A brief description  of the multibody system mechanics is given as the first step in this thesis to present the dynamical equations which will be the main tool to analyze the two-body tire model.  After establishing the basic theory about multibody systems to understand the main character in the thesis (the tire)  all the  physical components playing in the tire terrain interaction  will be defined together with some of the developed ways and models to describe the  tire rolling  on non-deformable terrain and the  tyre rolling on the deformable terrain. The two-body tire model definition and general description will be introduced.  Using the tools acquired on the course of the thesis  the  dynamic equations will be solved for the particular case of the two-body tire model rolling on a flat rigid surface. After solving the equation we are going to find out some incongruences with respect to reality and then we are going to have a proposal to adjust the model to agree with  real tires.

Samhället har genomgått en förändring från analoga system till digitala.Läromedel som används i skolan behöver följa med i utvecklingen. Syftet meddenna studie är att undersöka hur digitala läromedel i kemi ser ut. Det är även avintresse att ta reda på hur de digitala läromedlen gör för att skapa en bild avämnet kemi som är intresseväckande och intressant samt om dessa digitalaläromedel är utformade för att tillgodose det syfte som presenteras i kursplanenför kemi i grundskolan. Tre olika läromedel, Kemi Direkt från Sanomautbildning, PLUS Kemi från Natur & Kultur och Spektrum Kemi från Liber AB,undersöks med hänsyn till flera olika punkter och aspekter. Undersökningenomfattar hur dessa digitala läromedel presenteras för läsaren, vad det finns förolika möjligheter att ta del av materialet, vilka anpassningar läromedlettillhandahåller för såväl svaga som starka elever, vad det finns för material föratt underlätta planering, laborationer och bedömning. Vidare vad det finns föruppgifter och hur dessa uppgifter rättas eller bedöms, om de olika syftenauppfylls samt hur intressant och förstående är den information som presenterasom växthuseffekten och den förhöjda växthuseffekten. Alla tre läromedel finnssom fysiska böcker som sedan har digitaliserats och på olika sätt anpassats föratt finnas tillgängliga digitalt. Det medför att de inte upplevs som innovativa ochintressanta digitala läromedel även om det såklart inte heller finns stora fel ochbrister. Det framkommer att Spektrum Kemi är det läromedel som uppvisar denstörsta responsen på de undersökta parametrarna. Önskvärt skulle vara ett nyttläromedel som inte är en digitalisering av en tidigare förlaga utan som är skapadför att vara digital och använder tekniken och den digitala världens alla finesseroch möjligheter.

The space between stars is not empty, but filled with a thin gas and microscopic dust grains, together forming the so-called interstellar medium. Matter is concentrated into clouds of very different sizes, ranging from giant molecular cloud complexes to massive isolated dark small isolated cloudlets, called globules. In bright emission regions, surrounding young massive stars, one can find many tiny, isolated and cold objects appearing as dark spots against the background nebulosity. These objects are much smaller and less massive than normal globules. Such small clouds are the topic of the present Licentiate thesis, where they have been baptised globulettes. The analysis is based on H-alpha images of the Rosette Nebula and IC 1805 Nebula, collected with the Nordic Optical Telescope in the years 1999 and 2000. In total 151 globulettes in these two regions were catalogued, measured and analysed. Positions, orientations, sizes, masses, densities and pressures were derived, as well as their present condition with regard to gravitational stability. From these data, their origins and possible evolutionary history were discussed. Most globulettes are sharp-edged and well isolated from the surrounding. The size distributions are quite similar in the two studied nebulae. The masses and densities were derived from the extinction of light and the measured shape of the objects. In a few cases the masses have been estimated earlier by another team, from radio emission of CO gas, and our values are in line with their estimates for these particular globulettes. A majority of the objects have masses &lt; 20 Jupiter masses, and the mass distribution drops rapidly towards higher values. Very few objects have masses above 100 Jupiter masses, which we define as the lower mass limit for normal globules. However, there is no smooth overlap between the two types of clouds, which makes us conclude that globulettes represent a distinct, new class of objects. The column density profile of a typical globulette was found to be rather uniform in the central parts, but flattens at the periphery, as compared to what is expected from a sphere of constant volume density. The virial theorem, including only the kinetic and gravitational energy, indicates that all 133 globulettes are expanding or disrupting. However, other forces, such as outer gas and radiation pressures, can help to confine the globulettes. Our results show that about half of these objects are gravitationally bound and even unstable against contraction, which opens some evolutionary scenarios not expected in the first place. Some massive globulettes could therefore collapse to form stars with very low masses, for instance, so-called brown dwarfs, while the low-mass globulettes could contract to free-floating planets. Globulettes might have been formed either by the fragmentation of larger filaments, or by the disintegration of large molecular clouds originally hosting compact and small cores. At a later stage even the confine globulettes might disrupt because of evaporation form the action of external radiation and gas flows. or evaporate. However, preliminary calculations of their lifetimes show that some might survive for a relatively long time and even longer than their estimated contraction time. No evidence of embedded infrared-emitting sources was found in independent IR studies, but one cannot exclude that globulettes already host low-mass brown dwarfs or planets. / <p>Godkänd; 2006; 20070109 (haneit)</p>

This Licentiate thesis treats the impact of early dust on the Cosmic Microwave Background (CMB). The dust that is studied comes from the first generation of stars, which were hot and short-lived, ending their lives as giant supernovæ. In the supernova explosions, heavy elements, produced through the fusion in the stars, were ejected into the interstellar medium. These heavy elements condensed to form dust, which can absorb and thus perturb the Cosmic Microwave Background radiation. The dust contribution to this radiation is calculated and found negligible. However, as the dust will be produced within structures (like galaxy clusters), it will have a spatial correlation that could be used to detect it. This correlation is calculated using relevant assumptions. The planned Planck satellite is likely to be able to measure and thus confirm this correlation. / Godkänd; 2005; 20061110 (ysko)

Astrophysical observations constitute an increasingly important source of information, thanks to the high resolution of present and near-future terrestrial and orbiting observatories. Especially, the properties of matter at low temperatures and extremely high densities can only be studied by observations of compact stellar objects. Traditionally, astrophysicists distinguish between three different types of compact objects. These are white dwarfs, neutron stars, and black holes. Neutron stars are presumably unique astrophysical laboratories for a broad range of physical phenomena. Examples are exotic phases of matter at super-nuclear densities and hypothetical new states of matter, e.g., superconducting quark matter. This Licentiate thesis treats a subset of the exotic phases of matter that could exist in compact stellar objects. In particular, a model of three-flavour colour superconducting quark matter is derived and a signature for a new state of matter is suggested. The former is an effective so-called Nambu-Jona-Lasinio model of quark matter at high densities, which incorporates local colour and electric charge neutrality, as well as self consistently determined quark masses and superconducting condensates. The phase diagram of three-flavour colour superconducting quark matter is presented and the effect of superconducting condensates on the possible configurations of compact stars is discussed. In the second part of the thesis, it is shown that a hypothetical class of particles, so-called preons, which might be the building blocks of quarks and leptons, could allow for a new class of compact objects, preon stars. The properties of preon stars are estimated and potential methods to observe them are discussed. / Godkänd; 2005; 20070102 (haneit)

We use a map introduced by Berkovits to determine the first levels of the theta-expansion of vertex operators for leading Regge trajectory bosons in the pure spinor formalism. This expansion is then used to confirm that in the pure spinor formalism, the 3-point disc scattering of any leading Regge trajectory bosons reproduces the corresponding Ramond-Neveu-Schwarz result found by Schlotterer.

Background and purpose: Although proton therapy is becoming increasingly common as a radiotherapy modality, facilities offering proton therapy are still scarce in comparison to photon therapy. Sweden's new proton therapy facility, Skandionkliniken, is scheduled to being operation during August 2015, employing the pencil beam scanning technique. Given Skandionklinikens unique stance as the only facility offering proton therapy in Sweden as of this writing, it is important to minimize the need for measurements during quality assurance to free up beam time for patients and other endeavors. It is the purpose of this work to create a foundation for a method whereby dose distribution verification is done via Monte Carlo simulation by developing and performing simple validation of a beam model. As input for simulating a dose distribution, log files storing a wide variety of data on how the dose distribution was delivered were used. Method: GATE, an open source Monte Carlo code and built on top of Geant4, was used for all simulations. A beam model parameterizing phase space at the nozzle exit was developed. The beam model development process made use of the beam data library and log file data. Using an in house developed code to convert log file data to treatment plans readable by GATE allowed simulation of delivered dose distributions. For validation, gamma index tests were performed comparing measured and simulated dose distributions. Results: The beam model was found able to predict the spot size in almost all cases within 0.2 mm. Likewise, the beam model was able to predict the proton range within 0.2 mm. The energy spread was found to be more difficult to estimate; comparisons of simulated and measured curves for at six points around the Bragg peak yielded a maximum deviation of 0.86 mm. Several difficulties prevented easy interpretation of the results of the gamma index tests. If allowance is made for certain data manipulation, pass rates of 90% or above using the global method can be achieved for all depths and for both treatment plans scanned. Conclusion: Although some complications arose during validation, the beam model performance appears capable of producing accurate results. To produce a full product suitable for routine patient specific quality assurance, further work will be necessary. Significant computing power would also be mandatory for routine use, necessitating the acquisition of a dedicated computer cluster or using GPUs.

There has been an increasing interest in proton beam therapy (PBT) in recent years related to the advantageous depth-dose characteristics of proton beams compared to what is achievable with standard external photon beam radiotherapy (RT). With PBT, improved target dose conformity can be achieved together with a reduction in the dose to the organs at risk (OARs). This can for certain cases lead to an increased tumour control probability (TCP) at the same time as the probabilities for normal tissue complications (NTCP) and radiation-induced secondary cancers are reduced. However, there are challenges with PBT, in the form of uncertainties in the dose delivery to the patient, due to different influencing factors. These perturbing factors are contributing to the uncertainties during different steps in the RT flow process, from the treatment planning to the irradiation. In the present work, a comparative treatment planning study of PBT and photon RT for a few clinical liver- and stomach-cancer cases were performed with the aim of determining possible advantages of PBT. The treatment planning comparisons were performed by means of dosimetric evaluations and by use of tissue response models. The later included the calculation of TCP and NTCP as well as the assessment of risk of radiation-induced secondary cancer for the two compared RT techniques. A total of eleven patients previously treated with RT at Karolinska University Hospital were included in the study. Three of these patients had been treated for liver cancer and eight for stomach cancer. The photon plans which had been used in the real treatments at the hospital were taken as reference plans. The treatment planning for the liver cancer cases had been performed on conventional CT images, but 4D-CT images were used for target definition to account for the target motion.  Three distinct CT images were used in the planning of the stomach cancer cases, the original CT image study on which the photon plans had been done and two CT image studies with artificially changed physical density for some of the internal organs to simulate different possible fillings of the stomach. The extra- or reduced gas filling was drawn on the CT slices by the radiation oncologist to estimate two worst-case scenarios for changes in density within the irradiated volume. The results indicate an improved target dose conformity, dose homogeneity and sparing of OARs for the PBT plans compared to the photon RT plans for the two clinical cases studied. The sparing of the OARs was also observed in the form of decreased NTCP for the PBT plans. The PBT plans showed to be worse than the photon plans when some structures were replaced by air and water. In the case of extra air there was a shift of the higher doses beyond the distal edge of the planned proton range which caused both an increase of the irradiated volumes of sensitive normal tissues and of the maximum doses to the OARs. In the case of extra water in the stomach, the maximum range of the protons was reduced causing target underdosage.  The calculations of probabilities for radiation-induced secondary malignancies indicated a reduced risk for all the OARs with the proton plans for the liver cancer cases. For the stomach cancer cases, reduced risks were obtained for induction of cancer in the liver but an increased risk was calculated for the bowel(-)PTV, with the proton- compared to the photon-plans. The results of the calculations of risk for radiation-induced cancer in the kidneys were inconclusive. The assessment of risk of secondary cancer for other organs, not delineated in this work (to obtain the whole body risk), is needed in order to obtain more comprehensive and clinically useful results.

No description available.

This doctoral thesis treats parts of the solar wind interaction with the Martian atmosphere and the water-related features known as gullies. The composition of the escaping plasma at Mars has been investigated in an analysis of data from the IMA sensor, which is a part of the ASPERA-3 instrument suit onboard the European satellite Mars Express. The goal of the investigation is to determine if there are any high abundances of escaping ion species incorporating carbon, such as in CO_2^+ . The most abundant ion species was found to be O^+ and O_2^+, followed by CO_2^+. The following ratios were identifed: CO_2^+/O^+ = 0:2 and O_2^+ /O^+ = 0:9. The escaping plasma, in form of ion beam events, has also been correlated to the magnetic anomalies found on the surface, where no clear association was found. Similar ion beams have also been detected on Venus, which does not have any crustal magnetic fields, and hence the fields are not required for the formation process of the beams. The ion beams' dependence of the direction of the solar wind convection electric field has also been studied, where a correlation was found, suggesting that the ion beams are accelerated by this field. The studies mentioned above are important in order to understand the evolution of Mars and its atmosphere, as well as plasma acceleration processes at non-magnetized planetary bodies. On 5 December 2006 the ASPERA instruments of both Venus Express and Mars Express detected a large enhancement in their respective background count level. These readings are associated with events of SEPs (Solar Energetic Particles), which are believed to be coupled with the CMEs (Coronal Mass Ejection) identified 43 ¡ 67 hours after the SEPs. The CMEs occurred on the far side of the sun (with respect to the locations of Venus and Mars), which indicates that these events can a®ect the space weather in areas situated 90 degrees in both azimuthal directions in the heliosphere with respect to the target. During this event the heavy ion outflow from the atmosphere of Mars increased by one order of magnitude, suggesting that EUV flux levels significantly affect the atmospheric loss from unmagnetized bodies. The gully formations have been investigated with data from the MOC, MOLA and TES instruments onboard the satellite Mars Global Surveyor. The features suggest that there has been fluvial erosion on the surface of Mars. The shallow and deep aquifer models remain the most plausible formation theories. Gully formation processes are important to understand since their eroding agent may be liquid water. / Godkänd; 2008; 20080206 (ysko)