Filtyp
A model for calculating the noise in nonlinear optical processes arising from (nonquantum) stochastic fluctuations (mode beating) in and between the lasers participating in the nonlinear interaction has been previously developed. Assuming that all individual laser mode phases and laser modes are (statistically) independent (Gaussian statistics) and that the nonlinear interaction can be expressed a
The temperature in the thermal boundary layer close to the combustion chamber wall was measured under knocking and non-knocking conditions using dual-broadband rotational coherent anti-Stokes Raman Scattering (CARS). A horseshoe-shaped combustion extension was employed to get an optical access to the region near the combustion chamber wall. Time-resolved measurements of the cylinder pressure (at t
It is generally accepted that knocking combustion influences the heat transfer in SI engines. However, the effects of heat transfer on the onset of knock is still not clear due to lack of experimental data of the thermal boundary layer close to the combustion chamber wall. This paper presents measurements of the temperature in the thermal boundary layer under knocking and non-knocking conditions.
Pure rotational coherent anti-Stokes Raman scattering (CARS) has for the first time been investigated for pressures up to 44 MPa in nitrogen gas at room temperature. An atomic filter consisting of a heated cell with sodium vapour was successfully applied for suppression of stray light originating from the narrowband CARS pump laser beam. With increasing pressure the rotational CARS spectrum is smo
Cycle-resolved end-gas temperatures were measured using dual-broadband rotational CARS in a single-cylinder spark-ignition engine. Simultaneous cylinder pressure measurements were used as an indicator for knock and as input data to numerical calculations. The chemical processes in the end-gas have been analysed with a detailed kinetic mechanism for mixtures of iso-octane and n-heptane at different
Laser-induced fluorescence measurements have been performed in turbulent non-premixed flames close to the lift-off point and in laminar premixed acetylene flames. The spectrally analyzed fluorescence signal showed good correspondence to known spectra from glyoxal (C2H2O2). Laser-induced fluorescence spectra from glyoxal vapor using the same excitation wavelength of 428 nm showed the same strongest
To study the hydrology of peatlands and explore wetness distribution is difficultmainly due to the complexity of the surface of peatlands, and also due to the presence of permafrost underlain peatlands in the arctic regions. I have chosen the area called Stordalen mire in the arctic region in northern Sweden for my study.In this thesis, I aimed to study spatially distributed hydrological modelling
Two-dimensional visualization of soot has been realized in flames with the use of laser-induced fluorescence in C2 from laser-vaporized soot [LIF(C2)LVS]. Soot particles are heated to vaporization temperatures by the absorption of laser radiation. C2 radicals produced by this process are excited at wavelengths around 563 nm through the transition ν′ = 0 d3∏g←ν″ = 1 a3∏u, and the subsequent fluores
Biogenic volatile organic compounds (BVOCs), which are mainly emitted by vegetation, may create either positive or negative climate forcing feedbacks. In the Subarctic, BVOC emissions are highly responsive to temperature, but the effects of climatic warming on BVOC emissions have not been assessed in more extreme arctic ecosystems. The Arctic undergoes rapid climate change, with air temperatures i
Shrubs have increased in abundance and dominance in arctic and alpine regions in recent decades. This often dramatic change, likely due to climate warming, has the potential to alter both the structure and function of tundra ecosystems. The analysis of shrub growth is improving our understanding of tundra vegetation dynamics and environmental changes. However, dendrochronological methods developed
Arctic tundra ecosystems are warming almost twice as fast as the global average. Permafrost thaw and the resulting release of greenhouse gases from decomposing soil organic carbon have the potential to accelerate climate warming. In recent decades, Arctic tundra ecosystems have changed rapidly, including expansion of woody vegetation, in response to changing climate conditions. How such vegetation
Rapid climate warming in the tundra biome has been linked to increasing shrub dominance. Shrub expansion can modify climate by altering surface albedo, energy and water balance, and permafrost, yet the drivers of shrub growth remain poorly understood. Dendroecological data consisting of multi-decadal time series of annual shrub growth provide an underused resource to explore climate-growth relatio
Deeper winter snow is hypothesized to favor shrub growth and may partly explain the shrub expansion observed in many parts of the arctic during the last decades, potentially triggering biophysical feedbacks including regional warming and permafrost thawing. We experimentally tested the effects of winter snow depth on shrub growth and ecophysiology by measuring stem length and stem hydrogen (δ2H),
Imitation is a cornerstone in human development, serving both a cognitive function (e.g. in the acquisition and transmission of skills and knowledge) and a social-communicative function, whereby the imitation of familiar actions serves to maintain social interaction and promote prosociality. In nonhuman primates, this latter function is poorly understood, or even claimed to be absent, yet the evid
Androgen-deprivation therapy (ADT) for prostate cancer has been associated with increased risk for development of cardiovascular events and recent pooled analyses of randomized intervention trials suggest that this primarily is the case for patients with pre-existing cardiovascular disease treated with gonadotropin-releasing hormone receptor (GnRH-R) agonists. In the present study we investigated
A high diet quality according to the Swedish nutrition recommendations is associated with a reduced risk of cardiovascular disease in the population-based Malmö Diet and Cancer cohort. To further clarify this protective association, we examined the association between high diet quality and change in triglycerides, high density lipoprotein-cholesterol (HDL-C), and low density lipoprotein-cholestero
