Sökning: "two-step evolution"

Visar resultat 1 - 5 av 13 avhandlingar innehållade orden two-step evolution.

  1. 1. Predator psychology and mimicry evolution - a theoretical analysis

    Detta är en avhandling från Stockholm : Department of Zoology, Stockholm University

    Författare :Alexandra Balogh; Stockholms universitet.; [2009]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Müllerian mimicry; two-step evolution; gradual evolution; mutualism; predator psychology; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology Ethology and behavioural ecology; NATURVETENSKAP Biologi Terrestrisk; limnisk och marin ekologi Etologi och beteendeekologi; etologi; Ethology;

    Sammanfattning : The evolution of Müllerian mimicry depends on many factors, among which predator psychology is the most important one. Predator avoidance learning, generalization and discrimination are primary selective agents during the evolutionary process. LÄS MER

  2. 2. Towards Understanding of Selectivity & Enantioconvergence of an Epoxide Hydrolase

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Åsa Janfalk Carlsson; Uppsala universitet.; [2016]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Epoxide hydrolase; Epoxide; Enantioselectivity; Regioselectivity; Enantioconvergence; Crystal structures; Biocatalysis; Immobilization; Transient kinetics; CASTing; Directed evolution; Biokemi; Biochemistry;

    Sammanfattning : Epoxide hydrolase I from Solanum tuberosum (StEH1) and isolated variants thereof has been studied for mapping structure-function relationships with the ultimate goal of being able to in silico predict modifications needed for a certain activity or selectivity. To solve this, directed evoultion using CASTing and an ISM approach was applied to improve selectivity towards either of the enantiomeric product diols from (2,3-epoxypropyl)benzene (1). LÄS MER

  3. 3. Single fluid inclusion analysis using ToF-SIMS Implications for ancient Earth biodiversiy and paleoenvironment studies

    Detta är en avhandling från Stockholm : Department of Geological Sciences, Stockholm University

    Författare :Sandra Siljeström; Stockholms universitet.; [2011]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ToF-SIMS; time-of-flight secondary ion mass spectrometry; fluid inclusions; biomarkers; hopanes; steranes; early life; paleoenvironment; oil; eukaryotes; NATURAL SCIENCES Earth sciences; NATURVETENSKAP Geovetenskap; Geochemistry; geokemi;

    Sammanfattning : When and how life first emerged on the Earth is an area of intense research. Signs of the first life on Earth, including morphological fossils, are scarce and hard to interpret. An alternative approach is to study organic biomarkers, which are molecular fossils commonly considered as bona fide biosignatures. LÄS MER

  4. 4. Exploration of Non-Aqueous Metal-O2 Batteries via In Operando X-ray Diffraction

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Chenjuan Liu; Uppsala universitet.; [2017]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Keywords: lithium-oxygen batteries; sodium-oxygen batteries; metal-air; in operando X-ray diffraction; cathode materials; Kemi med inriktning mot materialkemi; Chemistry with specialization in Materials Chemistry;

    Sammanfattning : Non-aqueous metal-air (Li-O2 and Na-O2) batteries have been emerging as one of the most promising high-energy storage systems to meet the requirements for demanding applications due to their high theoretical specific energy. In the present thesis work, advanced characterization techniques are demonstrated for the exploration of metal-O2 batteries. LÄS MER

  5. 5. Molecular Motion in Frustrated Lewis Pair Chemistry: insights from modelling

    Detta är en avhandling från Stockholm : Department of Organic Chemistry, Stockholm University

    Författare :Maoping Pu; Stockholms universitet.; [2015]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; CO2 capture; hydrogen activation; molecular motion; ab initio molecular dynamics; frustrated Lewis pair; quantum chemical modelling; reaction mechanism; Organic Chemistry; organisk kemi;

    Sammanfattning : Mechanisms of reactions of the frustrated Lewis pairs (FLPs) with carbon dioxide (CO2) and hydrogen (H2) are studied by using quantum chemical modelling. FLPs are relatively novel chemical systems in which steric effects prevent a Lewis base (LB) from donating its electron pair to a Lewis acid (LA). LÄS MER