Blar i tittel Artikler, rapporter og annet (fysikk og teknologi)

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    • On-chip TIRF nanoscopy by applying Haar wavelet kernel analysis on intensity fluctuations induced by chip illumination 

      Jayakumar, Nikhil; Helle, Øystein I.; Agarwal, Krishna; Ahluwalia, Balpreet Singh (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 ...

    • On-Site Ribosome Remodeling by Locally Synthesized Ribosomal Proteins in Axons 

      Shigeoka, Toshiaki; Koppers, Max; Wong, Hovy Ho Wai; Lin, Julie Qiaojin; Cagnetta, Roberta; Dwivedy, Asha; de Freitas Nascimento, Janaina; van Tartwijk, Francesca W.; Ströhl, Florian; Cioni, Jean Michel; Schaeffer, Julia; Carrington, Mark; Kaminski, Clemens F.; Jung, Hosung; Harris, William A.; Holt, Christine E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-10)
      Ribosome assembly occurs mainly in the nucleolus, yet recent studies have revealed robust enrichment and translation of mRNAs encoding many ribosomal proteins (RPs) in axons, far away from neuronal cell bodies. Here, we report a physical and functional interaction between locally synthesized RPs and ribosomes in the axon. We show that axonal RP translation is regulated through a sequence motif, ...

    • One-Year Analysis of Dust Impact-Like Events Onto the MMS Spacecraft 

      Vaverka, Jakub; Pavlu, Jiri; Nouzak, Libor; Safrankova, Jana; Nemecek, Zdenek; Mann, Ingrid; Ye, Shengyi; Lindqvist, Per-Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-16)
      We present an analysis of 1‐year data of dust impacts observed on two of the Earth‐orbiting Magnetospheric Multiscale mission (MMS) spacecraft. The dust impact signals were identified in observations of the electric field probes and were registered simultaneously by monopole and dipole configurations of the instrument. This unique setup allows us to reliably identify changes in the spacecraft potential ...

    • OpenMetBuoy-v2021: An Easy-to-Build, Affordable, Customizable, Open-Source Instrument for Oceanographic Measurements of Drift and Waves in Sea Ice and the Open Ocean 

      Rabault, Jean; Nose, Takehiko; Hope, Gaute; Müller, Malte; Breivik, Øyvind; Voermans, Joey; Hole, Lars Robert; Bohlinger, Patrik; Waseda, Takuji; Kodaira, Tsubasa; Katsuno, Tomotaka; Johnson, Mark; Sutherland, Graig; Johansson, Anna Malin Kristin; Christensen, Kai Haakon; Garbo, Adam; Jensen, Atle; Gundersen, Olav; Marchenko, Aleksey; Babanin, Alexander (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-26)
      There is a wide consensus within the polar science, meteorology, and oceanography communities that more in situ observations of the ocean, atmosphere, and sea ice are required to further improve operational forecasting model skills. Traditionally, the volume of such measurements has been limited by the high cost of commercially available instruments. An increasingly attractive solution to this ...

    • The optical afterglow and host galaxy of GRB 000926 

      Fynbo, J.U.; Østensen, R.; Gorosabe, J.; Solheim, Jan Erik; Dall, T.H.; Hjorth, J.; Pedersen, H.; Andersen, M.I.; Møller, P.; Holland, S.; Smail, I.; Kobayashi, N.; Rol, E.; Vreeswijk, P.; Vrba, F.; Burud, I.; Jensen, B.L.; Henden, A.; Thomsen, B.; Canzian, B.; Castro Cer´on, J.M.; Castro-Tirado, A.J.; Cline, T.; Goto, M.; Greiner, J.; Hanski, M.T.; Hurley, K.; Pursimo, T.; Lund, N.; Tanvir, N.; Terada, H. (Journal article; Tidsskriftartikkel, 2001-04-11)
      We present the discovery of the Optical Transient (OT) of the long–duration gamma-ray burst GRB 000926. The optical transient was detected independently with the Nordic Optical Telescope and at Calar Alto 22.2 hours after the burst. At this time the magnitude of the transient was R = 19.36. The transient faded with a decay slope of about 1.7 during the first two days after which the slope increased ...

    • Optical transport, lifting and trapping of micro-particles by planar waveguides 

      Helle, Øystein Ivar; Ahluwalia, Balpreet Singh; Hellesø, Olav Gaute (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-03)
      Optical waveguides can be used to trap and transport micro-particles. The particles are held close to the waveguide surface by the evanescent field and propelled forward. We propose a new technique to lift and trap particles above the surface of the waveguides. This is made possible by a gap between two opposing, planar waveguides. The field emitted from each of the waveguide ends diverge fast, away ...

    • Optical trapping and propulsion of red blood cells on waveguide surfaces 

      Ahluwalia, Balpreet Singh; Mccourt, peter anthony; Huser, Thomas Rolf; Hellesø, Olav Gaute (Journal article; Tidsskriftartikkel; Peer reviewed, 2010)

    • Optical trapping in air on a single interference fringe 

      Schäpers, Aaron; Hellesø, Olav Gaute; Fick, Jochen (Journal article; Tidsskriftartikkel, 2023)
      Stable and reproducible trapping in air of 1 µm and 500 nm dielectric particles has been realized using a dual beam optical fiber tweezers with cleaved commercial single mode fibers. The influence of the interference fringes of the two coherent and counter-propagating trapping beam is investigated by controlling the fringe visibility. Optical trapping on a series of upto10 fringes or trapping on ...

    • OptiJ: Open-source optical projection tomography of large organ samples 

      Vallejo Ramirez, Pedro P.; Zammit, Joseph; Vanderpoorten, Oliver; Fergus, Riche; Blé, Francois-Xavier; Zhou, Xiao-Hong; Spiridon, Bogdan; Valentine, Christopher; Spasov, Simeon E.; Oluwasanya, Pelumi W.; Goodfellow, Gemma; Fantham, Marcus J.; Siddiqui, Omid; Alimagham, Farah; Robbins, Miranda; Stretton, Andrew; Simatos, Dimitrios; Hadeler, Oliver; Rees, Eric J.; Ströhl, Florian; Laine, Romain F.; Kaminski, Clemens F. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-30)
      The three-dimensional imaging of mesoscopic samples with Optical Projection Tomography (OPT) has become a powerful tool for biomedical phenotyping studies. OPT uses visible light to visualize the 3D morphology of large transparent samples. To enable a wider application of OPT, we present OptiJ, a low-cost, fully open-source OPT system capable of imaging large transparent specimens up to 13 mm tall ...

    • An Optimal Decision-Tree Design Strategy and Its Application to Sea Ice Classification from SAR Imagery 

      Lohse, Johannes; Doulgeris, Anthony Paul; Dierking, Wolfgang Fritz Otto (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-03)
      We introduce the fully automatic design of a numerically optimized decision-tree algorithm and demonstrate its application to sea ice classification from SAR data. In the decision tree, an initial multi-class classification problem is split up into a sequence of binary problems. Each branch of the tree separates one single class from all other remaining classes, using a class-specific selected feature ...

    • Organization of the magnetosphere during substorms 

      Zivkovic, Tatjana; Rypdal, Kristoffer (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      The change in degree of organization of the magnetosphere during substorms is investigated by analyzing various geomagnetic indices, as well as interplanetary magnetic field z-component and solar wind velocity x-component. We conclude that the magnetosphere self-organizes globally during substorms, but neither the magnetosphere nor the solar wind become more predictable in the course of a substorm. ...

    • Oscillations:Linear theory and applications in AFM 

      Olukan, Tuza Adeyemi; Santos, Sergio; Elsherbiny, Lamia; Chiesa, Matteo (Research report; Forskningsrapport, 2022)
      The theory of oscillations can be studied from a mathematical point of view in terms of differential equations. The differential equation is written and then the solution or solutions worked out and mathematically analysed. Provided physical, economic, social, or other phenomena can be modelled in terms of equivalent differential equations, the solutions and results are applicable to all phenomena ...

    • Outlier classification using autoencoders: Application for fluctuation driven flows in fusion plasmas 

      Kube, Ralph; Bianchi, Filippo Maria; LaBombard, Brian; Brunner, Dan (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-16)
      Understanding the statistics of fluctuation driven flows in the boundary layer of magnetically confined plasmas is desired to accurately model the lifetime of the vacuum vessel components. Mirror Langmuir probes (MLPs) are a novel diagnostic that uniquely allow us to sample the plasma parameters on a time scale shorter than the characteristic time scale of their fluctuations. Sudden large-amplitude ...

    • Outlier classification using Autoencoders: applications for fluctuation driven flows in fusion plasmas 

      Kube, Ralph; Bianchi, Filippo Maria; LaBombard, Brian; Brunner, Dan (Conference object; Konferansebidrag, 2018)

    • Overview: Recent advances in the understanding of the northern Eurasian environments and of the urban air quality in China-a Pan-Eurasian Experiment (PEEX) programme perspective 

      Lappalainen, Hanna K.; Petäjä, Tuukka; Vihma, Timo Pekka; Räisänen, Jouni; Baklanov, Alexander; Chalov, Sergey; Esau, Igor; Ezhova, Ekaterina; Leppäranta, Matti; Pozdnyakov, Dmitry; Pumpanen, Jukka; Andreae, Meinrat O.; Arshinov, Mikhail; Asmi, Eija; Bai, Jianhui; Bashmachnikov, Igor; Belan, Boris; Bianchi, Federico; Biskaborn, Boris; Boy, Michael; Bäck, Jaana; Cheng, Bin; Chubarova, Natalia; Duplissy, Jonathan; Dyukarev, Egor; Eleftheriadis, Konstantinos; Forsius, Martin; Heimann, Martin; Juhola, Sirkku; Konovalov, Vladimir; Konovalov, Igor; Konstantinov, Pavel; Köster, Kajar; Lapshina, Elena; Lintunen, Anna; Mahura, Alexander; Makkonen, Risto; Malkhazova, Svetlana; Mammarella, Ivan; Mammola, Stefano; Mazon, Stephany Buenrostro; Meinander, Outi; Mikhailov, Eugene; Miles, Victoria; Myslenkov, Stanislav; Orlov, Dmitry; Paris, Jean-Daniel; Pirazzini, Roberta; Popovicheva, Olga; Pulliainen, Jouni; Rautiainen, Kimmo; Sachs, Torsten; Shevchenko, Vladimir; Skorokhod, Andrey; Stohl, Andreas; Suhonen, Elli; Thomson, Erik S.; Tsidilina, Marina; Tynkkynen, Veli-Pekka; Uotila, Petteri; Virkkula, Aki; Voropay, Nadezhda; Wolf, Tobias; Yasunaka, Sayaka; Zhang, Jiahua; Qiu, Yubao; Ding, Aijun; Guo, Huadong; Bondur, Valery; Kasimov, Nikolay; Zilitinkevich, Sergej; Kerminen, Veli-Matti; Kulmala, Markku (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-06)
      The Pan-Eurasian Experiment (PEEX) Science Plan, released in 2015, addressed a need for a holistic system understanding and outlined the most urgent research needs for the rapidly changing Arctic-boreal region. Air quality in China, together with the long-range transport of atmospheric pollutants, was also indicated as one of the most crucial topics of the research agenda. These two geographical ...

    • Partially spatially coherent digital holographic microscopy and machine learning for quantitative analysis of human spermatozoa under oxidative stress condition 

      Dubey, Vishesh Kumar; Popova, Daria; Ahmad, Azeem; Acharya, Ganesh; Basnet, Purusotam; Mehta, Dalip Singh; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-05)
      Semen quality assessed by sperm count and sperm cell characteristics such as morphology and motility, is considered to be the main determinant of men’s reproductive health. Therefore, sperm cell selection is vital in assisted reproductive technology (ART) used for the treatment of infertility. Conventional bright field optical microscopy is widely utilized for the imaging and selection of sperm cells ...

    • Particle precipitation during NEIAL events : simultaneous ground based nighttime observations at Svalbard 

      Lunde, June; Løvhaug, Unni Pia; Gustavsson, Björn Johan (Journal article; Tidsskriftartikkel; Peer reviewed, 2009)

    • Particle precipitations during NEIAL events : simultaneous ground based observations at Svalbard 

      Lorentzen, Dag Arne; Lunde, June; Gustavsson, B; Ogawa, Y; Løvhaug, U.P.; Ogawa, Yasunobu (Journal article; Tidsskriftartikkel; Peer reviewed, 2007)
      In this paper we present Naturally Enhanced Ion Acoustic Lines (NEIALs) observed with the EISCAT Svalbard Radar (ESR). For the first time, long sequences of NEIALs are recorded, with more than 50 events within an hour, ranging from 6.4 to 140 s in duration. The events took place from ~08:45 to 10:00 UT, 22 January 2004. We combine ESR data with observations of optical aurora by a meridian scanning ...

    • Patch Size Evolution During Pulsating Aurora 

      Partamies, Noora; Bolmgren, Karl; Heino, Erkka; Ivchenko, Nickolay; Borovsky, Joseph E.; Sundberg, Hanna (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-30)
      We report both decreasing and increasing trends in the patch sizes during pulsating aurora events. About 150 pulsating auroral events over the Fennoscandian Lapland have been successfully analyzed for their average patch size, total patch area, and number of patches as a function of event time, typically 1–2 hr. An automatic routine has been developed to detect patches in the all‐sky camera images. ...

    • Performance Analysis of Roll-Invariant PolSAR Parameters from C-band images with Regard to Sea Ice Type Separation 

      Ratha, Debanshu; Johansson, Malin; Marinoni, Andrea; Eltoft, Torbjørn (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06)
      The Polarimetric Synthetic Aperture Radar (PolSAR) backscatter from a target is dependent on the incidence angle. Consequently, the associated roll invariant parameters are affected by changes in incidence angle. In this work, we identify a few of these parameters that remain robust in identifying sea ice features even under large incidence angle variations. We conclude that the helicity angle ...