Journal: Science

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AAAS

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0036-8075
1095-9203

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Publications 1 - 10 of 592
  • Genomic surveillance reveals multiple introductions of SARS-CoV-2 into Northern California
    Item type: Journal Article
    Deng, Xianding; Gu, Wei; Federman, Scot; et al. (2020)
    Science
    The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally, with >365,000 cases in California as of 17 July 2020. We investigated the genomic epidemiology of SARS-CoV-2 in Northern California from late January to mid-March 2020, using samples from 36 patients spanning nine counties and the Grand Princess cruise ship. Phylogenetic analyses revealed the cryptic introduction of at least seven different SARS-CoV-2 lineages into California, including epidemic WA1 strains associated with Washington state, with lack of a predominant lineage and limited transmission among communities. Lineages associated with outbreak clusters in two counties were defined by a single base substitution in the viral genome. These findings support contact tracing, social distancing, and travel restrictions to contain the spread of SARS-CoV-2 in California and other states.
  • Evolution and epidemic spread of SARS-CoV-2 in Brazil
    Item type: Journal Article
    Candido, Darlan S.; Claro, Ingra M.; de Jesus, Jaqueline G.; et al. (2020)
    Science
    Brazil currently has one of the fastest-growing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemics in the world. Because of limited available data, assessments of the impact of nonpharmaceutical interventions (NPIs) on this virus spread remain challenging. Using a mobility-driven transmission model, we show that NPIs reduced the reproduction number from >3 to 1 to 1.6 in São Paulo and Rio de Janeiro. Sequencing of 427 new genomes and analysis of a geographically representative genomic dataset identified >100 international virus introductions in Brazil. We estimate that most (76%) of the Brazilian strains fell in three clades that were introduced from Europe between 22 February and 11 March 2020. During the early epidemic phase, we found that SARS-CoV-2 spread mostly locally and within state borders. After this period, despite sharp decreases in air travel, we estimated multiple exportations from large urban centers that coincided with a 25% increase in average traveled distances in national flights. This study sheds new light on the epidemic transmission and evolutionary trajectories of SARS-CoV-2 lineages in Brazil and provides evidence that current interventions remain insufficient to keep virus transmission under control in this country.
  • Temperature limits to deep subseafloor life in the Nankai Trough subduction zone
    Item type: Journal Article
    Heuer, Verena B.; Inagaki, Fumio; Morono, Yuki; et al. (2020)
    Science
    Microorganisms in marine subsurface sediments substantially contribute to global biomass. Sediments warmer than 40°C account for roughly half the marine sediment volume, but the processes mediated by microbial populations in these hard-to-access environments are poorly understood. We investigated microbial life in up to 1.2-kilometer-deep and up to 120°C hot sediments in the Nankai Trough subduction zone. Above 45°C, concentrations of vegetative cells drop two orders of magnitude and endospores become more than 6000 times more abundant than vegetative cells. Methane is biologically produced and oxidized until sediments reach 80° to 85°C. In 100° to 120°C sediments, isotopic evidence and increased cell concentrations demonstrate the activity of acetate-degrading hyperthermophiles. Above 45°C, populated zones alternate with zones up to 192 meters thick where microbes were undetectable.
  • Neurorobotics for neurorehabilitation
    Item type: Other Journal Item
    Raspopovic, Stanisa (2021)
    Science
  • Increasing anthropogenic nitrogen in the North Pacific Ocean
    Item type: Journal Article
    Kim, Il-Nam; Lee, Kitack; Gruber, Nicolas; et al. (2014)
    Science
  • Spontaneous formation of urea from carbon dioxide and ammonia in aqueous droplets
    Item type: Journal Article
    Azizbaig Mohajer, Mercede; Basuri, Pallab; Evdokimov, Andrei; et al. (2025)
    Science
    Urea is a key molecule in the search for the origin of life and a basic chemical produced in large quantities by industry. Its formation from ammonia and carbon dioxide requires either high pressures and temperatures or, under milder conditions, catalysts or additional reagents. In this study, we observed the spontaneous formation of urea under ambient conditions from ammonia and carbon dioxide in the surface layer of aqueous droplets. Single, optically trapped droplets were probed by using Raman bands as markers. We found the surface layer to act like a microscopic flow reactor, with chemical gradients providing access to unconventional reaction pathways. This observation revealed a general mechanistic scheme for distinctive droplet chemistry. Interfacial chemistry is a possible nonenergetic route for urea formation under prebiotic conditions.
  • Surface waves and crustal structure on Mars
    Item type: Journal Article
    Kim, Doyeon; Banerdt, William Bruce; Ceylan, Savas; et al. (2022)
    Science
    We detected surface waves from two meteorite impacts on Mars. By measuring group velocity dispersion along the impact-lander path, we obtained a direct constraint on crustal structure away from the InSight lander. The crust north of the equatorial dichotomy had a shear wave velocity of approximately 3.2 kilometers per second in the 5- to 30-kilometer depth range, with little depth variation. This implies a higher crustal density than inferred beneath the lander, suggesting either compositional differences or reduced porosity in the volcanic areas traversed by the surface waves. The lower velocities and the crustal layering observed beneath the landing site down to a 10-kilometer depth are not a global feature. Structural variations revealed by surface waves hold implications for models of the formation and thickness of the martian crust.
  • Getting moore from solar cells
    Item type: Journal Article
    Norris, David J.; Aydil, Eray S. (2012)
    Science
  • Human activities shape global patterns of decomposition rates in rivers
    Item type: Journal Article
    Tiegs, Scott D.; Capps, Krista A.; Costello, David M.; et al. (2024)
    Science
    Rivers and streams contribute to global carbon cycling by decomposing immense quantities of terrestrial plant matter. However, decomposition rates are highly variable and large-scale patterns and drivers of this process remain poorly understood. Using a cellulose-based assay to reflect the primary constituent of plant detritus, we generated a predictive model (81% variance explained) for cellulose decomposition rates across 514 globally distributed streams. A large number of variables were important for predicting decomposition, highlighting the complexity of this process at the global scale. Predicted cellulose decomposition rates, when combined with genus-level litter quality attributes, explain published leaf litter decomposition rates with high accuracy (70% variance explained). Our global map provides estimates of rates across vast understudied areas of Earth and reveals rapid decomposition across continental-scale areas dominated by human activities.
Publications 1 - 10 of 592