Fakultet for naturvitenskap og teknologi: Nye registreringer
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Heavy-element–ligand covalence: ligand noninnocence in molybdenum and tungsten Viking-helmet Corroles
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-07)Extensive DFT calculations with several exchange–correlation functionals indicate that molybdenum-dichlorido Viking helmet corroles are noninnocent with significant Mo<sup>IV</sup>-corrole<sup>˙2−</sup> character. The effect is mediated by a Mo(4d)-corrole(π) orbital interaction similar to that postulated for MnCl, FeCl and FeNO corroles. The effect also appears to operate in tungsten-dichlorido ... -
Blind Super-Resolution Approach for Exploiting Illumination Variety in Optical-Lattice Illumination Microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-19)Optical-lattice illumination patterns help in pushing high spatial frequency components of the sample into the optical transfer function of a collection microscope. However, exploiting these high-frequency components require precise knowledge of illumination if reconstruction approaches similar to structured illumination microscopy are employed. Here, we present an alternate blind reconstruction ... -
Simulation of peak tension loads in Subsea power cables during installation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021)At present, most of the insurance claims in the offshore wind industry are due to cable failures where a large percentage occurs during the installation of the array and export cables. As the reliability of the cables depends on the location and installation method, it is important to map the risks involved, which can compromise the cable's integrity in individual projects. This paper presents ... -
A methodology for collecting donning times of thermal protective immersion suits intended to be worn by passengers on vessels operating in cold environments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021)Adequate thermal protection for passengers travelling on-board vessels in cold climate regions, such as that provided by thermal protective immersion suits (TPIS), enhances passenger survivability in emergency situations, in particular those requiring the abandonment of the vessel. As emergency abandonment is a time critical process, it is essential to consider the time required to correctly don the ... -
Year-around C- and L-band observation around the MOSAiC ice floe with high spatial and temporal resolution
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-12)In September 2019, the German research icebreaker Polarstern started the largest multidisciplinary Arctic expedition, the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) drift experiment. Being moored to ice floes at high Arctic for a whole year, thus including the winter season, the main goal of the expedition is to better understand and quantify relevant processes ... -
Observing electric field and neutral wind with EISCAT 3D
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-16)Measurements of height-dependent electric field (E) and neutral wind (u) are important governing parameters of the Earth's upper atmosphere, which can be used to study, for example, how auroral currents close or how energy flows between the ionized and neutral constituents. The new EISCAT 3D (E3D) incoherent scatter radar will be able to measure a three-dimensional ion velocity vector (v) at each ... -
Examination of turbulence impacts on ultra-short-term wind power and speed forecasts with machine learning
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-25)Wind turbines’ economic and secure operation can be optimized through accurate ultra-short-term wind power and speed forecasts. Turbulence, considered as a local short-term physical wind phenomenon, affects wind power generation. This paper investigates the use of turbulence intensity for ultra-short-term predictions of wind power and speed with a wind farm in the Arctic, including and excluding ... -
Structural and biochemical characterization of the environmental MBLs MYO-1, ECV-1 and SHD-1
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-28)Background: MBLs form a large and heterogeneous group of bacterial enzymes conferring resistance to b-lactam antibiotics, including carbapenems. A large environmental reservoir of MBLs has been identified, which can act as a source for transfer into human pathogens. Therefore, structural investigation of environmental and clinically rare MBLs can give new insights into structure–activity relationships ... -
CryoSat-2 Significant Wave Height in Polar Oceans Derived Using a Semi-Analytical Model of Synthetic Aperture Radar 2011–2019
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-18)This paper documents the retrieval of significant ocean surface wave heights in the Arctic Ocean from CryoSat-2 data. We use a semi-analytical model for an idealised synthetic aperture satellite radar or pulse-limited radar altimeter echo power. We develop a processing methodology that specifically considers both the Synthetic Aperture and Pulse Limited modes of the radar that change close to ... -
Probability distributions for wind speed volatility characteristics: A case study of Northern Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11)The Norwegian Arctic is rich in wind resources. The development of wind power in this region can boost green energy and also promote local economies. In wind power engineering, it is a tremendous advantage to base projects on a sound understanding of the intrinsic properties of wind resources in an area. Wind speed volatility, a phenomenon that strongly affects wind power generation, has not received ... -
Single-shot fringe pattern phase retrieval using improved period-guided bidimensional empirical mode decomposition and Hilbert transform
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-17)Fringe pattern analysis is the central aspect of numerous optical measurement methods, e.g., interferometry, fringe projection, digital holography, quantitative phase microscopy. Experimental fringe patterns always contain significant features originating from fluctuating environment, optical system and illumination quality, and the sample itself that severely affect analysis outcome. Before the ... -
Rapid Atlantification along the Fram Strait at the beginning of the 20th century
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-24)The recent expansion of Atlantic waters into the Arctic Ocean represents undisputable evidence of the rapid changes occurring in this region. Understanding the past variability of this “Atlantification” is thus crucial in providing a longer perspective on the modern Arctic changes. Here, we reconstruct the history of Atlantification along the eastern Fram Strait during the past 800 years using ... -
A Parsimonious Description and Cross-Country Analysis of COVID-19 Epidemic Curves
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-06)In a given country, the cumulative death toll of the first wave of the COVID-19 epidemic follows a sigmoid curve as a function of time. In most cases, the curve is well described by the Gompertz function, which is characterized by two essential parameters, the initial growth rate and the decay rate as the first epidemic wave subsides. These parameters are determined by socioeconomic factors and ... -
A 10-year record of Arctic summer sea ice freeboard from CryoSat-2
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-29)Satellite observations of pan-Arctic sea ice thickness have so far been constrained to winter months. For radar altimeters, conventional methods cannot differentiate leads from meltwater ponds that accumulate at the ice surface in summer months, which is a critical step in the ice thickness calculation. Here, we use over 350 optical and synthetic aperture radar (SAR) images from the summer months ... -
Putative fossils of chemotrophic microbes preserved in seep carbonates from Vestnesa Ridge, off northwest Svalbard, Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-20)The microbial key players at methane seeps are methanotrophic archaea and sulfate-reducing bacteria. They form spherical aggregates and jointly mediate the sulfate-dependent anaerobic oxidation of methane (SD–AOM: CH4 + SO42– → HCO3– + HS– + H2O), thereby inducing the precipitation of authigenic seep carbonates. While seep carbonates constitute valuable archives for molecular fossils of SD–AOM-mediating ... -
Sources and sinks of methane in sea ice: Insights from stable isotopes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-27)We report on methane (CH<sub>4)</sub> stable isotope (d<sup>13</sup>C and d<sup>2</sup> H) measurements from landfast sea ice collected near Barrow (Utqiagvik, Alaska) and Cape Evans (Antarctica) over the winter-to-spring transition. These measurements provide novel insights into pathways of CH<sub>4</sub> production and consumption in sea ice. We found substantial differences between the two ... -
Microstructure and fluid flow in the vicinity of basin bounding faults in rifts – The Dombjerg Fault, NE Greenland rift system
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-14)Faults commonly form loci for high fluid flux in sedimentary basins, where fluids, rocks and deformation processes frequently interact. Here, we elucidate the interaction of fluid flow, diagenesis and deformation near basin-bounding faults in sedimentary basins through a study in the vicinity (0–3.5 km) of the Dombjerg Fault in the NE Greenland rift system. Due to fault-controlled fluid circulation, ... -
Polar Lows - Moist Baroclinic Cyclones in Four Different Vertical Wind Shear Environments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-15)Polar lows are intense mesoscale cyclones that develop in polar marine air masses. Motivated by the large variety of their proposed intensification mechanisms, cloud structure, and ambient sub-synoptic environment, we use self-organising maps to classify polar lows. The method is applied to 370 polar lows in the north-eastern Atlantic, which were obtained by matching mesoscale cyclones from ... -
Estimating Remaining Carbon Budgets Using Temperature Responses Informed by CMIP6
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-12)A remaining carbon budget (RCB) estimates how much CO2 we can emit and still reach a specific temperature target. The RCB concept is attractive since it easily communicates to the public and policymakers, but RCBs are also subject to uncertainties. The expected warming levels for a given carbon budget has a wide uncertainty range, which increases with less ambitious targets, i.e., with higher CO2 ... -
Distinct methane-dependent biogeochemical states in Arctic seafloor gas hydrate mounds
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-02)Archaea mediating anaerobic methane oxidation are key in preventing methane produced in marine sediments from reaching the hydrosphere; however, a complete understanding of how microbial communities in natural settings respond to changes in the flux of methane remains largely uncharacterized. We investigate microbial communities in gas hydrate-bearing seafloor mounds at Storfjordrenna, offshore ...