Artikler, rapporter og annet (fysikk og teknologi): Nye registreringer
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Visualizing ultrastructural details of placental tissue with super-resolution structured illumination microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-14)Super-resolution fluorescence microscopy is a widely employed technique in cell biology research, yet remains relatively unexplored in the field of histopathology. Here, we describe the sample preparation steps and acquisition parameters necessary to obtain fluorescent multicolor super-resolution structured illumination microscopy (SIM) images of both formalin-fixed paraffin-embedded and cryo-preserved ... -
Dense dilated convolutions merging network for land cover classification
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-06)Land cover classification of remote sensing images is a challenging task due to limited amounts of annotated data, highly imbalanced classes, frequent incorrect pixel-level annotations, and an inherent complexity in the semantic segmentation task. In this article, we propose a novel architecture called the dense dilated convolutions' merging network (DDCM-Net) to address this task. The proposed ... -
Machine Learning for Arctic Sea Ice Physical Properties Estimation Using Dual-Polarimetric SAR Data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-22)This work introduces a novel method that combines machine learning (ML) techniques with dual-polarimetric (dual-pol) synthetic aperture radar (SAR) observations for estimating quad-polarimetric (quad-pol) parameters, which are presumed to contain geophysical sea ice information. In the training phase, the output parameters are generated from quad-pol observations obtained by Radarsat-2 (RS2), and ... -
Retrieval of Marine Surface Slick Dielectic Properties From Radarsat-2 Data via a Polarimetric Two-Scale Model
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-27)We propose the use of a polarimetric two-scale surface scattering model to retrieve the dielectric parameters of oil slick from the polarimetric synthetic aperture radar. The ocean surface is modeled as an ensemble of randomly orientated, slightly roughened, tilted facets, for which the small perturbation model is assumed to be valid under the condition of no tilt. The orientation of the random ... -
A Lagrangian Snow Evolution System for Sea Ice Applications (SnowModel‐LG): Part II - Analyses
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-02)Sea ice thickness is a critical variable, both as a climate indicator and for forecasting sea ice conditions on seasonal and longer time scales. The lack of snow depth and density information is a major source of uncertainty in current thickness retrievals from laser and radar altimetry. In response to this data gap, a new Lagrangian snow evolution model (SnowModel‐LG) was developed to simulate snow ... -
Magnetopause Compressibility at Saturn with Internal Drivers
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-07)We use magnetopause crossings of the Cassini spacecraft to study the response of Saturn's magnetosphere to changes in external and internal drivers. We explain how solar wind pressure can be corrected to account for the local variability in internal plasma particle pressure. The physics‐based method is applied to perform the most robust estimation of magnetopause compressibility at Saturn to date, ... -
Comparison Between Dielectric Inversion Results From Synthetic Aperture Radar Co- and Quad-Polarimetric Data via a Polarimetric Two-Scale Model
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-03)In this study, we compare the retrieval results for the dielectric properties of verified oil slick, acquired using airborne multifrequency synthetic aperture radar. A polarimetric two-scale model was used to invert the radar imagery by first employing solely the co-polarization channels, and then by employing the co-polarization channels in conjunction with the cross-polarization channels, and ... -
Platelet ice under Arctic pack ice in winter
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-17)The formation of platelet ice is well known to occur under Antarctic sea ice, where subice platelet layers form from supercooled ice shelf water. In the Arctic, however, platelet ice formation has not been extensively observed, and its formation and morphology currently remain enigmatic. Here, we present the first comprehensive, long‐term in situ observations of a decimeter thick subice platelet ... -
ELM-HTM guided bio-inspired unsupervised learning for anomalous trajectory classification
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-23)Artificial intelligent systems often model the solutions of typical machine learning problems, inspired by biological processes, because of the biological system is faster and much adaptive than deep learning. The utility of bio-inspired learning methods lie in its ability to discover unknown patterns, and its less dependence on mathematical modeling or exhaustive training. In this paper, we propose ... -
How Does El Niño–Southern Oscillation Change Under Global Warming—A First Look at CMIP6
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-22)The latest generation of coupled models, the sixth Coupled Models Intercomparison Project (CMIP6), is used to study the changes in the El Niño–Southern Oscillation (ENSO) in a warming climate. For the four future scenarios studied, the sea surface temperature variability increases in most CMIP6 models, but to varying degrees. This increase is linked to a weakening of the east‐west temperature gradient ... -
Trapped Particle Motion In Magnetodisc Fields
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-13)The spatial and temporal characterization of trapped charged particle trajectories in magnetospheres has been extensively studied in dipole magnetic field structures. Such studies have allowed the calculation of spatial quantities, such as equatorial loss cone size as a function of radial distance, the location of the mirror points along particular field lines (<i>L</i>‐shells) as a function of the ... -
Photonic-chip assisted correlative light and electron microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-07)Correlative light and electron microscopy (CLEM) unifies the versatility of light microscopy (LM) with the high resolution of electron microscopy (EM), allowing one to zoom into the complex organization of cells. Here, we introduce photonic chip assisted CLEM, enabling multi-modal total internal reflection fluorescence (TIRF) microscopy over large field of view and high precision localization of the ... -
In-Silico Evaluation of Glucose Regulation Using Policy Gradient Reinforcement Learning for Patients with Type 1 Diabetes Mellitus
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-11)In this paper, we test and evaluate policy gradient reinforcement learning for automated blood glucose control in patients with Type 1 Diabetes Mellitus. Recent research has shown that reinforcement learning is a promising approach to accommodate the need for individualized blood glucose level control algorithms. The motivation for using policy gradient algorithms comes from the fact that adaptively ... -
Extraordinary evanescent field confinement waveguide sensor for mid-infrared trace gas spectroscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-29)Nanophotonic waveguides are at the core of a great variety of optical sensors. These structures confine light along defined paths on photonic chips and provide light–matter interaction via an evanescent field. However, waveguides still lag behind free-space optics for sensitivity-critical applications such as trace gas detection. Short optical pathlengths, low interaction strengths, and spurious ... -
Incident Angle Dependence of Sentinel-1 Texture Features for Sea Ice Classification
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-04)Robust and reliable classification of sea ice types in synthetic aperture radar (SAR) images is needed for various operational and environmental applications. Previous studies have investigated the class-dependent decrease in SAR backscatter intensity with incident angle (IA); others have shown the potential of textural information to improve automated image classification. In this work, we investigate ... -
CO2 Increase Experiments Using the CESM: Relationship to Climate Sensitivity and Comparison of CESM1 to CESM2
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-14)We examine the response of the Community Earth System Model Versions 1 and 2 (CESM1 and CESM2) to abrupt quadrupling of atmospheric CO2 concentrations (4xCO2) and to 1% annually increasing CO2 concentrations (1%CO2). Different estimates of equilibrium climate sensitivity (ECS) for CESM1 and CESM2 are presented. All estimates show that the sensitivity of CESM2 has increased by 1.5 K or more over that ... -
Silicon substrate significantly alters dipole-dipole resolution in coherent microscope
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-16)Considering a coherent microscopy setup, influences of the substrate below the sample in the imaging performances are studied, with a focus on high refractive index substrate such as silicon. Analytical expression of 3D full-wave vectorial point spread function, i.e. the dyadic Green's function is derived for the optical setup together with the substrate. Numerical analysis are performed in order ... -
Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-13)Optical coherence tomography (OCT) is being increasingly adopted as a label-free and non-invasive technique for biomedical applications such as cancer and ocular disease diagnosis. Diagnostic information for these tissues is manifest in textural and geometric features of the OCT images, which are used by human expertise to interpret and triage. However, it suffers delays due to the long process of ... -
Properties and dynamics of mesoscale eddies in Fram Strait from a comparison between two high-resolution ocean-sea ice models
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-23)Fram Strait, the deepest gateway to the Arctic Ocean, is strongly influenced by eddy dynamics. Here we analyse the output from two eddy-resolving models (ROMS – Regional Ocean Modeling System; FESOM – Finite-Element Sea-ice Ocean Model) with around 1 km mesh resolution in Fram Strait, with a focus on their representation of eddy properties and dynamics. A comparison with mooring observations shows ... -
Integrated analysis of multi-sensor datasets and oil drift simulations - a free floating oil experiment in the open ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-20)A free‐floating oil spill experiment (two oil types) in the open ocean is described, and the results from slick characterization through integrated analysis of drift simulations with remote sensing and in situ data are discussed. We compare oil drift simulations (OpenOil), applying various configurations of wind, wave, and current information, with the observed slick positions and shape. We describe ...