activity
20172025
most citedMixing Up Contrastive Learning: Self-Supervised Representation Learning for Time Series

108 citations · 220 across the 18 of their papers we have counts for

collaborators

18 papers

cs.CV2025

Random Window Augmentations for Deep Learning Robustness in CT and Liver Tumor Segmentation

Eirik A. Østmo, Kristoffer K. Wickstrøm, Keyur Radiya +3

Contrast-enhanced Computed Tomography (CT) is important for diagnosis and treatment planning for various medical conditions. Deep learning (DL) based segmentation models may enable…

cs.CL2025

Natural Language Processing for Electronic Health Records in Scandinavian Languages: Norwegian, Swedish, and Danish

Ashenafi Zebene Woldaregay, Jørgen Aarmo Lund, Phuong Dinh Ngo +8

Background: Clinical natural language processing (NLP) refers to the use of computational methods for extracting, processing, and analyzing unstructured clinical text data, and hol…

cs.CY2024

Artificial intelligence to improve clinical coding practice in Scandinavia: a crossover randomized controlled trial

Taridzo Chomutare, Therese Olsen Svenning, Miguel Ángel Tejedor Hernández +8

\textbf{Trial design} Crossover randomized controlled trial. \textbf{Methods} An AI tool, Easy-ICD, was developed to assist clinical coders and was tested for improving both accura…

cs.LG2023

Approaching adverse event detection utilizing transformers on clinical time-series

Helge Fredriksen, Per Joel Burman, Ashenafi Woldaregay +2

Patients being admitted to a hospital will most often be associated with a certain clinical development during their stay. However, there is always a risk of patients being subject…

cs.CV2022★ 4 cited

A clinically motivated self-supervised approach for content-based image retrieval of CT liver images

Kristoffer Knutsen Wickstrøm, Eirik Agnalt Østmo, Keyur Radiya +3

Deep learning-based approaches for content-based image retrieval (CBIR) of CT liver images is an active field of research, but suffers from some critical limitations. First, they a…

stat.ML2022

The Kernelized Taylor Diagram

Kristoffer Wickstrøm, J. Emmanuel Johnson, Sigurd Løkse +4

This paper presents the kernelized Taylor diagram, a graphical framework for visualizing similarities between data populations. The kernelized Taylor diagram builds on the widely u…

stat.ML2022★ 108 cited

Mixing Up Contrastive Learning: Self-Supervised Representation Learning for Time Series

Kristoffer Wickstrøm, Michael Kampffmeyer, Karl Øyvind Mikalsen +1

The lack of labeled data is a key challenge for learning useful representation from time series data. However, an unsupervised representation framework that is capable of producing…

stat.ML2021★ 2 cited

RELAX: Representation Learning Explainability

Kristoffer K. Wickstrøm, Daniel J. Trosten, Sigurd Løkse +4

Despite the significant improvements that representation learning via self-supervision has led to when learning from unlabeled data, no methods exist that explain what influences t…

cs.LG2021

On the Use of Time Series Kernel and Dimensionality Reduction to Identify the Acquisition of Antimicrobial Multidrug Resistance in the Intensive Care Unit

Óscar Escudero-Arnanz, Joaquín Rodríguez-Álvarez, Karl Øyvind Mikalsen +2

The acquisition of Antimicrobial Multidrug Resistance (AMR) in patients admitted to the Intensive Care Units (ICU) is a major global concern. This study analyses data in the form o…

cs.LG2020★ 48 cited

Uncertainty-Aware Deep Ensembles for Reliable and Explainable Predictions of Clinical Time Series

Kristoffer Wickstrøm, Karl Øyvind Mikalsen, Michael Kampffmeyer +2

Deep learning-based support systems have demonstrated encouraging results in numerous clinical applications involving the processing of time series data. While such systems often a…

stat.ML2020

A Kernel to Exploit Informative Missingness in Multivariate Time Series from EHRs

Karl Øyvind Mikalsen, Cristina Soguero-Ruiz, Robert Jenssen

A large fraction of the electronic health records (EHRs) consists of clinical measurements collected over time, such as lab tests and vital signs, which provide important informati…

cs.LG2019

Time series cluster kernels to exploit informative missingness and incomplete label information

Karl Øyvind Mikalsen, Cristina Soguero-Ruiz, Filippo Maria Bianchi +2

The time series cluster kernel (TCK) provides a powerful tool for analysing multivariate time series subject to missing data. TCK is designed using an ensemble learning approach in…

stat.ML2019★ 41 cited

Noisy multi-label semi-supervised dimensionality reduction

Karl Øyvind Mikalsen, Cristina Soguero-Ruiz, Filippo Maria Bianchi +1

Noisy labeled data represent a rich source of information that often are easily accessible and cheap to obtain, but label noise might also have many negative consequences if not ac…

cs.NE2018★ 7 cited

Learning representations for multivariate time series with missing data using Temporal Kernelized Autoencoders

Filippo Maria Bianchi, Lorenzo Livi, Karl Øyvind Mikalsen +2

Learning compressed representations of multivariate time series (MTS) facilitates data analysis in the presence of noise and redundant information, and for a large number of variat…

stat.ML2018★ 4 cited

An Unsupervised Multivariate Time Series Kernel Approach for Identifying Patients with Surgical Site Infection from Blood Samples

Karl Øyvind Mikalsen, Cristina Soguero-Ruiz, Filippo Maria Bianchi +2

A large fraction of the electronic health records consists of clinical measurements collected over time, such as blood tests, which provide important information about the health s…

cs.NE2017

Classification of postoperative surgical site infections from blood measurements with missing data using recurrent neural networks

Andreas Storvik Strauman, Filippo Maria Bianchi, Karl Øyvind Mikalsen +3

Clinical measurements that can be represented as time series constitute an important fraction of the electronic health records and are often both uncertain and incomplete. Recurren…

cs.NE2017★ 4 cited

Learning compressed representations of blood samples time series with missing data

Filippo Maria Bianchi, Karl Øyvind Mikalsen, Robert Jenssen

Clinical measurements collected over time are naturally represented as multivariate time series (MTS), which often contain missing data. An autoencoder can learn low dimensional ve…

stat.ML2017★ 2 cited

Time Series Cluster Kernel for Learning Similarities between Multivariate Time Series with Missing Data

Karl Øyvind Mikalsen, Filippo Maria Bianchi, Cristina Soguero-Ruiz +1

Similarity-based approaches represent a promising direction for time series analysis. However, many such methods rely on parameter tuning, and some have shortcomings if the time se…