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Visar resultat 1 - 5 av 62 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. The evolution of ribonucleotide reductases

    Författare :Daniel Lundin; Anthony Poole; Britt-Marie Sjöberg; Christos Ouzounis; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Evolution; ribonucleotide reductase; horizontal gene transfer; phylogeny; protein classification; Molecular biology; Molekylärbiologi; Molecular Biology; molekylärbiologi;

    Sammanfattning : Ribonucleotide reductase (RNR) catalyses the transformation of RNA building blocks, ribonucleotides, to DNA building blocks, deoxyribonucleotides. This is the only extant reaction pathway for de novo synthesis of DNA building blocks and the enzyme is thus necessary for life. RNR is found in all but a few organisms. LÄS MER

  3. 2. On the origin and evolution of blue compact galaxies

    Författare :Göran A. Östlin; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; galaxies - compact; formation; evolution; starburst; interactions; dwarf; photometry; kinematics and dynamics; low surface brightness galaxies; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; astronomi; Astronomy;

    Sammanfattning : This thesis is focused on the origin and evolution of blue compact galaxies (BCGs). BCGs are low mass galaxies characterised by blue colours, low chemical abundances and high star formation rates. The gas consumtion time scale is considerable shorter than the age of the universe and thus the high star formation rate must be transient. LÄS MER

  4. 3. Stability and Statistical Analysis of Transient Waves in Fusion Plasmas

    Författare :Gergö Pokol; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; short-time Fourier transform; transient MHD mode; wavelet transform; quasi-linear diffusion; runaway electron; transient transport; stellarator; tokamak disruption; fusion plasma physics; whistler wave;

    Sammanfattning : Thermonuclear energy generation in magnetically confined plasmas offers an appealing energy source for coming generations. Some of the still unsolved problems in fusion plasma physics involve plasma transport and stability of plasma waves. Two such problems are addressed in the present thesis. LÄS MER

  5. 4. How transient interactions in the crowded cytosol affect protein mobility and stability

    Författare :Sarah Leeb; Mikael Oliveberg; Magnus Wolf-Watz; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; diffusive transient interactions; macromolecular crowding; protein stability; in-cell NMR; protein evolution; Biophysics; biofysik;

    Sammanfattning : Most biochemical reactions have evolved in crowded intracellular environments. However, the complexity of intracellular environments is often neglected in structural or functional studies of proteins. LÄS MER

  7. 5. Flow Maldistribution in Exhaust Aftertreatment Systems - Numerical Simulations

    Författare :Pratheeba Chanda Nagarajan; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Catalyst; Flow maldistribution; Transient; CFD Simulations; Reactive flows; Uniformity Index; Exhaust AfterTreatment Systems;

    Sammanfattning : To comply with the stringent emission norms under every driving condition, including the coldstart conditions and Real Driving Emissions (RDE) tests, accurate models that capture the spatial and temporal variation of flow distribution information in Exhaust AfterTreatment Systems (EATS) are required. This study is aimed at characterizing and quantifying flow distribution in EATS under transient conditions with realistic geometry that illustrates the complex nature of the flow conditions. LÄS MER