Viser treff 3721-3740 av 5327

    • Evaluation of a method to derive ionospheric conductivities using two auroral emissions (428 and 630 nm) measured with a photometer at Tromsø (69.6°N) 

      Adachi, K; Nozawa, Satonori; Ogawa, Y; Brekke, Asgeir; Hall, Chris; Fujii, Ryochi (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-03)
      This paper mainly aims at evaluating capabilities of derivation of ionospheric conductivities using two principal auroral emissions (427.8 and 630 nm). We have evaluated a photometric method of derivation of ionospheric conductivities based on simultaneous observations of a photometer (feld of view = ~1.2°), a digital camera, and the EISCAT UHF radar (feld of view = ~0.7°) operated at Tromsø, ...
    • Prospecting biotechnologically-relevant monooxygenases from cold sediment metagenomes: An in silico approach 

      Musumeci, Matias A.; Lozada, Mariana; Rial, Daniela V.; Cormack, Walter P. Mac; Jansson, Janet K.; Sjöling, Sara; Carroll, JoLynn; Dionisi, Hebe M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-09)
      The goal of this work was to identify sequences encoding monooxygenase biocatalysts with novel features by in silico mining an assembled metagenomic dataset of polar and subpolar marine sediments. The targeted enzyme sequences were Baeyer–Villiger and bacterial cytochrome P450 monooxygenases (CYP153). These enzymes have wide-ranging applications, from the synthesis of steroids, antibiotics, mycotoxins ...
    • Labilibaculum manganireducens gen. nov., sp. nov. and Labilibaculum filiforme sp. nov., Novel Bacteroidetes Isolated from Subsurface Sediments of the Baltic Sea 

      Vandieken, Verona; Marshall, Ian P.G.; Niemann, Helge; Engelen, Bert; Cypionka, Heribert (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-05)
      Microbial communities in deep subsurface sediments are challenged by the decrease in amount and quality of organic substrates with depth. In sediments of the Baltic Sea, they might additionally have to cope with an increase in salinity from ions that have diffused downward from the overlying water during the last 9000 years. Here, we report the isolation and characterization of four novel bacteria ...
    • Classification of low backscatter ocean regions using log-cumulants 

      Skrunes, Stine; Brekke, Camilla (Conference object; Konferansebidrag, 2015-01)
      In a synthetic aperture radar image, low backscatter regions of various origin can be observed in ocean areas. Operational oil spill detection services work to discriminate anthropogenic oil spills from natural phenomena such as seeps, low wind fields, thin ice and biogenic slicks. In this paper, we investigate the potential of using matrix log-cumulants for this purpose.
    • Stochastic modeling of scrape-off layer fluctuations 

      Kube, Ralph; Theodorsen, Audun; Garcia, Odd Erik; Brunner, Daniel; Kuang, Adam; LaBombard, Brian; Terry, James L. (Conference object; Konferansebidrag, 2017-08-24)
      1. Stochastic model of data time series <br> 2. Comparison to experimental measurements
    • Metallo-β-lactamase inhibitors by bioisosteric replacement: preparation, activity and binding 

      Skagseth, Susann; Akhter, Sundus; Paulsen, Marianne H; Muhammad, Zeeshan; Samuelsen, Ørjan; Leiros, Hanna-Kirsti S.; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-14)
      Bacterial resistance is compromising the use of β-lactam antibiotics including carbapenems. The main resistance mechanism against β-lactams is hydrolysis of the β-lactam ring mediated by serine- or metallo-β-lactamases (MBLs). Although several inhibitors of MBLs have been reported, none has been developed into a clinically useful inhibitor. Mercaptocarboxylic acids are among the most prominent ...
    • Dark zone of the Greenland Ice Sheet controlled by distributed biologically-active impurities 

      Ryan, Jonathan C.; Hubbard, Alun Lloyd; Stibal, Marek; Irvine-Fynn, Tristam D.; Cook, Joseph; Smith, Lawrence C.; Cameron, Karen; Box, Jason E (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-14)
      Albedo—a primary control on surface melt—varies considerably across the Greenland Ice Sheet yet the specific surface types that comprise its dark zone remain unquantified. Here we use UAV imagery to attribute seven distinct surface types to observed albedo along a 25 km transect dissecting the western, ablating sector of the ice sheet. Our results demonstrate that distributed surface impurities—an ...
    • Temperature and thermal emission of cosmic dust in the vicinity of the Sun, Vega and Fomalhaut. 

      Myrvang, Margaretha; Baumann, Carsten; Mann, Ingrid; Stamm, Johann Immanuel (Conference object; Konferansebidrag, 2018)
    • Dynamics of Dust Particles near Sun, Vega and Fomalhaut 

      Stamm, Johann Immanuel; Baumann, Carsten; Czechowski, Andrzej; Mann, Ingrid; Myrvang, Margaretha (Conference object; Konferansebidrag, 2018)
    • Effects of low oxygen concentrations on aerobic methane oxidation in seasonally hypoxic coastal waters 

      Steinle, Lea; Maltby, Johanna; Treude, Tina; Kock, Annette; Bange, Hermann W.; Engbersen, Nadine; Zopfi, Jakob; Lehmann, Moritz F.; Niemann, Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-29)
      Coastal seas may account for more than 75 % of global oceanic methane emissions. There, methane is mainly produced microbially in anoxic sediments from which it can escape to the overlying water column. Aerobic methane oxidation (MOx) in the water column acts as a biological filter, reducing the amount of methane that eventually evades to the atmosphere. The efficiency of the MOx filter is potentially ...
    • Pulsating aurora and cosmic noise absorption associated with growth-phase arcs 

      McKay, Derek; Partamies, Noora; Vierinen, Juha (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-18)
      The initial stage of a magnetospheric substorm is the growth phase, which typically lasts 1–2 h. During the growth phase, an equatorward moving, east–west extended, optical auroral arc is observed. This is called a growth-phase arc. This work aims to characterize the optical emission and riometer absorption signatures associated with growth-phase arcs of isolated substorms. This is done using ...
    • Non-triggered auroral substorms and long-period (1–4 mHz) geomagnetic and auroral luminosity pulsations in the polar cap 

      Yagova, Nadezda; Nosikova, Natalia; Baddeley, Lisa; Kozyreva, Olga; Lorentzen, Dag A.; Pilipenko, Vyacheslav; Johnsen, Magnar G. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-08)
      A study is undertaken into parameters of the polar auroral and geomagnetic pulsations in the frequency range 1– 4 mHz (Pc5/Pi3) during quiet geomagnetic intervals preceding auroral substorms and non-substorm background variations. Special attention is paid to substorms that occur under parameters of the interplanetary magnetic field (IMF) conditions typical for undisturbed days (“non-triggered ...
    • The red-sky enigma over Svalbard in December 2002 

      Sigernes, F.; Lloyd, N.; Hoppe, U.-P.; Degenstein, D.; Shumilov, N.; Moen, J.; Gjessing, Y.; Havnes, O.; Skartveit, A.; Raustein, E.; Ørbæk, J.B.; Deehr, CS (Journal article; Tidsskriftartikkel; Peer reviewed, 2005-07-27)
      On 6 December 2002, during winter darkness, an extraordinary event occurred in the sky, as viewed from Longyearbyen (78° N, 15° E), Svalbard, Norway. At 07:30 UT the southeast sky was surprisingly lit up in a deep red colour. The light increased in intensity and spread out across the sky, and at 10:00 UT the illumination was observed to reach the zenith. The event died out at about 12:30 UT. Spectral ...
    • Privacy preserving distributed computation of community health research data 

      Andersen, Anders; Saus, Merete (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-19)
      Research in community health introduces challenges regarding analysis of the research data. It involves multiple actors in a varity of arenas, and it is often directed towards the local community and children and their families. The legal, ethical and privacy issues involved introduce constraints upon the analysis performed. SNOOP combined with the D2Worm declarative modelling and infrastructure ...
    • Algal hot spots in a changing Arctic Ocean: Sea-ice ridges and the snow-ice interface 

      Fernández-Méndez, Mar; Olsen, Lasse Mork; Kauko, Hanna M.; Meyer, Amelie; Rösel, Anja; Merkouriadi, Ioanna; Mundy, Christopher John; Ehn, Jens K.; Johansson, Malin; Wagner, Penelope Mae; Ervik, Åse; Sorrell, BK; Duarte, Pedro; Wold, Anette; Hop, Haakon; Assmy, Phillipp (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-12)
      During the N-ICE2015 drift expedition north-west of Svalbard, we observed the establishment and development of algal communities in first-year ice (FYI) ridges and at the snow-ice interface. Despite some indications of being hot spots for biological activity, ridges are under-studied largely because they are complex structures that are difficult to sample. Snow infiltration communities can grow at ...
    • A method to improve high-resolution sea ice drift retrievals in the presence of deformation zones 

      Griebel, Jakob; Dierking, Wolfgang Fritz Otto (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-12)
      Retrievals of sea ice drift from synthetic aperture radar (SAR) images at high spatial resolution are valuable for understanding kinematic behavior and deformation processes of the ice at different spatial scales. Ice deformation causes temporal changes in patterns observed in sequences of SAR images; which makes it difficult to retrieve ice displacement with algorithms based on correlation and ...
    • Object-based detection of linear kinematic features in sea ice 

      Linow, Stefanie; Dierking, Wolfgang Fritz Otto (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-18)
      Inhomogenities in the sea ice motion field cause deformation zones, such as leads, cracks and pressure ridges. Due to their long and often narrow shape, those structures are referred to as Linear Kinematic Features (LKFs). In this paper we specifically address the identification and characterization of variations and discontinuities in the spatial distribution of the total deformation, which ...
    • Comparing SAR based short time-lag cross-correlation and Doppler derived sea ice drift velocities 

      Kræmer, Thomas; Johnsen, Harald; Brekke, Camilla; Engen, Geir (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-23)
      This paper shows initial results from estimating Doppler radial surface velocities (RVLs) over Arctic sea ice using the Sentinel-1A (S1A) satellite. Our study presents the first quantitative comparison between ice drift derived from the Doppler shifts and drift derived using time-series methods over comparable time scales. We compare the Doppler-derived ice velocities with global positioning system ...
    • Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming 

      Wallmann, Klaus; Riedel, M.; Hong, Wei-Li; Patton, Henry; Hubbard, Alun Lloyd; Pape, T.; Hsu, C.W.; Schmidt, C.; Johnson, Joel E.; Torres, M.E.; Andreassen, Karin; Berndt, C.; Bohrmann, G (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-08)
      Methane seepage from the upper continental slopes of Western Svalbard has previously been attributed to gas hydrate dissociation induced by anthropogenic warming of ambient bottom waters. Here we show that sediment cores drilled off Prins Karls Foreland contain freshwater from dissociating hydrates. However, our modeling indicates that the observed pore water freshening began around 8 ka BP when ...
    • Middle to Late Devonian–Carboniferous collapse basins on the Finnmark Platform and in the southwesternmost Nordkapp basin, SW Barents Sea 

      Koehl, Jean-Baptiste; Bergh, Steffen G; Henningsen, Tormod; Faleide, Jan Inge (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-28)
      The SW Barents Sea margin experienced a pulse of extensional deformation in the Middle–Late Devonian through the Carboniferous, after the Caledonian Orogeny terminated. These events marked the initial stages of formation of major offshore basins such as the Hammerfest and Nordkapp basins. We mapped and analyzed three major fault complexes, (i) the Måsøy Fault Complex, (ii) the Rolvsøya fault, and ...