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Potential for large-scale CO2 removal via enhanced rock weathering with croplands 期刊论文
NATURE, 2020, 583 (7815) : 242-+
作者:  David J. Beerling;  Euripides P. Kantzas;  Mark R. Lomas;  Peter Wade;  Rafael M. Eufrasio;  Phil Renforth;  Binoy Sarkar;  M. Grace Andrews;  Rachael H. James;  Christopher R. Pearce;  Jean-Francois Mercure;  Hector Pollitt;  Philip B. Holden;  Neil R. Edwards;  Madhu Khanna;  Lenny Koh;  Shaun Quegan;  Nick F. Pidgeon;  Ivan A. Janssens;  James Hansen;  Steven A. Banwart
收藏  |  浏览/下载:18/0  |  提交时间:2020/07/14

Enhanced silicate rock weathering (ERW), deployable with croplands, has potential use for atmospheric carbon dioxide (CO2) removal (CDR), which is now necessary to mitigate anthropogenic climate change(1). ERW also has possible co-benefits for improved food and soil security, and reduced ocean acidification(2-4). Here we use an integrated performance modelling approach to make an initial techno-economic assessment for 2050, quantifying how CDR potential and costs vary among nations in relation to business-as-usual energy policies and policies consistent with limiting future warming to 2 degrees Celsius(5). China, India, the USA and Brazil have great potential to help achieve average global CDR goals of 0.5 to 2gigatonnes of carbon dioxide (CO2) per year with extraction costs of approximately US$80-180 per tonne of CO2. These goals and costs are robust, regardless of future energy policies. Deployment within existing croplands offers opportunities to align agriculture and climate policy. However, success will depend upon overcoming political and social inertia to develop regulatory and incentive frameworks. We discuss the challenges and opportunities of ERW deployment, including the potential for excess industrial silicate materials (basalt mine overburden, concrete, and iron and steel slag) to obviate the need for new mining, as well as uncertainties in soil weathering rates and land-ocean transfer of weathered products.


  
GENDER-EQUITY AUDITS URGED FOR GRANT RECIPIENTS US national academy pushes to make grants contingent on gender equity 期刊论文
NATURE, 2020, 580 (7802) : 296-296
作者:  Subbaraman, Nidhi;  Davis, Sharde;  Woods, Joy Melody
收藏  |  浏览/下载:8/0  |  提交时间:2020/07/03

Funders should audit institutions'  policies to include and promote women, recommends report.


Funders should audit institutions'  policies to include and promote women, recommends report.


  
Abiotic hydrogen (H-2) sources and sinks near the Mid-Ocean Ridge (MOR) with implications for the subseafloor biosphere 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (24) : 13283-13293
作者:  Worman, Stacey L.;  Pratson, Lincoln F.;  Karson, Jeffrey A.;  Schlesinger, William H.
收藏  |  浏览/下载:12/0  |  提交时间:2020/06/09
biogeochemistry  origins of life  hydrogen  Mid-Ocean Ridge  microbes  
Estimating US fossil fuel CO2 emissions from measurements of C-14 in atmospheric CO2 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (24) : 13300-13307
作者:  Basu, Sourish;  Lehman, Scott J.;  Miller, John B.;  Andrews, Arlyn E.;  Sweeney, Colm;  Gurney, Kevin R.;  Xu, Xiaomei;  Southon, John;  Tans, Pieter P.
收藏  |  浏览/下载:14/0  |  提交时间:2020/06/09
fossil fuel CO2  radiocarbon  atmospheric inverse modeling  
Scientists exposed to coronavirus wonder: why weren't we notified? 期刊论文
NATURE, 2020, 579 (7800) : 480-481
作者:  Subbaraman, Nidhi
收藏  |  浏览/下载:4/0  |  提交时间:2020/07/03

US authorities are failing to test people and notify their contacts, a cornerstone of outbreak response.


Scientists exposed to coronavirus: why weren'  t we notified? US authorities are failing to test people and notify their contacts, a cornerstone of outbreak response.


  
Where I work 期刊论文
NATURE, 2020, 582 (7813) : 600-600
作者:  Bodin, Madeline;  Khan, Christin
收藏  |  浏览/下载:11/0  |  提交时间:2020/07/03

US federal biologist Christin Khan embraces risk above the Atlantic Ocean to monitor a rare species.


US federal biologist Christin Khan embraces risk above the Atlantic Ocean to monitor a rare species.


  
Localization and delocalization of light in photonic moire lattices 期刊论文
NATURE, 2020, 577 (7788) : 42-+
作者:  Wang, Peng;  Zheng, Yuanlin;  Chen, Xianfeng;  Huang, Changming;  Kartashov, Yaroslav V.;  Torner, Lluis;  Konotop, Vladimir V.;  Ye, Fangwei
收藏  |  浏览/下载:12/0  |  提交时间:2020/07/03

Moire lattices consist of two superimposed identical periodic structures with a relative rotation angle. Moire lattices have several applications in everyday life, including artistic design, the textile industry, architecture, image processing, metrology and interferometry. For scientific studies, they have been produced using coupled graphene-hexagonal boron nitride monolayers(1,2), graphene-graphene layers(3,4) and graphene quasicrystals on a silicon carbide surface(5). The recent surge of interest in moire lattices arises from the possibility of exploring many salient physical phenomena in such systems  examples include commensurable-incommensurable transitions and topological defects(2), the emergence of insulating states owing to band flattening(3,6), unconventional superconductivity(4) controlled by the rotation angle(7,8), the quantum Hall effect(9), the realization of non-Abelian gauge potentials(10) and the appearance of quasicrystals at special rotation angles(11). A fundamental question that remains unexplored concerns the evolution of waves in the potentials defined by moire lattices. Here we experimentally create two-dimensional photonic moire lattices, which-unlike their material counterparts-have readily controllable parameters and symmetry, allowing us to explore transitions between structures with fundamentally different geometries (periodic, general aperiodic and quasicrystal). We observe localization of light in deterministic linear lattices that is based on flatband physics(6), in contrast to previous schemes based on light diffusion in optical quasicrystals(12), where disorder is required(13) for the onset of Anderson localization(14) (that is, wave localization in random media). Using commensurable and incommensurable moire patterns, we experimentally demonstrate the twodimensional localization-delocalization transition of light. Moire lattices may feature an almost arbitrary geometry that is consistent with the crystallographic symmetry groups of the sublattices, and therefore afford a powerful tool for controlling the properties of light patterns and exploring the physics of periodic-aperiodic phase transitions and two-dimensional wavepacket phenomena relevant to several areas of science, including optics, acoustics, condensed matter and atomic physics.


  
Poultry through time 期刊论文
NATURE, 2020, 579 (7799) : 351-352
作者:  Cathomas, Flurin;  Russo, Scott J.
收藏  |  浏览/下载:6/0  |  提交时间:2020/07/03

A newly discovered 66.7-million-year-old fossil bird excavated in Belgium provides us with the best evidence so far for understanding when the living groups of birds first evolved and began to diverge.


Fossil sheds light on the evolution of crown-group birds.


  
Months-long thousand-kilometre-scale wobbling before great subduction earthquakes 期刊论文
NATURE, 2020, 580 (7805) : 628-+
作者:  Son, Hyungmok;  Park, Juliana J.;  Ketterle, Wolfgang;  Jamison, Alan O.
收藏  |  浏览/下载:16/0  |  提交时间:2020/05/13

Observed reversals in GNSS surface motions suggests greatly enhanced slab pull in the months preceding the great subduction earthquakes in Maule (Chile, 2010) and Tohoku-oki (Japan, 2011) of moment magnitudes 8.8 and 9.0.


Megathrust earthquakes are responsible for some of the most devastating natural disasters(1). To better understand the physical mechanisms of earthquake generation, subduction zones worldwide are continuously monitored with geophysical instrumentation. One key strategy is to install stations that record signals from Global Navigation Satellite Systems(2,3) (GNSS), enabling us to track the non-steady surface motion of the subducting and overriding plates before, during and after the largest events(4-6). Here we use a recently developed trajectory modelling approach(7) that is designed to isolate secular tectonic motions from the daily GNSS time series to show that the 2010 Maule, Chile (moment magnitude 8.8) and 2011 Tohoku-oki, Japan (moment magnitude 9.0) earthquakes were preceded by reversals of 4-8 millimetres in surface displacement that lasted several months and spanned thousands of kilometres. Modelling of the surface displacement reversal that occurred before the Tohoku-oki earthquake suggests an initial slow slip followed by a sudden pulldown of the Philippine Sea slab so rapid that it caused a viscoelastic rebound across the whole of Japan. Therefore, to understand better when large earthquakes are imminent, we must consider not only the evolution of plate interface frictional processes but also the dynamic boundary conditions from deeper subduction processes, such as sudden densification of metastable slab.


  
Exploring dynamical phase transitions with cold atoms in an optical cavity 期刊论文
NATURE, 2020, 580 (7805) : 602-+
作者:  Halbach, Rebecca;  Miesen, Pascal;  Joosten, Joep;  Taskopru, Ezgi;  Rondeel, Inge;  Pennings, Bas;  Vogels, Chantal B. F.;  Merkling, Sarah H.;  Koenraadt, Constantianus J.;  Lambrechts, Louis;  van Rij, Ronald P.
收藏  |  浏览/下载:8/0  |  提交时间:2020/07/03

Interactions between light and an ensemble of strontium atoms in an optical cavity can serve as a testbed for studying dynamical phase transitions, which are currently not well understood.


Interactions between atoms and light in optical cavities provide a means of investigating collective (many-body) quantum physics in controlled environments. Such ensembles of atoms in cavities have been proposed for studying collective quantum spin models, where the atomic internal levels mimic a spin degree of freedom and interact through long-range interactions tunable by changing the cavity parameters(1-4). Non-classical steady-state phases arising from the interplay between atom-light interactions and dissipation of light from the cavity have previously been investigated(5-11). These systems also offer the opportunity to study dynamical phases of matter that are precluded from existence at equilibrium but can be stabilized by driving a system out of equilibrium(12-16), as demonstrated by recent experiments(17-22). These phases can also display universal behaviours akin to standard equilibrium phase transitions(8,23,24). Here, we use an ensemble of about a million strontium-88 atoms in an optical cavity to simulate a collective Lipkin-Meshkov-Glick model(25,26), an iconic model in quantum magnetism, and report the observation of distinct dynamical phases of matter in this system. Our system allows us to probe the dependence of dynamical phase transitions on system size, initial state and other parameters. These observations can be linked to similar dynamical phases in related systems, including the Josephson effect in superfluid helium(27), or coupled atomic(28) and solid-state polariton(29) condensates. The system itself offers potential for generation of metrologically useful entangled states in optical transitions, which could permit quantum enhancement in state-of-the-art atomic clocks(30,31).