Viser treff 179-198 av 314

    • Machine Learning in Chronic Pain Research: A Scoping Review 

      Jenssen, Marit Dagny Kristine; Bakkevoll, Per Atle; Ngo, Phuong; Budrionis, Andrius; Fagerlund, Asbjørn Johansen; Tayefi, Maryam; Bellika, Johan Gustav; Godtliebsen, Fred (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-02)
      Given the high prevalence and associated cost of chronic pain, it has a significant impact on individuals and society. Improvements in the treatment and management of chronic pain may increase patients’ quality of life and reduce societal costs. In this paper, we evaluate state-of-the-art machine learning approaches in chronic pain research. A literature search was conducted using the PubMed, IEEE ...
    • Mapping climate change in European temperature distributions 

      Stainforth, David A.; Chapman, Sandra; Watkins, Nicholas W. (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Climate change poses challenges for decision makers across society, not just in preparing for the climate of the future but even when planning for the climate of the present day. When making climate sensitive decisions, policy makers and adaptation planners would benefit from information on local scales and for user-specific quantiles (e.g. the hottest/coldest 5% of days) and thresholds (e.g. ...
    • 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 ...
    • Matematisk kulturhistorie : artikkelsamling 

      Thorvaldsen, Steinar (Book; Bok, 2002-08)
    • Maximizing Interpretability and Cost-Effectiveness of Surgical Site Infection (SSI) Predictive Models Using Feature-Specific Regularized Logistic Regression on Preoperative Temporal Data 

      Kocbek, Primoz; Fijacko, Nino; Soguero-Ruiz, Cristina; Mikalsen, Karl Øyvind; Maver, Uros; Brzan, Petra Povalej; Stozer, Andraz; Jenssen, Robert; Skrøvseth, Stein Olav; Stiglic, Gregor (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-19)
      This study describes a novel approach to solve the surgical site infection (SSI) classification problem. Feature engineering has traditionally been one of the most important steps in solving complex classification problems, especially in cases with temporal data. The described novel approach is based on abstraction of temporal data recorded in three temporal windows. Maximum likelihood L1-norm ...
    • Modeling temporal fluctuations in avalanching system 

      Rypdal, Martin; Rypdal, Kristoffer (Working paper; Arbeidsnotat, 2008-07-22)
      We demonstrate how to model the toppling activity in avalanching systems by stochastic differential equations (SDEs). The theory is developed as a generalization of the classical mean field approach to sandpile dynamics by formulating it as a generalization of Itoh’s SDE. This equation contains a fractional Gaussian noise term representing the branching of an avalanche into small active clusters, ...
    • A modelling approach to assessing the timescale uncertainties in proxy series with chronological errors 

      Divine, D.V; Godtliebsen, F.; Rue, H. (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      The paper proposes an approach to assessment of timescale errors in proxy-based series with chronological uncertainties. The method relies on approximation of the physical process(es) forming a proxy archive by a random Gamma process. Parameters of the process are partly data-driven and partly determined from prior assumptions. For a particular case of a linear accumulation model and absolutely dated ...
    • Modelling suggests limited change in the reproduction number from reopening Norwegian kindergartens and schools during the COVID-19 pandemic 

      Rypdal, Martin Wibe; Rypdal, Veronika Gjertsen; Jakobsen, Per Kristen; Ytterstad, Elinor; Løvsletten, Ola; Klingenberg, Claus; Rypdal, Kristoffer (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-25)
      <i>Background</i> - To suppress the COVID-19 outbreak, the Norwegian government closed all schools on March 13, 2020. The kindergartens reopened on April 20, and the schools on April 27 and May 11 of 2020. The effect of these measures is largely unknown since the role of children in the spread of the SARS-CoV-2 virus is still unclear. There are only a few studies of school closures as a separate ...
    • Möbius and coboundary polynomials for matroids 

      Johnsen, Trygve; Verdure, Hugues (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-28)
      We study how some coefficients of two-variable coboundary polynomials can be derived from Betti numbers of Stanley–Reisner rings. We also explain how the connection with these Stanley–Reisner rings forces the coefficients of the two-variable coboundary polynomials and Möbius polynomials to satisfy certain universal equations.
    • Multicentennial Variability of the Sea Surface Temperature Gradient across the Subpolar North Atlantic over the Last 2.8 kyr 

      Miettinen, A.; Divine, D.V.; Koc, N.; Godtliebsen, F.; Hall, I.R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      A 2800-yr-long August sea surface temperature (aSST) record based on fossil diatom assemblages is generated from a marine sediment core from the northern subpolar North Atlantic. The record is compared with the aSST record from the Norwegian Sea to explore the variability of the aSST gradient between these areas during the late Holocene. The aSST records demonstrate the opposite climate tendencies ...
    • A Multiscale Wavelet-Based Test for Isotropy of Random Fields on a Regular Lattice 

      Thon, Kevin Otto; Geilhufe, Marc; Percival, Donald B. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-12-31)
      A test for isotropy of images modeled as stationary or intrinsically stationary random fields on a lattice is developed. The test is based on wavelet theory, and can operate on the horizontal and vertical scale of choice, or on any combination of scales. Scale is introduced through the wavelet variances (sometimes referred to as the wavelet power spectrum), which decompose the variance over ...
    • Nature reserves as a bioeconomic management tool. A simplified modeling approach 

      Flåten, Ola; Mjølhus, Einar (Working paper; Arbeidsnotat, 2006-02)
      This paper demonstrates analytically how a nature reserve may protect the total population, realize maximum sustainable yield (MSY), maximum economic yield (MEY) and consumer surplus (CS) and how this depends on biological growth, migration, reserve size and economic parameters. The pre-reserve population is assumed to follow the logistic growth law and two post-reserve growth models are discussed. ...
    • Network analysis of geomagnetic substorms using the SuperMAG database of ground-based magnetometer stations 

      Dods, Joe; Chapman, Sandra; Gjerløv, Jesper (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-09-26)
      The overall morphology and dynamics of magnetospheric substorms is well established in terms of the observed qualitative auroral features seen in ground-based magnetometers. This paper focuses on the quantitative characterization of substorm dynamics captured by ground-based magnetometer stations. We present the first analysis of substorms using dynamical networks obtained from the full available ...
    • Nijenhuis tensors in pseudoholomorphic curves neighborhoods 

      Kruglikov, Boris (Working paper; Arbeidsnotat, 2000)
      In this paper we consider the normal forms of almost complex structures in a neighborhood of pseudoholomorphic curve. We define normal bundles of such curves and study the properties of linear bundle almost complex structures. We describe 1-jet of the almost complex structure along a curve in terms of its Nijenhuis tensor. For pseudoholomorphic tori we investigate the problem of pseudoholomorphic ...
    • The NISK 2018 Proceedings: Message from the Programme Chairs 

      Mjølsnes, Stig Frode; Soleng, Ragnar (Journal article; Tidsskriftartikkel; Peer reviewed, 2018)
      This NISK Journal volume 11 is the published proceedings of the papers presented at NISK 2018: the 11th Norwegian Information Security Conference 2018 held on September 18-20, 2018 in Longyearbyen, Svalbard. The aim of the NISK conference series is to be the principal Norwegian research venue for presenting and discussing developments in the field of ICT security and privacy, and bringing together ...
    • Non-degenerate para-complex structures in 6D with large symmetry groups 

      Kruglikov, Boris; Winther, Henrik (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-20)
      For an almost product structure J on a manifold M of dimension 6 with non-degenerate Nijenhuis tensor N J, we show that the automorphism group G=Aut(M,J) has dimension at most 14. In the case of equality G is the exceptional Lie group G∗2. The next possible symmetry dimension is proved to be equal to 10, and G has Lie algebra sp(4,R). Both maximal and submaximal symmetric structures are globally ...
    • Numerical evaluation of line, surface and toroidal integrals on level sets of toroidally symmetric functions 

      Wiesenberger, Matthias; Gerrú, Raul; Held, Markus (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-05)
      We investigate strategies to numerically integrate closed lines and surfaces that are implicitly defined by level sets (iso-contours) of continuously differentiable toroidally symmetric functions. The “grid-transform” approach transforms quantities given in non-surface-aligned coordinates onto a numerically constructed surface-aligned grid. Here, line and surface integrals, as well as so-called ...
    • Objective Momentum Barriers in Wall Turbulence 

      Aksamit, Nikolas Olson; Haller, George (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-28)
      We use the recent frame-indifferent theory of diffusive momentum transport to identify internal barriers in wall-bounded turbulence. Formed by the invariant manifolds of the Laplacian of the velocity field, the barriers block the viscous part of the instantaneous momentum flux in the flow. We employ the level sets of single-trajectory Lagrangian diagnostic tools, the trajectory rotation average ...
    • ODEs whose Symmetry Groups are not Fiber-Preserving 

      Kruglikov, Boris Serafimovich; Schneider, Eivind (Journal article; Tidsskriftartikkel; Peer reviewed, 2023)
      We observe that, up to conjugation, a majority of higher order ODEs (ordinary differential equations) and ODE systems have only fiber-preserving point symmetries. By exploiting Lie's classification of Lie algebras of vector fields, we describe all exceptions to this in the case of scalar ODEs and systems of ODEs on a pair of functions. The scalar ODEs whose symmetry algebras are not fiber preserving ...
    • On a class of integrable systems of Monge-Ampère type 

      Doubrov, Boris; Ferapontov, Eugene V.; Kruglikov, Boris; Novikov, Vladimir S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-08)
      We investigate a class of multi-dimensional two-component systems of Monge-Ampère type that can be viewed as generalisations of heavenly type equations appearing in a self-dual Ricci-flat geometry. Based on the Jordan-Kronecker theory of the skew-symmetric matrix pencils, a classification of normal forms of such systems is obtained. All two-component systems of Monge-Ampère type turn out to be ...