Doktorgradsavhandlinger (NT-fak): Nye registreringer

Viser treff 121-140 av 294

    • Subglacial hydrology of the Fennoscandian and Barents Sea ice sheets 

      Shackleton, Calvin (Doctoral thesis; Doktorgradsavhandling, 2019-06-11)
      The drainage of meltwater beneath ice sheets exerts a fundamental control on ice flow variability, by regulating the lubrication of the ice-bed interface, and determining subglacial sediment shear strengths. This thesis investigates meltwater drainage of the Fennoscandian and Barents Sea ice sheets through the combined application of geomorphologically based reconstruction and modelling of subglacial ...

    • Scales of tectonic processes controlling fluid flow systems on the Svyatogor Ridge, Fram Strait 

      Waghorn, Kate Alyse (Doctoral thesis; Doktorgradsavhandling, 2019-06-13)
      The Svyatogor Ridge, located in the Fram strait, is a site hosting a fluid flow system. The Svyatogor Ridge is part of the inside corner high at the Knipovich Ridge-Molloy Transform fault intersection. The Knipovich Ridge is an ultra-slow, melt-poor spreading ridge with approximately 8 mm/yr spreading rate. At this northernmost segment of the Knipovich Ridge, spreading is predominantly accommodated ...

    • Bidirectional and Spectral Reflectance Properties of the Cladina stellaris and Flavocetraria nivalis lichens and the Racomitrium lanuginosum moss 

      Solheim, Inger (Doctoral thesis; Doktorgradsavhandling, 1998-06-04)
      In this thesis we present a scientific investigation of the spectral and bidirectional reflectance properties of two lichen species, <i>Flavocetraria nivalis</i> and <i>Cladina stellaris</i>, and one moss, <i>Racomitrium lanuginosum</i>. The spectral and bidirectional characterizations were based on high-quality laboratory measurements made in the European Goniometer facility, at the Joint Research ...

    • Differential invariants of Lie pseudogroups 

      Schneider, Eivind (Doctoral thesis; Doktorgradsavhandling, 2019-05-10)
      We compute differential invariants for several Lie pseudogroups, and use them for solving the equivalence and classification problem for a variety of mathematical structures appearing in geometry and mathematical physics. We demonstrate utility of the algebra of rational scalar differential invariants for solving these two problems, also in cases where the structures are given as solutions to a ...

    • Cryosphere-controlled methane release throughout the last glacial cycle 

      Serov, Pavel (Doctoral thesis; Doktorgradsavhandling, 2018-12-04)
      <p>The cryosphere of Arctic regions is undergoing rapid change due to century-scale global warming superimposed on millennial-scale natural climatic perturbations that started at the end of the last glacial cycle approximately 20,000 years ago [Slaymaker and Kelly, 2009]. The cryosphere refers to areas where low temperatures freeze water and form ice in the ocean (sea ice), on land (glaciers, ...

    • Quantification of the magnitude of net apparent erosion in the southwestern Barents Sea by using compaction trends in shales and sandstones – Implications for hydrocarbon exploration 

      Ktenas, Dimitrios (Doctoral thesis; Doktorgradsavhandling, 2019-03-28)
      On the Norwegian Continental Shelf, the western Barents Sea shelf is generally ice-free and proven by recent discoveries as a frontier area for hydrocarbon exploration. During the Cenozoic, most of the areas of the Barents Sea were subjected to significant uplift and erosion, processes that have had important consequences on the petroleum systems.<p> <p>This thesis aimed to investigate the ...

    • Solar resource assessment at high latitude regions 

      Babar, Bilal (Doctoral thesis; Doktorgradsavhandling, 2019-03-22)
      There has been a growing interest in accurately estimating surface solar radiation at high latitude locations. From a Scandinavian perspective, the installed solar photovoltaic share is increasing, primarily because of the declining cost of these systems, the introduction of various economic incentives and societal push to generate one’s own clean power. In the coming years, it is anticipated that ...

    • Monitoring of Marine Ice and its Thickness for Ship Anti-/De-icing - Experimental and Analytical Study using Infrared Thermography 

      Rashid, Taimur (Doctoral thesis; Doktorgradsavhandling, 2019-03-01)
      Ships operating in a cold climate face many challenges. There are several associated risks such as safety concerns, down time, energy consumption and limited resources. Amongst the key challenges, ship ice accretion is significant for cold climate operations. Exposing superstructures to the marine icing phenomenon can affect the ship’s operations, risking the safety of humans and machines. In this ...

    • The nonlinear nature of biology 

      Måløy, Marthe (Doctoral thesis; Doktorgradsavhandling, 2019-03-27)
      In this thesis, we explore the stability and the breakdown of stability of biological systems. The main examples are the blood system and invasion of cancer. However, the models presented in the thesis apply to several other examples. Biological systems are characterised by both competition and cooperation. Cooperation is based on an unsolvable dilemma: Even though mutual cooperation leads to ...

    • The EOS Formulation for Linear and Nonlinear Transient Scattering Problems 

      Lin, Aihua (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 

      Waage, Malin (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 

      Thode, Sunniva Katharina (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 

      Olufsen, Magne (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 

      Holsbø, Einar Jakobsen (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 

      Mikalsen, Karl Øyvind (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 

      Fjukstad, Bjørn (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 

      Antonsen, Tarjei (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 

      Jansson, Pär (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 

      Farnsworth, Wesley Randall (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 

      Kampffmeyer, Michael Christian (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 ...