Sökning: "Density contrast"

Visar resultat 1 - 5 av 340 avhandlingar innehållade orden Density contrast.

  1. 1. X-ray Phase Contrast Tomography : Setup and Scintillator Development

    Författare :Hanna Dierks; NanoLund: Centre for Nanoscience; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; x-rays; x-ray imaging; x-ray microscopy; X-ray detectors; perovskites; laboratory setups; phase contrast; μCT; scintillator; Phase contrast PC ; Tomography x-ray computed ;

    Sammanfattning : X-ray microscopy and micro-tomography (μCT) are valuable non-destructive examination methods in many disciplines such as bio-medical research, archaeometry, material science and paleontology. Besides being implemented at synchrotrons radiation sources, laboratory setups using an X-ray tube and high-resolution scintillation detector routinely provide information on the micrometre scale. LÄS MER

  3. 2. Liquid-Jet-Target Microfocus X-Ray Sources : Electron Guns, Optics and Phase-Contrast Imaging

    Författare :Tomi Tuohimaa; Hans M. Hertz; Stephen Wilkins; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; electron-impact; x-ray; brightness; liquid-jet-target; phase-contrast imaging; Engineering physics; Teknisk fysik;

    Sammanfattning : This Thesis describes the development of an electron-impact microfocus x-ray source and its application for phase-contrast imaging. The source is based on a novel, liquid-jet target concept. Stable and continuous operation can be achieved at substantially higher electron-beam power densities than conventional solid target based systems. LÄS MER

  4. 3. Forest edges in boreal landscapes - factors affecting edge influence

    Författare :Ulrika Jansson; Per-Anders Esseen; Mats Nilsson; Timo Kuuluvainen; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; aerial photographs; edge contrast; edge density; edge length; fetch size; forest fragmentation; lichen growth; line intersect sampling; pendulous lichen; photo interpretation; skogskant; flygbild; kantlängd; lav; Terrestrial ecology; Terrestisk ekologi; ekologisk botanik; Ecological Botany;

    Sammanfattning : The boreal forest in Fennoscandia has been subjected to major loss and fragmentation of natural forests due to intensive forestry. This has resulted in that forest edges are now abundant and important landscape features. Edges have documented effects on the structure, function and biodiversity in forests. LÄS MER

  5. 4. Laser-Driven Particle Acceleration - Improving Performance Through Smart Target Design

    Författare :Matthias Burza; Atomfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; wakefield; ultra-relativistic; ultra-intense; TNSA; Terawatt; sheath; proton; polarimetry; plasma mirror; plasma; Petawatt; particle; oscillation; Normarski; micromachining; LWFA; laser; interferometry; electron; contrast; acceleration; bubble; Fysicumarkivet A:2012:Burza;

    Sammanfattning : Laser-driven particle acceleration makes use of sub-picosecond, pulsed, high-power laser systems, capable of producing intensities ~10^{19} W/cm^2 at the laser focus to form plasmas, and use ultra-relativistic and nonlinear dynamics to produce quasistatic acceleration fields. This allows electrons to be accelerated to ~100 MeV over sub-centimetre distances, while protons may be accelerated to the ~10 MeV regime. LÄS MER

  7. 5. Mammographic breast density and postmenopausal hormone therapy

    Författare :Eva Lundström; Karolinska Institutet; Karolinska Institutet; []
    Nyckelord :Mammographic breast density; mammography; menopause; hormone therapy; tibolone; low dose intrauterine progestogen; Syndecan-1.;

    Sammanfattning : Breast cancer is the most frequent malignancy among women in the western world. More than one million women are estimated to be diagnosed with the disease every year. The breast is a target organ for sex steroids and hormonal treatments have been found to increase the risk for breast cancer. LÄS MER