Fakultet for naturvitenskap og teknologi: Recent submissions
Now showing items 3661-3680 of 5442
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Paleoceanographic development in Storfjorden, Svalbard, during the deglaciation and Holocene: evidence from benthic foraminiferal records
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014-08-07)Brines can have a profound influence on the relative abundance of calcareous and agglutinated foraminiferal faunas. Here we investigated the distribution of benthic foraminiferal species in four cores from a brine‐enriched environment in Storfjorden, Svalbard. Stratigraphically, the cores comprise the last 15 000 years. The purpose of the study was to reconstruct changes in the palaeoecology and ... -
3D Seismic Investigation of a Gas Hydrate and Fluid Flow System on an Active Mid‐Ocean Ridge; Svyatogor Ridge, Fram Strait
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-12)Tectonic settings play a large role in the development of fluid flow pathways for gas migrating through sedimentary strata. Many gas hydrate systems worldwide are located on either passive continental margins, in large contourite deposits on the slopes of passive continental margins or on subduction margins. The Svyatogor Ridge, however, located at the northwestern flank of the Knipovich Ridge and ... -
Retreat patterns and dynamics of the Sentralbankrenna glacial system, central Barents Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-26)The Barents Sea Ice Sheet (BSIS) is a good palaeo-analogue for the present day West Antarctic Ice Sheet. Both were marine-based ice sheets, particularly vulnerable to ocean warming and sea-level rise. Understanding the BSIS ice dynamics and patterns of retreat since the Last Glacial Maximum (LGM) is useful in developing our knowledge of spatial and temporal variations during marine-based ice sheet ... -
Aldol condensations on a 3-alkylidene-2,5-diketopiperazine - synthesis of two marine natural products
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06)The synthesis of two marine natural products containing a 3-alkylidene-6-arylidene-2,5-diketopiperazine scaffold by employing two consecutive aldol condensations starting with 1,4-diacetyl-2,5-diketopiperazine is reported. The target compounds contain a phenol or an imidazole group as aryl substituents, respectively, and suitable conditions for the aldol condensation of 1-acyl-3-alkylidene-2,5-dik ... -
Calculations of the EPR g-tensor using unrestricted two- and four-component relativistic approaches within the HF and DFT frameworks
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-06-08)Approaches and programs for calculations of the EPR g-tensor in the framework of the two- and four-component methods are still very rare. There are three main reasons for this: the wider community's unawareness of the importance of second- and higher order spin–orbit effects on the g-tensor, the methodological problems associated with performing such calculations and the lack of understanding of ... -
Large subglacial meltwater features in the central Barents Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-01)During the last glacial period large parts of the Arctic, including the Barents Sea, north of Norway and Russia, were covered by ice sheets. Despite several studies indicating that melting occurred beneath much of the Barents Sea ice sheet, very few meltwater-related landforms have been identified. We document ∼200 seafloor valleys in the central Barents Sea and interpret them to be tunnel valleys ... -
High frequency copolymer ultrasonic transducer array of size-effective elements
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-05)A layer-by-layer deposition method for producing dual-layer ultrasonic transducers from piezoelectric copolymers has been developed. The method uses a combination of customized and standard processing to obtain 2D array transducers with electrical connection of the individual elements routed directly to the rear of the substrate. A numerical model was implemented to study basic parameters effecting ... -
Efficient disease detection in gastrointestinal videos – global features versus neural networks
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-19)Analysis of medical videos from the human gastrointestinal (GI) tract for detection and localization of abnormalities like lesions and diseases requires both high precision and recall. Additionally, it is important to support efficient, real-time processing for live feedback during (i) standard colonoscopies and (ii) scalability for massive population-based screening, which we conjecture can be done ... -
Relativistic effects on the NMR parameters of Si, Ge, Sn, and Pb alkynyl compounds: Scalar versus spin-orbit effects
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-01)The NMR chemical shifts and indirect spin-spin coupling constants of 12 molecules containing <sup>29</sup>Si, <sup>73</sup>Ge, <sup>119</sup>Sn, and <sup>207</sup>Pb [X(CCMe)<sub>4</sub>, Me<sub>2</sub>X(CCMe)<sub>2</sub>, and Me<sub>3</sub>XCCH] are presented. The results are obtained from non-relativistic as well as two- and four-component relativistic density functional theory (DFT) calculations. ... -
Empirical Growth Models for the Renewable Energy Sector
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-25)Three simple, empirical models for growth of power consumption in the renewable energy sector are compared. These are the exponential, logistic, and power-law models. The exponential model describes growth at a fixed relative growth rate, the logistic model saturates at a fixed limit, while the power-law model describes slowing, but unlimited, growth. The model parameters are determined by regression ... -
Grounding line proximal sediment characteristics at a marine-based, late-stage ice stream margin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-12)Geomorphological evidence suggests that ice streams undergo frequent dynamic changes towards the end of their life cycles, but the associated sedimentary characteristics and processes remain poorly understood. Here, we present new sedimentological data from a Late Weichselian marine‐based ice stream in upper Bjørnøyrenna, northern Barents Sea, which experienced accelerated flow, intense calving of ... -
Poleward energy transport: is the standard definition physically relevant at all time scales?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-17)Poleward energy transport in the atmosphere and oceans constitutes an important branch of the global energy budget, and its role in the climate system has been the subject of many studies. In the atmosphere, the transport is affected by “eddies” and large scale meridional cells, both with zero net mass transport across latitude circles, but also partly by processes associated with a net transport ... -
Linking the Character of the Metal-Ligand Bond to the Ligand NMR Shielding in Transition-Metal Complexes: NMR Contributions from Spin-Orbit Coupling
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-06)Relativistic effects significantly affect various spectroscopic properties of compounds containing heavy elements. Particularly in Nuclear Magnetic Resonance (NMR) spectroscopy, the heavy atoms strongly influence the NMR shielding constants of neighboring light atoms. In this account we analyze paramagnetic contributions to NMR shielding constants and their modulation by relativistic spin–orbit ... -
Origin of Dual-Peak Phosphorescence and Ultralong Lifetime of 4,6-Diethoxy-2-carbazolyl-1,3,5-triazine
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-02)Recently, ultralong phosphorescence lifetime has been observed in 4,6-diethoxy-2-carbazolyl-1,3,5-triazine, and H-aggregation induced stabilization of the T1 state was suggested as its source. The response theory calculations demonstrate that the Davydov stabilization of the T1 state of the dimer is marginal with respect to the monomer and the corresponding transition moments are virtually the same. ... -
Palaeoceanography of the Barents Sea continental margin, north of Nordaustlandet, Svalbard, during the last 74 ka
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-17)We investigated gravity core HH11‐09GC from 488 m water depth at the northern Svalbard margin in order to reconstruct changes in Atlantic Water (AW) inflow to the Arctic Ocean. The study was based on the distribution patterns of benthic and planktic foraminifera, benthic and planktic oxygen and carbon isotopes, lithology and physical properties of the sediments. The core contains sediments from ... -
Screening and Design of Inhibitor Scaffolds for the Antibiotic Resistance Oxacillinase-48 (OXA-48) through Surface Plasmon Resonance Screening
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-11)The spread of antibiotic resistant bacteria is a global threat that shakes the foundations of modern healthcare. β-Lactamases are enzymes that confer resistance to β-lactam antibiotics in bacteria, and there is a critical need for new inhibitors of these enzymes for combination therapy together with an antibiotic. With this in mind, we have screened a library of 490 fragments to identify starting ... -
Accurate estimation of the illumination pattern’s orientation and wavelength in sinusoidal structured illumination microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-05)Structured illumination microscopy is able to improve the spatial resolution of wide-field fluorescence imaging by applying sinusoidal stripe pattern illumination to the sample. The corresponding computational image reconstruction requires precise knowledge of the pattern’s parameters, which are its phase (φ) and wave vector (<b>p</b>). Here, a computationally inexpensive method for estimation of ... -
Finite dimensional dynamics for nonlinear filtration equation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-01)We construct new finite dimensional submanifolds in the solution space of nonlinear differential filtration equations and describe the corresponding evolutionary dynamics. This method is implemented in a computer program of symbolic computations Maple. -
Variations in benthic foraminiferal assemblages in the Tagus mud belt during the last 5700 years: Implications for Tagus River discharge
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-31)We analyzed a 10-m sediment core retrieved at 82 m water depth off the coast of the Tagus River (Western Iberian Margin, Portugal) to investigate a linkage between variations in benthic foraminiferal assemblages and Tagus River discharge over the last 5700 years. Benthic foraminiferal assemblages were studied at high resolution in combination with the stable carbon and oxygen isotopic composition ... -
You Just Keep on Pushing My Love over the Borderline: A Rejoinder
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-06)<i>INTRODUCTION</i>: The point of departure for our paper is that most modern statistical models are built to be flexible enough to model diverse data generating mechanisms. Good statistical practice requires us to limit this flexibility, which is typically controlled by a small number of parameters, to the amount “needed” to model the data at hand. The Bayesian framework provides a natural method ...