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    • The crystal structure of haemoglobin from Atlantic cod 

      Helland, Ronny; Bjørkeng, Eva katrin; Rothweiler, Ulli; Sydnes, Magne Olav; Pampanin, Daniela Maria (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-16)
      The crystal structure of haemoglobin from Atlantic cod has been solved to 2.54 A˚ resolution. The structure consists of two tetramers in the crystallographic asymmetric unit. The structure of haemoglobin obtained from one individual cod suggests polymorphism in the tetrameric assembly.
    • Lessons learned from accident and near-accident experiences in traffic 

      Terum, Jens Andreas; Svartdal, Frode (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-17)
      The focus of this article is risky behavior in traffic. What do people learn from accidents and near-accidents? Experience with accidents may demand increased caution. However, near-accidents are inherently ambiguous: On the one hand, they signal that margins were good enough, inspiring increased risk-taking; on the other hand, they signal danger that could induce increased caution. To explore these ...
    • Reduced methane seepage from Arctic sediments during cold bottom-water conditions 

      Ferré, Benedicte; Jansson, Pär; Moser, Manuel; Serov, Pavel; Portnov, Aleksei D; Graves, Carolyn; Panieri, Giuliana; Gründger, Friederike; Berndt, Christian; Lehmann, Moritz F.; Niemann, Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-13)
      Large amounts of methane are trapped within gas hydrate in subseabed sediments in the Arctic Ocean, and bottom-water warming may induce the release of methane from the seafloor. Yet the effect of seasonal temperature variations on methane seepage activity remains unknown as surveys in Arctic seas are conducted mainly in summer. Here we compare the activity of cold seeps along the gas hydrate stability ...
    • Holocene environmental changes in Dicksonfjorden, west Spitsbergen, Svalbard 

      Joo, Young Ji; Forwick, Matthias; Park, Kwangkyu; Joe, Youngjin; Son, Yeong Ju; Nam, Seung-Il (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-26)
      Multi-proxy analyses of two sediment cores from Dicksonfjorden were performed to reconstruct Holocene environmental conditions in this northern branch of Isfjorden, the largest fjord system in Svalbard. Factors affecting the depositional processes include shifts in sources of sediments, ice rafting and regional glacio-isostatic rebound. Sediments were derived from Palaeozoic siliciclastics ...
    • Novel strategies for super-resolution fluorescence microscopy 

      Lahrberg, Marcel (Doctoral thesis; Doktorgradsavhandling, 2019-12-11)
      <p>Minimally invasive technologies to characterize the structure and functionality of biological samples on the cellular and molecular scale are fundamental to life sciences. Optical fluorescence imaging at visible wavelengths is able to acquire to do so. Due to the wavelike nature of light the maximum achievable resolution in conventional microscopy is limited by diffraction, about half the wavelength ...
    • Plasma fluctuations in the scrape-off layer and at the divertor target in Alcator C-Mod and their relationship to divertor collisionality and density shoulder formation 

      Kuang, AQ; LaBombard, Brian; Brunner, D; Garcia, Odd Erik; Kube, Ralph; Theodorsen, Audun (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-15)
      Experiments indicate that the formation of density shoulders in the far scrape-off layer (SOL) is associated with an increase in cross-field transport and the propagation of coherent structures of high density known as blobs. It has been suggested that far SOL divertor collisionality (Λ<sub>div</sub>) may be a controlling parameter in this physics, which could be challenging for heat flux mitigation ...
    • Super-condenser enables labelfree nanoscopy 

      Ströhl, Florian; Opstad, Ida Sundvor; Tinguely, Jean-Claude; Dullo, Firehun Tsige; Mela, Ioanna; Osterrieth, Johannes W.M; Ahluwalia, Balpreet Singh; Kaminski, Clemens F. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-22)
      Labelfree nanoscopy encompasses optical imaging with resolution in the 100 nm range using visible wavelengths. Here, we present a labelfree nanoscopy method that combines coherent imaging techniques with waveguide microscopy to realize a <i>super-condenser</i> featuring maximally inclined coherent darkfield illumination with artificially stretched wave vectors due to large refractive indices of the ...
    • Warming trends and long-range dependent climate variability since year 1900: A Bayesian approach 

      Myrvoll-Nilsen, Eirik; Fredriksen, Hege-Beate; Sørbye, Sigrunn Holbek; Rypdal, Martin wibe (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-21)
      Temporal persistence in unforced climate variability makes detection of trends in surface temperature difficult. Part of the challenge is methodological since standard techniques assume a separation of time scales between trend and noise. In this work we present a novel Bayesian approach to trend detection under the assumption of long-range dependent natural variability, and we use estimates of ...
    • An Optimal Decision-Tree Design Strategy and Its Application to Sea Ice Classification from SAR Imagery 

      Lohse, Johannes; Doulgeris, Anthony Paul; Dierking, Wolfgang Fritz Otto (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-03)
      We introduce the fully automatic design of a numerically optimized decision-tree algorithm and demonstrate its application to sea ice classification from SAR data. In the decision tree, an initial multi-class classification problem is split up into a sequence of binary problems. Each branch of the tree separates one single class from all other remaining classes, using a class-specific selected feature ...
    • OptiJ: Open-source optical projection tomography of large organ samples 

      Vallejo Ramirez, Pedro P.; Zammit, Joseph; Vanderpoorten, Oliver; Fergus, Riche; Blé, Francois-Xavier; Zhou, Xiao-Hong; Spiridon, Bogdan; Valentine, Christopher; Spasov, Simeon E.; Oluwasanya, Pelumi W.; Goodfellow, Gemma; Fantham, Marcus J.; Siddiqui, Omid; Alimagham, Farah; Robbins, Miranda; Stretton, Andrew; Simatos, Dimitrios; Hadeler, Oliver; Rees, Eric J.; Ströhl, Florian; Laine, Romain F.; Kaminski, Clemens F. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-30)
      The three-dimensional imaging of mesoscopic samples with Optical Projection Tomography (OPT) has become a powerful tool for biomedical phenotyping studies. OPT uses visible light to visualize the 3D morphology of large transparent samples. To enable a wider application of OPT, we present OptiJ, a low-cost, fully open-source OPT system capable of imaging large transparent specimens up to 13 mm tall ...
    • On derivatives of smooth functions represented in multiwavelet bases 

      Anderson, Joel; Harrison, Robert J.; Sekino, Hideo; Sundahl, Bryan; Beylkin, Gregory; Fann, George I.; Jensen, Stig Rune; Sagert, Irina (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-24)
      We construct high-order derivative operators for smooth functions represented via discontinuous multiwavelet bases. The need for such operators arises in order to avoid artifacts when computing functionals involving high-order derivatives of solutions of integral equations. Previously high-order derivatives had to be formed by repeated application of a first-derivative operator that, while uniquely ...
    • Ice‐margin retreat and grounding‐zone dynamics during initial deglaciation of the Storfjordrenna Ice Stream, western Barents Sea 

      Shackleton, Calvin; Winsborrow, Monica; Andreassen, Karin; Lucchi, Renata Giulia; Bjarnadóttir, Lilja Rún (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-11)
      Processes occurring at the grounding zone of marine terminating ice streams are crucial to marginal stability, influencing ice discharge over the grounding‐line, and thereby regulating ice‐sheet mass balance. We present new marine geophysical data sets over a ~30×40 km area from a former ice‐stream grounding zone in Storfjordrenna, a large cross‐shelf trough in the western Barents Sea, south of ...
    • Use of simulator training to mitigate risks in arctic shipping operations 

      Røds, Johan-Fredrik; Gudmestad, Ove Tobias (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06)
      Over the recent years, ship traffic in the polar areas has increased. There is reason to believe that this traffic, and especially the cruise traffic, will increase further as the ice retracts towards the poles. There is also reason to believe that with the continued focus and exposure of the Polar Region, the cruise tourism to the region will grow. The increased presence in the polar areas will ...
    • Developing a New Machine-Learning Algorithm for Estimating Chlorophyll-a Concentration in Optically Complex Waters: A Case Study for High Northern Latitude Waters by Using Sentinel 3 OLCI 

      Blix, Katalin; Li, Juan; Massicotte, Philippe; Matsuoka, Atsushi (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-04)
      The monitoring of Chlorophyll-a (Chl-a) concentration in high northern latitude waters has been receiving increased focus due to the rapid environmental changes in the sub-Arctic, Arctic. Spaceborne optical instruments allow the continuous monitoring of the occurrence, distribution, and amount of Chl-a. In recent years, the Ocean and Land Color Instruments (OLCI) onboard the Sentinel 3 (S3) A and B ...
    • Assessment of the RISAT-1 FRS-2 Mode for Oil Spill Observation 

      Skrunes, Stine; Brekke, Camilla; Espeseth, Martine M. (Peer reviewed; Chapter, 2017-12-04)
      Synthetic aperture radar data acquired by the Radar Imaging Satellite (RISAT-1) over experimental oil spills is here investigated. One quad-polarization scene in the Fine Resolution Alternate Polarization Stripmap (FRS-2) mode is analyzed to evaluate the potential of using this mode for oil spill observation.<br> Oil slicks of varying type and age are clearly detected in the HH and VV channels, with ...
    • Investigating the effect of class-imbalance on convolutional neural networks for angiodysplasia detection 

      Kaspersen, Oskar Anstein (Master thesis; Mastergradsoppgave, 2019-10-31)
      In this thesis, we look at a deep learning approach to AD detection and focus specifically on the problem of class imbalance, which arises from the fact that lesions only occupy a small part of the images, by analyzing how weighting of the loss function can help address this issue. Balancing the weights of the foreground and background class in the cost-function was found to be crucial to achieve ...
    • Evolution of contourite drifts in regions of slope failures at eastern Fram Strait 

      Osti, Giacomo; Waghorn, Kate Alyse; Waage, Malin; Plaza-Faverola, Andreia; Ferré, Benedicte (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-15)
      Geotechnical characteristics of contouritic deposition often lead to preconditioning slope instabilities and failures along glaciated and formerly glaciated continental margins.<br> However, internal depositional geometry is also an important factor in triggering instabilities. This work highlights the importance of the tectonic and oceanographic evolution of the Northwestern (NW) Svalbard margin ...
    • The effects of terlipressin and direct portacaval shunting on liver hemodynamics following 80% hepatectomy in the pig 

      Hammond, John S.; Godtliebsen, Fred; Steigen, Sonja Eriksson; Guha, I. Neil; Wyatt, Judy; Revhaug, Arthur; Lobo, Dileep N.; Mortensen, Kim Erlend (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-15)
      Liver failure is the major cause of death following liver resection. Post-resection portal venous pressure (PVP) predicts liver failure, is implicated in its pathogenesis, and when PVP is reduced, rates of liver dysfunction decrease. The aim of the present study was to characterize the hemodynamic, biochemical, and histological changes induced by 80% hepatectomy in non-cirrhotic pigs and determine ...
    • Dust observations with antenna measurements and its prospects for observations with Parker Solar Probe and Solar Orbiter 

      Mann, Ingrid; Nouzak, Libor; Vaverka, Jakub; Antonsen, Tarjei; Fredriksen, Åshild; Issautier, Karine; Malaspina, David; Meyer-Vernet, Nicole; Pavlu, Jiri; Sternovsky, Zoltan; Stude, Joan; Ye, Shengyi; Zaslavsky, Arnaud (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-10)
      The electric and magnetic field instrument suite FIELDS on board the NASA Parker Solar Probe and the radio and plasma waves instrument RPW on the ESA Solar Orbiter mission that explore the inner heliosphere are sensitive to signals generated by dust impacts. Dust impacts have been observed using electric field antennas on spacecraft since the 1980s and the method was recently used with a number of ...
    • Understanding Cassini RPWS Antenna Signals Triggered by Dust Impacts 

      Ye, Shengyi; Vaverka, Jakub; Nouzak, Libor; Sternovsky, Zoltan; Zaslavsky, Arnaud; Mann, Ingrid; Hsu, H-W.; Averkamp, Terrance, F.; Sulaiman, AH; Pisa, D.; Hospodarsky, G. B.; Kurth, W.S.; Horanyi, M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-04)
      Electric field antennas are capable of detecting dust impacts in different space environment. We analyze the dust impact signals detected by the Cassini Radio and Plasma Wave Science instrument at different locations around Saturn and compare them with dust impact signals simulated in laboratory conditions and numerically. The spacecraft potential, the size, and capacitance of the impacted element ...