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  • Nature Publishing Group  (7,449)
  • Blackwell Publishing Ltd  (6,387)
  • 2000-2004  (13,836)
  • 2004  (6,793)
  • 2003  (7,043)
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Publisher
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  • 2000-2004  (13,836)
Year
  • 1
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    The effects of surfactants on spilling breaking waves (2003)
    Nature Publishing Group
    In:  Nature, 421 (6922). pp. 520-523.
    Details
    Publication Date: 2016-05-10
    Description: Breaking waves markedly increase the rates of air–sea transfer of momentum, energy and mass. In light to moderate wind conditions, spilling breakers with short wavelengths are observed frequently. Theory and laboratory experiments have shown that, as these waves approach breaking in clean water, a ripple pattern that is dominated by surface tension forms at the crest. Under laboratory conditions and in theory, the transition to turbulent flow is triggered by flow separation under the ripples, typically without leading to overturning of the free surface15. Water surfaces in nature, however, are typically contaminated by surfactant films that alter the surface tension and produce surface elasticity and viscosity16, 17. Here we present the results of laboratory experiments in which spilling breaking waves were generated mechanically in water with a range of surfactant concentrations. We find significant changes in the breaking process owing to surfactants. At the highest concentration of surfactants, a small plunging jet issues from the front face of the wave at a point below the wave crest and entraps a pocket of air on impact with the front face of the wave. The bubbles and turbulence created during this process are likely to increase air–sea transfer.
    Type: Article , PeerReviewed
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  • 2
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    The ‘zero charge’ partitioning behaviour of noble gases during mantle melting (2003)
    Nature Publishing Group
    In:  Nature, 423 (6941). pp. 738-741.
    Details
    Publication Date: 2015-11-24
    Description: Noble-gas geochemistry is an important tool for understanding planetary processes from accretion to mantle dynamics and atmospheric formation. Central to much of the modelling of such processes is the crystal–melt partitioning of noble gases during mantle melting, magma ascent and near-surface degassing5. Geochemists have traditionally considered the 'inert' noble gases to be extremely incompatible elements, with almost 100 per cent extraction efficiency from the solid phase during melting processes. Previously published experimental data on partitioning between crystalline silicates and melts has, however, suggested that noble gases approach compatible behaviour, and a significant proportion should therefore remain in the mantle during melt extraction. Here we present experimental data to show that noble gases are more incompatible than previously demonstrated, but not necessarily to the extent assumed or required by geochemical models. Independent atomistic computer simulations indicate that noble gases can be considered as species of 'zero charge' incorporated at crystal lattice sites. Together with the lattice strain model9, 10, this provides a theoretical framework with which to model noble-gas geochemistry as a function of residual mantle mineralogy.
    Type: Article , PeerReviewed
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  • 3
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    Genomic islands in pathogenic and environmental microorganisms (2004)
    Nature Publishing Group
    In:  Nature Reviews Microbiology, 2 (5). pp. 414-424.
    Details
    Publication Date: 2020-06-23
    Description: Horizontal gene transfer is an important mechanism for the evolution of microbial genomes. Pathogenicity islands — mobile genetic elements that contribute to rapid changes in virulence potential — are known to have contributed to genome evolution by horizontal gene transfer in many bacterial pathogens. Increasing evidence indicates that equivalent elements in non-pathogenic species — genomic islands — are important in the evolution of these bacteria, influencing traits such as antibiotic resistance, symbiosis and fitness, and adaptation in general. This review discusses the recent lessons that have been learned from pathogenicity islands in pathogenic microorganisms and how they apply to the role of genomic islands in commensal, symbiotic and environmental bacteria.
    Type: Article , PeerReviewed
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  • 4
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    Break-up of the Atlantic Deep Western Boundary Current into eddies at 8°S (2004)
    Nature Publishing Group
    In:  Nature, 432 . pp. 1018-1020.
    Details
    Publication Date: 2017-03-09
    Description: The existence in the ocean of deep western boundary currents, which connect the high-latitude regions where deep water is formed with upwelling regions as part of the global ocean circulation, was postulated more than 40 years ago1. These ocean currents have been found adjacent to the continental slopes of all ocean basins, and have core depths between 1,500 and 4,000 m. In the Atlantic Ocean, the deep western boundary current is estimated to carry (10–40) times 106 m3 s-1 of water2, 3, 4, 5, transporting North Atlantic Deep Water—from the overflow regions between Greenland and Scotland and from the Labrador Sea—into the South Atlantic and the Antarctic circumpolar current. Here we present direct velocity and water mass observations obtained in the period 2000 to 2003, as well as results from a numerical ocean circulation model, showing that the Atlantic deep western boundary current breaks up at 8° S. Southward of this latitude, the transport of North Atlantic Deep Water into the South Atlantic Ocean is accomplished by migrating eddies, rather than by a continuous flow. Our model simulation indicates that the deep western boundary current breaks up into eddies at the present intensity of meridional overturning circulation. For weaker overturning, continuation as a stable, laminar boundary flow seems possible.
    Type: Article , PeerReviewed
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  • 5
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    In situ experimental evidence of the fate of a phytodetritus pulse at the abyssal sea floor (2003)
    Nature Publishing Group
    In:  Nature, 424 . pp. 763-765.
    Details
    Publication Date: 2017-03-07
    Description: More than 50% of the Earth' s surface is sea floor below 3,000 m of water. Most of this major reservoir in the global carbon cycle and final repository for anthropogenic wastes is characterized by severe food limitation. Phytodetritus is the major food source for abyssal benthic communities, and a large fraction of the annual food load can arrive in pulses within a few days1, 2. Owing to logistical constraints, the available data concerning the fate of such a pulse are scattered3, 4 and often contradictory5, 6, 7, 8, 9, 10, hampering global carbon modelling and anthropogenic impact assessments. We quantified (over a period of 2.5 to 23 days) the response of an abyssal benthic community to a phytodetritus pulse, on the basis of 11 in situ experiments. Here we report that, in contrast to previous hypotheses5, 6, 7, 8, 9, 10, 11, the sediment community oxygen consumption doubled immediately, and that macrofauna were very important for initial carbon degradation. The retarded response of bacteria and Foraminifera, the restriction of microbial carbon degradation to the sediment surface, and the low total carbon turnover distinguish abyssal from continental-slope ‘deep-sea’ sediments.
    Type: Article , PeerReviewed
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  • 6
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    Paleoceanographic implications of genetic variation in living North Atlantic Neogloboquadrina pachyderma (2003)
    Nature Publishing Group
    In:  Nature, 424 (6946). pp. 299-302.
    Details
    Publication Date: 2017-03-07
    Description: The shells of the planktonic foraminifer Neogloboquadrina pachyderma have become a classical tool for reconstructing glacial–interglacial climate conditions in the North Atlantic Ocean1, 2, 3. Palaeoceanographers utilize its left- and right-coiling variants, which exhibit a distinctive reciprocal temperature and water mass related shift in faunal abundance both at present and in late Quaternary sediments1, 2, 4, 5. Recently discovered cryptic genetic diversity in planktonic foraminifers6, 7, 8 now poses significant questions for these studies. Here we report genetic evidence demonstrating that the apparent ‘single species’ shell-based records of right-coiling N. pachyderma used in palaeoceanographic reconstructions contain an alternation in species as environmental factors change. This is reflected in a species-dependent incremental shift in right-coiling N. pachyderma shell calcite δ18O between the Last Glacial Maximum and full Holocene conditions. Guided by the percentage dextral coiling ratio, our findings enhance the use of δ18O records of right-coiling N. pachyderma for future study. They also highlight the need to genetically investigate other important morphospecies to refine their accuracy and reliability as palaeoceanographic proxies.
    Type: Article , PeerReviewed
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  • 7
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    Strong hemispheric coupling of glacial climate through continental freshwater discharge and ocean circulation (2004)
    Nature Publishing Group
    In:  Nature, 430 . pp. 851-856.
    Details
    Publication Date: 2017-03-07
    Description: The climate of the last glacial period was extremely variable, characterized by abrupt warming events in the Northern Hemisphere, accompanied by slower temperature changes in Antarctica and variations of global sea level. It is generally accepted that this millennial-scale climate variability was caused by abrupt changes in the ocean thermohaline circulation. Here we use a coupled ocean–atmosphere–sea ice model to show that freshwater discharge into the North Atlantic Ocean, in addition to a reduction of the thermohaline circulation, has a direct effect on Southern Ocean temperature. The related anomalous oceanic southward heat transport arises from a zonal density gradient in the subtropical North Atlantic caused by a fast wave-adjustment process. We present an extended and quantitative bipolar seesaw concept that explains the timing and amplitude of Greenland and Antarctic temperature changes, the slow changes in Antarctic temperature and its similarity to sea level, as well as a possible time lag of sea level with respect to Antarctic temperature during Marine Isotope Stage 3.
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  • 8
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    Iron and phosphorus co-limit nitrogen fixation in the eastern tropical North Atlantic (2004)
    Nature Publishing Group
    In:  Nature, 429 . pp. 292-294.
    Details
    Publication Date: 2017-03-10
    Description: The role of iron in enhancing phytoplankton productivity in high nutrient, low chlorophyll oceanic regions was demonstrated first through iron-addition bioassay experiments1 and subsequently confirmed by large-scale iron fertilization experiments2. Iron supply has been hypothesized to limit nitrogen fixation and hence oceanic primary productivity on geological timescales3, providing an alternative to phosphorus as the ultimate limiting nutrient4. Oceanographic observations have been interpreted both to confirm and refute this hypothesis5, 6, but direct experimental evidence is lacking7. We conducted experiments to test this hypothesis during the Meteor 55 cruise to the tropical North Atlantic. This region is rich in diazotrophs8 and strongly impacted by Saharan dust input9. Here we show that community primary productivity was nitrogen-limited, and that nitrogen fixation was co-limited by iron and phosphorus. Saharan dust addition stimulated nitrogen fixation, presumably by supplying both iron and phosphorus10, 11. Our results support the hypothesis that aeolian mineral dust deposition promotes nitrogen fixation in the eastern tropical North Atlantic.
    Type: Article , PeerReviewed
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  • 9
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    Deep Roots of the Messinian Salinity Crisis (2003)
    Nature Publishing Group
    In:  Nature, 422 . pp. 602-606.
    Details
    Publication Date: 2019-09-23
    Description: The Messinian salinity crisis—the desiccation of the Mediterranean Sea between 5.96 and 5.33 million years (Myr) ago1—was one of the most dramatic events on Earth during the Cenozoic era2. It resulted from the closure of marine gateways between the Atlantic Ocean and the Mediterranean Sea, the causes of which remain enigmatic. Here we use the age and composition of volcanic rocks to reconstruct the geodynamic evolution of the westernmost Mediterranean from the Middle Miocene epoch to the Pleistocene epoch (about 12.1–0.65 Myr ago). Our data show that a marked shift in the geochemistry of mantle-derived volcanic rocks, reflecting a change from subduction-related to intraplate-type volcanism, occurred between 6.3 and 4.8 Myr ago, largely synchronous with the Messinian salinity crisis. Using a thermomechanical model, we show that westward roll back of subducted Tethys oceanic lithosphere and associated asthenospheric upwelling provides a plausible mechanism for producing the shift in magma chemistry and the necessary uplift (approx1 km) along the African and Iberian continental margins to close the Miocene marine gateways, thereby causing the Messinian salinity crisis.
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  • 10
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    Managing fisheries in a changing climate (2004)
    Nature Publishing Group
    In:  Nature, 429 .
    Details
    Publication Date: 2017-03-10
    Description: No need to wait for more information: industrialized fishing is already wiping out stocks.
    Type: Article , NonPeerReviewed
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