Fakultet for naturvitenskap og teknologi: Recent submissions
Now showing items 2141-2160 of 5379
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The Pseudoalteromonas multipartite genome: distribution and expression of pangene categories, and a hypothesis for the origin and evolution of the chromid
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-21)Bacterial genomes typically consist of one large chromosome, but can also include secondary replicons. These so-called multipartite genomes are scattered on the bacterial tree of life with the majority of cases belonging to Proteobacteria. Within the class gamma-proteobacteria, multipartite genomes are restricted to the two families <i>Vibrionaceae</i> and <i>Pseudoalteromonadaceae</i>. Whereas the ... -
User Engagement in Developing Use-Inspired Glacial Lake Outburst Flood Decision Support Tools in Juneau and the Kenai Peninsula, Alaska
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-15)Glacial lake outburst floods (GLOFs) significantly affect downstream communities in Alaska. Notably, GLOFs originating from Suicide Basin, adjacent to Mendenhall Glacier, have impacted populated areas in Juneau, Alaska since 2011. On the Kenai Peninsula, records of GLOFs from Snow Glacier date as far back as 1949, affecting downstream communities and infrastructure along the Kenai and Snow river ... -
Roll motion on small traditional Norwegian fishing vessels
(Master thesis; Mastergradsoppgave, 2021-08-09)Roll motion is one of the six degrees of freedom and is the most difficult to predict, as roll motion is extremely sensitive to the viscous effect and induced flow separation. The smaller fishing vessel fleet commonly operates in almost all weather conditions, and sometimes in remote areas with cold arctic water where rescue can be far away and difficult. The safety of fishers depends on the vessel's ... -
Semi-supervised target classification in multi-frequency echosounder data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-12)Acoustic target classification in multi-frequency echosounder data is a major interest for the marine ecosystem and fishery management since it can potentially estimate the abundance or biomass of the species. A key problem of current methods is the heavy dependence on the manual categorization of data samples. As a solution, we propose a novel semi-supervised deep learning method leveraging a few ... -
Study of waveguide background at visible wavelengths for on-chip nanoscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-17)On-chip super-resolution optical microscopy is an emerging field relying on waveguide excitation with visible light. Here, we investigate two commonly used high-refractive index waveguide platforms, tantalum pentoxide (Ta<sub>2</sub>O<sub>5</sub>) and silicon nitride (Si<sub>3</sub>N<sub>4</sub>), with respect to their background with excitation in the range 488–640 nm. The background strength from ... -
Computer Modelling of an Enzyme Reference Reaction for Empirical Valence Bond Simulation
(Master thesis; Mastergradsoppgave, 2020-11-04)It is extensively recognized that an enzyme functions through reducing the energy of activation of its elemental reaction and the catalytic effect of an enzyme is as a result of a change in activation free energy obtained relative to a reference reaction in water of the same mechanism. In this study, chorismate mutase which is an enzyme that catalyzes biochemical reactions for chorismate conversion ... -
Antibiotic Resistance Breakers: Design and Synthesis of OXA-48 Inhibitors
(Master thesis; Mastergradsoppgave, 2020-06-01)Antibiotic resistance is threatening the achievements of modern medicine and will evidentially lead to a situation, in which we stand helpless against common bacterial infections. The largest and most widely used group of antibiotics are the β-lactams. One of the major resistance determinants against β-lactam antibiotics is the expression of hydrolytic enzymes, called β-lactamases (BLs). The main ... -
Measurement of snow water equivalent using drone-mounted ultra-wide-band radar
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-02)The use of unmanned aerial vehicle (UAV)-mounted radar for obtaining snowpack parameters has seen considerable advances over recent years. However, a robust method of snow density estimation still needs further development. The objective of this work is to develop a method to reliably and remotely estimate snow water equivalent (SWE) using UAV-mounted radar and to perform initial field experiments. ... -
Øvelse gjør mester? - Maktpyramide og trening i politiet
(Master thesis; Mastergradsoppgave, 2021-07-01)Masteroppgaven stiller spørsmål om tjenestepersoner i politiet gis adekvate treningsmessige forutsetninger for å leve opp til krav og forventninger om at samfunnsoppdraget skal løses med minst mulig bruk av makt i tråd med prinsippene om nødvendighet, forsvarlighet og forholdsmessighet nedfelt i politiloven § 6. Studien er gjennomført som en kvantitativ spørreundersøkelse med mål å kartlegge ... -
Avradikalisering og intervensjon: Utfordringer og mulige endringer
(Master thesis; Mastergradsoppgave, 2021-06-27)Endinger i verdensstrukturen har bidratt til utvikling av den tradisjonelle sikkerhetsrealiteten, mot mer komplekse og sammensatte systemer. Disse kompleksiteter har ført til dannelsen av nye risikoer og handlingsmønstre i håndteringen av radikalisering og voldelig ekstremisme. Denne studien handler om utfordringer som er tilfellet på ulike nivåer av det etablerte forebyggingssystemet. Oppgaven ser ... -
Lipids as Versatile Solvents for Chemical Synthesis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-23)Development of safe, renewable, cheap and versatile solvents is a longstanding challenge in chemistry. We show here that vegetable oils and related systems can become prominent solvents for organic synthesis. Suzuki–Miyaura, Hiyama, Stille, Sonogashira and Heck cross-couplings proceed with quantitative yields in a range of vegetable oils, fish oil, butter and waxes used as solvents. Appropriate ... -
Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-03)The organic-rich shales of the Middle Triassic Botneheia Formation in Svalbard and its correlative units offshore are considered important source rock intervals for oil and gas generation in the Norwegian Barents Shelf region. Detailed investigation of these intervals is essential to better understand the intra source rock variations and thus to improve exploration models. As source rocks are rarely ... -
Revisiting Trans-Arctic Maritime Navigability in 2011–2016 from the Perspective of Sea Ice Thickness
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-14)Arctic navigation has become operational in recent decades with the decline in summer sea ice. To assess the navigability of trans-Arctic passages, combined model and satellite sea ice thickness (CMST) data covering both freezing seasons and melting seasons are integrated with the Arctic Transportation Accessibility Model (ATAM). The trans-Arctic navigation window and transit time are thereby obtained ... -
Bacteriophage origin of some minimal ATP-dependent DNA ligases: a new structure from Burkholderia pseudomallei with striking similarity to Chlorella virus ligase
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-21)DNA ligases, the enzymes responsible for joining breaks in the phosphodiester backbone of DNA during replication and repair, vary considerably in size and structure. The smallest members of this enzyme class carry out their functions with pared-down protein scaffolds comprising only the core catalytic domains. Here we use sequence similarity network analysis of minimal DNA ligases from all biological ... -
Auroral Image Processing Techniques - Machine Learning Classification and Multi-Viewpoint Analysis
(Doctoral thesis; Doktorgradsavhandling, 2021-09-30)Every year, millions of scientific images are acquired in order to study the auroral phenomena. The accumulated data contain a vast amount of untapped information that can be used in auroral science. Yet, auroral research has traditionally been focused on case studies, where one or a few auroral events have been investigated and explained in detail. Consequently, theories have often been developed ... -
Convergence and completeness for square-well Stark resonant state expansions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-02)In this paper, we investigate the completeness of the Stark resonant states for a particle in a square-well potential. We find that the resonant state expansions for target functions converge inside the potential well and that the existence of this convergence does not depend on the depth of the potential well, <i>V</i><sub>0</sub>. By analyzing the asymptotic form of the terms in these expansions, ... -
Constructing a partially transparent computational boundary for UPPE using leaky modes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-19)In this paper, we introduce a method for creating a transparent computational boundary for the simulation of unidirectional propagation of optical beams and pulses using leaky modes. The key element of the method is the introduction of an artificial-index material outside a chosen computational domain and utilization of the quasi-normal modes associated with such artificial structure. The method is ... -
Nonlinear optics
(Doctoral thesis; Doktorgradsavhandling, 2021-09-24)Nonlinear light-matter interactions have been drawing attention of physicists since the 1960's. Quantum mechanics played a significant role in their description and helped to derive important formulas showing the dependence on the intensity of the electromagnetic field. High intensity light is able to generate second and third harmonics which translates to generation of electromagnetic field with ... -
Individual-Based Modeling of COVID-19 Vaccine Strategies
(Master thesis; Mastergradsoppgave, 2021-06-01)COVID-19 is a respiratory disease with influenza-like symptoms originating from Wuhan, China, towards the end of 2019. There has been developed multiple vaccines to contain the virus and to protect the most vulnerable people in society. In this thesis we look at two different vaccination strategies to prevent most deaths and years of life lost. We conclude that the safest and most consistent strategy ... -
Short-Term Load Forecasting with Missing Data using Dilated Recurrent Attention Networks
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-06)Forecasting the dynamics of time-varying systems is essential to maintaining the sustainability of the systems. Recent studies have discovered that Recurrent Neural Networks(RNN) applied in the forecasting tasks outperform conventional models that include AutoRegressive Integrated Moving Average(ARIMA). However, due to the structural limitation of vanilla RNN which holds unit-length internal ...