Nye registreringer

  • Change of the high-latitude ionosphere during heating by a powerful short radio wave of the EISCAT/Heating complex according to signals of the GLONASS satellite and the incoherent scattering radar 

    Tereshchenko, E. D.; Milichenko, A. N.; Rietveld, Michael T; Chernyakov, S. M.; Shvets, M. V. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018)
    Results of observations of variations of temperature, electron concentration and total electron content of the high-latitude region of the ionosphere during its modification by powerful short radio waves of the heating complex EISCAT/Heating (Tromsø, Norway) according to signals of the GLONASS satellites and the incoherent scattering UHF EISCAT radar (Tromsø, Norway) have been provided. The geometry ...
  • Methane bubbles in the Arctic Ocean. Quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere 

    Jansson, Pär (Doctoral thesis; Doktorgradsavhandling, 2018-11-09)
    Intensive but heterogeneous and transient seepage of methane (CH4) bubbles from the seafloor exist west of Prins Karls Forland (PKF), offshore western Svalbard. The powerful greenhouse gas CH4, has 32 times higher warming potential than carbon dioxide (CO2) and if seepage of CH4 from the seafloor reaches the atmosphere, it will contribute to the warming climate. Warming of the oceans may in turn, ...
  • Insight into the fluorescence quenching of Trp214 at HSA by the Dimetridazole ligand from simulation 

    Pomogaev, Valdimir A; Ramazanov, Ruslan R; Ruud, Kenneth; Artyukhov, Victor Ya (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-08-24)
    Spectroscopy is an important tool for detecting drug binding to amino acid sequences. One such important spectroscopic process is the fluorescence quenching due to charge transfer (CT) processes between a drug molecule and the chromophore center of Human Serum Albumin (HSA). We present a theoretical investigation of the CT occurring upon electronic excitation when a dimetridazole (Dmz) molecule ...
  • Design and development of a context-aware knowledge-based module for identifying relevant information and information gaps in patients with type 1 diabetes self-collected health data 

    Giordanengo, Alain; Øzturk, Pinar; Hansen, Anne Helen; Årsand, Eirik; Grøttland, Astrid; Hartvigsen, Gunnar (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-11)
    <p><i>Background</i>: Patients with diabetes use an increasing number of self-management tools in their daily life. However, health institutions rarely use the data generated by these services mainly due to (1) the lack of data reliability, and (2) medical workers spending too much time extracting relevant information from the vast amount of data produced. This work is part of the FullFlow project, ...
  • Exceptionally simple PDE 

    The, Dennis (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-08)
    We give local descriptions of parabolic contact structures and show how their flat models yield explicit PDE having symmetry algebras isomorphic to all complex simple Lie algebras except <math><msub is="true"><mrow is="true"><mi mathvariant="fraktur" is="true">sl</mi></mrow><mrow is="true"><mn is="true">2</mn></mrow></msub></math>. This yields a remarkably uniform generalization of the Cartan–Engel ...
  • Spreading of drill cuttings and sediment recovery of three exploration wells of different ages, SW Barents Sea, Norway 

    Junttila, Juho; Dijkstra, Noortje; Sørensen, Steffen Aagaard (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-14)
    Five stations (≤250 m from the well heads) from three exploration wells of different ages from the SW Barents Sea were studied to investigate the spreading of drill cuttings and sediment quality. Two of the wells were drilled before the restriction of use of oil-based drilling fluids (1993). Elevated concentrations of Ba were found in sediments near all the wells with the highest concentrations ...
  • Iron‐Catalyzed Carbenoid Transfer Reactions of Vinyl Sulfoxonium Ylides: An Experimental and Computational Study 

    Vaitla, Janakiram; Bayer, Annette; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-15)
    A method for the generation of unprecedented vinyl carbenoids from sulfoxonium ylides has been developed and applied in the synthesis of a diverse array of heterocycles such as indolizines, pyrroles, 3‐pyrrolin‐2‐ones, and furans. The reactions proceed by FeBr<sub>2</sub> catalysis under mild reaction conditions with a broad substrate scope. A reaction pathway involving iron carbenoids is proposed ...
  • Ionospheric Response Observed by EISCAT During the 6–8 September 2017 Space Weather Event: Overview 

    Yamauchi, M; Sergiengko, Timothy; Enell, Carl-Fredrik; Schillings, A.; Slapak, R.; Johnsen, Magnar Gullikstad; Tjulin, A.; Nilsson, H. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-03)
    We present ionospheric plasma conditions observed by the EISCAT radars in Tromsø and on Svalbard, covering 68°–81° geomagnetic latitude, during 6–8 September 2017. This is a period when X2.2 and X9.3 X‐ray flares occurred, two interplanetary coronal mass ejections (ICMEs) arrived at the Earth accompanied by enhancements of MeV‐range energetic particle flux in both the solar wind (SEP event) and inner ...
  • Rhodium-Catalyzed Hydrocarboxylation: Mechanistic Analysis Reveals Unusual Transition State for Carbon–Carbon Bond Formation 

    Pavlovic, Ljiljana; Vaitla, Janakiram; Bayer, Annette; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-12)
    The mechanism of rhodium-COD-catalyzed hydrocarboxylation of styrene derivatives and α,β-unsaturated carbonyl compounds with CO<sub>2</sub> has been investigated using density functional theory (PBE-D2/IEFPCM). The calculations support a catalytic cycle as originally proposed by Mikami and co-workers including β-hydride elimination, insertion of the unsaturated substrate into a rhodium–hydride bond, ...
  • Mutational analysis of the pro-peptide of a marine intracellular subtilisin protease supports its role in inhibition 

    Bjerga, Gro Elin Kjæreng; Larsen, Øivind; ARSIN, Hasan; Williamson, Adele Kim; Garcia-Moyano, Antonio; Leiros, Ingar; Puntervoll, Pål (Journal article; Tidsskriftartikkel; Preprint; Manuskript, 2018-06-16)
    Intracellular subtilisin proteases (ISPs) have important roles in protein processing during the stationary phase in bacteria. Their unregulated protein degrading activity may have adverse effects inside a cell, but little is known about their regulatory mechanism. Until now, ISPs have mostly been described from <i>Bacillus</i> species, with structural data from a single homolog. Here, we study a ...
  • Cordilleran ice-sheet growth fueled primary productivity in the Gulf of Alaska, northeast Pacific Ocean 

    Müller, Juliane; Romero, Oscar; Cowan, Ellen A.; McClymont, Erin L.; Forwick, Matthias; Asahi, Hirofumi; März, Christian; Moy, Christopher M.; Suto, Itsuki; Mix, Alan; Stoner, Joseph (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-02-15)
    Fertilization of the ocean by eolian dust and icebergs is an effective mechanism to enhance primary productivity. In particular, high-nutrient, low-chlorophyll (HNLC) areas where phytoplankton growth is critically iron-limited, such as the subarctic Pacific Ocean and the Southern Ocean, are proposed to respond to increases in bioavailable Fe supply with enhanced phytoplankton productivity and carbon ...
  • First Observations of Recurring HF-Enhanced Topside Ion Line Spectra Near the Fourth Gyroharmonic 

    Rexer, Theresa; Gustavsson, Björn Johan; Leyser, Thomas; Rietveld, Michael T; Yeoman, Tim; Grydeland, Tom (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-28)
    We present first incoherent scatter radar observations of systematically recurring, high‐frequency (HF)‐enhanced ion line spectra at the topside F‐region ionosphere, during magnetic field aligned HF pumping in an O‐mode polarization. The European Incoherent Scatter UHF radar was directed in magnetic zenith on 9–11 March 2016 while stepping the pump frequency across the double resonance of the fourth ...
  • Area and volume of mid-latitude glacier-like forms on Mars 

    Brough, Stephen; Hubbard, Bryn; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-04)
    Although a substantial ice cover has been identified within the mid-latitudes of Mars, there is uncertainty regarding the formation, current and former volume, and dynamic evolution of these ice masses. Here, we present the first comprehensive ice volume estimate of martian glacier-like forms (GLFs) from systematic population scale mapping and volumetric analysis. The outlines of 1243 GLFs were ...
  • Holocene development of subarctic permafrost peatlands in Finnmark, northern Norway 

    Kjellman, Sofia E.; Axelsson, Pia E.; Etzelmüller, Bernd; Westermann, Sebastian; Sannel, A. Britta K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-01)
    Subarctic permafrost peatlands are important soil organic carbon pools, and improved knowledge about peat properties and peatland sensitivity to past climate change is essential when predicting future response to a warmer climate and associated feedback mechanisms. In this study, Holocene peatland development and permafrost dynamics of four subarctic peat plateaus in Finnmark, northern Norway have ...
  • EISCAT Observation of Wave‐Like Fluctuations in Vertical Velocity of Polar Mesospheric Summer Echoes Associated With a Geomagnetic Disturbance 

    Lee, Young-Sook; Kim, Young Ha; Kim, Kyung-Chan; Kwak, Young-Sil; Sergiengko, Timothy; Kirkwood, Sheila; Johnsen, Magnar Gullikstad (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-04)
    By analyzing a data set from the European Incoherent SCATter (EISCAT) Very High Frequency (VHF) radar at Tromsø, we find that both radar reflectivity and upward ion velocity in a polar mesospheric summer echo (PMSE) layer simultaneously increased at the commencement of a local geomagnetic disturbance, which occurred at midnight on 9 July 2013. The onset of the upward velocity was followed by periodic ...
  • Early to middle Cenozoic paleoenvironment and erosion estimates of the southwestern Barents Sea: Insights from a regional mass-balance approach 

    Lasabuda, Amando Putra Ersaid; Laberg, Jan Sverre; Knutsen, Stig-Morten; Høgseth, Gert (Journal article; Tidsskriftartikkel; Manuskript, 2018-06-02)
    The Cenozoic pre-glacial development of the southwestern Barents Sea is discussed, with focus on the early to middle Cenozoic net erosion that was poorly constrained. From 2D and 3D seismic mapping, the western Barents Sea continental margin development shows a complex history of structural configuration of highs and basins related to the Greenland and Eurasian plate movement and subsequent seafloor ...
  • Evaluating CM-SAF solar radiation CLARA-A1 and CLARA-A2 datasets in Scandinavia 

    Babar, Bilal; Graversen, Rune; Boström, Tobias (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-26)
    Estimating/retrieving solar radiation through satellite-based remote sensing provides larger spatial coverage compared to other methods. Accurate estimates of incoming solar radiation is important when planning new solar energy installations. In addition, these estimates are also used in climate studies. Geostationary satellites are ideal for estimating solar radiation but cannot be used for high ...
  • Biochemical characterization of ParI, an orphan C5-DNA methyltransferase from Psychrobacter arcticus 273-4 

    Grgic, Miriam; Williamson, Adele Kim; Bjerga, Gro Elin Kjæreng; Altermark, Bjørn; Leiros, Ingar (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-25)
    <p>Cytosine-specific DNA methyltransferases are important enzymes in most living organisms. In prokaryotes, most DNA methyltransferases are members of the type II restriction-modification system where they methylate host DNA, thereby protecting it from digestion by the accompanying restriction endonucleases. DNA methyltransferases can also act as solitary enzymes having important roles in controlling ...
  • Biogeochemical evidence of anaerobic methane oxidation on active submarine mud volcanoes on the continental slope of the Canadian Beaufort Sea 

    Lee, Dong-Hun; Kim, Jung-Hyun; Lee, Yung Mi; Stadnitskaia, Alina; Jin, Young Keun; Niemann, Helge; Kim, Young-Gyun; Shin, Kyung-Hoon (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-20)
    In this study, we report lipid biomarker patterns and phylogenetic identities of key microbial communities mediating anaerobic oxidation of methane (AOM) in active mud volcanoes (MVs) on the continental slope of the Canadian Beaufort Sea. The carbon isotopic compositions (δ13C) of sn-2- and sn-3-hydroxyarchaeol showed the highly 13C-depleted values (−114 ‰ to −82 ‰) associated with a steep depletion ...
  • The effect of vertical mixing on the horizontal drift of oil spills 

    Röhrs, Johannes; Dagestad, Knut-Frode; Asbjørnsen, Helene; Nordam, Tor; Skancke, Jørgen; Jones, Cathleen; Brekke, Camilla (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-21)
    Vertical and horizontal transport mechanisms for marine oil spills are investigated using numerical model simulations. To realistically resolve the 3-D development of a spill on the ocean surface and in the water column, recently published parameterizations for the vertical mixing of oil spills are implemented in the open-source trajectory framework OpenDrift (https://doi.org/10.5281/zenodo.1300358, ...

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