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norskFakultet for naturvitenskap og teknologi: Nye registreringer
Viser treff 2901-2920 av 5336
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Four dimensional quantification of Kelvin-Helmholtz instabilities in the polar summer mesosphere using volumetric radar imaging
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-13)We present and characterize in time and three spatial dimensions a Kelvin‐Helmholtz Instability (KHI) event from polar mesospheric summer echoes (PMSE) observed with the Middle Atmosphere Alomar Radar System. We use a newly developed radar imaging mode, which observed PMSE intensity and line of sight velocity with high temporal and angular resolution. The identified KHI event occurs in a narrow layer ... -
Physical controls of dynamics of methane venting from a shallow seep area west of Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-06)We investigate methane seepage on the shallow shelf west of Svalbard during three consecutive years, using discrete sampling of the water column, echosounder-based gas flux estimates, water mass properties, and numerical dispersion modelling. The results reveal three distinct hydrographic conditions in spring and summer, showing that the methane content in the water column is controlled by a combination ... -
Analysis of Oil Spill and Sea Ice Measurements Using Full-Polarimetric and Hybrid-Polarity Synthetic Aperture Radar data
(Doctoral thesis; Doktorgradsavhandling, 2019-12-05)Synthetic Aperture Radar (SAR) data has been used for decades to detect oil slicks and monitoring sea ice. With increased oil and gas exploration in the Arctic follows higher risk for oil spills. Knowledge of the sea ice and oil spills is important for making clever and efficient decisions in a hectic and non-hectic operational situation. The potential and limitations of the hybrid-polarity (HP) SAR ... -
Cosmic noise absorption during solar proton events in WACCM-D and riometer observations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-18)Solar proton events (SPEs) cause large‐scale ionization in the middle atmosphere leading to ozone loss and changes in the energy budget of the middle atmosphere. The accurate implementation of SPEs and other particle ionization sources in climate models is necessary to understand the role of energetic particle precipitation in climate variability. We use riometer observations from 16 riometer stations ... -
Spatial extent of solar proton impact in the Earth's atmosphere - Observations and modeling
(Doctoral thesis; Doktorgradsavhandling, 2019-12-18)Solar proton events cause large-scale ionization in the Earth's middle atmosphere leading to chemical changes, changes in the energy budget of the middle atmosphere, and radio wave absorption. The accurate implementation of the spatial impact of solar protons and other particle ionization sources in climate models is necessary to understand the role of energetic particle precipitation in natural ... -
Power-law scaling of uncorrelated plasma bursts
(Conference object; Konferansebidrag, 2019-07) -
Benthic Foraminifera in Arctic Methane Hydrate Bearing Sediments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-10)Benthic foraminifera have been widely used as proxy for paleo-methane emissions, mainly based on their stable isotopic signature. In cold seeps, the ecology of these organisms remains uncertain, in particular their ability to thrive during active phases of seepage. In this study, we evaluate the benthic foraminiferal response to methane seepage in Arctic sediments. We do so by examining living and ... -
Impact of drill cutting releases on benthic foraminifera at three exploration wells drilled between 1992 and 2012 in the SW Barents Sea, Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-04)The aim of this study is to identify the environmental impact of drill cuttings (DC) released around three wells drilled in 1992, 2000 and 2012 in the SW Barents Sea. Foraminiferal assemblages are studied in cores taken along transects <250 m from wells. Well E-1992 shows no impact of DC on foraminifera indicating that low amounts of released DC limit environmental impact. Impact at wells G-2000 and ... -
Lessons learned from accident and near-accident experiences in traffic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-17)The focus of this article is risky behavior in traffic. What do people learn from accidents and near-accidents? Experience with accidents may demand increased caution. However, near-accidents are inherently ambiguous: On the one hand, they signal that margins were good enough, inspiring increased risk-taking; on the other hand, they signal danger that could induce increased caution. To explore these ... -
Quality of life in substance use disorder patients with and without attention deficit hyperactivity disorder 12 months after treatment: a naturalistic follow-up study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-22)There is sparse research on quality of life (QoL) as an outcome measure in patients with substance use disorders (SUD), with or without attention deficit hyperactivity disorder (ADHD). We aimed to investigate whether SUD patients with and without ADHD (SUD + ADHD vs. SUD − ADHD) differed in QoL at baseline and at a 12-month follow-up after SUD treatment. The groups were additionally compared with ... -
Sylfjellet: a new outcrop of the Paleogene Van Mijenfjorden Group in Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-05)A hitherto unrecognized Paleogene outcrop has been discovered at Sylfjellet, a mountain located at the northern side of Isfjorden, Svalbard. The strata, which cover an area of 0.8 km2, have until now been assigned to the Lower Cretaceous succession of the Adventdalen Group. In this study, the Sylfjellet site was studied in detail to provide an updated structural and sedimentological description of ... -
Postglacial paleoceanography of the western Barents Sea: Implications for alkenone-based sea surface temperatures and primary productivity
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-11)The increasing influence of Atlantic Water (AW) in the Barents Sea, a process known as “Atlantification”, is gradually decreasing sea ice cover in the region. Ongoing global climate warming is likely to be one of its drivers, but to further understand the role of natural variability and the biogeochemical impacts of the inflow of AW into the western Barents Sea, we reconstructed sea surface temperatures ... -
Advancing Deep Learning for Automatic Autonomous Vision-based Power Line Inspection
(Doctoral thesis; Doktorgradsavhandling, 2019-12-03)Electricity is fundamental to the ability to function of almost all modern-day societies. To maintain the reliability, availability, and sustainability of electricity supply, electric utilities are usually required to perform visual inspections on their electrical grids regularly. These inspections have been typically carried out using a combination of airborne surveys via low-flying helicopters and ... -
Synthetic Aperture Radar Remote Sensing of Operational Platform Produced Water Releases
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-03)Oil spill detection services based on satellite synthetic aperture radar (SAR) frequently detect oil slicks close to platforms due to legal releases of produced water. Separating these slicks from larger releases, e.g., due to accidental leakage is challenging. The aim of this work is to investigate the SAR characteristics of produced water, including the typical appearance in HH/VV data, possible ... -
Data-driven modeling and prediction of blood glucose dynamics: Machine learning applications in type 1 diabetes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-26)<i>Background</i>: Diabetes mellitus (DM) is a metabolic disorder that causes abnormal blood glucose (BG) regulation that might result in short and long-term health complications and even death if not properly managed. Currently, there is no cure for diabetes. However, self-management of the disease, especially keeping BG in the recommended range, is central to the treatment. This includes actively ... -
Evolution of a rock slope failure at Skredkallen, Vannøya
(Master thesis; Mastergradsoppgave, 2019-11-15)Rock slope failures are known major contributors to landscape evolution in alpine Norway, and also pose a threat to people and infrastructure in the present day. By examining the history of rock slope failures at active rockslide sites an understanding of recurrence intervals and triggering mechanisms can be achieved. The focus of this study is to form a complete picture of the evolution of an area ... -
Four-component relativistic time-dependent density-functional theory using a stable noncollinear DFT ansatz applicable to both closed- and open-shell systems
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-14)We present a formulation of relativistic linear response time-dependent density functional theory for the calculation of electronic excitation energies in the framework of the four-component Dirac-Coulomb Hamiltonian. This approach is based on the noncollinear <i>ansatz</i> originally developed by Scalmani and Frisch [J. Chem. Theory Comput. 8, 2193 (2012)] and improves upon the past treatment of ... -
Relativistic four-component linear damped response TDDFT for electronic absorption and circular dichroism calculations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-21)We present a detailed theory, implementation, and a benchmark study of a linear damped response time-dependent density functional theory (TDDFT) based on the relativistic four-component (4c) Dirac–Kohn–Sham formalism using the restricted kinetic balance condition for the small-component basis and a noncollinear exchange–correlation kernel. The damped response equations are solved by means of a ... -
Quantitatively reinterpreting atomic force microscopy via the data science paradigm
(Doctoral thesis; Doktorgradsavhandling, 2019-11-22)From the invention of the atomic force microscope (AFM) in 1986, tremendous efforts have been put into developing this tool. The AFM has long been considered as one of the top choices to probe the nanoscale world with the ability to achieve nanoscale resolution imaging of surfaces under different environments. Advances in instrumentation combined with the exploitation of sophisticated data analysis ... -
Separation and characterisation of mineral oil slicks and newly formed sea ice in L-band synthetic aperture radar
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-14)Maritime activities in the Arctic Ocean is increasing and consequently the risk for an oil spill there is rising. Synthetic Aperture Radar (SAR) is used operationally to detect and monitor oil slicks and for sea ice monitoring and observations. Leads are often used for ship routing and within the leads newly formed sea ice is often present. Separation between the low backscatter areas that constitutes ...
