Viser treff 180-199 av 290

    • Octaiodoporphyrin and Octaiodocorrole: Isolation of a Cis Porphyrin Tautomer 

      Thomassen, Ivar Kristian (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 ...
    • The Omni-Kernel Architecture: Scheduler Control Over All Resource Consumption in Multi-Core Computing Systems 

      Kvalnes, Åge Andre (Doctoral thesis; Doktorgradsavhandling, 2014-03-13)
      Clouds commonly employ virtual machine technology to leverage and efficiently utilize computational resources in data centers. The workloads encapsulated by virtual machines contend for the resources of their hosting machines and interference from resource sharing can cause unpredictable performance. Despite the use of virtual machine technology, the role of the operating system as an arbiter of ...
    • On Automated Classification of Sea Ice Types in SAR Imagery 

      Lohse, Johannes (Doctoral thesis; Doktorgradsavhandling, 2021-03-12)
      With the Arctic sea ice continuously decreasing in both extent and thickness, fast and robust production of reliable ice charts becomes more important to ensure the safety of Arctic operations. This thesis focuses on the development of automated algorithms for the mapping of sea ice from synthetic aperture radar (SAR) images. It presents a thorough background on the topics of sea ice observations ...
    • On local and long-range transported air pollution in Svalbard 

      Dekhtyareva, Alena (Doctoral thesis; Doktorgradsavhandling, 2019-09-11)
      Climate change, health of the residents and ecosystems in the Arctic region are impacted by local and long-range transported air pollution. Local emissions in the Arctic are important, but overlooked issue. Despite there have been extensive modelling and measurement studies of long-range transport of short-lived climate forcers to Svalbard, the effect of local emissions from diesel and coal power ...
    • On polar lows and their formation 

      Stoll, Patrick Johannes (Doctoral thesis; Doktorgradsavhandling, 2020-09-18)
      Polar lows are small, but extreme cyclones that develop in marine polar air mass. They feature one of the largest natural hazards in the polar regions. Their associated strong winds, high waves, substantial amounts of snow fall, low visibility and possibility for ice accumulation on ships and airplanes cause threats for coastal communities and marine operations. Hence, accurate prediction of polar ...
    • On sea-ice forecasting 

      Fritzner, Sindre Markus (Doctoral thesis; Doktorgradsavhandling, 2020-05-15)
      Accurate sea-ice prediction is essential for safe operations in the Arctic and potentially also for weather forecast at high-latitudes. The increasing number of sea-ice related satellite observations in the Arctic can be used to improve the model predictions through data assimilation. For sea ice, sea-ice concentration (SIC) observations have been available for many years. Observational information ...
    • On the Evolvability of OXA-48. A comprehensive study of new functions within the β-lactamase OXA-48 

      Fröhlich, Christopher (Doctoral thesis; Doktorgradsavhandling, 2021-08-27)
      Our understanding of how antimicrobial resistance enzymes evolve to expand their substrate spectrum is limited. OXA-48, an enzyme able to catalyse the hydrolysis of β-lactam drugs, has become one of the most successfully disseminating β-lactamases. Although OXA-48 hydrolyses penicillins with high efficiency, its activity towards oxyimino cephalosporins, such as ceftazidime, is limited. Thus, ceftazidime ...
    • On the Generalized Curvature Ocean Surface Scattering Model for the NRCS and Doppler Frequency and its application to ocean surface wind retrieval from Synthetic Aperture Radar data 

      Said, Faozi (Doctoral thesis; Doktorgradsavhandling, 2015-01-23)
      Ocean wind monitoring is an integral part of weather forecasting, maritime shipping lane planning, offshore wind research, as well as the study of climate patterns. Satellite radar instruments, such as Synthetic Aperture Radars (SAR), can help achieve this important task by monitoring the wind conditions over the sea surface. Using specially developed functions, called geophysical model functions, ...
    • On the linkage between atmospheric circulation changes and Arctic climate change 

      Heiskanen, Tuomas Ilkka Henrikki (Doctoral thesis; Doktorgradsavhandling, 2022-06-10)
      Polar amplification is a prominent feature of recent and projected climate change. The Arctic region shows some of the strongest signs of climate change, including sea-ice retreat and temperatures increasing at twice the rate averaged over the northern hemisphere. A major concern for humanity is the sea-level rise associated with the melting of the ice-sheets and glaciers due to climate change. The ...
    • On the time-dependence of climate sensitivity 

      Eiselt, Kai-Uwe (Doctoral thesis; Doktorgradsavhandling, 2023-11-03)
      Climate sensitivity is the change of the global-mean surface temperature in response to a doubling of the CO2 concentration. It is typically used to describe climate change and to inform decision-making for mitigation and adaptation. Climate sensitivity is often estimated in numerical climate model experiments. A remarkable result from these experiments is that climate sensitivity changes over time. ...
    • On-chip optical nanoscopy: towards high throughput and multi-modality 

      Helle, Øystein Ivar (Doctoral thesis; Doktorgradsavhandling, 2019-11-07)
      Super-resolution microscopy techniques improve the resolution of the optical microscope beyond the diffraction limit of light. A range of different techniques demands different optical configurations and clever illuminating strategies to enhance the resolution. This has led to the development of advanced instrumentation, where the super-resolution mechanisms are adding both cost and bulk to the ...
    • Operationalising Critical Infrastructure Resilience. From Assessment to Management 

      Rød, Bjarte (Doctoral thesis; Doktorgradsavhandling, 2020-09-03)
      Over recent decades, it has been evident that society relies heavily on critical infrastructures (CIs) to provide and maintain vital societal functions, such as water, electricity and transportation. Traditionally, in order to ensure the delivery of such functions, the focus has been on protecting the infrastructures’ systems from adverse and extreme events. However, large-scale events, such as ...
    • Optical Forces, Waveguides and Micro Raman Spectroscopy 

      Løvhaugen, Pål (Doctoral thesis; Doktorgradsavhandling, 2012-12-21)
      Optical waveguides are used to confine propagating light. In a dielectric waveguide, a small part of the propagating light travels along and just outside the waveguide surface. This evanescent field can interact with objects on the waveguide surface. Two effects of this light-matter interaction are presented, optical forces and Raman scattering. Optical forces are caused by changes in the momentum ...
    • Optical properties of snow and sea ice field measurements, parameterization schemes and validation 

      Pedersen, Christina Alsvik (Doctoral thesis; Doktorgradsavhandling, 2007-12)
      Optiske Egenskaper av Snø og Sjøis: Felt målinger, Modellbeskrivelse og Validering av Modeller I dag hersker det liten tvil om at de raske temperatur endringene vi er vitne til er menneskeskapte. Temperaturen øker dobbelt så hurtig i Arktis i forhold til i resten av verden, med den konsekvensen at sjøisen i Arktis smelter med akselererende hastighet. Klimamodeller kan beskrive fortidens, nåtidens ...
    • Optical remote sensing of water quality parameters retrieval in the Barents Sea 

      Asim, Muhammad (Doctoral thesis; Doktorgradsavhandling, 2023-03-31)
      <p>This thesis addresses various aspects of monitoring water quality indicators (WQIs) using optical remote sensing technologies. The dynamic nature of aquatic systems necessitate frequent monitoring at high spatial resolution. Machine learning (ML)-based algorithms are becoming increasingly common for these applications. ML algorithms are required to be trained by a significant amount of training ...
    • Optical Waveguides for Infrared Spectroscopic Detection of Molecular Gases 

      Vlk, Marek (Doctoral thesis; Doktorgradsavhandling, 2021-06-18)
      Fields like medical diagnostics, urban and industrial environmental monitoring or basic microbiological research greatly benefit from advances in chemical and biological sensing. These applications require rapid sample analysis, reduced needs for sample handling, or good sensor network. Such demands can be met with miniaturised sensors utilising methods which secure sufficient sensitivity and ...
    • Origins and impacts of spatial and temporal long-range dependence in the climate system 

      Fredriksen, Hege-Beate (Doctoral thesis; Doktorgradsavhandling, 2017-11-27)
      The internal variability of most Earth surface temperatures has a power spectral density well described by a power law, S(f) ~ f<sup>-β</sup>, and we typically observe 0 < β < 1. This characterizes variability exhibiting long-range dependence (LRD), which has no characteristic time scale. However, there is no consensus about the physical mechanisms behind this property, and the topic of this thesis ...
    • The OXA-class of β-lactamases. A structural view on antibiotic resistance 

      Lund, Bjarte Aarmo (Doctoral thesis; Doktorgradsavhandling, 2017-09-01)
      Antibiotic resistance is a topic that concerns everyone, and by 2050 deaths due to antibiotic resistant bacteria may surpass number of deaths due to cancer. The OXA-class of antibiotic resistance enzymes is a formidable threat, but has not received the same attention as other resistance enzymes. The goal of the project was to understand antibiotic resistance enzymes at an atomic scale and to develop ...
    • Palaeoenvironment of the Barents Sea during the last deglaciation and Holocene : processes and timing 

      Rüther, Denise Christina (Doctoral thesis; Doktorgradsavhandling, 2012-03-01)
      The scope of this PhD thesis is twofold: Firstly, processes, patterns and timing of the last deglaciation in the Barents Sea are reconstructed and secondly, depositional conditions on the Barents shelf during Holocene are elucidated. This cumulative PhD thesis encompasses an introductory part and five papers - three as first-author and two as co-author. Three papers are focused on the most prominent ...
    • Paleoceanography of the NE North Atlantic during the Holocene 

      Groot, Diane (Doctoral thesis; Doktorgradsavhandling, 2014-09-26)
      This thesis aimed at enhancing our understanding of the oceanographic variability of the Nordic Seas during the last 11,000 years. The Nordic Seas are a key area within the Atlantic Meridional Overturning Circulation (AMOC), a process which helps to maintain the present mild climate of northwestern Europe through its meridional heat transport and plays an important role in global heat distribution. ...