Viser treff 451-470 av 942

    • Learning nanoscale motion patterns of vesicles in living cells 

      Sekh, Arif Ahmed; Opstad, Ida Sundvor; Birgisdottir, Åsa Birna; Myrmel, Truls; Ahluwalia, Balpreet Singh; Agarwal, Krishna; Prasad, Dilip K. (Chapter; Bokkapittel, 2020)
      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 ...
    • Learning representations of multivariate time series with missing data 

      Bianchi, Filippo Maria; Livi, Lorenzo; Mikalsen, Karl Øyvind; Kampffmeyer, Michael C.; Jenssen, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-19)
      Learning compressed representations of multivariate time series (MTS) facilitates data analysis in the presence of noise and redundant information, and for a large number of variates and time steps. However, classical dimensionality reduction approaches are designed for vectorial data and cannot deal explicitly with missing values. In this work, we propose a novel autoencoder architecture based on ...
    • Level crossings and excess times due to a superposition of uncorrelated exponential pulses 

      Theodorsen, Audun; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-10)
      A well-known stochastic model for intermittent fluctuations in physical systems is investigated. The model is given by a superposition of uncorrelated exponential pulses, and the degree of pulse overlap is interpreted as an intermittency parameter. Expressions for excess time statistics, that is, the rate of level crossings above a given threshold and the average time spent above the threshold, are ...
    • Level crossings, excess times, and transient plasma-wall interactions in fusion plasmas 

      Theodorsen, Audun; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-04-19)
      Based on a stochastic model for intermittent fluctuations in the boundary region of magnetically confined plasmas, an expression for the level crossing rate is derived from the joint distribution of the process and its derivative. From this the average time spent by the process above a certain threshold level is obtained. This provides novel predictions of plasma–wall interactions due to transient ...
    • Light and photosynthetic microalgae: A review of cellular- and molecular-scale optical processes 

      Lehmuskero, Anni Maria; Chauton, Matilde Skogen; Boström, Tobias (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-08)
      Light and its interaction with microalgae are essential concerns in the context of microalgae studies. The optical properties of microalgae have a great impact on the remote sensing ocean color, underwater light distribution and biomass accumulation, to mention some areas. A deep understanding of these processes requires knowledge on both the physical light interaction mechanisms with algae, and ...
    • Linear scaling Coulomb interaction in the multiwavelet basis, a parallel implementation 

      Jensen, Stig Rune; Juselius, Jonas; Durdek, Antoine Pacifique Romain; Flå, Tor; Wind, Peter; Frediani, Luca (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-08-27)
      We present a parallel and linear scaling implementation of the calculation of the electrostatic potential arising from an arbitrary charge distribution. Our approach is making use of the multi-resolution basis of multiwavelets. The potential is obtained as the direct solution of the Poisson equation in its Green’s function integral form. In the multiwavelet basis, the formally non local ...
    • Linking sea ice deformation to ice thickness redistribution using high-resolution satellite and airborne observations 

      Von Albedyll, Luisa; Haas, Christian; Dierking, Wolfgang Fritz Otto (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-04)
      An unusual, large, latent-heat polynya opened and then closed by freezing and convergence north of Greenland’s coast in late winter 2018. The closing presented a natural but well-constrained full-scale ice deformation experiment. We observed the closing of and deformation within the polynya with satellite synthetic-aperture radar (SAR) imagery and measured the accumulated effects of dynamic ...
    • Live-cell imaging of human spermatozoa using structured illumination microscopy 

      Opstad, Ida Sundvor; Popova, Daria; Acharya, Ganesh; Basnet, Purusotam; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-05)
      Structural details of spermatozoa are interesting from the perspectives of fundamental biology and growing reproductive health problems. Studies of nanostructural details of these extremely motile cells have been limited to fixed cells, largely using electron microscopy. Here we provide the protocols for and demonstrate live-cell multi-color super-resolution imaging of human spermatozoa using ...
    • Localized mesosphere-stratosphere-troposphere radar echoes from the E region at 69 degrees N: Properties and physical mechanisms 

      Rapp, Markus; Leitert, Lasse; Latteck, Ralph; Zecha, Marius; Hoffmann, Peter; Höffner, Josef; Hoppe, Ulf-Peter; La Hoz, Cesar; Thrane, Eivind (Journal article; Tidsskriftartikkel; Peer reviewed, 2011-02-25)
      We present the first observations, to our knowledge, of a new class of high‐latitude mesosphere‐stratosphere‐troposphere radar echoes from the E region as observed with the Arctic Lidar Observatory for Middle Atmosphere Research wind radar during the period 2004–2008. These echoes occur primarily during the summer months and in the altitude range from 93 to 114 km, with a pronounced peak of maximum ...
    • The long sunspot cycle 23 predicts a significant temperature decrease in cycle 24 

      Solheim, Jan Erik; Stordahl, Kjell; Humlum, Ole (Journal article; Tidsskriftartikkel; Peer reviewed, 2012-02-16)
      Relations between the length of a sunspot cycle and the average temperature in the same and the next cycle are calculated for a number of meteorological stations in Norway and in the North Atlantic region. No significant trend is found between the length of a cycle and the average temperature in the same cycle, but a significant negative trend is found between the length of a cycle and the ...
    • Long-range memory in internal and forced dynamics of millennium-long climate model simulations 

      Østvand, Lene; Nilsen, Tine; Rypdal, Kristoffer; Divine, Dmitry, V.; Rypdal, Martin wibe (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
      Northern Hemisphere (NH) temperature records from a palaeoclimate reconstruction and a number of millennium-long climate model experiments are investigated for long-range memory (LRM). The models are two Earth system models and two atmosphere–ocean general circulation models. The periodogram, detrended fluctuation analysis and wavelet variance analysis are applied to examine scaling properties ...
    • A long-term proxy for sea ice thickness in the Canadian Arctic: 1996-2020 

      Glissenaar, Isolde A.; Landy, Jack Christopher; Babb, David G.; Dawson, Geoffrey J.; Howell, Stephen E. L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-15)
      . This study presents a long-term winter sea ice thickness proxy product for the Canadian Arctic based on a random forest regression model – applied to ice charts and scatterometer data, trained on CryoSat-2 observations, and applying an ice type–sea ice thickness correction using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) – that provides 25 years of sea ice thickness ...
    • Longitudinal development of a substorm brightening arc 

      Aslaksen, Torsten; Shiokawa, K.; Ieda, A.; Nakajima, A.; Sakaguchi, K.; Nomura, R.; Greffen, M.; Spanswick, E.; Donovan, E.; Mende, S. B.; McFadden, J.; Glassmeier, K. H.; Angelopoulos, V.; Miyashita, Y. (Journal article; Tidsskriftartikkel; Peer reviewed, 2009)
    • A low-cost coastal buoy for ice and metocean measurements 

      Petrich, Christian; O'Sadnick, Megan Eileen; Kleven, Øystein; Sæther, Irina Vasiljeva (Conference object; Konferansebidrag, 2019-06)
      Regionally, an ice cover in fjords of mainland Norway may form and break up repeatedly during winter. Due to relatively high water temperatures, the freeze-up process is expected to be related to freshwater-induced stratification in the fjords in conjunction with low air temperatues. In an attempt to identify the variability of water conditions in the fjords leading up to and during ice cover ...
    • Low-dimensionality and predictability of solar wind and global magnetosphere during magnetic storms 

      Zivkovic, Tatjana; Rypdal, Kristoffer (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      The storm index SYM-H, the solar wind velocity v, and interplanetary magnetic field Bz show no signatures of low-dimensional dynamics in quiet periods, but tests for determinism in the time series indicate that SYM-H exhibits a significant low-dimensional component during storm time, suggesting that self-organization takes place during magnetic storms. Even though our analysis yields no discernible ...
    • Low-frequency radio absorption in Cassiopeia A 

      Arias, Maria; Vink, J; De Gasperin, F; Salas, P; Oonk, JBR; Van Weeren, RJ; Van Amesfoort, AS; Anderson, J; Beck, R; Bell, ME; Bentum, MJ; Best, P; Blaauw, R; Breitling, F; Broderick, JW; Brouw, WN; Bruggen, M; Butcher, HR; Ciardi, B; De Geus, E; Deller, A; Van Dijk, PCG; Duscha, S; Eisloffel, J; Garrett, MA; Grie?meier, JM; Gunst, AW; Van Haarlem, MP; Heald, G; Hessels, J; Horandel, J; Holties, HA; Van Der Horst, AJ; Iacobelli, M; Juette, E; Krankowski, A; Van Leeuwen, J; Mann, G; McKay, Derek; McKean, JP; Mulder, H; Nelles, A; Orru, E; Paas, H; Pandey-Pommier, M; Pandey, VN; Pekal, R; Pizzo, R; Polatidis, AG; Reich, W; Rottgering, HJA; Rothkaehl, H; Schwarz, DJ; Smirnov, O; Soida, M; Steinmetz, M; Tagger, M; Thoudam, S; Toribio, MC; Vocks, C; Van Der Wiel, MHD; Wijers, RAMJ; Wucknitz, O; Zarka, P; Zucca, Philippe M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-08)
      <i>Context</i>: Cassiopeia A is one of the best-studied supernova remnants. Its bright radio and X-ray emission is due to shocked ejecta. Cas A is rather unique in that the unshocked ejecta can also be studied: through emission in the infrared, the radio-active decay of <sup>44</sup>Ti, and the low-frequency free-free absorption caused by cold ionised gas, which is the topic of this paper.<p> ...
    • Lumikot: Fast auroral transients during the growth phase of substorms 

      McKay, Derek; Paavilainen, Tuula; Gustavsson, Björn Johan; Kvammen, Andreas; Partamies, Noora (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-25)
      The development of a magnetospheric substorm may be classified into three phases: growth, expansion, and recovery. The growth phase is important as it includes processes that lead to the expansion. In a recent growth-phase study, a type of fast discrete auroral transient phenomena -- referred to as Lumikot -- were observed. The Lumikot are several kilometers across and move in the high-energy ...
    • M3D-VTON: A Monocular-to-3D Virtual Try-On Network 

      Zhao, Fuwei; Xie, Zhenyu; Kampffmeyer, Michael; Dong, Haoye; Han, Songfang; Zheng, Tianxiang; Zhang, Tao; Liang, Xiaodan (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-28)
      Virtual 3D try-on can provide an intuitive and realistic view for online shopping and has a huge potential commercial value. However, existing 3D virtual try-on methods mainly rely on annotated 3D human shapes and garment templates, which hinders their applications in practical scenarios. 2D virtual try-on approaches provide a faster alternative to manipulate clothed humans, but lack the rich and ...
    • Machine learning assisted multifrequency AFM: Force model prediction 

      Elsherbiny, Lamiaa; Santos Hernandez, Sergio; Gadelrab, Karim; Olukan, Tuza; Font, Josep; Barcons, Victor; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-05)
      Multifrequency atomic force microscopy (AFM) enhances resolving power, provides extra contrast channels, and is equipped with a formalism to quantify material properties pixel by pixel. On the other hand, multifrequency AFM lacks the ability to extract and examine the profile to validate a given force model while scanning. We propose exploiting data-driven algorithms, i.e., machine learning packages, ...
    • Machine learning assisted quantification of graphitic surfaces exposure to defined environments 

      Lai, Chia-Yun; Santos, Sergio; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-17)
      We show that it is possible to submit the data obtained from physical phenomena as complex as the tip-surface interaction in atomic force microscopy to a specific question of interest and obtain the answer irrespective of the complexity or unknown factors underlying the phenomena. We showcase the power of the method by asking “how many hours has this graphite surface been exposed to ambient conditions?” ...