Fakultet for naturvitenskap og teknologi: Recent submissions
Now showing items 841-860 of 5316
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On the time-dependence of climate sensitivity
(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. ... -
Origin and Economic Potential of Lithium-mineralized Granitic Pegmatites in Helgeland, North Norway
(Mastergradsoppgave; Master thesis, 2023-08-04)A comprehensive set of analytical techniques, encompassing geological, petrographic, mineralogical, and zircon U-Pb-Hf isotopic compositions, was employed to investigate a relatively poorly known pegmatite field located in Helgeland, North Norway. The Paleoproterozoic basement gneisses in the area have U-Pb zircon crystallization ages between 1870 ± 12 and 1811 ± 6 Ma, meaning that they belong to ... -
Exploring late Pleistocene bioturbation on Yermak Plateau to assess sea-ice conditions and primary productivity through the Ethological Ichno Quotient
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-13)Central Arctic, interglacial intervals have traditionally been associated with diverse and intense bioturbation, and abundant foraminifera, interpreted as indicating relatively low sea-ice concentrations and productive surface waters, while glacial intervals, typically barren, support the inverse. In this respect, the Yermak Plateau is anomalous. Biomarker studies suggest that glacial intervals were ... -
Selective Imputation for Multivariate Time Series Datasets with Missing Values
(Journal article; Tidsskriftartikkel, 2023-01-31)Multivariate time series often contain missing values for reasons such as failures in data collection mechanisms. Since these missing values can complicate the analysis of time series data, imputation techniques are typically used to deal with this issue. However, the quality of the imputation directly affects the performance of downstream tasks. In this paper, we propose a selective imputation ... -
The South American monsoon approaches a critical transition in response to deforestation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-04)The Amazon rainforest is threatened by land-use change and increasing drought and fire frequency. Studies suggest an abrupt dieback of large parts of the rainforest after partial forest loss, but the critical threshold, underlying mechanisms, and possible impacts of forest degradation on the monsoon circulation remain uncertain. Here, we use a nonlinear dynamical model of the moisture transport ... -
Radar studies of plasma parameters in the polar cap and the auroral zone
(Doctoral thesis; Doktorgradsavhandling, 2018-04-11)Incoherent scatter radar measurements are an important source for studies of ionospheric plasma parameters. Data from the EISCAT Svalbard radar (ESR), which covers the polar cap and cusp, and from the EISCAT Tromsø radars, which covers the auroral zone, can be used to obtain information about the electron density, electron- and ion temperature, and line-of-sight plasma velocity. As the ESR started ... -
ScopeSense: An 8.5-Month Sport, Nutrition, and Lifestyle Lifelogging Dataset
(Chapter; Bokkapittel, 2023-03-29)Nowadays, most people have a smartphone that can track their everyday activities. Furthermore, a significant number of people wear advanced smartwatches to track several vital biomarkers in addition to activity data. However, it is still unclear how these data can actually be used to improve certain aspects of people’s lives. One of the key challenges is that the collected data is often massive and ... -
Capturing Nutrition Data for Sports: Challenges and Ethical Issues
(Chapter; Bokkapittel, 2023)Nutrition plays a key role in an athlete’s performance, health, and mental well-being. Capturing nutrition data is crucial for analyzing those relations and performing necessary interventions. Using traditional methods to capture long-term nutritional data requires intensive labor, and is prone to errors and biases. Artificial Intelligence (AI) methods can be used to remedy such problems by using ... -
Centre for ice, Cryosphere, Carbon and Climate (iC3)- closing large scale uncertainty in Polar ice sheet impacts on the global carbon cycle
(Conference object; Konferansebidrag, 2023-08)Recently funded for 10 years by the Research Council of Norway centres of excellence scheme, iC3 aims to fill a major research gap in polar science by quantifying the future impact of ice sheet change on Earth’s carbon cycle over policy-relevant timescales. It will achieve this by uniting complementary expertise at UiT The Arctic University of Norway, the Norwegian Polar Institute and a network of ... -
Enhancing Decision-making in the Electric Power Sector with Machine Learning and Optimization
(Doctoral thesis; Doktorgradsavhandling, 2023-10-23)<p>The electric power system infrastructure is essential for modern economies and societies, as it provides the electricity needed to power homes, businesses, and industries. It is of critical importance that the operation of the electric power system is optimized to serve the electricity demand reliably and sustainably. Advances in machine learning and optimization have enabled the potential to ... -
Assimilation of high-resolution ice charts in a coupled ocean-sea-ice model
(Journal article; Tidsskriftartikkel, 2019)In this study, we show assimilation results from a coupled ocean sea-ice model. The model has a horizontal resolution of 2.5 km. In the assimilation system, we assimilate high-resolution ice charts, structured on a 1 km grid. We compare the assimilation of passive microwave observations with the assimilation of ice charts. It is shown that the ice charts have a larger impact on the assimilation ... -
Benthic foraminiferal investigations in Middle to Late Quaternary sections of Kongsfjordhallet, north-west Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-29)Stratigraphic sites in north-west Svalbard record at least six significant glacial advances in the last 200 Ky, and sediments deposited under locally high relative sea level during intervening interstadials or interglacials contain abundant benthic foraminifera. We present a biostratigraphic record from the Kongsfjordhallet site in the Kongsfjorden area that covers five high relative sea-level events ... -
Image analysis and segmentation of polar mesospheric summer echoes
(Conference object; Konferansebidrag, 2022-07) -
Auxiliary Network: Scalable and agile online learning for dynamic system with inconsistently available inputs
(Journal article; Tidsskriftartikkel, 2022-04-13)Streaming classification methods assume the number of input features is fixed and always received. But in many real-world scenarios, some features are reliable while others are unreliable or inconsistent. We propose a novel online deep learning-based model called Auxiliary Network (Aux-Net), which is scalable and agile and can handle any number of inputs at each time instance. The Aux-Net model is ... -
Mapping and characterization of unstable slopes with Sentinel-1 multi-geometry InSAR (activity line 2: public sector applications)
(Research report; Forskningsrapport, 2020)This is a high-level report that summarizes the main achievements and results of the research and development conducted in the project “Mapping and Characterization of unstable slopes with Sentinel-1 multi-geometry InSAR (activity line 2: public sector applications)”, where multi-geometry Sentinel-1 Synthetic Aperture Radar Interferometry (InSAR) is used for improving characterization of unstable ... -
Emergency management competence needs: Education and training for key emergency management personnel in a maritime Arctic environment MARPART2-(MAN), Project Report 2
(Research report; Forskningsrapport, 2020)This report focuses on competence demands among key management personnel responsible for maritime emergency response. The report has a special focus on competence challenges related to operations in an Arctic environment. -
A multi-source-to-sink system in a dynamic plate tectonic setting: the Cenozoic of the Barents Sea, Norwegian Arctic
(Conference object; Konferansebidrag, 2022)<p>When multiple source areas are located on a continuously moving plate margin relative to a sink, the signal propagation in the source-to-sink system may vary significantly in time and space. How fast and severe the impact of tectonics and climate is on sediment erosiontransfer-deposition in this dynamic setting is still not well understood. Similarly, how do we quantify the relative sediment ... -
Underexplored continental shelf gateways: timing, mechanisms and role of SW Barents Sea Gateway, Norwegian Arctic
(Conference object; Konferansebidrag, 2022)Ocean gateways connecting ocean basins are crucial for water and heat circulation, which influence global temperature, climate evolution and sediment distribution. While deep-water gateways have been a major research focus by the community, very little attention has been drawn to shallower gateways located on the continental shelves, where such circulation also takes place. In this study, we investigate ... -
Sediment source-to-sink analysis in the Norwegian Arctic
(Conference object; Konferansebidrag, 2022) -
Structured Illumination Microscopy of Biological Structures
(Conference object; Konferansebidrag, 2018)<p>Resolution in optical microscopy has long been limited to the Abbe diffraction limit, i.e. about 250 nm laterally for visible wavelengths on a very good microscope. In the last two decades several techniques have been devised to circumvent this limit: an achievement which was recognized with the 2014 Nobel Prize in Chemistry. Structured Illumination Microscopy (SIM) was the first of these techniques ...