Viser treff 121-140 av 947

    • 3D full-wave multi-scattering forward solver for coherent microscopes 

      Qin, Yingying; Butola, Ankit; Agarwal, Krishna (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-21)
      A rigorous forward model solver for conventional coherent microscope is presented. The forward model is derived from Maxwell’s equations and models the wave behaviour of light matter interaction. Vectorial waves and multiple-scattering effect are considered in this model. Scattered field can be calculated with given distribution of the refractive index of the biological sample. Bright field images ...
    • The altitude of green OI 557.7 nm and blue N2+ 427.8 nm aurora 

      Whiter, Daniel K.; Partamies, Noora; Gustavsson, Bjorn Johan; Kauristie, Kirsti (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-06)
      We have performed a large statistical study of the peak emission altitude of green O(1D2–1S0) (557.7 nm) and blue 1 N (427.8 nm) aurora using observations from a network of all-sky cameras stationed across northern Finland and Sweden recorded during seven winter seasons from 2000 to 2007. Both emissions were found to typically peak at about 114 km. The distribution of blue peak altitudes is more ...
    • Horizontal Correlation Functions of Wind Fluctuations in the Mesosphere and Lower Thermosphere 

      Poblet, Facundo L.; Vierinen, Juha; Avsarkisov, Victor; Conte, J. Federico; Charuvil Asokan, Harikrishnan; Jacobi, Christoph; Chau, Jorge L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-01)
      Measurements of kinetic energy in vortical and divergent fluctuations in the mesosphere and lower thermosphere can be used to study stratified turbulence (ST) and gravity waves. This can be done using horizontal correlation functions of the fluctuating component of velocity. This study introduces a novel method for estimating these correlation functions using radars that observe Doppler shifts ...
    • A Comparison of Arctic Ocean Sea Ice Export Between Nares Strait and the Canadian Arctic Archipelago 

      Howell, S.E.L.; Babb, D.G.; Landy, Jack Christopher; Moore, G.W.K.; Montpetit, B.; Brady, M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-13)
      Nares Strait and the channels of the Canadian Arctic Archipelago (CAA) act as conduits for sea ice export from the Arctic Ocean but have never been directly compared. Here, we perform such a comparison for both the sea ice area and volume fluxes from October 2016 to December 2021. Nares Strait provided the largest average seasonal (October through September) ice area flux of 95 ± 8 × 10<sup>3</sup> ...
    • Synoptic Variability in Satellite Altimeter-Derived Radar Freeboard of Arctic Sea Ice 

      Nab, Carmen; Mallett, Robbie; Gregory, William; Landy, Jack Christopher; Lawrence, Isobel; Willatt, Rosemary; Stroeve, Julienne; Tsamados, Michel (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-09)
      Satellite observations of sea ice freeboard are integral to the estimation of sea ice thickness. It is commonly assumed that radar pulses from satellite-mounted Ku-band altimeters penetrate through the snow and reflect from the snow-ice interface. We would therefore expect a negative correlation between snow accumulation and radar freeboard measurements, as increased snow loading weighs the ice floe ...
    • Transmission structured illumination microscopy with tunable frequency illumination using tilt mirror assembly 

      Samanta, Krishnendu; Ahmad, Azeem; Tinguely, Jean-Claude; Ahluwalia, Balpreet Singh; Joseph, Joby (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-26)
      We present experimental demonstration of tilt-mirror assisted transmission structured illumination microscopy (tSIM) that offers a large field of view super resolution imaging. An assembly of custom-designed tilt-mirrors are employed as the illumination module where the sample is excited with the interference of two beams reflected from the opposite pair of mirror facets. Tunable frequency structured ...
    • Stiffness tensor estimation of anisotropic crystal using point contact method and unscented Kalman filter 

      Kalimullah, Nur M.M.; Shukla, Kaushik; Shelke, Amit; Habib, Anowarul (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-02)
      The potential application of Lithium Niobate (LiNbO3) crystal is immense, specifically in the domain of metasurfaces and nano-resonators. However, the practical application of LiNbO<sub>3</sub> is impeded due to unreliable experimental techniques and inaccurate inversion algorithms for material characterization. In the current research, material characterization of anisotropic crystal is proposed ...
    • Image inpainting in acoustic microscopy 

      Habib, Anowarul; Banerjee, Pragyan; Mishra, Sibasish; Yadav, Nitin; Agarwal, Krishna; Melandsø, Frank; Prasad, Dilip K (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-27)
      Scanning acoustic microscopy (SAM) is a non-ionizing and label-free imaging modality used to visualize the surface and internal structures of industrial objects and biological specimens. The image of the sample under investigation is created using high-frequency acoustic waves. The frequency of the excitation signals, the signal-to-noise ratio, and the pixel size all play a role in acoustic image ...
    • A clinically motivated self-supervised approach for content-based image retrieval of CT liver images 

      Wickstrøm, Kristoffer; Østmo, Eirik Agnalt; Radiya, Keyur; Mikalsen, Karl Øyvind; Kampffmeyer, Michael; Jenssen, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-09)
      Deep learning-based approaches for content-based image retrieval (CBIR) of computed tomography (CT) liver images is an active field of research, but suffer from some critical limitations. First, they are heavily reliant on labeled data, which can be challenging and costly to acquire. Second, they lack transparency and explainability, which limits the trustworthiness of deep CBIR systems. We address ...
    • Highly sensitive quantitative phase microscopy and deep learning aided with whole genome sequencing for rapid detection of infection and antimicrobial resistance 

      Ahmad, Azeem; Hettiarachchi, Ramith; Khezri, Abdolrahman; Ahluwalia, Balpreet Singh; Wadduwage, Dushan; Ahmad, Rafi (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-12)
      Current state-of-the-art infection and antimicrobial resistance (AMR) diagnostics are based on culture-based methods with a detection time of 48–96 h. Therefore, it is essential to develop novel methods that can do real-time diagnoses. Here, we demonstrate that the complimentary use of label-free optical assay with whole-genome sequencing (WGS) can enable rapid diagnosis of infection and AMR. Our ...
    • The Departure from Mixed-Layer Similarity During the Afternoon Decay of Turbulence in the Free-Convective Boundary Layer: Results from Large-Eddy Simulations 

      Elguernaoui, Omar; Reuder, Joachim; Li, Dan; Maronga, Bjørn; Bakhoday Paskyabi, Mostafa; Wolf, Tobias; Esau, Igor (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-21)
      This study analyses the departure of the velocity-variances profiles from their quasi-steady state described by the mixed-layer similarity, using large-eddy simulations with different prescribed shapes and time scales of the surface kinematic heat flux decay. Within the descriptive frames where the time is tracked solely by the forcing time scale (either constant or time-dependent) describing the ...
    • Extreme Horizontal Wind Perturbations in the Mesosphere and Lower Thermosphere Over South America Associated With the 2022 Hunga Eruption 

      Poblet, Facundo L.; Chau, Jorge L.; Conte, J. Federico; Vierinen, Juha; Suclupe, Jose; Liu, Alan; Rodriguez, Rodolfo R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-13)
      On 15 January 2022, the Hunga volcano produced a massive explosion that generated perturbations in the entire atmosphere. Nonetheless, signatures in the mesosphere and lower thermosphere (MLT) have been challenging to identify. We report MLT horizontal wind perturbations using three multistatic specular meteor radars on the west side of South America (spanning more than 3,000 km). The most ...
    • Sea Ice Remote Sensing—Recent Developments in Methods and Climate Data Sets 

      Sandven, Stein; Spreen, Gunnar; Heygster, Georg; Girard-Ardhuin, Fanny; Farrell, Sinéad L.; Dierking, Wolfgang Fritz Otto; Allard, Richard A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-03)
      Sea ice monitoring by polar orbiting satellites has been developed over more than four decades and is today one of the most well-established applications of space observations. This article gives an overview of data product development from the first sensors to the state-of-the-art regarding retrieval methods, new products and operational data sets serving climate monitoring as well as daily operational ...
    • Single-Molecule Sizing through Nanocavity Confinement 

      Jacquat, Raphaël P. B.; Krainer, Georg; Peter, Quentin A. E.; Babar, Ali Nawaz; Vanderpoorten, Oliver; Xu, Catherine K.; Welsh, Timothy J.; Kaminski, Clemens F.; Keyser, Ulrich F.; Baumberg, Jeremy J.; Knowles, Tuomas P. J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-24)
      : An approach relying on nanocavity confinement is developed in this paper for the sizing of nanoscale particles and single biomolecules in solution. The approach, termed nanocavity diffusional sizing (NDS), measures particle residence times within nanofluidic cavities to determine their hydrodynamic radii. Using theoretical modeling and simulations, we show that the residence time of particles ...
    • Solved and unsolved riddles about low-latitude daytime valley region plasma waves and 150-km echoes 

      Chau, Jorge Luis; Longley, William; Reyes, Pablo; Pedatella, Nick; Otsuka, Yuichi; Stolle, Claudia; Liu, Huixin; Vierinen, Juha; Milla, Marco; Hysell, David L.; Oppenheim, Meers; Patra, A.; Lehmacher, G; Kudeki, Erhan (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-27)
      The Earth’s atmosphere near both the geographic and magnetic equators and at altitudes between 120 and 200 km is called the low-latitude valley region (LLVR) and is among the least understood regions of the ionosphere/thermosphere due to its complex interplay of neutral dynamics, electrodynamics, and photochemistry. Radar studies of the region have revealed puzzling daytime echoes scattered from ...
    • RELAX: Representation Learning Explainability 

      Wickstrøm, Kristoffer; Trosten, Daniel Johansen; Løkse, Sigurd Eivindson; Boubekki, Ahcene; Mikalsen, Karl Øyvind; Kampffmeyer, Michael; Jenssen, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-11)
      Despite the significant improvements that self-supervised representation learning has led to when learning from unlabeled data, no methods have been developed that explain what influences the learned representation. We address this need through our proposed approach, RELAX, which is the first approach for attribution-based explanations of representations. Our approach can also model the uncertainty ...
    • Preconditioning of Summer Melt Ponds From Winter Sea Ice Surface Temperature 

      Thielke, Linda; Fuchs, Niels; Spreen, Gunnar; Tremblay, Bruno; Birnbaum, Gerit; Huntemann, Marcus; Hutter, Nils; Itkin, Polona; Jutila, Arttu; Webster, Melinda A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-22)
      Comparing helicopter-borne surface temperature maps in winter and optical orthomosaics in summer from the year-long Multidisciplinary drifting Observatory for the Study of Arctic Climate expedition, we find a strong geometric correlation between warm anomalies in winter and melt pond location the following summer. Warm anomalies are associated with thinner snow and ice, that is, surface depression ...
    • Comparing quality of breast cancer care in the Netherlands and Norway by federated propensity score analytics 

      Hamersma, Dave T.; Schreuder, Kay; Geleijnse, Gijs; Heeg, Erik; Cellamare, Matteo; Lobbes, Marc B. I.; Mureau, Marc A. M.; Koppert, Linetta B.; Skjerven, Helle; Nygård, Jan Franz; Groothuis-Oudshoorn, Catharina G. M.; Siesling, Sabine (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-05)
      Purpose - The aim of the study was to benchmark and compare breast cancer care quality indicators (QIs) between Norway and the Netherlands using federated analytics preventing transfer of patient-level data.<p> <p>Methods - Breast cancer patients (2017–2018) were retrieved from the Netherlands Cancer Registry and the Cancer Registry of Norway. Five European Society of Breast Cancer Specialists ...
    • Predicting Regions of Local Recurrence in Glioblastomas Using Voxel-Based Radiomic Features of Multiparametric Postoperative MRI 

      Cepeda, Santiago; Luppino, Luigi Tommaso; Pérez-Núñez, Angel; Solheim, Ole Skeidsvoll; García-García, Sergio; Velasco-Casares, María; Karlberg, Anna Maria; Eikenes, Live; Sarabia, Rosario; Arrese, Ignacio; Zamora, Tomás; Gonzalez, Pedro; Jiménez-Roldán, Luis; Kuttner, Samuel (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-22)
      The globally accepted surgical strategy in glioblastomas is removing the enhancing tumor. However, the peritumoral region harbors infiltration areas responsible for future tumor recurrence. This study aimed to evaluate a predictive model that identifies areas of future recurrence using a voxel-based radiomics analysis of magnetic resonance imaging (MRI) data. This multi-institutional study included ...
    • Energy budget diagnosis of changing climate feedback 

      Cael, B. B.; Bloch-Johnson, Jonah; Ceppi, Paulo; Fredriksen, Hege-Beate; Goodwin, Philip; Gregory, Jonathan M.; Smith, Christopher J.; Williams, Richard G. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-21)
      The climate feedback determines how Earth’s climate responds to anthropogenic forcing. It is thought to have been more negative in recent decades due to a sea surface temperature “pattern effect,” whereby warming is concentrated in the western tropical Pacific, where nonlocal radiative feedbacks are very negative. This phenomenon has however primarily been studied within climate models. We diagnose ...