Viser treff 4081-4100 av 5414

    • A late-Holocene multi-proxy record from the northern Norwegian margin: Temperature and salinity variability 

      Berben, Sarah Miche Patricia; Husum, Katrine; Sørensen, Steffen Aagaard (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-01)
      To elucidate the natural variability of Atlantic and Coastal water, a late-Holocene multi-proxy analysis is performed on a marine sediment core from the northern Norwegian margin. This includes planktic foraminiferal fauna and their preservation indicators, stable isotopes (δ18Oc, δ13C), sub-surface temperature (SSTMg/Ca) and salinity (SSS) records based on paired Mg/Ca and δ18Oc measurements of ...
    • New capabilities of the upgraded EISCAT high-power HF facility 

      Rietveld, Michael T; Senior, Andrew; Markkanen, Jussi; Westman, Assar (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-22)
      The high-power HF (high-frequency) facility (commonly known as Heating) near Tromsø, Norway, which is an essential part of the European Incoherent Scatter Scientific Association, has been upgraded in certain key areas in recent years. It is one of only four similar facilities in the world operating at present. An updated description of the facility is given, together with scientific motivation and ...
    • The influence of a model subglacial lake on ice dynamics and internal layering 

      Gudlaugsson, Eythor; Humbert, Angelika; Kleiner, Thomas; Kohler, Jack; Andreassen, Karin (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-04-05)
      As ice flows over a subglacial lake, the drop in bed resistance leads to an increase in ice velocities and a draw down of isochrones and cold ice. The ice surface flattens as it adjusts to the lack of resisting forces at the base. The rapid transition in velocity induces changes in ice viscosity and releases deformation energy that can raise the temperature locally. Recent studies of Antarctic ...
    • Gender differences in the association between grip strength and mortality in older adults: results from the KORA-age study 

      Arvandi, Marjan; Strasser, Barbara; Meisinger, Christa; Volaklis, Konstantinos; Gothe, Raffaella Matteucci; Siebert, Uwe; Ladwig, Karl Heinz; Grill, Eva; Horsch, Alexander; Laxy, Michael; Peters, Annette; Thorand, Barbara (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-30)
      Background: Reduced muscular strength in the old age is strongly related to activity impairment and mortality. However, studies evaluating the gender-specific association between muscularity and mortality among older adults are lacking. Thus, the objective of the present study was to examine gender differences in the association between muscular strength and mortality in a prospective population-based ...
    • Characterization of a cold-active and salt tolerant esterase identified by functional screening of Arctic metagenomic libraries 

      De Santi, Concetta; Altermark, Bjørn; Pierechod, Marcin Miroslaw; Ambrosino, Luca; de Pascale, Donatella; Willassen, Nils Peder (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-19)
      Background: The use of metagenomics in enzyme discovery constitutes a powerful approach to access to genomes of unculturable community of microorganisms and isolate novel valuable biocatalysts for use in a wide range of biotechnological and pharmaceutical fields. Results: Here we present a novel esterase gene (lip3) identified by functional screening of three fosmid metagenomic libraries, ...
    • The structure of the metallo-β-lactamase VIM-2 in complex with a triazolylthioacetamide inhibitor 

      Christopeit, Tony; Yang, Ke-Wu; Yang, Shao-Kang; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11)
      The increasing number of pathogens expressing metallo-β-lactamases (MBLs), and in this way achieving resistance to β-lactam antibiotics, is a significant threat to global public health. A promising strategy to treat such resistant pathogens is the co-administration of MBL inhibitors together with β-lactam antibiotics. However, an MBL inhibitor suitable for clinical use has not yet been identified. ...
    • The Polarizable Continuum Model Goes Viral! Extensible, Modular and Sustainable Development of Quantum Mechanical Continuum Solvation Models 

      Di Remigio, Roberto (Doctoral thesis; Doktorgradsavhandling, 2017-01-16)
      Synergistic theoretical and experimental approaches to challenging chemical problems have become more and more widespread, due to the availability of efficient and accurate ab initio quantum chemical models. Limitations to such an approach do, however, still exist. The vast majority of chemical phenomena happens in complex environments, where the molecule of interest can interact with a large number ...
    • Demetalation of copper undecaarylcorroles: Molecular structures of a free-base undecaarylisocorrole and a gold undecaarylcorrole 

      Capar, Jan; Zonneveld, Job; Berg, Steffen; Isaksson, Johan; Gagnon, Kevin J.; Kolle, Ekaney Thomas; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-06-27)
      Copper undecaarylcorroles were found to undergo acid-induced demetalation with unusual ease under both reductive and nonreductive conditions. The resulting free-base undecaarylcorroles were found to be rather reactive, readily photooxygenating to yield 5/10-hydroxyisocorroles and open-chain tetrapyrroles. The use of nonreductive conditions led to 50-75% yields of undecaarylisocorroles, a new class ...
    • Spectral characteristics of instrumental and climate model surface temperatures 

      Fredriksen, Hege-Beate; Rypdal, Kristoffer (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-05)
      The spatiotemporal temperature variability for several gridded instrumental and general circulation climate model data is characterized, contrasting power spectra of local and global temperatures, land and sea temperatures, and temperatures of different regions. There is generally a high degree of agreement between the spectral characteristics of instrumental and climate model data. All but the ...
    • Early-warning signals for the onsets of Greenland interstadials and the younger dryas-preboreal transition 

      Rypdal, Martin wibe (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-20)
      The climate system approaches a tipping point if the prevailing climate state loses stability, making a transition to a different state possible. A result from the theory of randomly driven dynamical systems is that the reduced stability in the vicinity of a tipping point is accompanied by increasing fluctuation levels and longer correlation times (critical slowing down) and can in principle serve ...
    • On Data-Independent Properties for Density-Based Dissimilarity Measures in Hybrid Clustering 

      Møllersen, Kajsa; Dhar, Subhra; Godtliebsen, Fred (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-12)
      Hybrid clustering combines partitional and hierarchical clustering for computational effectiveness and versatility in cluster shape. In such clustering, a dissimilarity measure plays a crucial role in the hierarchical merging. The dissimilarity measure has great impact on the final clustering, and data-independent properties are needed to choose the right dissimilarity measure for the problem ...
    • Four-component relativistic density functional theory with the polarisable continuum model: application to EPR parameters and paramagnetic NMR shifts 

      Di Remigio, Roberto; Repisky, Michal; Komorovsky, Stanislav; Hrobárik, Peter; Frediani, Luca; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-01)
      The description of chemical phenomena in solution is as challenging as it is im- portant for the accurate calculation of molecular properties. Here, we present the implementation of the polarizable continuum model (PCM) in the four-component Dirac–Kohn–Sham density functional theory framework, o ↵ ering a cost-e ↵ ective way to concurrently model solvent and relativistic e ↵ ects. The ...
    • Indirect NMR spin-spin coupling constants in diatomic alkali halides 

      Jaszuński, Michał; Antušek, Andrej; Demissie, Taye Beyene; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-28)
      We report the Nuclear Magnetic Resonance (NMR) spin–spin coupling constants for diatomic alkali halides MX, where M = Li, Na, K, Rb, or Cs and X = F, Cl, Br, or I. The coupling constants are determined by supplementing the non-relativistic coupled-cluster singles-and-doubles (CCSD) values with relativistic corrections evaluated at the four-component density-functional theory (DFT) level. These ...
    • Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data 

      Singhroha, Sunny; Bünz, Stefan; Plaza-Faverola, Andreia; Chand, Shyam (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-09-23)
      We have estimated the seismic attenuation in gas hydrate and free-gas-bearing sediments from high-resolution P-cable 3D seismic data from the Vestnesa Ridge on the Arctic continental margin of Svalbard. P-cable data have a broad bandwidth (20–300 Hz), which is extremely advantageous in estimating seismic attenuation in a medium. The seismic quality factor (Q), the inverse of seismic attenuation, ...
    • Submarginal drumlin formation and late Holocene history of Fláajökull, southeast Iceland 

      Jónsson, Sverrir A.; Benediktsson, Ívar Örn; Ingólfsson, Ólafur; Schomacker, Anders; Bergsdóttir, Helga Lucia; Jacobson Jr., William R.; Linderson, Hans (Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
      Fláajökull is a non-surging outlet glacier draining the south-eastern part of the Vatnajökull, southeast Iceland. Fláajökull was stationary or advanced slightly between 1966 and 1995 and formed a prominent end moraine. Glacial retreat since then has revealed a cluster of 15 drumlins. This study focuses on the morphology and sedimentology of the drumlins. They are 100–600 m long, 40–130 m wide, and ...
    • Production of fluorescent dissolved organic matter in Arctic Ocean sediments 

      Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin (Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
      Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the ...
    • Arctic megaslide at presumed rest 

      Geissler, Wolfram H.; Gebhardt, Catalina; Gross, Felix; Wollenburg, Jutta; Jensen, Laura; Schmidt-Aursch, Mechita; Krastel, Sebastian; Elger, Judith; Osti, Giacomo (Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
      Slope failure like in the Hinlopen/Yermak Megaslide is one of the major geohazards in a changing Arctic environment. We analysed hydroacoustic and 2D high-resolution seismic data from the apparently intact continental slope immediately north of the Hinlopen/Yermak Megaslide for signs of past and future instabilities. Our new bathymetry and seismic data show clear evidence for incipient slope ...
    • Trends and variability of polar mesopause region temperatures attributed to atmospheric dynamics and solar activity 

      Holmen, Silje Eriksen (Doctoral thesis; Doktorgradsavhandling, 2016-12-19)
      The mesopause region can be considered a "boundary region" between the neutral atmosphere, where atmospheric constituents and momentum are transported mainly by winds and turbulent eddies, and the ionosphere, where the main transport mechanism is molecular diffusion. In the mesopause, complex interactions between dynamics and photochemistry occur, and we are far from a complete understanding of these ...
    • Freshwater ostracods (Crustacea) and environmental variability of polygon ponds in the tundra of the Indigirka Lowland, north-east Siberia 

      Schneider, Andrea; Wetterich, Sebastian; Schirrmeister, Lutz; Herzschuh, Ulrike; Meyer, Hanno; Pestryakova, Luidmila A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
      Freshwater ostracods (Crustacea, Ostracoda) are valuable biological indicators. In Arctic environments, their habitat conditions are barely known and the abundance and diversity of ostracods is documented only in scattered records with incomplete ecological characterization. To determine the taxonomic range of ostracod assemblages and their habitat conditions in polygon ponds in the Indigirka Lowland, ...
    • Mutational, structural and inhibitory investigations of metallo-β-lactamases involved in antibiotic resistance 

      Skagseth, Susann (Doctoral thesis; Doktorgradsavhandling, 2017-02-16)
      This thesis focuses on metallo-β-lactamases (MBLs) enzymes that break down a wide variety of antibiotics. Bacteria harboring genes expressing MBLs are antibiotic resistant. If the MBL genes are found on mobile genetic elements, the spread of the genes between bacteria becomes easier. To date, there are no MBL inhibitors available for blocking the enzyme activity, and thus there is an urgent need to ...