Browsing Institutt for matematikk og statistikk by Title
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2d gauge theories and generalized geometry
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014) 
Abelian equations and rank problems for planar webs
(Journal article; Tidsskriftartikkel; Peer reviewed, 20060504)We find an invariant characterization of planar webs of maximum rank. For 4webs, we prove that a planar 4web is of maximum rank three if and only if it is linearizable and its curvature vanishes. This result leads ... 
Almost complex homogeneous spaces with semisimple isotropy
(Master thesis; Mastergradsoppgave, 201205)We classify the almost complex structures on homogeneous spaces M = G/H of real dimension less than or equal to 6 with semisimple isotropy group H. 
Anomaly of linearization and auxiliary integrals
(Chapter; Bokkapittel, 20071220)In this note we discuss some formal properties of universal linearization operator, relate this to brackets of nonlinear differential operators and discuss application to the calculus of auxiliary integrals, used in ... 
Applying the ICM algorithm for separating pictures consisting of two main parts, background and object application to fMRI recordings and mole pictures
(Master thesis; Mastergradsoppgave, 20090515)This work concentrates on using the ICM algorithm for image restoration. The algorithm has been applied to fMRI recordings and mole pictures 
Arctic tipping points
(Master thesis; Mastergradsoppgave, 20150515)The Arctic is warming much faster than the entire planet, and this causes severe melting of sea ice. However, the climate of different regions of the Earth is interconnected, and changes in the amount of ice in the Arctic ... 
Are there multiple scaling regimes in Holocene temperature records?
(Journal article; Tidsskriftartikkel, 20150717)The concept of multiple scaling regimes in temperature time series is examined, with emphasis on the question whether or not a monoscaling model can be rejected from the data at hand. A model with only one regime is ... 
Attribution in the presence of a longmemory climate response
(Journal article; Tidsskriftartikkel, 20150810)Multiple, linear regression is employed to attribute variability in the global surface temperature to various forcing components and prominent internal climatic modes. The purpose of the study is to asses how sensitive ... 
Automatic nematode detection in cod fillets (Gadus morhua L.) by hyperspectral imaging
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012)Detection of objects embedded in tissue, using visible light, is difficult due to light scattering. The optical properties of the surrounding tissue will influence the spectral characteristics of the light interacting with ... 
Automatic Segmentation of Dermoscopic Images by Iterative Classification
(Journal article; Tidsskriftartikkel; Peer reviewed, 2011)Accurate detection of the borders of skin lesions is a vital first step for computer aided diagnostic systems. This paper presents a novel automatic approach to segmentation of skin lesions that is particularly suitable ... 
Bayesian modeling and significant features exploration in wavelet power spectra
(Journal article; Tidsskriftartikkel; Peer reviewed, 2007) 
Bayesian multiscale analysis of images modeled as Gaussian Markov random fields
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012)A Bayesian multiscale technique for the detection of statistically significant features in noisy images is proposed. The prior is defined as a stationary intrinsic Gaussian Markov random field on a toroidal graph, which ... 
The Capabilities of the EISCAT Svalbard Radar for Interhemispheric Coordinated Studies
(Journal article; Tidsskriftartikkel; Peer reviewed, 2002)In this article we want to present the EISCAT Svalbard Radar (ESR) in some detail, as well as some of the instruments of interest for ionospheric and magnetospheric research that are located in the vicinity of it. We ... 
The categorical theory of relations and quantization
(Working paper; Arbeidsnotat, 20011030)In this paper we develops a categorical theory of relations and use this formulation to define the notion of quantization for relations. Categories of relations are defined in the context of symmetric monoidal categories. They ... 
Causality in Scale Space as an Approach to Change Detection
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012)Kernel density estimation and kernel regression are useful ways to visualize and assess the structure of data. Using these techniques we define a temporal scale space as the vector space spanned by bandwidth and a temporal ... 
Compatibility, multibrackets and integrability of systems of PDEs
(Journal article; Tidsskriftartikkel; Peer reviewed, 20080220)We establish an efficient compatibility criterion for a system of generalized complete intersection type in terms of certain multibrackets of differential operators. These multibrackets generalize the higher Jacobi Mayer ... 
Deformation of big pseudoholomorphic disks and application to the Hanh pseudonorm
(Journal article; Tidsskriftartikkel; Peer reviewed, 20030414)We simplify proof of the theorem that close to any pseudoholomorphic disk there passes a pseudoholomorphic disk of arbitrary close size with any predescribed sufficiently close direction. We apply these results to the ... 
Deforming the vacuum. On the physical origin and numerical calculation of the Casimir effect.
(Master thesis; Mastergradsoppgave, 20140514)A new method for calculating the Casimir force between compact objects was introduced in May 2012 by Per Jakobsen and Isak Kilen. In this method a regularization procedure is used to reduce the pressure to the solution of ... 
DeltaProt : a software toolbox for comparative genomics
(Journal article; Tidsskriftartikkel; Peer reviewed, 2010) 
Differential invariants of the 2D conformal Lie algebra action
(Master thesis; Mastergradsoppgave, 20080215)In this thises we consider the Lie algebra that corresponds to the Lie pseudogroup of all conformal transformations on the plane. This conformal Lie algebra is canonically represented as a Lie algebra of vector fields ...