Artikler, rapporter og annet (fysikk og teknologi): Nye registreringer
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Artefact removal in ground truth deficient fluctuations-based nanoscopy images using deep learning
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-08)Image denoising or artefact removal using deep learning is possible in the availability of supervised training dataset acquired in real experiments or synthesized using known noise models. Neither of the conditions can be fulfilled for nanoscopy (super-resolution optical microscopy) images that are generated from microscopy videos through statistical analysis techniques. Due to several physical ... -
Machine learning derived input-function in a dynamic 18F-FDG PET study of mice
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-13)Tracer kinetic modelling, based on dynamic <sup>18</sup>F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is used to quantify glucose metabolism in humans and animals. Knowledge of the arterial input-function (AIF) is required for such measurements. Our aim was to explore two non-invasive machine learning-based models, for AIF prediction in a small-animal dynamic FDG PET study. 7 tissue ... -
Photonic-chip based free space beam shaping and steering for advanced optical microscopy application
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-12)Photonic-chip-based light illumination has recently found applications in optical microscopy and nanoscopy methodologies. The photonic chip removes the dependency on imaging objective lenses to generate the required illumination patterns for different microscopy methods. Until now, all the reported chip-based optical microscopy methods exploit the evanescent field present on top of a waveguide surface ... -
Drone-Mounted UWB Snow Radar: Technical Improvements and Field Results
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-04)Drone borne radar systems have seen considerable advances over recent years, and the application of drone-mounted continuous wave (CW) radars for remote sensing of snow properties has great potential. Regardless, major challenges remain in antenna design for which both low weight and small size combined with high gain and bandwidth are important design parameters. Additional limiting factors for CW ... -
Soft thresholding schemes for multiple signal classification algorithm
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-28)Multiple signal classification algorithm (MUSICAL) exploits temporal fluctuations in fluorescence intensity to perform super-resolution microscopy by computing the value of a super-resolving indicator function across a fine sample grid. A key step in the algorithm is the separation of the measurements into signal and noise subspaces, based on a single user-specified parameter called the threshold. ... -
Learning Nanoscale Motion Patterns of Vesicles in Living Cells
(Conference object; Konferansebidrag, 2020-08-05)Detecting and analyzing nanoscale motion patterns of vesicles, smaller than the microscope resolution (~250 nm), inside living biological cells is a challenging problem. State-of-the-art CV approaches based on detection, tracking, optical flow or deep learning perform poorly for this problem. We propose an integrative approach, built upon physics based simulations, nanoscopy algorithms, and shallow ... -
Oil-Spill-Response-Oriented Information Products Derived From a Rapid-Repeat Time Series of SAR Images
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-19)New quantitative and semiautomated methods for analyzing oil slick evolution using a time series of L-band synthetic aperture radar (SAR) images with short repeat time are developed and explored. In this study, two methods that are complementary in terms of identifying temporal changes within an oil slick are presented. The two methods reflect two ways of evaluating the oil slicks. The first method ... -
Predicting the suitability of lateritic soil type for low cost sustainable housing with image recognition and machine learning techniques
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-10)From a sustainability point of view, laterites-compressed earth bricks (LCEB) are a promising substitute for building structures in place of the conventional concrete masonry units. On the other hand, techniques for identifying and classifying laterites soil for compressed earth bricks (CEB) production are still relying on direct human expertise or ‘experts’. Human experts exploit direct visual ... -
Robustness of SAR Sea Ice Type classification across incidence angles and seasons at L-band
(Journal article; Tidsskriftartikkel, 2020-11-16)In recent years, space-borne synthetic aperture radar (SAR) polarimetry has become a valuable tool for sea ice type retrieval. L-band SAR has proven to be sensitive toward deformed sea ice and is complementary compared with operationally used C-band SAR for sea ice type classification during the early and advanced melt seasons. Here, we employ an artificial neural network (ANN)-based sea ice type ... -
Comparing wavelet and Fourier perspectives on the decomposition of meridional energy transport into synoptic and planetary components
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-04)The Arctic region shows some of the world's most significant signs of climate change; for instance, a negative trend in summer sea‐ice cover of around 15% per decade and Arctic amplified surface‐air warming that is three times the global average. The atmospheric energy transport plays an important role in the Arctic climate. Recently a Fourier‐based method for studying the atmospheric energy transport ... -
Waveguide asymmetric long-period grating couplers as refractive index sensors
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-29)A highly sensitive integrated photonic transducer is designed by utilizing asymmetric long-period gratings on a silicon waveguide. These gratings are formed by periodic perturbation of the waveguide width, leading to coupling between the fundamental mode and the 1st order asymmetric leaky mode. The coupled modes are studied via finite-element and finite-difference time-domain methods. Only a single ... -
Object detection neural network improves Fourier ptychography reconstruction
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-23)High resolution microscopy is heavily dependent on superb optical elements and superresolution microscopy even more so. Correcting unavoidable optical aberrations during post-processing is an elegant method to reduce the optical system’s complexity. A prime method that promises superresolution, aberration correction, and quantitative phase imaging is Fourier ptychography. This microscopy technique ... -
Evaluation of adhesive-free focused high-frequency PVDF copolymer transducers fabricated on spherical cavities
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-16)A layer-by-layer deposition method for fabricating a focused ultrasonic transducer from piezoelectric copolymers has been developed. The fabrication process involves engraving a spherical cavity of 2 mm diameter on polyethyleneimines (PEI) polymer substrate. Surface roughness of the engraved spherical cavity is measured and compared with simulated line scan. Then, the transducer response was ... -
Unsupervised supervoxel-based lung tumor segmentation across patient scans in hybrid PET/MRI
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-29)Tumor segmentation is a crucial but difficult task in treatment planning and follow-up of cancerous patients. The challenge of automating the tumor segmentation has recently received a lot of attention, but the potential of utilizing hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI), a novel and promising imaging modality in oncology, is still under-explored. Recent ... -
Superresolving the kidney – a practical comparison of fluorescence nanoscopy of the glomerular filtration barrier
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-05)Immunofluorescence microscopy is routinely used in the diagnosis of and research on renal impairments. However, this highly specific technique is restricted in its maximum resolution to about 250 nm in the lateral and 700 nm in the axial directions and thus not sufficient to investigate the fine subcellular structure of the kidney’s glomerular filtration barrier. In contrast, electron microscopy ... -
Short-Term Load Forecasting with Missing Data using Dilated Recurrent Attention Networks
(Conference object; Konferansebidrag, 2020-02-06)Forecasting the dynamics of time-varying systems is essential to maintaining the sustainability of the systems. Recent studies have discovered that Recurrent Neural Networks(RNN) applied in the forecasting tasks outperform conventional models that include AutoRegressive Integrated Moving Average(ARIMA). However, due to the structural limitation of vanilla RNN which holds unit-length internal ... -
High space-bandwidth in quantitative phase imaging using partially spatially coherent digital holographic microscopy and a deep neural network
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-16)Quantitative phase microscopy (QPM) is a label-free technique that enables monitoring of morphological changes at the subcellular level. The performance of the QPM system in terms of spatial sensitivity and resolution depends on the coherence properties of the light source and the numerical aperture (NA) of objective lenses. Here, we propose high space-bandwidth quantitative phase imaging using ... -
Productive detours – Atlantic water inflow and acoustic backscatter in the major troughs along the Svalbard shelf
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-30)Atlantic Water (AW) flowing along the western and northern Svalbard shelf-break extends the Atlantic domain into the Arctic and is the region’s major source of heat, nutrients and advected plankton. We investigated the inflow and recirculation of AW into four major troughs that cut into the Svalbard shelf, the Isfjorden, Kongsfjorden, Hinlopen and Kvitøya Troughs, and related the circulation patterns ... -
On-chip TIRF nanoscopy by applying Haar wavelet kernel analysis on intensity fluctuations induced by chip illumination
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-09)Photonic-chip based TIRF illumination has been used to demonstrate several on-chip optical nanoscopy methods. The sample is illuminated by the evanescent field generated by the electromagnetic wave modes guided inside the optical waveguide. In addition to the photokinetics of the fluorophores, the waveguide modes can be further exploited for introducing controlled intensity fluctuations for exploitation ... -
Highly temporal stable, wavelength-independent, and scalable field-of-view common-path quantitative phase microscope
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-11)<p><i>Significance:</i> High temporal stability, wavelength independency, and scalable field of view (FOV) are the primary requirements of a quantitative phase microscopy (QPM) system. The high temporal stability of the system provides accurate measurement of minute membrane fluctuations of the biological cells that can be an indicator of disease diagnosis. <p><i>Aim:</i> The main aim of this work ...