Now showing items 61-80 of 5012

    • On the degree of varieties of sum of squares 

      Ferguson, Andrew; Ottaviani, Giorgio; Safey el Din, Mohab; Teixeira Turatti, Ettore (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-10)
      We study the problem of how many different sum of squares decompositions a general polynomial <i>f</i> with SOS-rank <i>k</i> admits. We show that there is a link between the variety SOS<sub><i>k</sub></i>(<i>f</i>) of all SOS-decompositions of <i>f</i> and the orthogonal group O(<i>k</i>). We exploit this connection to obtain the dimension of SOS<sub><i>k</sub></i>(<i>f</i>) and show that its degree ...
    • Arctic Freeboard and Snow Depth From Near-Coincident CryoSat-2 and ICESat-2 (CRYO2ICE) Observations: A First Examination of Winter Sea Ice During 2020–2022 

      Hansen, Renee Mie Fredensborg; Skourup, Henriette; Rinne, Eero; Høyland, Knut Vilhelm; Landy, Jack Christopher; Merkouriadi, Ioanna; Forsberg, René (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-18)
      In the summer of 2020, ESA changed the orbit of CryoSat-2 to align periodically with NASA's ICESat-2 mission, a campaign known as CRYO2ICE, which allows for near-coincident CryoSat-2 and ICESat-2 observations in space and time over the Arctic until summer 2022, where the CRYO2ICE Antarctic campaign was initiated. This study investigates the Arctic CRYO2ICE radar and laser freeboards acquired by ...
    • The span of singular tuples of a tensor beyond the boundary format 

      Sodomaco, Luca; Teixeira Turatti, Ettore (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-10)
      A singular <i>k</i>-tuple of a tensor T of format (<i>n<sub>1</sub></i>, ..., <i>n</i><sub><i><k></i></sub>) is essentially a complex critical point of the distance function from <i>T</i> constrained to the cone of tensors of format (<i>n</i><sub>1</sub>, ..., <i>n<sub>k</sub></i>) of rank at most one. A generic tensor has finitely many complex singular <i>k</i>-tuples, and their number depends only ...
    • Kulturens effekt på sikkerhetsatferd En kvalitativ studie av polske bygg- og anleggsarbeidere i Norge – forholdet mellom kultur, jobbkrav, ressurser og sikkerhetsatferd 

      Strand Jonsmyr, Ida (Master thesis; Mastergradsoppgave, 2024-06-28)
      Bygg- og anleggsbransjen utgjør en svært risikabel arbeidsplass, noe som gjenspeiler seg i omfanget av arbeidsulykker. Av berørte parter er utenlandske, og spesielt polske arbeidere, overrepresentert på skadestatistikken i forbindelse med de mest alvorlige arbeidsulykkene (Mostue et al., 2022). For å sikre en trygg arbeidsplass for alle aktører anses det som nødvendig å drive kontinuerlig ...
    • Migrasjon - en radikal forandring? En eksplorativ litteraturstudie om samspillet mellom migrasjon, radikalisering og samfunnssikkerhet i Norge 

      Vuckovic, Edin (Master thesis; Mastergradsoppgave, 2024-06-03)
      Studien undersøker hvordan migrasjon påvirker samfunnssikkerheten i Norge med tanke på radikalisering. Problemstillingen belyses gjennom en eksplorativ litteraturstudie, basert på en dokumentanalyse av eksisterende forskning. Studien benytter internasjonalt anerkjente teorier for å analysere sammenhengen mellom migrasjon og radikalisering i norsk kontekst. Funnene viser at migrasjonens komplekse ...
    • Utvikling av en positiv sikkerhetskultur gjennom økt risikoforståelse 

      Haugen, Maria (Master thesis; Mastergradsoppgave, 2024-05-30)
      Denne studien undersøker hvilke utfordringer organisasjoner i tunnelbransjen møter i utviklingen av en positiv sikkerhetskultur. En sektor som har en av de høyeste ulykkesratene i landet (Arbeidstilsynet, 2019). Sikkerhetskultur er identifisert som en viktig faktor i arbeidet mot en tryggere arbeidsplass. Tidligere forskning viser imidlertid at det fortsatt er behov for å utforske måter å optimalisere ...
    • Quantification of impedance and mechanical properties of Zeonor using scanning acoustic microscopy 

      Ojha, Shivam; Agarwal, Komal; Shelke, Amit; Habib, Anowarul (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-27)
      This article explores the potential of Zeonor, a transparent cyclic olefin polymer, for applications in transparent acoustic/photo-acoustic transducers. Despite its widespread use in optics, microfluidics, medical devices, and electronics, Zeonor’s acoustic properties remain understudied. To extend this, the current work employs scanning acoustic microscopy (SAM) to obtain its mechanical properties. ...
    • An exploratory study of self-supervised pre-training on partially supervised multi-label classification on chest X-ray images 

      Dong, Nanqing; Kampffmeyer, Michael Christian; Su, Haoyang; Xing, Eric (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-06-14)
      This paper serves as the first empirical study on self-supervised pre-training on partially supervised learning, an emerging yet unexplored learning paradigm with missing annotations. This is particularly important in the medical imaging domain, where label scarcity is the main challenge of practical applications. To promote the awareness of partially supervised learning, we leverage partially ...
    • Deep learning derived input function in dynamic [18F]FDG PET imaging of mice 

      Kuttner, Samuel; Luppino, Luigi Tommaso; Convert, Laurence; Sarrhini, Otman; Lecomte, Roger; Kampffmeyer, Michael Christian; Sundset, Rune; Jenssen, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-11)
      Dynamic positron emission tomography and kinetic modeling play a critical role in tracer development research using small animals. Kinetic modeling from dynamic PET imaging requires accurate knowledge of an input function, ideally determined through arterial blood sampling. Arterial cannulation in mice, however, requires complex, time-consuming and terminal surgery, meaning that longitudinal ...
    • Using clustering to understand intra-city warming in heatwaves: insights into Paris, Montreal, and Zurich 

      Zhao, Yongling; Strebel, Dominik; Derome, Dominique; Esau, Igor; Li, Qi; Carmeliet, Jan (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-05-10)
      We introduce a novel methodological advancement by clustering paired near-surface air temperature with the planetary boundary layer height to characterize intra-city clusters for analytics. To illustrate this approach, we analyze three heatwaves (HWs): the 2019 HW in Paris, the 2018 HW in Montreal, and the 2017 HW in Zurich. We assess cluster-based characteristics before, during, and after ...
    • Social robots in research on social and cognitive development in infants and toddlers: A scoping review 

      Flatebø, Solveig; Tran, Ngoc Nha Vi; Wang, Catharina Elisabeth Arfwedson; Bongo, Lars Ailo Aslaksen (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-05-15)
      There is currently no systematic review of the growing body of literature on using social robots in early developmental research. Designing appropriate methods for early childhood research is crucial for broadening our understanding of young children’s social and cognitive development. This scoping review systematically examines the existing literature on using social robots to study social and ...
    • Generalized identifiability of sums of squares 

      Ottaviani, Giorgio; Teixeira Turatti, Ettore (Journal article; Tidsskriftartikkel; Peer reviewed, 2025)
    • Binary forms of suprageneric rank and the multiple root loci 

      González Nevado, Alejandro; Teixeira Turatti, Ettore (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-11)
      We state the relation between the variety of binary forms of given rank and the dual of the multiple root loci. This is a new result for the suprageneric rank that appears as a continuation of the cited work by Buczyński, Han, Mella and Teitler. We describe the strata of these varieties and explore their singular loci.
    • Hypsochlorins 

      Larsen, Simon; Conradie, Jeanet; Desbois, Nicolas; Gros, Claude Philippe; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-19)
      Both the Soret and Q bands of chlorin e6 complexes blueshift on going from Zn to Pd to Pt as the coordinated metal, establishing the latter two complexes as hypsochlorins. DFT/TDDFT calculations indicate that the blueshifts appear to be related to the presence of the electronegative metal ion, which lowers the orbital energies of the HOMO and HOMO-1, while leaving the LUMOs relatively unaffected.
    • A Robust Framework for Distributional Shift Detection Under Sample-Bias 

      Torpmann-Hagen, Birk Sebastian Frostelid; Riegler, Michael; Halvorsen, Pål; Johansen, Dag (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-24)
      Deep Neural Networks have been shown to perform poorly or even fail altogether when deployed in real-world settings, despite exhibiting excellent performance on initial benchmarks. This typically occurs due to relative changes in the nature of the production data, often referred to as distributional shifts. In an attempt to increase the transparency, trustworthiness, and overall utility of deep ...
    • NOIRE-Net–a convolutional neural network for automatic classification and scaling of high-latitude ionograms 

      Kvammen, Andreas; Vierinen, Juha-Pekka; Huyghebaert, Devin Ray; Rexer, Theresa; Spicher, Andres; Gustavsson, Björn Johan; Floberg, Jens (Journal article; Tidsskriftartikkel, 2024-06-03)
      Millions of ionograms are acquired annually to monitor the ionosphere. The accumulated data contain untapped information from a range of locations, multiple solar cycles, and various geomagnetic conditions. In this study, we propose the application of deep convolutional neural networks to automatically classify and scale high-latitude ionograms. A supervised approach is implemented and the networks ...
    • Dissipation Rates of Mesospheric Stratified Turbulence From Multistatic Meteor-Radar Observations 

      Vierinen, Juha-Pekka; Poblet, F.L.; Chau, J.L.; Avsarkisov, V.; Pecseli, Hans Laszlo; Tsutsumi, M.; Nozawa, S.; Johnsen, Magnar Gullikstad; Latteck, R.; Gulbrandsen, Njål (Journal article; Tidsskriftartikkel, 2024-06-06)
      Stratified turbulence (ST) has been proposed as a model for the dynamics of the mesosphere-lower thermosphere (MLT) region. This theory postulates that for horizontal mesoscales (∼1–400 km), the kinetic energy of horizontal winds dissipates from large to small scales with an approximately mean constant rate. In this investigation, dissipation rates are quantified using meteor-radar observations ...
    • Plasmonic nano-bowls for monitoring intra-membrane changes in liposomes, and DNA-based nanocarriers in suspension 

      Das, Sathi; Tinguely, Jean-Claude; Obuobi, Sybil Akua Okyerewa; Skalko Basnet, Natasa; Saxena, Kanchan; Ahluwalia, Balpreet Singh; Singh Mehta, Dalip (Journal article; Tidsskriftartikkel, 2024-03-12)
      Programmable nanoscale carriers, such as liposomes and DNA, are readily being explored for personalized medicine or disease prediction and diagnostics. The characterization of these nanocarriers is limited and challenging due to their complex chemical composition. Here, we demonstrate the utilization of surface-enhanced Raman spectroscopy (SERS), which provides a unique molecular fingerprint of ...
    • Theoretical Photoelectron Spectroscopy of Metal-Metal Quintuple Bonds: Relativity-Driven Reordering of Frontier Orbitals 

      Ghosh, Abhik; Conradie, Jeanet (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-01)
      A recent reinvestigation of the gas-phase photoelectron spectra of Group 6 metal−metal quadruple-bonded complexes with scalar-relativistic DFT calculations showed that common exchange-correlation functionals reproduce the lowest ionization potentials in a semiquantitative manner. The finding encouraged us to undertake a DFT study of metal− metal quintuple bonds in a set of bisamidinato complexes ...
    • Application of generalized aurora computed tomography to the EISCAT-3D project 

      Tanaka, Yoshimasa; Ogawa, Yasunobu; Kadokura, Akira; Aso, Takehiko; Gustavsson, Björn Johan; Brändström, Urban; Sergienko, Tima; Ueno, Genta; Saita, Satoko (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-05-29)
      EISCAT_3D is a project to build a multi-site phased-array incoherent scatter radar system in northern Fenno-Scandinavia. We demonstrate via numerical simulation how useful monochromatic images taken by a multi-point imager network are for auroral research in the EISCAT_3D project. We apply the generalized aurora computed tomography (G-ACT) method to modelled observational data from real instruments, ...