Doktorgradsavhandlinger (NT-fak): Recent submissions
Now showing items 141-160 of 305
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The EOS Formulation for Linear and Nonlinear Transient Scattering Problems
(Doctoral thesis; Doktorgradsavhandling, 2019-03-29)This thesis developed the EOS formulations of solving nonlinear transient scatterings, both for 1D case and 3D Maxwell's equations. This method can be accurately and stably implemented using one particular choice of numerical scheme for the inside of the objects and for the required integral representations of the boundary values. For a stable numerical solution, the time step needs to be confined ... -
3D and 4D seismic investigations of fluid flow and gas hydrate systems
(Doctoral thesis; Doktorgradsavhandling, 2019-02-18)Using the state-of-the-art high resolution P-Cable 3D seismic system, in this thesis we (1) study the shallow strata (<1km below seabed) and describe the geological controls and driving mechanisms for fluid leakage at two sites in the northern Barents Sea, and (2) introduce a new time-lapse seismic method for high-frequency (~30-350 Hz) P-Cable seismic data. The study areas are interesting as ... -
Iron dependent gene regulation and siderophore systems in Vibrionaceae
(Doctoral thesis; Doktorgradsavhandling, 2017-03-15)Bacteria live in fluctuating environments, which they sense and respond to through gene regulation. Availably of iron is an example of an element fluctuating and that can Bacteria sense.Iron is an essential micronutrient that is scares in several environments, especially in a host. The ferric uptake regulator, Fur, is the major iron level sensing protein and regulator of iron acquisition systems in ... -
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 ... -
Small data: practical modeling issues in human-model -omic data
(Doctoral thesis; Doktorgradsavhandling, 2019-02-08)Human-model data are very valuable and important in biomedical research. Ethical and economical constraints limit the access to such data, and consequently these datasets rarely comprise more than a few hundred observations. As measurements are comparatively cheap, the tendency is to measure as many things as possible for the few, valuable participants in a study. With -omics technologies it is cheap ... -
Advancing Unsupervised and Weakly Supervised Learning with Emphasis on Data-Driven Healthcare
(Doctoral thesis; Doktorgradsavhandling, 2019-02-15)In healthcare, vast amounts of data are stored digitally in the electronic health records (EHRs). EHRs represent a largely untapped source of clinically relevant information, which combined with advances in machine learning, have the potential to transform healthcare into a more data-driven direction. However, due to the complexity and poor quality of the EHRs, data-driven healthcare is facing many ... -
Toward Reproducible Analysis and Exploration of High-Throughput Biological Datasets
(Doctoral thesis; Doktorgradsavhandling, 2019-01-21)This dissertation argues that we can develop unified systems for reproducible exploration and analysis of high-throughput biological datasets. We propose an approach, Small Modular Entities (SME), that orchestrates the execution of analysis pipelines and data exploration applications. We realize SMEs using software container technologies together with well-defined interfaces, configuration, and ... -
In-situ Measurements of Mesospheric Aerosols - On the observable characteristics of nanoscale ice and meteoric smoke particles
(Doctoral thesis; Doktorgradsavhandling, 2019-01-24)Two sounding rocket payloads were launched from Andøya Space Centre (69.29 N, 16.02 E) during the summer of 2016 within the MAXIDUSTY campaign. Their payloads contained instrumentation aimed at investigating the characteristics of nanoscale aerosols in the upper summer mesosphere, and the role of these particles in phenomena like noctilucent clouds and polar mesospheric summer echoes (PMSE). The ... -
Methane bubbles in the Arctic Ocean. Quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere
(Doctoral thesis; Doktorgradsavhandling, 2018-11-09)Intensive but heterogeneous and transient seepage of methane (CH4) bubbles from the seafloor exist west of Prins Karls Forland (PKF), offshore western Svalbard. The powerful greenhouse gas CH4, has 32 times higher warming potential than carbon dioxide (CO2) and if seepage of CH4 from the seafloor reaches the atmosphere, it will contribute to the warming climate. Warming of the oceans may in turn, ... -
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. ... -
Advancing Segmentation and Unsupervised Learning Within the Field of Deep Learning
(Doctoral thesis; Doktorgradsavhandling, 2018-10-19)Due to the large improvements that deep learning based models have brought to a variety of tasks, they have in recent years received large amounts of attention. However, these improvements are to a large extent achieved in supervised settings, where labels are available, and initially focused on traditional computer vision tasks such as visual object recognition. Specific application domains that ... -
Reconstructing the Paleoproterozoic sulfur cycle: Insights from the multiple sulfur isotope record of the Zaonega Formation, Karelia, Russia
(Doctoral thesis; Doktorgradsavhandling, 2018-11-08)Earth’s oxygen-rich atmosphere and its capacity to sustain complex life is the most paramount feature that distinguishes Earth from all other planets. The irreversible oxygenation of atmosphere occurred about half way through Earth’s history at ~2.3 Ga (the Great Oxidation Event – GOE) when for the first-time photosynthetic oxygen production surpassed the consumption by chemical reactions allowing ... -
Unmanned aerial vehicles for marine mammal surveys in arctic and sub-arctic regions
(Doctoral thesis; Doktorgradsavhandling, 2018-06-19)New tools and methods are needed to monitor marine resources so that industrial activities can be conducted without (or at least minimizing) adverse impacts on species of concern. UAVs can be used as a complementary or alternative tool to current methods for monitoring and research of marine mammals. This study highlights current knowledge gaps and the need for further empirical testing of these ... -
Advancing relativistic electronic structure methods for solids and in the time domain
(Doctoral thesis; Doktorgradsavhandling, 2018-08-28)Effects arising from the special theory of relativity significantly influence the electronic structure and properties of molecules and solid-state materials containing heavy elements. At the same time, the inclusion of the relativistic effects in theoretical and computational models increases their methodological complexity and the computational cost. In the solid state, additional challenges ... -
KAIRA - The Kilpisjärvi Atmospheric Imaging Receiver Array
(Doctoral thesis; Doktorgradsavhandling, 2018-08-24)The Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) is a phased-array radio detector located in Arctic Finland, where auroral electron precipitation is common. This unique deployment of a modern radio telescope in an unconventional location has resulted in a novel and powerful instrument capable of carrying out a large variety of remote-sensing, geoscience experiments. This work presents a ... -
Octaiodoporphyrin and Octaiodocorrole: Isolation of a Cis Porphyrin Tautomer
(Doctoral thesis; Doktorgradsavhandling, 2018-09-28)Iodinated aromatics are excellent starting materials for further elaboration via transition-metal-catalyzed cross-coupling reactions. Considering the diverse applications of porphyrins and corroles - as photosensitizers in photodynamic therapy, dye sensitized solar cells, near-infrared dyes, gas sensors, nonlinear optical materials, and catalysts - the synthetic potential of β-polyiodinated or ... -
Statistical properties of intermittent fluctuations in the boundary of fusion plasmas
(Doctoral thesis; Doktorgradsavhandling, 2018-06-14)Fluctuation-induced plasma–wall interactions is a major concern for the next generation, high duty-cycle magnetic confinement fusion devices. The turbulence is generated in the outboard midplane transition region between the confined core plasma and the scrape-off layer where magnetic field lines intersect material walls. Here, filaments of hot and dense plasma, elongated in the field direction, ... -
Multi-frequency radar remote sensing of sea ice. Modelling and interpretation of polarimetric multi-frequency radar signatures of sea ice
(Doctoral thesis; Doktorgradsavhandling, 2018-06-08)This thesis deals with polarimetric multi-frequency radar signatures of sea ice. It presents a thorough background on the topic and three case studies. The first study presents a global sensitivity analysis of the fully polarimetric radar backscatter response from snow covered sea ice. The analysis is global in the sense that it takes into account the observed ranges of sea ice properties that ... -
Mid/Late Devonian-Carboniferous extensional faulting in Finnmark and the SW Barents Sea
(Doctoral thesis; Doktorgradsavhandling, 2018-05-24)In northern Norway, late/post-Caledonian extension initiated along inverted, brittle-ductile thrusts, e.g. Sørøya-Ingøya shear zone, which truncated existing, margin-oblique, late Neoproterozoic, Timanian faults and margin-parallel, latest Mesoproterozoic-mid Neoproterozoic faults related to the opening of the Asgard Sea and Iapetus Ocean. Inverted thrusts were active through the Devonian and early ... -
Synthesis and inhibitor design of carbapenemase inhibitors
(Doctoral thesis; Doktorgradsavhandling, 2018-05-24)The efficiency of bacteria in acquiring resistance for their survival ensures a never-ending war against resistance. The only tactic to curtail the resistance crisis is to keep pace with it, e.g. by continuous development of new antibiotics with activity against resistant bacteria or revival of existing agents by inhibiting the mechanisms of resistance. β-lactams are the largest and most widely used ...