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norskFakultet for naturvitenskap og teknologi: Nye registreringer
Viser treff 2621-2640 av 5379
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The effect of an experimental decrease in salinity on the viability of the subarctic planktonic foraminifera Neogloboquadrina incompta
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-27)Chemical signatures in the calcite of shells of polar and subpolar planktonic foraminifera have been frequently used to trace and quantify past meltwater discharge events. This approach assumes that the foraminifera can tolerate low salinity under extended periods. To obtain a first experimental constraint on salinity tolerance of Subarctic foraminifera, we carried out a culturing experiment with ... -
The tectonized central peak of the Mjølnir Impact Crater, Barents Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-04)The Mjølnir structure, SW Barents Sea, is one of the best-preserved marine impact craters on Earth. After impact on the paleo-seafloor about 142 Ma ago, this crater experienced an atypical deformation of its central peak, which is now elevated ~435 m above the crater rims. Here, we investigate the effect of far-field tectonic stresses on the central peak uplift based on interpretation of new ... -
Transferring grains from single-grain luminescence discs to SEM specimen stubs
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-21)The grain transfer protocol presents a step-by-step guide on how to successfully transfer positioned grains from a single-grain luminescence disc to a scanning electron microscope (SEM) specimen stub and how to transport them between laboratories. Single-grain luminescence analysis allows the determination of luminescence characteristics for individual sand-sized grains. By combining such luminescence ... -
Adamastor – an ocean that never existed?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-08)<p>Existing models of tectonic evolution of the Neoproterozoic orogenic system rimming the shores of the South Atlantic Ocean (the Araçuaí–Ribeira–Congo and Dom Feliciano–Kaoko–Gariep belts) interpret the belts as subduction-related orogens and emphasize the role of the “Adamastor Ocean” in their pre-collisional evolution. A critical problem in such an interpretation is the confined nature of the ... -
Redox fluctuations, trace metal enrichment and phosphogenesis in the ~2.0 Ga Zaonega Formation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-24)The ~2.0 Ga Zaonega Formation (ZF) holds one of the oldest phosphorites in the geologic record, reaching >15% P<sub>2</sub>O<sub>5</sub>. Understanding the depositional conditions that enabled sedimentary phosphorus enrichment in this unit will thus help us to interpret the significance of the temporal distribution of phosphorites in Earth’s early history. Here we use an array of major and trace ... -
Reduced Arctic sea ice extent during the mid-Pliocene Warm Period concurrent with increased Atlantic-climate regime
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-01)Quantifying the contribution of poleward oceanic heat transport to the Arctic Ocean is important for making future sea ice and climate predictions. To highlight its potential importance in a warmer world, we present a new record of water-mass exchange between the Atlantic and the Arctic Oceans using the authigenic neodymium isotopic composition of marine sediments from the Fram Strait during the ... -
A boundary integral approach to the modeling of surface waves in a wave tank
(Master thesis; Mastergradsoppgave, 2020-06-14)Boundary integral equations (BIEs) are used to model surface waves in a wave tank. Assuming an ideal fluid, the velocity of the fluid can be considered as a potential flow and be modeled by the Laplace equation on the domain. The domain in this case will be a section of a wave channel with an incoming wave from the right, a rigid bottom, a reflective wall on the right and a time varying surface that ... -
Konvergerende og divergerende tankegang i matematisk utforskning. En kvantitativ analyse av elevbesvarelser
(Master thesis; Mastergradsoppgave, 2020-06-01)Fra og med høsten 2020 vil det være et økt fokus på undersøkende matematikkundervisning i norsk skole på grunn av fagfornyelsen. Dette kommer tydelig frem i de nye læreplanene i matematikk. Formålet med denne studien er å få økt innsikt i hvordan man kan vurdere undersøkende matematikkproblemer, og med det få innsikt i elevenes utgangspunkt i forkant av fagfornyelsen. For å oppnå dette er det utviklet ... -
Matematisk resonnering og argumentasjon. En kvalitativ studie av elevers resonnering i ulike nivåer av undersøkende undervisning.
(Master thesis; Mastergradsoppgave, 2020-05-31)Hensikten med studien er å få et innblikk i hvordan elever resonnerer og argumenterer i ulike nivåer av åpenhet i undersøkende matematikkundervisning. I denne studien har jeg besvart på følgende problemstilling: Hvordan resonnerer og argumenterer elever i videregående skole i undersøkende undervisning av ulike nivåer av åpenhet? Studien har en kvalitativ tilnærming og bygger på observasjonsnotater, ... -
A study of generative adversarial networks to improve classification of microscopic foraminifera
(Master thesis; Mastergradsoppgave, 2020-05-30)Foraminifera are single-celled organisms with shells that live in the marine environment and can be found abundantly as fossils in e.g. sediment cores. The assemblages of different species and their numbers serves as an important source of data for marine, geological, climate and environmental research. Steps towards automatic classification of foraminifera using deep learning (DL) models have ... -
A bidirectional pulse propagation model for extreme nonlinear optics: derivation and implementation.
(Master thesis; Mastergradsoppgave, 2020-05-13)With growing capabilities of high-intensity laser beams to generate ultra-short pulses of light, the simulation of pulse propagation in nonlinear media is expected to catch up with the front-line experimental setups. Among the challenges of nonlinear material response modeling is the ability to capture the back-scatter effect - a phenomenon inherently elusive for the well-established methods of ... -
Interplanetary dust fluxes observed with Parker Solar Probe
(Master thesis; Mastergradsoppgave, 2020-06-29)The mission Parker Solar Probe (PSP) provides a new opportunity to make in-situ measurements of dust impacts closer to the Sun than ever before, eventually going as close as ∼ 10 solar radii or ∼ 0.05 AU. PSP can measure dust impacts from monopole measurements of the spacecraft’s electric potential to one of its antennas using its FIELDS instrument. In this work impact rates data is compared ... -
Cross-Phase Based Multi-Camera Video Synchronization Calibration with Sub Frame Rate Accuracy
(Master thesis; Mastergradsoppgave, 2020-06-29)In auroral research, it is necessary to accurately measure the time-shift differences between varying light sources. Such measurements can be carried out using two or more digital cameras, or between different regions of an image obtained using a single camera. An example of this is measurements of the time-shifts between prompt auroral emissions originating from different altitude regions during ... -
Salt-driven evolution of a gas hydrate reservoir in Green Canyon, Gulf of Mexico
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09)The base of the gas hydrate stability zone (GHSZ) is a critical interface, providing a first-order estimate of gas hydrate distribution. Sensitivity to thermobaric conditions makes its prediction challenging particularly in the regions with dynamic pressure-temperature regime. In Green Canyon in the northern Gulf of Mexico (Block GC955), the seismically inferred base of the GHSZ is 450 meters (1476 ... -
On polar lows and their formation
(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 ... -
Information Collection Platform for Smart Nudging. A Microservice-Based Approach.
(Master thesis; Mastergradsoppgave, 2020-06-30)This thesis aims to explore the problem of integrating heterogeneous data sources into the Smart Nudge system. The Smart Nudge system is a system that produces personalised nudges that are contextually relevant to each user. The system relies on access to live data that could be constructed and presented in specific ways to influence users behaviour towards an agreed-upon goal. The goal is to ascertain ... -
Multi-user application for recording physical activity on exercise bicycles for people with intellectual disabilities
(Master thesis; Mastergradsoppgave, 2020-06-30)This thesis extends research into the application of an exergame for individuals with intellectual disabilities. Individuals with intellectual disabilities have a more sedentary lifestyle than the general population, and the need for regular physical activity is high. The World Health Organization recommends 150 minutes of physical activity each week. Exergames can contain elements that excite ... -
Sequence analysis of nonulosonic acid biosynthetic gene clusters in Vibrionaceae and Moritella viscosa
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-20)Nonulosonic acid (NulO) biosynthesis in bacteria is directed by <i>nab</i> gene clusters that can lead to neuraminic, legionaminic or pseudaminic acids. Analysis of the gene content from a set mainly composed of <i>Aliivibrio salmonicida</i> and <i>Moritella viscosa</i> strains reveals the existence of several unique nab clusters, for which the NulO products were predicted. This prediction method ... -
Toward Detecting Infection Incidence in People With Type 1 Diabetes Using Self-Recorded Data (Part 1): A Novel Framework for a Personalized Digital Infectious Disease Detection System
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-12)<i>Background</i>: Type 1 diabetes is a chronic condition of blood glucose metabolic disorder caused by a lack of insulin secretion from pancreas cells. In people with type 1 diabetes, hyperglycemia often occurs upon infection incidences. Despite the fact that patients increasingly gather data about themselves, there are no solid findings that uncover the effect of infection incidences on key ... -
A Novel Approach for Continuous Health Status Monitoring and Automatic Detection of Infection Incidences in People With Type 1 Diabetes Using Machine Learning Algorithms (Part 2): A Personalized Digital Infectious Disease Detection Mechanism
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-12)<i>Background</i>: Semisupervised and unsupervised anomaly detection methods have been widely used in various applications to detect anomalous objects from a given data set. Specifically, these methods are popular in the medical domain because of their suitability for applications where there is a lack of a sufficient data set for the other classes. Infection incidence often brings prolonged ...
