Fakultet for naturvitenskap og teknologi: Nye registreringer
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Impact of Arctic shelf summer stratification on Holocene climate variability
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-21)Understanding the dynamic of freshwater and sea-ice export from the Arctic is crucial to better comprehend the potential near-future climate change consequences. Here, we report nitrogen isotope data of a core from the Laptev Sea to shed light on the impact of the Holocene Siberian transgression on the summer stratification of the Laptev Sea. Our data suggest that the oceanographic setting was ... -
High-resolution landform assemblage along a buried glacio-erosive surface in the SW Barents Sea revealed by P-Cable 3D seismic data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-01)The Quaternary sedimentary record in the Arctic captures a diverse and evolving range of landscapes reflecting cli-mate changes. Here we study the geological landform assemblage of the Upper Regional Unconformity (URU) in theSW Barents Sea. The aims are (i) to characterize buried geological landforms on a meter-scale resolution, (ii) to un-derstand their link with underlying structures, and (iii) ... -
Deglacial dynamics of the Vestfjorden - Trænadjupet palaeo-ice stream, northern Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-18)Few well‐dated records of the deglacial dynamics of the large palaeo‐ice streams of the major Northern Hemisphere ice sheets are presently available, a prerequisite for an improved understanding of the ice‐sheet response to the climate warming of this period. Here we present a transect of gravity‐core samples through Trænadjupet and Vestfjorden, northern Norway, the location of the Trænadjupet – ... -
Non-Oberbeck-Boussinesq zonal flow generation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-26)Novel mechanisms for zonal flow (ZF) generation for both large relative density fluctuations and background density gradients are presented. In this non-Oberbeck–Boussinesq (NOB) regime ZFs are driven by the Favre stress, the large fluctuation extension of the Reynolds stress, and by background density gradient and radial particle flux dominated terms. Simulations of a nonlinear full-F gyro-fluid ... -
Reply to 'Challenges with dating weathering products to unravel ancient landscapes'
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-15)<i>Introduction</i>: As the title of the correspondence by Fossen et al.1 suggests, determining the age of landscape elements of the Earth surface is difficult. We thus welcome the opportunity to clarify our arguments on the contentious themes touched upon by Fredin et al.2 The age of landscapes has been a recurring research topic for the last century. Often, landscape ages can be deduced indirectly ... -
Submarine geomorphology at the front of the retreating hansbreen tidewater glacier, hornsund fjord, southwest spitsbergen
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-01)A 1:10,000 scale bathymetric map as well as 1:20,000 scale backscattering and geomorphological maps of two bays Isbjørnhamna and Hansbukta in the Hornsund fjord (Spitsbergen) present the submarine relief that was primarily formed during and after the retreat of the Hansbreen tidewater glacier. Geomorphological mapping was performed using multibeam bathymetric data and seismoacoustic profiling. The ... -
Non-heuristic automatic techniques for overcoming low signal-to-noise-ratio bias of localization microscopy and multiple signal classification algorithm
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-21)Localization microscopy and multiple signal classification algorithm use temporal stack of image frames of sparse emissions from fluorophores to provide super-resolution images. Localization microscopy localizes emissions in each image independently and later collates the localizations in all the frames, giving same weight to each frame irrespective of its signal-to-noise ratio. This results in a ... -
Reinforced Auto-Zoom Net: Towards Accurate and Fast Breast Cancer Segmentation in Whole-Slide Images
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-20)Convolutional neural networks have led to significant breakthroughs in the domain of medical image analysis. However, the task of breast cancer segmentation in whole-slide images (WSIs) is still underexplored. WSIs are large histopathological images with extremely high resolution. Constrained by the hardware and field of view, using high-magnification patches can slow down the inference process and ... -
Survey of conditions for artificial aurora experiments at EISCAT Tromsø using dynasonde data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-02-14)We report a brief survey on conditions for artificial aurora optical experiments in F region heating with O-mode at the EISCAT Tromsø site using dynasonde data from 2000 to 2017. The results obtained in our survey indicate the following: The possible conditions for conducting artificial aurora experiments are concentrated in twilight hours in both evening and morning, compared with late-night hours; ... -
K2 Campaign 5 observations of pulsating subdwarf B stars: Binaries and super-Nyquist frequencies
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-05)We report the discovery of three pulsating subdwarf B stars in binary systems observed with the <i>Kepler</i> space telescope during Campaign 5 of K2. EPIC 211696659 (SDSS J083603.98+155216.4) is a g-mode pulsator with a white dwarf companion and a binary period of 3.16 d. EPICs 211823779 (SDSS J082003.35+173914.2) and 211938328 (LB 378) are both p-mode pulsators with main-sequence F companions. The ... -
Nonlocal damage mechanics for quantification of health for piezoelectric sensor
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-18)In this paper, a novel method to quantify the incubation of damage on piezoelectric crystal is presented. An intrinsic length scale parameter obtained from nonlocal field theory is used as a novel measure for quantification of damage precursor. Features such as amplitude decay, attenuation, frequency shifts and higher harmonics of guided waves are commonly-used damage features. Quantification of the ... -
The molecular origin of cold adaptation: A comparative study of cold- and warm-active uracil DNA glycosylase
(Doctoral thesis; Doktorgradsavhandling, 2007-05-25)During the last decade or so, scientists at the Norwegian Structural Biology Centre (NorStruct) have used the enzyme uracil DNA glycosylase (UDG) as a model system in the study of cold-adaptation, protein-DNA recognition and enzyme specificity. The cod UDG (cUDG) and human UDG (hUDG) are thoroughly biologically characterized and there are established well-functioning recombinant expression systems ... -
Risk Assessment of Hazards Due to the Installation and Maintenance of Onshore Wind Turbines
(Peer reviewed; Book; Chapter, 2018-06-11)In this work, an assessment of four types of risks is carried out for wind turbines during four phases, namely: transportation, installation, operation and maintenance. This work mainly focuses on onshore type of wind turbines and briefly mentioning the offshore wind turbines. The introduction gives an overview of the main parts and components of wind turbine, in addition to discussing the process ... -
Failure intensity of offshore power plants under varying maintenance policies
(Journal article; Peer reviewed; Tidsskriftartikkel, 2019-01-06)System reliability of an offshore power plant with several gas turbine engines is analyzed in this study to understand the failure intensity of a selected gas turbine engines under varying maintenance activities. A set of event data of a selected gas turbine engine is considered to identify system failure intensity levels, where unknown maintenance actions were implemented (i.e. various repairs ... -
Auroral molecular-emission effects on the atomic oxygen line at 777.4 nm
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-16)One of the representative auroral emission lines that radiates from F-region heights and is measurable on the ground is the 777.4 nm line from excited atomic oxygen. This line has been adopted, along with another E-region emission line, for example 427.8 nm, to estimate the mean energy and total energy flux of precipitating auroral electrons. The influence of emissions from part of the molecular ... -
Isocorroles as Homoaromatic NIR-Absorbing Chromophores: A First Quantum Chemical Study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-08-10)Density functional theory calculations of magnetically induced current densities have revealed high diatropic ring currents in unsubstituted isocorrole consistent with homoaromatic character. An examination of the Kohn-Sham molecular orbitals showed clear evidence of homoconjugative interactions in four occupied π-type molecular orbitals as well as in the LUMO. Remarkably, substituents at the saturated ... -
Depositional processes on the distal Scoresby Trough Mouth Fan (ODP Site 987): Implications for the Pleistocene evolution of the Scoresby Sund Sector of the Greenland Ice Sheet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-28)The investigation of trough mouth fans (TMFs), important paleoclimatic archives on mid- and high-latitude continental margins, has so far mainly been based on the integration of various types of acoustic data supplemented with short sediments cores. In consequence, sedimentological and chronological data about parts of TMFs deposited prior to the Last Glacial Maximum remains sparse. Here, we re-evaluate ... -
The airglow layer emission altitude cannot be determined unambiguously from temperature comparison with lidars
(Journal article; Peer reviewed; Tidsskriftartikkel, 2018)I investigate the nightly mean emission height and width of the OH*(3–1) layer by comparing nightly mean temperatures measured by the ground-based spectrometer GRIPS 9 and the Na lidar at ALOMAR. The data set contains 42 coincident measurements taken between November 2010 and February 2014, when GRIPS 9 was in operation at the ALOMAR observatory (69.3° N, 16.0° E) in northern Norway. To closely ... -
Impact of sea ice drift retrieval errors, discretization and grid type on calculations of ice deformation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-03)We studied two issues to be considered in the calculation of parameters characterizing sea ice deformation: the effect of uncertainties in an automatically retrieved sea ice drift field, and the influence of the type of drift vector grid. Sea ice deformation changes the local ice mass balance and the interaction between atmosphere, ice, and ocean, and constitutes a hazard to marine traffic and ... -
Shrinkage estimation of rate statistics
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-08)This paper presents a simple shrinkage estimator of rates based on Bayesian methods. Our focus is on crime rates as a motivating example. The estimator shrinks each town’s observed crime rate toward the country-wide average crime rate according to town size. By realistic simulations we confirm that the proposed estimator outperforms the maximum likelihood estimator in terms of global risk. We also ...