| 41. |
- Barlow, M. J., et al.
(författare)
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Detection of a Noble Gas Molecular Ion, (ArH+)-Ar-36, in the Crab Nebula
- 2013
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 342:6164, s. 1343-1345
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Tidskriftsartikel (refereegranskat)abstract
- Noble gas molecules have not hitherto been detected in space. From spectra obtained with the Herschel Space Observatory, we report the detection of emission in the 617.5- and 1234.6-gigahertz J = 1-0 and 2-1 rotational lines of (ArH+)-Ar-36 at several positions in the Crab Nebula, a supernova remnant known to contain both molecular hydrogen and regions of enhanced ionized argon emission. Argon-36 is believed to have originated from explosive nucleosynthesis in massive stars during core-collapse supernova events. Its detection in the Crab Nebula, the product of such a supernova event, confirms this expectation. The likely excitation mechanism for the observed (ArH+)-Ar-36 emission lines is electron collisions in partially ionized regions with electron densities of a few hundred per centimeter cubed.
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| 42. |
- Barreda, V. D., et al.
(författare)
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Eocene Patagonia Fossils of the Daisy Family
- 2010
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 329:5999, s. 1621-1621
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Tidskriftsartikel (refereegranskat)abstract
- Fossil evidence suggests that daisies and sunflowers may have originated in South America more than 47 million years ago.
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| 43. |
- Bastviken, David, et al.
(författare)
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Freshwater Methane Emissions Offset the Continental Carbon Sink
- 2011
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 331:6013, s. 50-50
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Tidskriftsartikel (refereegranskat)abstract
- Inland waters (lakes, reservoirs, streams, and rivers) are often substantial methane (CH4) sources in the terrestrial landscape. They are, however, not yet well integrated in global greenhouse gas (GHG) budgets. Data from 474 freshwater ecosystems and the most recent global water area estimates indicate that freshwaters emit at least 103 teragrams of CH4 year−1, corresponding to 0.65 petagrams of C as carbon dioxide (CO2) equivalents year−1, offsetting 25% of the estimated land carbon sink. Thus, the continental GHG sink may be considerably overestimated, and freshwaters need to be recognized as important in the global carbon cycle.
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| 44. |
- Beer, Christian, et al.
(författare)
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Terrestrial Gross Carbon Dioxide Uptake: Global Distribution and Covariation with Climate
- 2010
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 329:5993, s. 834-838
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Tidskriftsartikel (refereegranskat)abstract
- Terrestrial gross primary production (GPP) is the largest global CO2 flux driving several ecosystem functions. We provide an observation-based estimate of this flux at 123 +/- 8 petagrams of carbon per year (Pg C year(-1)) using eddy covariance flux data and various diagnostic models. Tropical forests and savannahs account for 60%. GPP over 40% of the vegetated land is associated with precipitation. State-of-the-art process-oriented biosphere models used for climate predictions exhibit a large between-model variation of GPP's latitudinal patterns and show higher spatial correlations between GPP and precipitation, suggesting the existence of missing processes or feedback mechanisms which attenuate the vegetation response to climate. Our estimates of spatially distributed GPP and its covariation with climate can help improve coupled climate-carbon cycle process models.
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| 45. |
- Belgrano, Andrea
(författare)
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How Fisheries Affect Evolution
- 2013
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 342, s. 1176-1177
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Annan publikation (refereegranskat)abstract
- Commercial fishing alters the genetic traits of fish stocks.
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| 46. |
- Bellmund, Jacob L.S., et al.
(författare)
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Navigating cognition : Spatial codes for human thinking
- 2018
-
Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 362:6415
-
Forskningsöversikt (refereegranskat)abstract
- The hippocampal formation has long been suggested to underlie both memory formation and spatial navigation. We discuss how neural mechanisms identified in spatial navigation research operate across information domains to support a wide spectrum of cognitive functions. In our framework, place and grid cell population codes provide a representational format to map variable dimensions of cognitive spaces. This highly dynamic mapping system enables rapid reorganization of codes through remapping between orthogonal representations across behavioral contexts, yielding a multitude of stable cognitive spaces at different resolutions and hierarchical levels. Action sequences result in trajectories through cognitive space, which can be simulated via sequential coding in the hippocampus. In this way, the spatial representational format of the hippocampal formation has the capacity to support flexible cognition and behavior.
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| 47. |
- Benlloch, Reyes, et al.
(författare)
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An Antagonistic Pair of FT Homologs Mediates the Control of Flowering Time in Sugar Beet
- 2010
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 330, s. 1397-1400
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Tidskriftsartikel (refereegranskat)abstract
- Cultivated beets (Beta vulgaris ssp. vulgaris) are unable to form reproductive shoots during the first year of their life cycle. Flowering only occurs if plants get vernalized, that is, pass through the winter, and are subsequently exposed to an increasing day length (photoperiod) in spring. Here, we show that the regulation of flowering time in beets is controlled by the interplay of two paralogs of the FLOWERING LOCUS T (FT) gene in Arabidopsis that have evolved antagonistic functions. BvFT2 is functionally conserved with FT and essential for flowering. In contrast, BvFT1 represses flowering and its down-regulation is crucial for the vernalization response in beets. These data suggest that the beet has evolved a different strategy relative to Arabidopsis and cereals to regulate vernalization.
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| 48. |
- Bennett, Keith D.
(författare)
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Comment on "Sedimentary DNA from a submerged site reveals wheat in the British Isles 8000 years ago"
- 2015
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 349:6245
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Smith et al. (Reports, 27 February 2015, p. 998) identify wheat DNA from an 8000-calendar-years-before-the-present archaeological site in southern England and conclude that wheat was traded to Britain 2000 years before the arrival of agriculture. The DNA samples are not dated, either directly or from circumstantial evidence, so there is no chronological evidence to support the claim.
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| 49. |
- Berggren, Magnus, 1968-, et al.
(författare)
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How conducting polymer electrodes operate
- 2019
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Ingår i: Science. - Washington, DC, United States : American Association for the Advancement of Science (A A A S). - 0036-8075 .- 1095-9203. ; 364:6437, s. 233-234
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
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| 50. |
- Bergmann, O, et al.
(författare)
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Neuroscience. Why adults need new brain cells
- 2013
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Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 340:6133, s. 695-696
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Tidskriftsartikel (refereegranskat)
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