Viser treff 543-562 av 939

    • Nanoscopy of bacterial cells immobilized by holographic optical tweezers 

      Diekmann, Robin; Wolfson, Deanna; Spahn, Christoph; Heilemann, Mike; Schuttpelz, Mark; Huser, Thomas (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-13)
      Imaging non-adherent cells by super-resolution far-field fluorescence microscopy is currently not possible because of their rapid movement while in suspension. Holographic optical tweezers (HOTs) enable the ability to freely control the number and position of optical traps, thus facilitating the unrestricted manipulation of cells in a volume around the focal plane. Here we show that immobilizing ...
    • Necessary Conditions for Warm Inflow Toward the Filchner Ice Shelf, Weddell Sea 

      Daae, Kjersti; Hattermann, Tore; Darelius, Elin Maria K.; Mueller, Rachael D.; Naughten, Kaitlin A; Timmermann, Ralph; Hellmer, Hartmut H. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-09)
      Understanding changes in Antarctic ice shelf basal melting is a major challenge for predicting future sea level. Currently, warm Circumpolar Deep Water surrounding Antarctica has limited access to the Weddell Sea continental shelf; consequently, melt rates at Filchner‐Ronne Ice Shelf are low. However, large‐scale model projections suggest that changes to the Antarctic Slope Front and the coastal ...
    • Negational symmetry of quantum neural networks for binary pattern classification 

      Dong, Nanqing; Kampffmeyer, Michael; Voiculescu, Irina; Xing, Eric (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-27)
      Although quantum neural networks (QNNs) have shown promising results in solving simple machine learning tasks recently, the behavior of QNNs in binary pattern classification is still underexplored. In this work, we find that QNNs have an Achilles’ heel in binary pattern classification. To illustrate this point, we provide a theoretical insight into the properties of QNNs by presenting and analyzing ...
    • A nested high-resolution unstructured grid 3-D ocean-sea ice-ice shelf setup for numerical investigations of the Petermann ice shelf and fjord 

      Prakash, Abhay; Zhou, Qin; Hattermann, Tore; Bao, Weiyang; Graversen, Rune Grand; Kirchner, Nina (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-18)
      Three-dimensional numerical simulation of circulation in fjords hosting marine-terminating ice shelves is challenging because of the complexity of processes involved in such environments. This often requires a comprehensive model setup. The following elements are needed: bathymetry (usually unknown beneath the glacier tongue), ice shelf draft (impacting water column thickness), oceanographic state ...
    • A new auroral phenomenon, the anti-black aurora 

      Nel, A.E.; Kosch, M.J.; Keith Whiter, Daniel; Gustavsson, Björn Johan; Aslaksen, Torun Helene (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-19)
      Black auroras are small-scale features embedded in the diffuse background aurora, typically occurring post-substorm after magnetic midnight and with an eastward drift imposed. Black auroras show a significant reduction in optical brightness compared to the surrounding diffuse aurora, and can appear as slow-moving arcs or rapidly-moving patches and arc segments. We report, for the first time, an even ...
    • New capabilities of the upgraded EISCAT high-power HF facility 

      Rietveld, Michael T; Senior, Andrew; Markkanen, Jussi; Westman, Assar (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-22)
      The high-power HF (high-frequency) facility (commonly known as Heating) near Tromsø, Norway, which is an essential part of the European Incoherent Scatter Scientific Association, has been upgraded in certain key areas in recent years. It is one of only four similar facilities in the world operating at present. An updated description of the facility is given, together with scientific motivation and ...
    • A new method of inferring the size, number density, and charge of mesospheric dust from its in situ collection by the DUSTY probe 

      Havnes, Ove; Antonsen, Tarjei; Baumgarten, Gerd; Hartquist, Thomas W.; Biebricher, Alexander; Fredriksen, Åshild; Friedrich, Martin; Hedin, Jonas (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-15)
      <p>We present a new method of analyzing measurements of mesospheric dust made with DUSTY rocket-borne Faraday cup probes. It can yield the variation in fundamental dust parameters through a mesospheric cloud with an altitude resolution down to 10 cm or less if plasma probes give the plasma density variations with similar height resolution. A DUSTY probe was the first probe that unambiguously detected ...
    • A new spectral harmonization algorithm for Landsat-8 and Sentinel-2 remote sensing reflectance products using machine learning: a case study for the Barents Sea (European Arctic) 

      Asim, Muhammad; Matsuoka, Atsushi; Ellingsen, Pål Gunnar; Brekke, Camilla; Eltoft, Torbjørn; Blix, Katalin (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-12)
      The synergistic use of Landsat-8 operational land imager (OLI) and Sentinel-2 multispectral instrument (MSI) data products provides an excellent opportunity to monitor the dynamics of aquatic ecosystems. However, the merging of data products from multisensors is often adversely affected by the difference in their spectral characteristics. In addition, the errors in the atmospheric correction (AC) ...
    • A New Technique for Investigating Dust Charging in the PMSE Source Region 

      Mahmoudian, Alireza; Kosch, Michael J.; Vierinen, Juha; Rietveld, Michael T (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-21)
      A new technique for investigating dust charging in the PMSE (polar mesospheric summer echoes) source region is proposed and discussed in this paper. The first high-frequency (HF) modulation of the PMSE with varying pump power was employed during a recent experimental campaign at EISCAT (European Incoherent Scatter Scientific Association). Two experiment setups including HF pump power stepping as ...
    • New ways of looking at very small holes – using optical nanoscopy to visualize liver sinusoidal endothelial cell fenestrations 

      Øie, Cristina Ionica; Mönkemöller, Viola; Hübner, Wolfgang; Schüttpelz, Mark; Mao, Hong; Ahluwalia, Balpreet Singh; Huser, Thomas Rolf; McCourt, Peter Anthony (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-10)
      Super-resolution fluorescence microscopy, also known as nanoscopy, has provided us with a glimpse of future impacts on cell biology. Far-field optical nanoscopy allows, for the first time, the study of sub-cellular nanoscale biological structures in living cells, which in the past was limited to electron microscopy (EM) (in fixed/dehydrated) cells or tissues. Nanoscopy has particular utility in the ...
    • Newly-formed sea ice distinction near the oil platform Prirazlomnaya in the Pechora Sea using polarimetric Radarsat-2 SAR observations 

      Ivonin, Dmitry; Ivanov, Andrey; Johansson, Malin; Brekke, Camilla (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-01)
      A polarimetric approach developed to discriminate oil slicks and look-alikes was used to study the polarimetric properties of newly-formed ice (NFI) observed near the Prirazlomnaya oil platform. This approach is based on the multipolarization parameter called Resonant to Non-resonant signal Damping (RND), which is related to the ratio between the ice damping and the short wind waves and wave breakings. ...
    • Next-generation Space Object Radar Tracking Simulator: SORTS++ 

      Kastinen, D; Vierinen, Juha; Kero, Johan; Hesselbach, S; Grydeland, Tom; Krag, Holger (Journal article; Tidsskriftartikkel, 2019)
      We describe the software toolbox SORTS++ which is the next-generation Space Object Radar Tracking Simulator (SORTS). This toolbox is able to simulate general Space Surveillance and Tracking (SST) applications from catalogue maintenance to cold-start performance for radar systems or collections of radar systems. We have applied this toolbox to the EISCAT 3D radar system, currently under construction, ...
    • Noisy multi-label semi-supervised dimensionality reduction 

      Mikalsen, Karl Øyvind; Soguero-Ruiz, Cristina; Bianchi, Filippo Maria; Jenssen, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-29)
      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 accounted for. How to fully utilize noisy labels has been studied extensively within the framework of standard supervised machine learning over a period of several decades. However, very little research has been conducted ...
    • Non-gaussian clustering of SAR images for glacier change detection 

      Akbari, Vahid; Doulgeris, Anthony Paul; Eltoft, Torbjørn (Journal article; Tidsskriftartikkel, 2010-12)
      Our aim is to use unsupervised, non-Gaussian clustering of Arctic glaciers for post-classification change detection. Firstly, we demonstrate the consistency of non-Gaussian clustering algorithms for Envisat ASAR images by characterizing the expected random error level for different SAR acquisition conditions (such as incidence angle). This allows us to determine whether an observed variation is ...
    • Non-Gaussian Clustering of SAR images for Glacier Change Detection 

      Akbari, Vahid; Eltoft, Torbjørn; Doulgeris, Anthony Paul (Conference object; Konferansebidrag, 2010)
    • Non-heuristic automatic techniques for overcoming low signal-to-noise-ratio bias of localization microscopy and multiple signal classification algorithm 

      Agarwal, Krishna; Macháň, Radek; Prasad, Dilip Kumar (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-21)
      Localization microscopy and multiple signal classification algorithm use temporal stack of image frames of sparse emissions from fluorophores to provide super-resolution images. Localization microscopy localizes emissions in each image independently and later collates the localizations in all the frames, giving same weight to each frame irrespective of its signal-to-noise ratio. This results in a ...
    • Non-Oberbeck-Boussinesq zonal flow generation 

      Held, M; Wiesenberger, M; Kube, Ralph; Kendl, Alexander (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-26)
      Novel mechanisms for zonal flow (ZF) generation for both large relative density fluctuations and background density gradients are presented. In this non-Oberbeck–Boussinesq (NOB) regime ZFs are driven by the Favre stress, the large fluctuation extension of the Reynolds stress, and by background density gradient and radial particle flux dominated terms. Simulations of a nonlinear full-F gyro-fluid ...
    • Non-trace full-F gyro-fluid interchange impurity advection 

      Reiter, E.; Wiesenberger, M.; Held, Markus; Zarate-Segura, G.W.; Kendl, A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-01)
      A full-F isothermal gyro-fluid model and code (which is based on the full distribution function F compared to only small fluctuations) is extended to handle self-consistent coupling of multiple quasi-neutral ion species via the polarisation equation in the long wavelength approximation. The numerical model is used to determine two-dimensional interchange driven ‘blob’ transport in a plasma with ...
    • Non-triggered auroral substorms and long-period (1–4 mHz) geomagnetic and auroral luminosity pulsations in the polar cap 

      Yagova, Nadezda; Nosikova, Natalia; Baddeley, Lisa; Kozyreva, Olga; Lorentzen, Dag A.; Pilipenko, Vyacheslav; Johnsen, Magnar G. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-08)
      A study is undertaken into parameters of the polar auroral and geomagnetic pulsations in the frequency range 1– 4 mHz (Pc5/Pi3) during quiet geomagnetic intervals preceding auroral substorms and non-substorm background variations. Special attention is paid to substorms that occur under parameters of the interplanetary magnetic field (IMF) conditions typical for undisturbed days (“non-triggered ...
    • Nonlocal damage mechanics for quantification of health for piezoelectric sensor 

      Habib, Anowarul; Shelke, Amit; Amjad, U; Pietsch, Ullrich; Banerjee, S (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-18)
      In this paper, a novel method to quantify the incubation of damage on piezoelectric crystal is presented. An intrinsic length scale parameter obtained from nonlocal field theory is used as a novel measure for quantification of damage precursor. Features such as amplitude decay, attenuation, frequency shifts and higher harmonics of guided waves are commonly-used damage features. Quantification of the ...