Browsing Bergen Open Research Archive by Author "Brun, Morten"

Now showing items 1-13 of 13

    • Brain Tumor Segmentation Based on Minimum Spanning Tree 

      Mayala, Simeon Sahani; Herdlevær, Ida Ajvazi; Haugsøen, Jonas Bull; Anandan, Shamundeeswari; Gavasso, Sonia; Brun, Morten (Journal article; Peer reviewed, 2022-03-11)
      In this paper, we propose a minimum spanning tree-based method for segmenting brain tumors. The proposed method performs interactive segmentation based on the minimum spanning tree without tuning parameters. The steps ...

    • Candidate markers for stratification and classification in rheumatoid arthritis 

      Bader, Lucius; Gullaksen, Stein-Erik; Blaser, Nello; Brun, Morten; Bringeland, Gerd Haga; Sulen, Andre; Gjesdal, Clara Gram; Vedeler, Christian A.; Gavasso, Sonia (Peer reviewed; Journal article, 2019-07-05)
      Rheumatoid arthritis (RA) is a chronic autoimmune, inflammatory disease, characterized by synovitis in small- and medium-sized joints and, if not treated early and efficiently, joint damage, and destruction. RA is a ...

    • Determining homology of an unknown space from a sample 

      Brun, Morten; Garcia Pascual, Belen; Salbu, Lars Moberg (Journal article; Peer reviewed, 2023)
      The homology of an unknown subspace of Euclidean space can be determined from the intrinsic Čech complex of a sample of points in the subspace, without reference to the ambient Euclidean space. More precisely, given a ...

    • Epistemic uncertainty quantification in deep learning classification by the Delta method 

      Nilsen, Geir Kjetil; Munthe-Kaas, Antonella Zanna; Skaug, Hans Julius; Brun, Morten (Journal article; Peer reviewed, 2022)
      The Delta method is a classical procedure for quantifying epistemic uncertainty in statistical models, but its direct application to deep neural networks is prevented by the large number of parameters . We propose a low ...

    • GUBS: Graph-Based Unsupervised Brain Segmentation in MRI Images 

      Mayala, Simeon Sahani; Herdlevær, Ida Ajvazi; Haugsøen, Jonas Bull; Anandan, Shamundeeswari; Blaser, Nello; Gavasso, Sonia; Brun, Morten (Journal article; Peer reviewed, 2022)
      Brain segmentation in magnetic resonance imaging (MRI) images is the process of isolating the brain from non-brain tissues to simplify the further analysis, such as detecting pathology or calculating volumes. This paper ...

    • Integrative omics-analysis of lipid metabolism regulation by peroxisome proliferator-activated receptor a and b agonists in male Atlantic cod 

      Eide, Marta; Goksøyr, Anders; Yadetie, Fekadu; Gilabert, Alejandra; Bartosova, Zdenka; Frøysa, Håvard Guldbrandsen; Fallahi, Shirin; Zhang, Xiaokang; Blaser, Nello; Jonassen, Inge; Bruheim, Per; Alendal, Guttorm; Brun, Morten; Porte, Cinta; Karlsen, Odd André (Journal article; Peer reviewed, 2023-03-22)
      Lipid metabolism is essential in maintaining energy homeostasis in multicellular organisms. In vertebrates, the peroxisome proliferator-activated receptors (PPARs, NR1C) regulate the expression of many genes involved in ...

    • The parameterized complexity of finding minimum bounded chains 

      Blaser, Nello; Brun, Morten; Salbu, Lars Moberg; Vågset, Erlend Raa (Journal article; Peer reviewed, 2024)
      Finding the smallest d-chain with a specific (d − 1)-boundary in a simplicial complex is known as the Minimum Bounded Chain problem (MBCd). MBCd is NP-hard for all d ≥2. In this paper, we prove that it is also W[1]-hard ...

    • The Rectangle Complex of a Relation 

      Brun, Morten; Salbu, Lars Moberg (Journal article; Peer reviewed, 2023)
      We construct a simplicial complex, the rectangle complex of a relation R, and show that it is homotopy equivalent to the Dowker complex of . This results in a short and conceptual proof of functorial versions of Dowker’s ...

    • Relative Persistent Homology 

      Blaser, Nello; Brun, Morten (Journal article; Peer reviewed, 2020)
      The alpha complex efficiently computes persistent homology of a point cloud X in Euclidean space when the dimension d is low. Given a subset A of X, relative persistent homology can be computed as the persistent homology ...

    • Relative Persistent Homology 

      Blaser, Nello; Brun, Morten (Journal article; Peer reviewed, 2022)
      The alpha complex efficiently computes persistent homology of a point cloud X in Euclidean space when the dimension d is low. Given a subset A of X, relative Čech persistent homology can be computed as the persistent ...

    • Sparse Dowker nerves 

      Brun, Morten; Blaser, Nello (Peer reviewed; Journal article, 2019-06-29)
      We propose sparse versions of filtered simplicial complexes used to compute persistent homology of point clouds and of networks. In particular, we extend the Sparse Čech Complex of Cavanna et al. (A geometric perspective ...

    • Sparse Nerves in Practice 

      Blaser, Nello; Brun, Morten (Peer reviewed; Journal article, 2019)
      Topological data analysis combines machine learning with methods from algebraic topology. Persistent homology, a method to characterize topological features occurring in data at multiple scales is of particular interest. ...

    • The use of heuristics in intuitive mathematical judgment 

      Reber, Rolf; Brun, Morten; Mitterndorfer, Karoline (Journal article, 2008-07-16)
      Anecdotal evidence points to the use of beauty as an indication for truth in mathematical problem solving. Two experiments examined the use of heuristics and tested the assumption that participants use symmetry as a cue ...