Sökning: "step magnetic fields"

Visar resultat 1 - 5 av 19 avhandlingar innehållade orden step magnetic fields.

  1. 1. Transport, Turbulence and Instabilities in Cosmic Magnetic Fields

    Författare :Giuseppe Di Bernardo; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cosmic Rays; Interstella Medium; Galactic Magnetic Fields; Magnetohydrodynamics Turbulence; Accretion Discs;

    Sammanfattning : This decade has seen a large number of space missions, which, alongside ground-based radio, optical and gamma-ray telescopes, have enabled a deep insight into the non-thermal astrophysical environments. Interstellar Medium (ISM), Supernovae Remnants (SNRs) and Black-Hole (BH) accretion discs (ADs) are only a few examples of natural habitat of interaction of relativistic particles and magnetic fields, largely mediated by the action of the turbulence. LÄS MER

  3. 2. From irrotational flows to turbulent dynamos

    Författare :Fabio Del Sordo; Axel Brandenburg; Mordecai-Mark Mac Low; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; astrophysics; magnetic fields; insterstellar medium; MHD; dynamo; turbulence; instability; Astronomy; astronomi;

    Sammanfattning : Many of the celestial bodies we know are found to be magnetized:the Earth, many of the planets so far discovered, the Sun and other stars,the interstellar space, the Milky Way and other galaxies.The reason for that is still to be fully understood, and this work is meant to be a step in that direction. LÄS MER

  4. 3. Office work and physical factors : health aspects of electromagnetic fields and light

    Författare :Monica Sandström; Kjell Hansson Mild; Gunnar Nordberg; Umeå universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Facial skin symptoms; office illness; electrical hypersensitivity; physical environment; flicker; jitter; neurophysiological effects;

    Sammanfattning : The overall aim of this thesis is to increase our knowledge of the physical environment of office workers with special focus on electromagnetic fields and to address the question of whether electromagnetic fields can directly or indirectly contribute to symptoms or discomfort among video display terminal ( VDT) workers. Furthermore, we have measured light modulation from various commonly used light sources in laboratory conditions and, as a second step, used modulated light as stimulus for provocation of neurophysiological responses in persons with perceived “electrical hypersensitivity” (EHS). LÄS MER

  5. 4. Safety and health effects in high and ultra-high field MR

    Författare :Boel Hansson; Lund Diagnostisk radiologi; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Magnetic Resonance Imaging; UHF; MR safety; Patient compliance;

    Sammanfattning : Background: More than 70 million magnetic resonance (MR) examinations are produced every year. Patients and personnel are exposed to electromagnetic fields at levels that exceed those normally found in our surroundings or in industry. LÄS MER

  7. 5. Flux emergence: flares and coronal mass ejections driven by dynamo action underneath the solar surface

    Författare :Jörn Warnecke; Axel Brandenburg; Dikpati Mausumi; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; astronomi; teoretisk astrofysik; Theoretical Astrophysics; Space and Plasma Physics; rymd- och plasmafysik;

    Sammanfattning : Helically shaped magnetic field structuresknown as coronal mass ejections (CMEs) are closely related to so-called eruptive flares. On the one hand, these events are broadly believed to be due tothe buoyant rise of magnetic flux tubes from the bottom of the convection zone to the photosphere where they form structures such as sunspots. LÄS MER