Sökning: "Dan Sun"

Visar resultat 1 - 5 av 7 avhandlingar innehållade orden Dan Sun.

  1. 1. Dynamics and Mechanisms of Adaptive Evolution in Bacteria

    Författare :Song Sun; Dan Andersson; Diarmaid Hughes; Josep Casadesús; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; adaptive evolution; mutation; genome rearrangements; antibiotic resistance; gene amplification; genome reduction; directed evolution; Biologi med inriktning mot mikrobiologi; Biology with specialization in Microbiology;

    Sammanfattning : Determining the properties of mutations is fundamental to understanding the mechanisms of adaptive evolution. The major goal of this thesis is to investigate the mechanisms of bacterial adaptation to new environments using experimental evolution. LÄS MER

  3. 2. Measuring the solar atmosphere

    Författare :Jaime de la Cruz Rodríguez; Göran Scharmer; Dan Kiselman; Mats Carlsson; Gianna Cauzzi; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; Chromosphere; Spectropolarimetry; Solar observations; Spectral lines; Solar magnetic fields; Astronomy; Astronomi; Astronomy; astronomi;

    Sammanfattning : The new CRISP filter at the Swedish 1-m Solar Telescope provides opportunities for observing the solar atmosphere with unprecedented spatial resolution and cadence. In order to benefit from the high quality of observational data from this instrument, we have developed methods for calibrating and restoring polarized Stokes images, obtained at optical and near infrared wavelengths, taking into account field-of-view variations of the filter properties. LÄS MER

  4. 3. Three-dimensional mapping of fine structure in the solar atmosphere

    Författare :Vasco M. J. Henriques; Dan Kiselman; Göran Scharmer; Hector Socas-Navarro; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; sunspots; Swedish 1-meter Solar Telescope; active regions; image processing; sunspot penumbra; Astronomy; astronomi;

    Sammanfattning : The effects on image formation through a tilted interference filter in a converging beam are investigated and an adequate compensation procedure is established. A method that compensates for small-scale seeing distortions is also developed with the aim of co-aligning non-simultaneous solar images from different passbands. LÄS MER

  5. 4. Physical properties of chromospheric features : Plage, peacock jets, and calibrating it all

    Författare :Alexander G. M. Pietrow; Dan Kiselman; Jaime de la Cruz Rodríguez; Malcolm Druett; Gianna Cauzzi; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; chromosphere; plage; jets; imaging; spectropolarimetry; Astronomy; astronomi;

    Sammanfattning : The chromosphere is a complex and dynamic layer of the solar atmosphere, largely dominated by the local magnetic field configuration. It acts as an important interface between the photosphere below it and the hot corona above. However, studying this layer is not straightforward, as it is largely transparent in optical wavelengths. LÄS MER

  7. 5. Investigating magnetic fields in the solar chromosphere

    Författare :Alexander Pietrow; Dan Kiselman; Jaime de la Cruz Rodr´ıguez; Oleg Kochukhov; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; chromosphere; plage; Astronomy; astronomi;

    Sammanfattning : Solar plage has been the topic of many studies since its initial description in the mid 19th century, but as of yet it has not been understood to the point where we can reproduce all aspects of these active regions in quasi-realistic numerical models. To a large extent, this is caused by an incomplete understanding of the magnetic structure that drives the activity in these areas. LÄS MER