad P Senanayak, Bingyan Yang, Tudor H Thomas, Nadja Giesbrecht, Wenchao Huang, Eliot Gann, Bhaskaran Nair, Karl Goedel, Suchi Guha, Xavier Moya, Christopher R McNeill, Pablo Docampo, Aditya Sadhanala, Richard H Friend, Henning Sirringhaus
Fundamental understanding of the charge transport physics of hybrid lead halide perovskite semiconductors is important for advancing their use in high-performance optoelectronics. We use field-effect transistors (FETs) to probe the charge transport mechanism in thin films of methylammonium lead iodide (MAPbI3). We show that through optimization of thin-film microstructure and source-drain contact modifications, it is possible to significantly minimize instability and hysteresis in FET characteristics and demonstrate an electron field-effect mobility (μFET) of 0...
January 2017: Science Advances
Claudia Tortiglione, Maria Rosa Antognazza, Angela Tino, Caterina Bossio, Valentina Marchesano, Antonella Bauduin, Mattia Zangoli, Susana Vaquero Morata, Guglielmo Lanzani
Current implant technology uses electrical signals at the electrode-neural interface. This rather invasive approach presents important issues in terms of performance, tolerability, and overall safety of the implants. Inducing light sensitivity in living organisms is an alternative method that provides groundbreaking opportunities in neuroscience. Optogenetics is a spectacular demonstration of this, yet is limited by the viral transfection of exogenous genetic material. We propose a nongenetic approach toward light control of biological functions in living animals...
January 2017: Science Advances
Viviane V Menezes, Alison M Macdonald, Courtney Schatzman
Southern Ocean abyssal waters, in contact with the atmosphere at their formation sites around Antarctica, not only bring signals of a changing climate with them as they move around the globe but also contribute to that change through heat uptake and sea level rise. A repeat hydrographic line in the Indian sector of the Southern Ocean, occupied three times in the last two decades (1994, 2007, and, most recently, 2016), reveals that Antarctic Bottom Water (AABW) continues to become fresher (0.004 ± 0.001 kg/g decade(-1)), warmer (0...
January 2017: Science Advances
Sofi Jonsson, Agneta Andersson, Mats B Nilsson, Ulf Skyllberg, Erik Lundberg, Jeffra K Schaefer, Staffan Åkerblom, Erik Björn
The input of mercury (Hg) to ecosystems is estimated to have increased two- to fivefold during the industrial era, and Hg accumulates in aquatic biota as neurotoxic methylmercury (MeHg). Escalating anthropogenic land use and climate change are expected to alter the input rates of terrestrial natural organic matter (NOM) and nutrients to aquatic ecosystems. For example, climate change has been projected to induce 10 to 50% runoff increases for large coastal regions globally. A major knowledge gap is the potential effects on MeHg exposure to biota following these ecosystem changes...
January 2017: Science Advances
Xiao Lin, Ido Kaminer, Xihang Shi, Fei Gao, Zhaoju Yang, Zhen Gao, Hrvoje Buljan, John D Joannopoulos, Marin Soljačić, Hongsheng Chen, Baile Zhang
Launching of plasmons by swift electrons has long been used in electron energy-loss spectroscopy (EELS) to investigate the plasmonic properties of ultrathin, or two-dimensional (2D), electron systems. However, the question of how a swift electron generates plasmons in space and time has never been answered. We address this issue by calculating and demonstrating the spatial-temporal dynamics of 2D plasmon generation in graphene. We predict a jet-like rise of excessive charge concentration that delays the generation of 2D plasmons in EELS, exhibiting an analog to the hydrodynamic Rayleigh jet in a splashing phenomenon before the launching of ripples...
January 2017: Science Advances
Hengchun Ye, Eric J Fetzer, Sun Wong, Bjorn H Lambrigtsen
Convective precipitation-localized, short-lived, intense, and sometimes violent-is at the root of challenges associated with observation, simulation, and prediction of precipitation. The understanding of long-term changes in convective precipitation characteristics and their role in precipitation extremes and intensity over extratropical regions are imperative to future water resource management; however, they have been studied very little. We show that annual convective precipitation total has been increasing astonishingly fast, at a rate of 18...
January 2017: Science Advances
Shannon E Loomis, James M Russell, Dirk Verschuren, Carrie Morrill, Gijs De Cort, Jaap S Sinninghe Damsté, Daniel Olago, Hilde Eggermont, F Alayne Street-Perrott, Meredith A Kelly
The gradient of air temperature with elevation (the temperature lapse rate) in the tropics is predicted to become less steep during the coming century as surface temperature rises, enhancing the threat of warming in high-mountain environments. However, the sensitivity of the lapse rate to climate change is uncertain because of poor constraints on high-elevation temperature during past climate states. We present a 25,000-year temperature reconstruction from Mount Kenya, East Africa, which demonstrates that cooling during the Last Glacial Maximum was amplified with elevation and hence that the lapse rate was significantly steeper than today...
January 2017: Science Advances
Haohua Tu, Yuan Liu, Marina Marjanovic, Eric J Chaney, Sixian You, Youbo Zhao, Stephen A Boppart
Understanding the role of the tumor microenvironment in carcinogenesis has reshaped cancer research. Events at both microscopic (molecular) and macroscopic (tissue) scales have been identified in engineered tumor microenvironments involving in vitro cultures, live tissue xenografts, and transgenic animals. However, these events have not been comprehensively observed under unperturbed (authentic) conditions free of exogenous labeling or genetic modification. The lack of a suitable imaging methodology has largely limited our understanding of the complex interrelations and possible causal links involved in carcinogenesis and metastasis within the tumor microenvironment...
January 2017: Science Advances
Ali Maziz, Alessandro Concas, Alexandre Khaldi, Jonas Stålhand, Nils-Krister Persson, Edwin W H Jager
A need exists for artificial muscles that are silent, soft, and compliant, with performance characteristics similar to those of skeletal muscle, enabling natural interaction of assistive devices with humans. By combining one of humankind's oldest technologies, textile processing, with electroactive polymers, we demonstrate here the feasibility of wearable, soft artificial muscles made by weaving and knitting, with tunable force and strain. These textile actuators were produced from cellulose yarns assembled into fabrics and coated with conducting polymers using a metal-free deposition...
January 2017: Science Advances
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