Recent additions

  • Evaluating Deep Q-Learning Algorithms for Controlling Blood Glucose in In Silico Type 1 Diabetes 

    Angel, Tejedor H Miguel; Hjerde, Sigurd; Myhre, Jonas Nordhaug; Godtliebsen, Fred (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-07)
    Patients with type 1 diabetes must continually decide how much insulin to inject before each meal to maintain blood glucose levels within a healthy range. Recent research has worked on a solution for this burden, showing the potential of reinforcement learning as an emerging approach for the task of controlling blood glucose levels. In this paper, we test and evaluate several deep Q-learning algorithms ...
  • Generalized Teleparallel de Sitter geometries 

    Coley, Alan; Landry, Alexandre; van den Hoogen, Robert; McNutt, David Duncan (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-30)
    Theories of gravity based on teleparallel geometries are characterized by the torsion, which is a function of the coframe, derivatives of the coframe, and a zero curvature and metric compatible spin-connection. The appropriate notion of a symmetry in a teleparallel geometry is that of an affine symmetry. Due to the importance of the de Sitter geometry and Einstein spaces within General Relativity, ...
  • Geographical study of the stroke incidence and mortality rates using Bayesian analysis 

    Shu, Li-Wei Janice (Master thesis; Mastergradsoppgave, 2023-09-21)
    There is large geographical variation in the stroke incidence rate worldwide. In addition, stroke is one of the diseases with highest mortality rate. In this thesis, our main focus is to examine if there are any geographical variation in stroke incidence and mortality rates in Norway. We approach this study using models within the Bayesian framework. Before performing analysis, we first introduce ...
  • On elementary particles as representations of the Poincaré group 

    Martínez Marín, Pau (Master thesis; Mastergradsoppgave, 2023-08-14)
    This thesis is concerned with the definition of elementary particles as irreducible projective unitary representations of the Poincaré group. During the contents of this work, we will introduce the relevant prerequisites and results. Concerning differential geometry, we will discuss smooth manifolds, Lie groups and Lie algebras. About quantum mechanics, we will introduce Hilbert spaces and the basic ...
  • The poset of Specht ideals for hyperoctahedral groups 

    Debus, Sebastian; Moustrou, Philippe; Riener, Cordian Benedikt; Verdure, Hugues (Journal article; Tidsskriftartikkel, 2023)
    Specht polynomials classically realize the irreducible representations of the symmetric group. The ideals defined by these polynomials provide a strong connection with the combinatorics of Young tableaux and have been intensively studied by several authors. We initiate similar investigations for the ideals defined by the Specht polynomials associated to the hyperoctahedral group <i>B<sub>n</sub></i>. ...
  • Linear slices of Hyperbolic polynomials and positivity of symmetric polynomial functions 

    Riener, Cordian Benedikt; Schabert, Robin Leonid (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-17)
    A real univariate polynomial of degree n is called hyperbolic if all of its n roots are on the real line. Such polynomials appear quite naturally in different applications, for example, in combinatorics and optimization. The focus of this article is on families of hyperbolic polynomials which are determined through k linear conditions on the coefficients. The coefficients corresponding to such a ...
  • A Heterotic Kodaira--Spencer Theory at One-Loop 

    Ashmore, Anthony; Murgas Ibarra, Javier Jose; McNutt, David Duncan; Strickland-Constable, Charles; Svanes, Eirik Eik; Tennyson, David; Winje, Sander (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-23)
    We consider a heterotic version of six-dimensional Kodaira-Spencer gravity derived from the heterotic superpotential. We compute the one-loop partition function and fnd it can be expressed as a product of holomorphic Ray-Singer torsions. We discuss its topological properties and potential gauge and gravitational anomalies. We show these anomalies can be cancelled using Green-Schwarz-like ...
  • The South American monsoon approaches a critical transition in response to deforestation 

    Bochow, Nils; Boers, Niklas (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 ...
  • Laplace transformation of Lie class ω = 1 overdetermined systems 

    Kruglikov, Boris (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-20)
    In this paper, we investigate overdetermined systems of scalar PDEs on the plane with one common characteristic, whose general solution depends on one function of one variable. We describe linearization of such systems and their integration via Laplace transformation, relating this to Lie's integration theorem and formal theory of PDEs.
  • Is there a break in scaling on centennial time scales in Holocene temperature records? 

    Nilsen, Tine; Rypdal, Kristoffer; Fredriksen, Hege-Beate (Conference object; Konferansebidrag, 2017)
  • Second-order PDEs in four dimensions with half-flat conformal structure 

    Berjawi, S.; Ferapontov, Eugene V.; Kruglikov, Boris; Novikov, Vladimir S (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-29)
    We study second-order partial differential equations (PDEs) in four dimensions for which the conformal structure defined by the characteristic variety of the equation is half-flat (self-dual or anti-self-dual) on every solution. We prove that this requirement implies the Monge–Ampère property. Since half-flatness of the conformal structure is equivalent to the existence of a non-trivial dispersionless ...
  • Real Root Finding for Equivariant Semi-algebraic Systems 

    Riener, Cordian; Safey el Din, Mohab (Conference object; Konferansebidrag, 2018)
    Let <i><b>R</b></i> be a real closed field. We consider basic semi-algebraic sets defined by <i>n</i>-variate equations/inequalities of s symmetric polynomials and an equivariant family of polynomials, all of them of degree bounded by 2<i>d</i> &#60; <i>n</i>. Such a semi-algebraic set is invariant by the action of the symmetric group. We show that such a set is either empty or it contains a point ...
  • Extreme Event Statistics in Dst, SYM-H, and SMR Geomagnetic Indices 

    Bergin, A.; Chapman, Sandra; Watkins, N.W.; Moloney, N.R.; Gjerløv, Jesper (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-20)
    Extreme space weather events are rare, and quantifying their likelihood is challenging, often relying on geomagnetic indices obtained from ground-based magnetometer observations that span multiple solar cycles. The Dst index ring-current monitor, derived from an hourly average over four low-latitude stations, is a benchmark for extreme space weather events, and has been extensively studied ...
  • Temporal evolution of under-ice meltwater layers and false bottoms and their impact on summer Arctic sea ice mass balance 

    Salganik, Evgenii; Katlein, Christian; Lange, Benjamin; Matero, Ilkka; Lei, Ruibo; Fong, Allison A.; Fons, Steven; Divine, Dmitry; Oggier, Marc; Castellani, Giulia; Bozzato, Deborah; Chamberlain, Emelia; Hoppe, Clara J. M.; Müller, Oliver; Gardner, Jessie; Rinke, Annette; Simoes Pereira, Patric; Ulfsbo, Adam; Marsay, Christopher; Webster, Melinda; Maus, Sønke; Høyland, Knut Vilhelm; Granskog, Mats (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-31)
    Low-salinity meltwater from Arctic sea ice and its snow cover accumulates and creates under-ice meltwater layers below sea ice.These meltwater layers can result in the formation of new ice layers, or false bottoms, at the interface of this low-salinity meltwater and colder seawater. As part of the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC), we used a ...
  • Seafood production in Northern Norway: Analyzing variation and co-development in aquaculture and coastal fisheries 

    Espinasse, Marina; Mikkelsen, Eirik Inge; Sørbye, Sigrunn Holbek; Skern-Mauritzen, Mette; Falk-Andersson, Jannike; Fauchald, Per (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-27)
    Norway is one of the leading ocean-based food production nations. Its seafood industry comprises wild-capture fisheries and farmed fish production. Both industries play a provisional role but also contribute to economic development of the country and help sustain coastal communities, particularly, in Northern Norway. Coastal fishery has been the staple industry in Northern Norway for centuries, while ...
  • Mapping the shape and dimension of three-dimensional Lagrangian coherent structures and invariant manifolds 

    Aksamit, Nikolas Olson (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-10)
    We introduce maps of Cauchy–Green strain tensor eigenvalues to barycentric coordinates to quantify and visualize the full geometry of three-dimensional deformation in stationary and non-stationary fluid flows. As a natural extension of Lagrangian coherent structure diagnostics, which provide separate scalar fields and a one-dimensional quantification of fluid deformation, our barycentric mapping ...
  • Students’ mathematical beliefs and motivation in the context of inquiry-based mathematics teaching 

    Pedersen, Ida Friestad; Haavold, Per Øystein (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-29)
    In this paper, we investigate the learning experiences, beliefs and motivations of students in classes where the mathematics teachers have received support for using inquiry-based learning activities. Data were collected from 248 students in the age-range 11–16 using electronic questionnaires. Our results show that key features of inquiry-based mathematics were only moderately reflected in these ...
  • A quasi-objective single buoy approach for un- derstanding Lagrangian coherent structures and sea ice dynamics 

    Aksamit, Nikolas Olson; Scharien, Randall K.; Hutchings, Jennifer; Lukovich, Jennifer (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-11)
    Sea ice drift and deformation, namely sea ice dynamics, play a significant role in atmosphere–ice–ocean coupling. Deformation patterns in sea ice can be observed over a wide range of spatial and temporal scales, though high-resolution objective quantification of these features remains difficult. In an effort to better understand local deformation of sea ice, we adapt the trajectory-stretching exponents ...
  • Charting the solar cycle 

    Chapman, Sandra (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-09)
    Sunspot records reveal that whilst the Sun has an approximately 11 year cycle of activity, no two cycles are of the same duration. Since this activity is a direct driver of space weather at Earth, this presents an operational challenge to quantifying space weather risk. We recently showed that the Hilbert transform of the sunspot record can be used to map the variable cycle length onto a regular ...
  • Global Dynamical Network of the Spatially Correlated Pc2 Wave Response for the 2015 St. Patrick's Day Storm 

    Chaudhry, S.; Chapman, Sandra; Gjerloev, J.; Beggan, C.D. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-26)
    We show the global dynamics of spatial correlation of Pc2 wave activity can track the evolution of the 2015 St. Patrick's Day geomagnetic storm for an 8 hr time window around onset. The global spatially coherent response is tracked by forming a dynamical network from 1 s data using the full set of 100+ ground-based magnetometer stations collated by SuperMAG and Intermagnet. The pattern of spatial ...

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