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

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    • E-pile model of self-organized criticality 

      Rasmussen, Jens Juul; Milovanov, Alexander V.; Rypdal, Kristoffer (Working paper; Arbeidsnotat, 2007-11-28)
      The concept of percolation is combined with a self-consistent treatment of the interaction between the dynamics on a lattice and the external drive. Such a treatment can provide a mechanism by which the system evolves to criticality without fine tuning, thus offering a route to self-organized criticality (SOC) which in many cases is more natural than the weak random drive combined with ...

    • Eastward-expanding auroral surges observed in the post-midnight sector during a multiple-onset substorm 

      Tanaka, Yoshimasa; Ogawa, Yasunobu; Kadokura, Akira; Partamies, Noora; Whiter, Daniel; Enell, Carl-Fredrik; Brändström, Urban; Sergienko, Tima; Gustavsson, Björn Johan; Kozlovsky, Alexander; Miyaoka, Hiroshi; Yoshikawa, Akimasa (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-09)
      We present three eastward-expanding auroral surge (EEAS) events that were observed intermittently at intervals of about 15 min in the post-midnight sector (01:55–02:40 MLT) by all-sky imagers and magnetometers in northern Europe. It was deduced that each surge occurred just after each onset of a multiple-onset substorm, which was small-scale and did not clearly expand westward, because they were ...

    • Eddy Detection in the Marginal Ice Zone with Sentinel-1 Data Using YOLOv5 

      Khachatrian, Eduard; Sandalyuk, Nikita V.; Lozou, Pigi (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-24)
      The automatic detection and analysis of ocean eddies in the marginal ice zone via remote sensing is a very challenging task but of critical importance for scientific applications and anthropogenic activities. Therefore, as one of the first steps toward the automation of the eddy detection process, we investigated the potential of applying YOLOv5, a deep convolutional neural network architecture, to ...

    • Effect of caffeine and other xanthines on liver sinusoidal endothelial cell ultrastructure 

      Mao, Hong; Szafranska, Karolina; Kruse, Larissa Dorothea; Holte, Christopher Florian; Wolfson, Deanna; Ahluwalia, Balpreet Singh; Whitchurch, Cynthia B.; Cole, Louise; Lockwood, Glen P.; Diekmann, Robin; Le Couteur, David; Cogger, Victoria C.; McCourt, Peter Anthony (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-17)
      Xanthines such as caffeine and theobromine are among the most consumed psychoactive stimulants in the world, either as natural components of cofee, tea and chocolate, or as added ingredients. The present study assessed if xanthines affect liver sinusoidal endothelial cells (LSEC). Cultured primary rat LSEC were challenged with xanthines at concentrations typically obtained from normal consumption of ...

    • Effect of dynamical friction on interchange motion of plasma filaments 

      Kube, Ralph; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)

    • The effect of electron bite-outs on artificial electron heating and the PMSE overshoot. 

      Belova, E.; Kassa, M.; Havnes, O. (Journal article; Peer reviewed; Tidsskriftartikkel, 2005-12-23)
      We have considered the effect that a local reduction in the electron density (an electron bite-out), caused by electron absorption on to dust particles, can have on the artificial electron heating in the height region between 80 to 90 km, where noctilucent clouds (NLC) and the radar phenomenon PMSE (Polar Mesospheric Summer Echoes) are observed. With an electron density profile without ...

    • Effect of suprathermal electrons on the intensity and Doppler frequency of electron plasma lines. 

      Guio, Patrick; Lilensten, J. (Journal article; Tidsskriftartikkel, 1999)
      In an incoherent scattering radar experiment, the spectral measurement of the so-called up- and downshifted electron plasma lines provides information about their intensity and their Doppler frequency. These two spectral lines correspond, in the backscatter geom- etry, to two Langmuir waves travelling towards and away from the radar. In the daytime ionosphere, the presence of a small percentage ...

    • The effect of vertical mixing on the horizontal drift of oil spills 

      Röhrs, Johannes; Dagestad, Knut-Frode; Asbjørnsen, Helene; Nordam, Tor; Skancke, Jørgen; Jones, Cathleen; Brekke, Camilla (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-21)
      Vertical and horizontal transport mechanisms for marine oil spills are investigated using numerical model simulations. To realistically resolve the 3-D development of a spill on the ocean surface and in the water column, recently published parameterizations for the vertical mixing of oil spills are implemented in the open-source trajectory framework OpenDrift (https://doi.org/10.5281/zenodo.1300358, ...

    • Effect of Wind Direction and Incidence Angle on Polarimetric SAR Observations of Slicked and Unslicked Sea Surfaces 

      Skrunes, Stine; Brekke, Camilla; Jones, Cathleen Elaine; Espeseth, Martine; Holt, Benjamin (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-12)
      The objective of this paper is to investigate the dependency of oil spill observations in polarimetric SAR data on imaging geometry, i.e., on incidence angle and look direction relative to the wind. The study is based on quad-polarization data acquired by the Uninhabited Aerial Vehicle Synthetic Aperture Radar over experimental oil slicks under relatively high winds of 10–12 m/s over an 8-hour period. ...

    • Effect on the longitudinal coherence properties of a pseudothermal light source as a function of source size and temporal coherence 

      Ahmad, Azeem; Mahanty, Tanmoy; Dubey, Vishesh; Butola, Ankit; Ahluwalia, Balpreet Singh; Mehta, Dalip Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-01)
      In the present Letter, a synthesized pseudothermal light source having high temporal coherence (TC) and low spatial coherence (SC) properties is used. The longitudinal coherence (LC) properties of the spatially extended monochromatic light source are systematically studied. The pseudothermal light source is generated from two different monochromatic laser sources: He–Ne (at 632 nm) and DPSS (at 532 ...

    • Effects of Ocean Acidification and Warming on Sperm Activity and Early Life Stages of the Mediterranean Mussel (Mytilus galloprovincialis) 

      Vihtakari, Mikko; Hendriks, Iris E.; Holding, Johnna; Renaud, Paul E.; Duarte, Carlos M.; Havenhand, Jon N. (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Larval stages are among those most vulnerable to ocean acidification (OA). Projected atmospheric CO2 levels for the end of this century may lead to negative impacts on communities dominated by calcifying taxa with planktonic life stages. We exposed Mediterranean mussel (Mytilus galloprovincialis) sperm and early life stages to pHT levels of 8.0 (current pH) and 7.6 (2100 level) by manipulating pCO2 ...

    • Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar 

      Viswanathan, Lakshmi Narayanan; Häggström, Ingemar; Mann, Ingrid (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-23)
      We present the results from investigation of spectra of polar mesospheric summer echoes (PMSE) observed with EISCAT VHF 224 MHz radar during energetic particle precipitation events in the summer of 2019. We used the sudden enhancements in electron densities derived from the VHF observations above 90 km as indicators of particle precipitation. We find that the altitude extent of the PMSE increased ...

    • Effects of substorm electrojet on declination along concurrent geomagnetic latitudes in the northern auroral zone 

      Edvardsen, Inge; Johnsen, Magnar Gullikstad; Løvhaug, Unni Pia (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-02)
      The geomagnetic field often experiences large fluctuations, especially at high latitudes in the auroral zones. We have found, using simulations, that there are significant differences in the substorm signature, in certain coordinate systems, as a function of longitude. This is confirmed by the analysis of real, measured data from comparable locations. Large geomagnetic fluctuations pose ...

    • Effects of the tropospheric large-scale circulation on European winter temperatures during the period of amplified Arctic warming 

      Vihma, Timo; Graversen, Rune; Chen, Linling; Handorf, Dörthe; Skific, Natasa; Francis, Jennifer A.; Tyrrell, Nicholas; Hall, Richard; Hanna, Edward; Uotila, Petteri; Dethloff, Klaus; Karpechko, Alexey Yu.; Björnsson, Halldór; Overland, James E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-08)
      We investigate factors influencing European winter (DJFM) air temperatures for the period 1979–2015 with the focus on changes during the recent period of rapid Arctic warming (1998–2015). We employ meteorological reanalyses analysed with a combination of correlation analysis, two pattern clustering techniques, and backtrajectory airmass identification. In all five selected European regions, severe ...

    • Efficient photoelectrocatalytic degradation of amoxicillin using nano-TiO<inf>2</inf> photoanode thin films: A comparative study with photocatalytic and electrocatalytic methods 

      Alaydaroos, Alia Husain; Sydorenko, Jekaterina; Palanisamy, Selvakumar; Chiesa, Matteo; Al Hajri, Ebrahim (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-24)
      Excessive utilization of antibiotics in human, animal, and aquaculture poses a substantial threat to human health and the environment. Photoelectrochemical processes are increasingly applied for water remediation because they generate oxidizing species and mineralize organic pollutants, making even small water quantities more amenable for utilization. Thus, this study presents the fabrication of an ...

    • Eigen-analysis reveals components supporting super-resolution imaging of blinking fluorophores 

      Agarwal, Krishna; Prasad, Dilip Kumar (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-30)
      This paper presents eigen-analysis of image stack of blinking fluorophores to identify the components that enable super-resolved imaging of blinking fluorophores. Eigen-analysis reveals that the contributions of spatial distribution of fluorophores and their temporal photon emission characteristics can be completely separated. While cross-emitter cross-pixel information of spatial distribution ...

    • EISCAT 3D: the next generation international atmosphere and geospace research radar 

      Kero, Johan; Kastinen, D; Vierinen, Juha; Grydeland, Tom; Heinselman, Craig J.; Markkanen, Jussi; Tjulin, A. (Journal article; Tidsskriftartikkel, 2019)
      EISCAT_3D is the next generation international atmosphere- and geospace research radar under development in Arctic Europe. Construction have started in September 2017 and the radar system is expected to be operational in the end of 2021. The EISCAT_3D facility will be distributed across three sites in Northern Scandinavia - in Skibotn, Norway, near Kiruna in Sweden, and near Karesuvanto in Finland. ...

    • Electron Bulk Heating at Saturn’s Magnetopause 

      Cheng, I; Achilleos, Nicholas; Masters, A; Lewis, G; Kane, M; Guio, Patrick (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-25)
      Magnetic reconnection at the magnetopause (MP) energizes ambient plasma via the release of magnetic energy and produces an “open” magnetosphere allowing solar wind particles to directly enter the system. At Saturn, the nature of MP reconnection remains unclear. The current study examines electron bulk heating at MP crossings, in order to probe the relationship between observed and predicted reconnection ...

    • Electron Density Depletion Region Observed in the Polar Cap Ionosphere 

      Bjoland, Lindis Merete; Ogawa, Y.; Løvhaug, Unni Pia; Lorentzen, Dag Arne; Hatch, Spencer Mark; Oksavik, Kjellmar (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-16)
      This paper presents and discusses electron density depletion regions observed with the incoherent scatter EISCAT Svalbard Radar (ESR) located at 75.43°N geomagnetic latitude. The data include several decades of measurements, which make them suitable for studying statistical features and characteristics of the ionospheric parameters. Here we focus on the electron density depletions and their dependence ...

    • The electron energy distribution during HF pumping, a picture painted with all colors. 

      Rietveld, Michael T.; Gustavsson, B.; Sergienko, T.; Grydeland, Tom; La Hoz, Cesar; Kosch, M.J.; Brändström, B.U.E.; Leyser, T.B.; Isham, B.; Gallop, P.; Aso, T.; Ejiri, M.; Steen, A.; Kaila, K.; Jussila, J.; Holma, H. (Journal article; Peer reviewed; Tidsskriftartikkel, 2005-07-28)
      The shape of the electron energy distribution has long been a central question in the field of highfrequency radio-induced optical emission experiments. This report presents estimates of the electron energy distribution function, fe(E), from 0 to 60 eV, based on optical multiwavelength (6300, 5577, 8446, 4278 A° ) data and 930-MHz incoherent scatter radar measurements of ion temperature, electron ...