Recent additions

  • Quantitative assessment of morphology and sub-cellular changes in macrophages and trophoblasts during inflammation 

    Singh, Rajwinder; Dubey, Vishesh; Wolfson, Deanna; Ahmad, Azeem; Butola, Ankit; Acharya, Ganesh; Singh Mehta, Dalip; Basnet, Purusotam; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-12)
    In pregnancy during an inflammatory condition, macrophages present at the feto-maternal junction release an increased amount of nitric oxide (NO) and pro-inflammatory cytokines such as TNF-α and INF-γ, which can disturb the trophoblast functions and pregnancy outcome. Measurement of the cellular and sub-cellular morphological modifications associated with inflammatory responses are important in order ...
  • Dust sputtering within the inner heliosphere: a modelling study 

    Baumann, Carsten; Myrvang, Margaretha; Mann, Ingrid (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-03)
    The aim of this study is to investigate how sputtering by impacting solar wind particles influence the lifetime of dust particles in the inner heliosphere near the Sun.<p><p> We consider three typical dust materials: silicate, Fe<sub>0.4</sub>Mg<sub>0.6</sub>O and carbon and describe their sputtering yields based on atomic yields given by the Stopping and Range of Ions in Matter (SRIM) package. ...
  • Can Mineral Oil Slicks Be Distinguished From Newly Formed Sea Ice Using Synthetic Aperture Radar? 

    Johansson, Malin; Espeseth, Martine; Brekke, Camilla; Holt, Benjamin (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-18)
    In this feasibility study discriminating oil slicks and newly formed sea ice using SAR imagery is investigated, using imagery from the L-band high-resolution Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) airborne and the satellite C-band RADARSAT-2 (RS-2) systems. To determine the separability of these two varying but similar appearing low backscatter ocean surfaces, multi-polarization ...
  • Auroral classification ergonomics and the implications for machine learning 

    McKay, Derek; Kvammen, Andreas (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-09)
    The machine-learning research community has focused greatly on bias in algorithms and have identified different manifestations of it. Bias in training samples is recognised as a potential source of prejudice in machine learning. It can be introduced by the human experts who define the training sets. As machine-learning techniques are being applied to auroral classification, it is important to identify ...
  • Getting adhesion force maps with an amplitude-modulation AFM in tapping mode 

    Chiesa, Matteo; Santos, Sergio; Lai, Chia-Yun; Olukan, Tuza Adeyemi (Research report; Forskningsrapport, 2020-07)
    Here we demonstrate how to get adhesion force maps with an amplitude-modulation AFM in tapping mode. Our method is tapping mode but it is carried out at ultra-small amplitudes in the presence of surface water layers. The tip is made to vibrated under the water layer in what we call Small Amplitude Small Set-point AM AFM. We show how this is done with an example based on the Cypher scanning probe ...
  • CMIP5 model selection for ISMIP6 ice sheet model forcing: Greenland and Antarctica 

    Barthel, Alice; Agosta, Cécile; Little, Christopher M.; Hattermann, Tore; Jourdain, Nicolas; Goelzer, Heiko; Nowicki, Sophie; Seroussi, Helene; Straneo, Fiammetta; Bracegirdle, Thomas J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-06)
    The ice sheet model intercomparison project for CMIP6 (ISMIP6) effort brings together the ice sheet and climate modeling communities to gain understanding of the ice sheet contribution to sea level rise. ISMIP6 conducts stand-alone ice sheet experiments that use space- and time-varying forcing derived from atmosphere–ocean coupled global climate models (AOGCMs) to reflect plausible trajectories for ...
  • Reconstructing force profiles with an amplitude-modulation AFM in tapping mode 

    Olukan, Tuza Adeyemi; Lai, Chia-Yun; Santos, Sergio; Amadei, Carlo Alberto; Chiesa, Matteo (Research report; Forskningsrapport, 2020-07)
    Here we demonstrate how to reconstruct force profiles with an amplitude-modulation AFM operated in in standard tapping mode. Our example is based on the Cypher scanning probe microscope from Asylum Research. The method is based on Sader and Katan’s algorithm, but we have implemented an experimental set-up that allows for robust reconstruction. We discuss the details here.
  • Explaining decisions of deep neural networks used for fish age prediction 

    Ordonez, Alba; Eikvil, Line; Salberg, Arnt-Børre; Harbitz, Alf; Murray, Sean Meling; Kampffmeyer, Michael (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-19)
    Age-reading of fish otoliths (ear stones) is important for the sustainable management of fish resources. However, the procedure is challenging and requires experienced readers to carefully examine annual growth zones. In a recent study, convolutional neural networks (CNNs) have been demonstrated to perform reasonably well on automatically predicting fish age from otolith images. In the present study, ...
  • Large-Scale Detection and Categorization of Oil Spills from SAR Images with Deep Learning 

    Bianchi, Filippo Maria; Espeseth, Martine; Borch, Njål Trygve (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-14)
    We propose a deep-learning framework to detect and categorize oil spills in synthetic aperture radar (SAR) images at a large scale. Through a carefully designed neural network model for image segmentation trained on an extensive dataset, we obtain state-of-the-art performance in oil spill detection, achieving results that are comparable to results produced by human operators. We also introduce a ...
  • First observations of the McMurdo-South Pole oblique ionospheric HF channel 

    Chartier, Alex T.; Vierinen, Juha; Jee, Geonhwa (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-09)
    We present the first observations from a new low-cost oblique ionosonde located in Antarctica. The transmitter is located at McMurdo Station, Ross Island, and the receiver at Amundsen–Scott Station, South Pole. The system was demonstrated successfully in March 2019, with the experiment yielding over 30 000 ionospheric echoes over a 2-week period. These data indicate the presence of a stable E layer ...
  • On the relation between polarimetric synthetic aperture radar (SAR) features and sea ice melt pond fraction 

    Fors, Ane Schwenke; Doulgeris, Anthony Paul; Renner, Angelika; Brekke, Camilla; Gerland, Sebastian (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-12)
    In this study we examine the relationship between sea ice melt pond fraction and two polarimetric C-band synthetic aperture radar (SAR) features. Three high-resolution SAR scenes were recorded in the Fram Strait in late summer 2011, covering iceberg-fast first-year and old sea ice. In addition, melt pond fraction was retrieved from photographs recorded during a helicopter flight at the study area. ...
  • Mapping sea-ice types from Sentinel-1 considering the surface-type dependent effect of incidence angle 

    Lohse, Johannes; Doulgeris, Anthony Paul; Dierking, Wolfgang (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-23)
    Automated classification of sea-ice types in Synthetic Aperture Radar (SAR) imagery is complicated by the class-dependent decrease of backscatter intensity with Incidence Angle (IA). In the log-domain, this decrease is approximately linear over the typical range of space-borne SAR instruments. A global correction does not consider that different surface types show different rates of decrease in ...
  • Ice extent in sub-arctic fjords and coastal areas from 2001 to 2019 analyzed from MODIS imagery 

    O'Sadnick, Megan Eileen; Petrich, Chris; Brekke, Camilla; Skardhamar, Jofrid (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-03)
    Results examining variations in the ice extent along the Norwegian coastline based on the analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) images from 2001 to 2019, February through May, are presented. A total of 386 fjords and coastal areas were outlined and grouped into ten regions to assess seasonal and long-term trends in ice extent. In addition, three fjords were examined to ...
  • Added value of multitemporal polarimetric UAVSAR data for permanent scatterers detection 

    Nikaein, Tina; Akbari, Vahid; Arefi, Hossein (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-05)
    In the last decades, differential synthetic aperture radar (SAR) interferometric (InSAR) (DInSAR) techniques have been used to estimate the Earth's surface deformation with high resolution. In this paper, we present an approach for increasing the quantity of permanent scattered pixels. These pixels are selected for DInSAR processing based on polarimetric information prepared by new sensors. The ...
  • The impact of system noise in polarimetric SAR imagery on oil spill observations 

    Espeseth, Martine; Brekke, Camilla; Jones, Cathleen Elaine; Holt, Benjamin; Freeman, Anthony (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-16)
    The effects of both system additive and multiplicative noise on the X-, C-, and L-band synthetic aperture radar (SAR) data covering oil slicks are examined. Prior studies have attempted to characterize such oil slicks, primarily through analysis of polarimetric SAR data. In this article, we factor in system noise that is added to the backscattered signal, introducing artifacts that can easily be ...
  • Sampling moiré method: a tool for sensing quadratic phase distortion and its correction for accurate quantitative phase microscopy 

    Jayakumar, Nikhil; Ahmad, Azeem; Mehta, Dalip Singh; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-24)
    The advantages of quantitative phase microscopy (QPM) such as label-free imaging with high spatial sensitivity, live cell compatibility and high-speed imaging makes it viable for various biological applications. The measurement accuracy of QPM strongly relies on the shape of the recorded interferograms, whether straight or curved fringes are recorded during the data acquisition. Moreover, for a ...
  • Automatic fringe pattern enhancement using truly adaptive period-guided bidimensional empirical mode decomposition 

    Gocłowski, Paweł; Trusiak, Maciej; Ahmad, Azeem; Styk, Adam; Mico, Vicente; Ahluwalia, Balpreet Singh; Patorski, Krzysztof (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-19)
    Fringe patterns encode the information about the result of a measurement performed via widely used optical full-field testing methods, e.g., interferometry, digital holographic microscopy, moiré techniques, structured illumination etc. Affected by the optical setup, changing environment and the sample itself fringe patterns are often corrupted with substantial noise, strong and uneven background ...
  • Sub-nanometer height sensitivity by phase shifting interference microscopy under environmental fluctuations 

    Ahmad, Azeem; Dubey, Vishesh Kumar; Butola, Ankit; Tinguely, Jean-Claude; Ahluwalia, Balpreet Singh; Mehta, Dalip Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-18)
    Phase shifting interferometric (PSI) techniques are among the most sensitive phase measurement methods. Owing to its high sensitivity, any minute phase change caused due to environmental instability results into, inaccurate phase measurement. Consequently, a well calibrated piezo electric transducer (PZT) and highly-stable environment is mandatory for measuring accurate phase map using PSI implementation. ...
  • Measuring Wind Speed Using the Internal Stabilization System of a Quadrotor Drone 

    Simma, Magdalena; Mjøen, Håvard; Boström, Tobias (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-16)
    This article proposes a method of measuring wind speed using the data logged by the autopilot of a quadrotor drone. Theoretical equations from works on quadrotor control are utilized and supplemented to form the theoretical framework. Static thrust tests provide the necessary parameters for calculating wind estimates. Flight tests were conducted at a test site with laminar wind conditions with the ...
  • Electron heating by HF pumping of high-latitude ionospheric F-region plasma near magnetic zenith 

    Leyser, Thomas B; Gustavsson, Björn Johan; Rexer, Theresa; Rietveld, Michael T (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-06)
    High-frequency electromagnetic pumping of ionospheric F-region plasma at high and mid latitudes gives the strongest plasma response in magnetic zenith, antiparallel to the geomagnetic field in the Northern Hemisphere. This has been observed in optical emissions from the pumped plasma turbulence, electron temperature enhancements, filamentary magnetic field-aligned plasma density irregularities, and ...

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