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norskFakultet for naturvitenskap og teknologi
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Mutational analysis of the pro-peptide of a marine intracellular subtilisin protease supports its role in inhibition
(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
(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
(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
(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
(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 ... -
Early to middle Cenozoic paleoenvironment and erosion estimates of the southwestern Barents Sea: Insights from a regional mass-balance approach
(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
(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
(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
(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
(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, ... -
Control of Blood Glucose for Type-1 Diabetes by Using Reinforcement Learning with Feedforward Algorithm
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-30)<p><i>Background</i>: Type-1 diabetes is a condition caused by the lack of insulin hormone, which leads to an excessive increase in blood glucose level. The glucose kinetics process is difficult to control due to its complex and nonlinear nature and with state variables that are difficult to measure.</p> <p><i>Methods</i>: This paper proposes a method for automatically calculating the basal and ... -
Assessing polarimetric SAR sea-ice classifications using consecutive day images
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015)This paper investigates automatic segmentation and classification of C-band, polarimetric synthetic aperture radar (SAR) satellite images of Arctic sea ice under freezing conditions prior to melt. The objective is to investigate the robustness of the results obtained under slightly varying environmental conditions and different viewing geometries. Initially, three geographically overlapping SAR ... -
From widespread Mississippian to localized Pennsylvanian extension in central Spitsbergen, Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-21)In the Devonian–Carboniferous, a rapid succession of clustered extensional and contractional tectonic events is thought to have affected sedimentary rocks in central Spitsbergen, Svalbard. These events include Caledonian post-orogenic extensional collapse associated with the formation of thick Early–Middle Devonian basins, Late Devonian–Mississippian Ellesmerian contraction, and Early–Middle ... -
Holocene glacier history of Svalbard: Retracing the style of (de-)glaciation
(Doctoral thesis; Doktorgradsavhandling, 2018-12-06)Through the Holocene, Svalbard glaciers have exhibited at least two phases of re-advance, one during the Early Holocene and another throughout the entire Late Holocene. No geomorphological features have been identified corresponding to glacier re-advances between 9.0 – 4.5 ka BP. The Early Holocene glacier re-advances identified across Svalbard and they correspond to a diverse range of glacier sizes. ... -
An efficient pseudo-spectral method for the description of atomic electronic wave functions – Application to the hydrogen atom in a uniform magnetic field
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-27)<p>The mapping of an electronic state on a real-space support lattice may offer advantages over a basis set ansatz in cases where there are linear dependences due to basis set overcompleteness or when strong internal or external fields are present. Such discretization methods are also of interest because they allow for the convenient numerical integration of matrix elements of local operators. We ... -
Unraveling the Microscopic Origin of Triplet Lasing from Organic Solids
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-16)We present a heuristic mechanism for the origin of the unusual triplet lasing from (E)-3-(((4-nitrophenyl)imino)methyl)-2H-thiochroman-4-olate·BF<sub>2</sub>. We demonstrate that whereas the moderate lifetime (1.03 μs) of the first triplet state (T<sub>1</sub>) prohibits triplet–triplet annihilation, the relatively faster S<sub>1</sub> → T<sub>1</sub> intersystem crossing and the 10<sup>4</sup> times ... -
Resolution-of-identity accelerated relativistic two- and four-component electron dynamics approach to chiroptical spectroscopies
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-27)We present an implementation and application of electron dynamics based on real-time time-dependent density functional theory (RT-TDDFT) and relativistic 2-component X2C and 4-component Dirac–Coulomb (4c) Hamiltonians to the calculation of electron circular dichroism and optical rotatory dispersion spectra. In addition, the resolution-of-identity approximation for the Coulomb term (RI-J) is introduced ... -
Rare and Nonexistent Nitrosyls: Periodic Trends and Relativistic Effects in Ruthenium and Osmium Porphyrin-Based {MNO}7 Complexes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-14)Relativistic and nonrelativistic density functional theory calculations were used to investigate rare or nonexistent ruthenium and osmium analogues of nitrosylhemes. Strong ligand field effects and, to a lesser degree, relativistic effects were found to destabilize {RuNO}<sup>7</sup> porphyrins relative to their {FeNO}<sup>7</sup> analogues. Substantially stronger relativistic effects account for ... -
Ship speed power performance under relative wind profiles in relation to sensor fault detection
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-19)Statistical Data analysis and visualization approaches to identify ship speed power performance under relative wind (i.e. apparent wind) profiles are considered in this study. Ship performance and navigation data of a selected vessel are analyzed, where various data anomalies, i.e. sensor related erroneous data conditions, are identified. Those erroneous data conditions are investigated and several ... -
Investigation of Thermo-Optical Phase Modulator for Chip Based Structured Illumination Microscopy
(Master thesis; Mastergradsoppgave, 2018-11-21)Optical nanoscopy is an emerging field and enables super-resolution of biological cells. Among the existing nanoscopy techniques, structured illumination microscopy (SIM) is most promising candidate for live cell imaging due to its high-imaging speed, limited photo-toxicity and its suitability with most commonly used fluorophore. One of research focus of the optics group at the department is to ...
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