Fakultet for naturvitenskap og teknologi: Nye registreringer
Viser treff 4101-4120 av 5414
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Investigations of summer sea ice with X and C-band multi-polarimetric synthetic aperture radar (SAR)
(Doctoral thesis; Doktorgradsavhandling, 2017-03-17)In this thesis, we explore the possibilities and limitations of using space-borne multi-polarimetric SAR in summer sea ice investigations. Both X and C-band data are examined. The study utilizes two data sets collected in the Arctic in 2011 (Fram Strait) and 2012 (north of Spitsbergen). Both sets combine satellite SAR scenes with co-located ground and air-borne measurements. Firstly, the study ... -
Depositional environment, ichnological features and oxygenation of Permian to earliest Triassic marine sediments in central Spitsbergen, Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016)Late Early Permian–lowermost Triassic carbonate, siliceous (spiculites) and clastic marine sediments in the Marmierfjellet area (Isfjorden, central Spitsbergen) contain a relatively diverse and abundant trace fossil assemblage providing important information about the depositional processes. The Vøringen Member (Late Artinskian–Kungurian) of the Kapp Starostin Formation (Late Artinskian–? Changhsingian) ... -
GreenBST: Energy-efficient concurrent search tree
(Conference object; Konferansebidrag, 2016-08-09)Like other fundamental abstractions for energy-efficient com- puting, search trees need to support both high concurrency and fine- grained data locality. However, existing locality-aware search trees such as ones based on the van Emde Boas layout (vEB-based trees), poorly support concurrent (update) operations while existing highly-concurrent search trees such as the non-blocking binary search ... -
Biochemical characterization of a family 15 carbohydrate esterase from a bacterial marine Arctic metagenome
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016)Background The glucuronoyl esterase enzymes of wood-degrading fungi (Carbohydrate Esterase family 15; CE15) form part of the hemicellulolytic and cellulolytic enzyme systems that break down plant biomass, and have possible applications in biotechnology. Homologous enzymes are predicted in the genomes of several bacteria, however these have been much less studied than their fungal counterparts. ... -
Interpreting the paramagnetic NMR spectra of potential Ru(III) metallodrugs: synergy between experiment and relativistic DFT calculations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-06-16)Ruthenium-based compounds are potential candidates for use as anticancer metallodrugs. The central ruthenium atom can be in the oxidation state +2 (e.g., RAPTA, RAED) or +3 (e.g., NAMI, KP). In this study we focus on paramagnetic NAMI analogs of a general structure [4-R-pyH]+ <i>trans</i>-[Ru<sup>III</sup>Cl<sub>4</sub>(DMSO)(4-R-py)]<sup>−</sup>, where 4-R-py stands for a 4-substituted pyridine. ... -
Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-11)Gas hydrates stored on continental shelves are susceptible to dissociation triggered by environmental changes. Knowledge of the timescales of gas hydrate dissociation and subsequent methane release are critical in understanding the impact of marine gas hydrates on the ocean–atmosphere system. Here we report a methane efflux chronology from five sites, at depths of 220–400 m, in the southwest Barents ... -
Nanoscopy of bacterial cells immobilized by holographic optical tweezers
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-13)Imaging non-adherent cells by super-resolution far-field fluorescence microscopy is currently not possible because of their rapid movement while in suspension. Holographic optical tweezers (HOTs) enable the ability to freely control the number and position of optical traps, thus facilitating the unrestricted manipulation of cells in a volume around the focal plane. Here we show that immobilizing ... -
Two-stage exhumation of subducted Saxothuringian continental crust records underplating in the subduction channel and collisional forced folding (Krkonoše-Jizera Mts., Bohemian Massif)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-08)The Krkonoše-Jizera Massif in the northern part of the Variscan Bohemian Massif provides insight into the exhumation mechanisms for subducted continental crust. The studied region exposes a relatively large portion of a flat-lying subduction-related complex that extends approximately 50 km away from the paleosuture. wide extent of HP-LT metamorphism has been confirmed by new P-T estimates indicating ... -
Ice-sheet-driven methane storage and release in the Arctic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-07)It is established that late-twentieth and twenty-first century ocean warming has forced dissociation of gas hydrates with concomitant seabed methane release. However, recent dating of methane expulsion sites suggests that gas release has been ongoing over many millennia. Here we synthesize observations of B1,900 fluid escape features—pockmarks and active gas flares—across a previously glaciated ... -
Evidence for ice-free summers in the late Miocene central Arctic Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-04-04)Although the permanently to seasonally ice-covered Arctic Ocean is a unique and sensitive component in the Earth’s climate system, the knowledge of its long-term climate history remains very limited due to the restricted number of pre-Quaternary sedimentary records. During Polarstern Expedition PS87/2014, we discovered multiple submarine landslides along Lomonosov Ridge. Removal of younger ... -
Deconvoluting complex structural histories archived in brittle fault zones
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-16)Brittle deformation can saturate the Earth’s crust with faults and fractures in an apparently chaotic fashion. The details of brittle deformational histories and implications on, for example, seismotectonics and landscape, can thus be difficult to untangle. Fortunately, brittle faults archive subtle details of the stress and physical/chemical conditions at the time of initial strain localization ... -
Constraints on oceanic methane emissions west of Svalbard from atmospheric in situ measurements and Lagrangian transport modeling
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-10) -
On the performance and energy efficiency of the PGAS programming model on multicore architectures
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-15) -
Electronic structure of small surfactants: a continuum solvation study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-07-18)The e ect of surfaces and interfaces on the structure and properties of molecules is of a great interest in a number of biological and technological applications. Nevertheless, such an investigation is extremely challenging from an experimental point of view, due to the bidimensionality of the environment. In recent years, we have developed a framework to study molecules at surfaces ... -
Long-lasting Cadomian magmatic activity along an active northern Gondwana margin: U–Pb zircon and Sr–Nd isotopic evidence from the Brunovistulian Domain, eastern Bohemian Massif
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-03)Cadomian magmatic complexes of the Brunovistulian Domain crop out at the eastern termination of the Bohemian Massif. However, the age, nature and geotectonic affinity of some of pre-Variscan (meta-)igneous rock complexes from this domain are still unknown. Geochronological and geochemical study of the granitic rocks across the Brunovistulian Domain reveals new information about the timing and nature ... -
Oil spill characterization in the hybrid-polarity SAR domain using log-cumulants
(Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-10-18)Log-cumulants have proven to be an interesting tool for evaluating the statistical properties of potential oil spills in polarimetric Synthetic Aperture Radar (SAR) data within the common horizontal (H) and vertical (V) polarization basis. The use of first, second, and third order sample log-cumulants has shown potential for evaluating the texture and the statistical distributions, as well as ... -
Benthic foraminiferal growth seasons implied from Mg/Ca-temperature correlations for three Arctic species
(Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-11-22)Core-top sediment samples from Kongsfjorden, Svalbard, and adjacent fjord and shelf areas were collected in order to investigate a potential relationship between Mg/Ca-ratios of Arctic benthic foraminifera and the ambient bottom water temperatures (BWT). The area is influenced by large seasonal variation in factors such as light and temperature, which is further strengthened by oceanographic shifts, ... -
Paleoceanographic development during the last deglaciation and Holocene, over the Bear Island slide scar, SW Barents Sea
(Master thesis; Mastergradsoppgave, 2017-02-02)The investigated sediment core HH13-243 GC is located under the present flow of the warm and saline Atlantic Water (AW), but close to, glaciated continental margins. The core site is situated in an area that is sensitive to changes and reflects the paleoceanography of the northernmost Norwegian Sea and the Western Barents Sea. We investigated the changes in inflow of Atlantic water and the ... -
On RAM performance of production facilities operating under the Barents Sea harsh environmental conditions
(Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-05-19)Oil and gas (O&G) industry is expanding its activities into Arctic offshore, where is characterised with severe operating conditions and less-developed infrastructure. Such conditions affect the reliability, availability, and maintainability (RAM) of offshore O&G plants, operations, and activities through different scenarios. Plant RAM analysis provides key information for decision-making on, for ... -
Availability assessment of oil and gas processing plants operating under dynamic Arctic weather conditions
(Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-03-19)We consider the assessment of the availability of oil and gas processing facilities operating under Arctic conditions. The novelty of the work lies in modelling the time-dependent effects of environmental conditions on the components failure and repair rates. This is done by introducing weather-dependent multiplicative factors, which can be estimated by expert judgements given the scarce data available ...