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  • Springer  (99.135)
  • Wiley  (34.822)
  • Hindawi  (16.972)
  • American Geophysical Union
  • 2020-2022
  • 2010-2014  (157.515)
  • 2000-2004
  • 1995-1999
  • 2013  (157.515)
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  • 2020-2022
  • 2010-2014  (157.515)
  • 2000-2004
  • 1995-1999
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  • 1
    Publikationsdatum: 2024-03-22
    Beschreibung: The Sr/Ca ratio of coral aragonite is used to reconstruct past sea surface temperature (SST). Twentyone laboratories took part in an interlaboratory study of coral Sr/Ca measurements. Results show interlaboratory bias can be significant, and in the extreme case could result in a range in SST estimates of 7°C. However, most of the data fall within a narrower range and the Porites coral reference material JCp- 1 is now characterized well enough to have a certified Sr/Ca value of 8.838 mmol/mol with an expanded uncertainty of 0.089 mmol/mol following International Association of Geoanalysts (IAG) guidelines. This uncertainty, at the 95% confidence level, equates to 1.5°C for SST estimates using Porites, so is approaching fitness for purpose. The comparable median within laboratory error is 〈0.5°C. This difference in uncertainties illustrates the interlaboratory bias component that should be reduced through the use of reference materials like the JCp-1. There are many potential sources contributing to biases in comparative methods but traces of Sr in Ca standards and uncertainties in reference solution composition can account for half of the combined uncertainty. Consensus values that fulfil the requirements to be certified values were also obtained for Mg/Ca in JCp-1 and for Sr/Ca and Mg/Ca ratios in the JCt-1 giant clam reference material. Reference values with variable fitness for purpose have also been obtained for Li/Ca, B/Ca, Ba/Ca, and U/Ca in both reference materials. In future, studies reporting coral element/Ca data should also report the average value obtained for a reference material such as the JCp-1.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2024-01-16
    Beschreibung: Earth system climate models generally underestimate dissolved oxygen concentrations in the deep eastern equatorial Pacific. This problem is associated with the "nutrient trapping" problem, described by Najjar et al. [1992], and is, at least partially, caused by a deficient representation of the Equatorial Intermediate Current System (EICS). Here we emulate the unresolved EICS in the UVic earth system climate model by locally increasing the zonal isopycnal diffusivity. An anisotropic diffusivity of ∼50,000 m 2 s-1 yields an improved global representation of temperature, salinity and oxygen. In addition, it (1) resolves most of the local "nutrient trapping" and associated oxygen deficit in the eastern equatorial Pacific and (2) reduces spurious zonal temperature gradients on isopycnals without affecting other physical metrics such as meridional overturning or air-sea heat fluxes. Finally, climate projections of low-oxygenated waters and associated denitrification change sign and apparently become more plausible
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2023-12-31
    Beschreibung: The major structural characteristics of zooplankton communities that inhabit 35 Arctic lakes in the catchment basin of the Anabar River (Yakutia) have been analyzed. The ecological state of the lakes has been evaluated. The structure-forming abiotic factors that have the greatest influence on the formation of zooplankton communities have been revealed using the indirect ordination method.
    Materialart: Article , PeerReviewed
    Format: text
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  • 4
    Publikationsdatum: 2023-11-29
    Beschreibung: We present data on the co-registered geochemistry (in situ mass spectrometry) and microbiology (pyrosequencing of 16S rRNA genes; V1, V2, V3 regions) in five fluid samples from Irina II in the Logatchev hydrothermal field. Two samples were collected over 24min from the same spot and further three samples were from spatially distinct locations (20cm, 3m and the overlaying plume). Four low-temperature hydrothermal fluids from the Irina II are composed of the same core bacterial community, namely specific Gammaproteobacteria and Epsilonproteobacteria, which, however, differs in the relative abundance. The microbial composition of the fifth sample (plume) is considerably different. Although a significant correlation between sulfide enrichment and proportions of Sulfurovum (Epsilonproteobacteria) was found, no other significant linkages between abiotic factors, i.e. temperature, hydrogen, methane, sulfide and oxygen, and bacterial lineages were evident. Intriguingly, bacterial community compositions of some time series samples from the same spot were significantly more similar to a sample collected 20cm away than to each other. Although this finding is based on three single samples only, it provides first hints that single hydrothermal fluid samples collected on a small spatial scale may also reflect unrecognized temporal variability. However, further studies are required to support this hypothesis.
    Materialart: Article , PeerReviewed
    Format: text
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  • 5
    Publikationsdatum: 2023-11-03
    Beschreibung: In the past three decades, deductive games have become interesting from the algorithmic point of view. Deductive games are two players zero sum games of imperfect information. The first player, called "codemaker", chooses a secret code and the second player, called "codebreaker", tries to break the secret code by making as few guesses as possible, exploiting information that is given by the codemaker after each guess. A well known deductive game is the famous Mastermind game. In this paper, we consider the so called Black-Peg variant of Mastermind, where the only information concerning a guess is the number of positions in which the guess coincides with the secret code. More precisely, we deal with a special version of the Black-Peg game with n holes and k 〉= n colors where no repetition of colors is allowed. We present a strategy that identifies the secret code in O(n log n) queries. Our algorithm improves the previous result of Ker-I Ko and Shia-Chung Teng (1985) by almost a factor of 2 for the case k = n. To our knowledge there is no previous work dealing with the case k 〉 n. Keywords: Mastermind; combinatorial problems; permutations; algorithms
    Materialart: Article , PeerReviewed
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  • 6
    Publikationsdatum: 2023-11-03
    Beschreibung: We present a new quantum-inspired evolutionary algorithm, the attractor population QEA (apQEA). Our benchmark problem is a classical and difficult problem from Combinatorics, namely finding low-discrepancy colorings in the hypergraph of arithmetic progressions on the first n integers, which is a massive hypergraph (e.g., with approx. 3.88 ×1011 hyperedges for n = 250 000). Its optimal low-discrepancy coloring bound is known and it has been a long-standing open problem to give practically and/or theoretically efficient algorithms. We show that apQEA outperforms known QEA approaches and the classical combinatorial algorithm (Sárközy 1974) by a large margin. Regarding practicability, it is also far superior to the SDP-based polynomial-time algorithm of Bansal (2010), the latter being a breakthrough work from a theoretical point of view. Thus we give the first practical algorithm to construct optimal colorings in this hypergraph, up to a constant factor. We hope that our work will spur further applications of Algorithm Engineering to Combinatorics.
    Materialart: Article , PeerReviewed
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  • 7
    facet.materialart.
    Unbekannt
    Springer
    Publikationsdatum: 2023-07-18
    Beschreibung: ‘Transgovernance: Advancing Sustainability Governance’ analyses what implications recent and ongoing changes in the relations between politics, science and media – together characterized as the emergence of a knowledge democracy – may have for governance for sustainable development, on global and other levels of societal decision making, and vice versa: How can the discussion on sustainable development contribute to a knowledge democracy? How can concepts such as second modernity, reflexivity, configuration theory, (meta)governance theory and cultural theory contribute to a ‘transgovernance’ approach which goes beyond mainstream sustainability governance? This volume presents contributions from various angles: international relations, governance and metagovernance theory, (environmental) economics and innovation science. It offers challenging insights regarding institutions and transformation processes, and into the paradigms behind contemporary sustainability governance. This book gives the sustainability governance debate a new context. It transforms classical questions into new options for societal decision making and identifies starting points and strategies aimed at effective governance of transitions to sustainability.
    Sprache: Englisch
    Materialart: info:eu-repo/semantics/book
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    facet.materialart.
    Unbekannt
    Springer
    Publikationsdatum: 2023-07-18
    Materialart: info:eu-repo/semantics/book
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    facet.materialart.
    Unbekannt
    Springer
    In:  EPIC3Earth System Science: Bridging the gaps between disciplines—A multi-disciplinary Helmholtz Graduate Research School, Berlin Heidelberg, Springer, 7 p., pp. 83-89, ISBN: 978-3-642-32235-8
    Publikationsdatum: 2023-06-21
    Beschreibung: Geophysical data acquired along the Antarctic passive margins constrain the structure and geometry of the deformed continental crust. Crustal thickness estimates range between 7 and 50 km and the Antarctic continent–ocean transition zone (COTZ) extends up to 100–670 km towards the ocean. Continental deformation prior to rifting over a c. 100 million years long time span resulted in crustal stretching factors varying between 1.8 and 5.9. The time span of deformation was sufficiently large and the rifting velocity low enough to extend the margin by up to 300–400 km. Crustal thinning generates a significant subsidence and shallow water passages might already have developed during the rifting phase along the margin. Accounting for accurate continental margin deformation has also consequences for plate-tectonic reconstructions.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Inbook , peerRev
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    facet.materialart.
    Unbekannt
    Springer
    In:  EPIC3Earth system science: bridging the gap between disciplines, Earth system science: bridging the gap between disciplines, Heidelberg, Springer, 7 p., pp. 97-103, ISBN: 978-3-642-32234-1
    Publikationsdatum: 2023-06-21
    Beschreibung: Information about past environmental conditions is preserved in the elemental signature of biogenic marine carbonates. Thus, trace element to calcium ratios (Me/Ca) of biogenic calcium carbonates, such as bivalve shells, are often used to reconstruct past environmental conditions at the time of carbonate formation (Foster et al., 2008). In this study, we examine the suitability of the long-lived (〉 400 years) bivalve Arctica islandica as a high-resolution bioarchive by measuring Me/Ca ratios in the shell carbonate. Pb/Ca concentrations in A. islandica shells reflect anthropogenic gasoline lead consumption and further provide a centennial record of lead pollution for the collection site off the coast of Virginia, USA. With A. islandica shells from the North Sea we test the hypothesis that Ba/Ca and Mn/Ca ratios are indicators of the diatom abundance. Our results indicate that statistically both ratios correlate well with the diatom abundance, and yet, on a year-to-year base, there is no consistent reflection of diatom abundance patterns in the Ba/Ca and Mn/Ca annual profiles. These findings indicate that primary production affects Ba/Ca and Mn/Ca shell ratios, though we suggest that both elements are coupled to primary production through different processes and are affected by further, yet unknown processes.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Inbook , peerRev
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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