Sökning: "EXTINCTION"

Visar resultat 16 - 20 av 267 avhandlingar innehållade ordet EXTINCTION.

1. 16. Optical investigations and characterization of soot of different morphology and maturity

   Författare :Sandra Török; Förbränningsfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Laser-induced incandescence; Extinction; Elastic light scattering; mini-CAST; Soot; Brown carbon; Black carbon; Maturity; Morphology; Fysicumarkivet A:2021:Török;

   Sammanfattning : The formation path from small poorly absorbing incipient soot to larger fractal-like strongly absorbing black soot is extensive, and along this path the optical and physicochemical properties of the soot evolve. Soot emitted into the atmosphere may originate from some stage of this process, which will result in a wide spectrum of carbonaceous aerosols in the atmosphere which may interact with the sun and influence the radiative balance of the earth. LÄS MER

3. 17. Transient Phenomena in CO and Hydrocarbon Oxidation over Supported Platinum Catalysts

   Författare :Per-Anders Carlsson; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; mean-field kinetics simulations; ignition; environmental heterogeneous catalysis; flow-reactor studies; periodic operation; extinction; low-temperature activity; transient methods; in situ spectroscopy;

   Sammanfattning : The aim with this thesis work was to better understand transient phenomena involved in the low-temperature oxidation of CO and hydrocarbons by oxygen over typical oxidation catalysts. Supported platinum catalysts were prepared and carefully studied under transient conditions by means of flow-reactor experiments, different in situ spectroscopic (FTIR and XANES) methods in combination with mass spectrometry and mean-field kinetics simulations. LÄS MER

4. 18. Distribution Patterns and Metapopulation Dynamics of Epiphytic Mosses and Lichens

   Författare :Tord Snäll; Håkan Rydin; Johan Ehrlén; Christine Ray; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; plant; metapopulation; model; parameterization; connectivity; dispersal; colonization; extinction; epiphytic; bryophyte; lichen; boreal; fragmentation; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

   Sammanfattning : This thesis examines the relative importance of local conditions, dispersal and dynamics of the trees on epiphyte distribution patterns and colonization-extinction dynamics. Study species are the mosses Orthotrichum speciosum and O. obtusifolium, and the red-listed Neckera pennata. LÄS MER

5. 19. Multi-Dimensional Quantitative Laser-based Diagnostics - Development and Practial Applications

   Författare :Rikard Wellander; Förbränningsfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Post injection; Structured illumination; Mie scattering; Dense sprays; Extinction coefficient; Signal attenuation; Laser extinction; Multiple scattering; Scattering measurements; Planar laser induced fluorescence; Time resolved; Imaging through turbulent media; Three-dimensional image acquisition; Diesel particulate filter regeneration; Wall impingent; Biodiesel; LII; Large-bore gas Engine; Pre-chamber ignition; Fysicumarkivet A:2014:Wellander;

   Sammanfattning : Laser based optical diagnostic methods are routinely used in combustion research. Many of the more common approaches are based on illuminating a cross-section of the sample with a thin laser sheet. For example, by targeting an electronic transition in a molecule, its concentration within the plane illuminated by the laser sheet can be deduced. LÄS MER

7. 20. Ancient genomics of Baltic seals : Insights on the past Baltic grey seal and harp seal populations

   Författare :Maiken Hemme Bro-Jørgensen; Kerstin Lidén; Morten Tange Olsen; Aikaterini Glykou; Olle Karlsson; Stockholms universitet; []
   Nyckelord :HUMANIORA; HUMANITIES; Ancient DNA; Baltic Sea; DNA preservation; extinction; mitogenome; seal hunting; sex identification; arkeologi med inriktning mot laborativ arkeologi; Scientific Archaeology;

   Sammanfattning : This thesis aims to study and describe the ancient populations of grey and harp seals in the Baltic Sea, and to present new methodological approaches for general use in ancient DNA studies.The dissertation is comprised of five studies: a review of the use of paleogenetics in studying ancient human-marine mammal interactions; a method paper investigating patterns of DNA preservation in ancient pinniped samples; a method paper presenting a genetic sex identification method for ancient pinnipeds; a population genomic study of the Baltic grey seal; and a population genomic study of the now extinct Baltic harp seal. LÄS MER