Sökning: "scatter"

Visar resultat 1 - 5 av 175 avhandlingar innehållade ordet scatter.

  1. 1. Evaluation of attenuation and scatter corrections in lung and brain SPECT

    Författare :Agnetha Gustafsson; Bertil Axelsson; Göteborgs universitet Avdelningen för radiofysik Department of Radiations Physics; []
    Nyckelord :SPECT; attenuation; scatter; detectability; Monte Carlo simulation; MEDICINE; MEDICIN;

    Sammanfattning : Single Photon Emission Computed Tomography (SPECT) is used to image functional processes in the human body. The image process is affected by physical effects such as attenuation, scatter, spatial resolution and statistical noise. LÄS MER

  3. 2. Novel computational methods for image analysis and quantification using position sensitive radiation detectors

    Författare :Alejandro Sanchez Crespo; Stig A. Larsson; Magnus Dahlbom; Stockholms universitet; []
    Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; SPET; PET; CMOS; spatial resolution; photon depth of interaction; positron annihilation; positron range; non-collinearity; scatter; attenuation; lung ventilation; lung perfusion; breast tumour; Medicine; Medicin;

    Sammanfattning : The major advantage of position sensitive radiation detector systems lies in their ability to non invasively map the regional distribution of the emitted radiation in real-time. Three of such detector systems were studied in this thesis, gamma-cameras, positron cameras and CMOS image sensors. LÄS MER

  4. 3. Bird orientation: external cues and ecological factors

    Författare :Johan Bäckman; Evolutionär ekologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; tracking radar; Emlen funnel.; Animal ecology; Djurekologi; oscillatory orientation; roosting flight; scatter; concentration; heading; cue calibration; light dependent; magnetoreception; subcutaneous fat stores; body condition; energetics; geomagnetic field; visual cues; orientation; birds; migration;

    Sammanfattning : Birds are generally capable of accurate orientation. In this thesis I present studies about the external cues and the ecological factors that influences bird orientation. A multitude of environmental cues are used to select and maintain a proper direction. LÄS MER

  5. 4. Auroral and meteor applications of the EISCAT incoherent scatter radar

    Författare :Asta Pellinen-Wannberg; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Incoherent scatter; aurora; meteors;

    Sammanfattning : .... LÄS MER

  7. 5. Solitary waves and enhanced incoherent scatter ion lines

    Författare :Jonas Ekeberg; Lars Eliasson; Kristof Stasiewicz; Jan Trulsen; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; plasma waves and instabilities; nonlinear phenomena; solitons and solitary waves; ionosphere; Sun: corona; incoherent scatter radar; MHD; plasmavågor och instabiliteter; ickelinjära fenomen; solitoner och solitära vågor; jonosfär; solen: korona; inkoherent spridningsradar; MHD; Geocosmophysics and plasma physics; Geokosmofysik och plasmafysik; Space physics; Rymdfysik; Plasma physics; Plasmafysik; Non-linear dynamics; chaos; Icke-linjär dynamik; kaos; fysik; Physics; rymd- och plasmafysik; Space and Plasma Physics;

    Sammanfattning : This thesis addresses solitary waves and their significance for auroral particle acceleration, coronal heating and incoherent scatter radar spectra. Solitary waves are formed due to a balance of nonlinear and dispersive effects. LÄS MER