Designs for future nuclear fusion power reactors rely on the ability to create a stable plasma (hot ionized gas of hydrogen isotopes) as a medium with which to sustain nuclear fusion reactions. My dissertation work involves designing, constructing, testing, installing, operating, and validating a new diagnostic for spherical tokamaks, a type of reactor test facility. Through detecting charged particles emitted from the plasma, this instrument can be used to study fusion reaction rates within the plasma and how they are affected by plasma perturbations. Quantitatively assessing nuclear fusion reaction rates at specific locations inside the plasma and as a function of time can provide valuable data that can be used to evaluate theory-based simulations related to energy transport and plasma stability. The Proton Detector (PD), installed in the Mega Amp Spherical Tokamak (MAST) at the Culham Centre for Fusion Energy (CCFE) in Abingdon, England, was the first instru- ment to experimentally detect 3 MeV Protons and 1 MeV Tritons created from deuterium- deuterium (hydrogen isotopes) nuclear fusion reactions inside a spherical tokamak’s plasma. The PD consists of an array of particle detectors with a protective housing and the neces- sary signal conditioning electronics and readout. After several years of designing (which included simulations for detector orientations), fabricating, and testing the PD, it was installed in MAST and data were collected over a period of two months in the summer of 2013. Proton and triton rates as high as 200 kHz were measured and an initial radial profile of these fusion reaction rates inside the plasma was extracted. These results will be compared to a complementary instrument at MAST as well as theory-based simulations and form the knowledge basis for developing a larger future in- strument. The design and performance of all instrument components (electrical, computa- tional, mechanical), and subsequent data analysis methods and results are described in this dissertation.

The tree amplitudes of string theory low-energy effective actions admit a diagrammatic expansion in terms of higher-than-cubic contact terms. These tree amplitudes can be used to build loop amplitudes using unitary cuts or the forward limit. In this thesis we study the possibility of constructing four-point cubic representations for the resulting one-loop contact terms that obey the Bern-Carrasco-Johansson (BCJ) color-kinematics relation. From the string theory effective action we study the contact terms carrying ζ2, ζ3, ζ4, and ζ5. For the even ζ2 and ζ4 cases we find that the cubic representations are incompatible with the BCJ relations, as expected from their disappearance in the closed-string effective action. We find a unique, local set of numerators at ζ3 that obey the BCJ relations. For ζ5 we find two choices of representations: one obeys BCJ but requires non-trivial contributions for the tadpole; the other contains no tadpoles but breaks one of the BCJ relations.

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<p>QC 20150603</p>

Denna studie behandlar energibegreppet i geografiämnet. Energibegreppet är komplext, inte minst för att det behandlas i olika kontexter med olika betydelser. Som lärare i naturvetenskapsämnena vill man förstå elevernas lärande om naturvetenskapliga begrepp, även om lärandet ligger utanför de egna ämnena. Syftet med studien är därför att kvalitativt undersöka hur energibegreppet behandlas i geografiämnet för att få en djupare förståelse för hur naturvetenskapsundervisningen och geografiundervisningen kan komplettera varandra. Sex samhällskunskapslärare i årkurserna 4–6 intervjuades om deras användning av energibegreppet. Deras uttalanden tematiserades och jämfördes med de fyra nyckelidéer om energibegreppet som Duit lyfter fram som centrala ur ett naturvetenskapligt perspektiv. Tre nyckelidéer kunde identifieras i lärarnas beskrivningar av hur de behandlar energibegreppet i geografiämnet. Tre teman kunde också urskiljas i datan. Studien pekar på att energibegreppet behandlas i geografiämnet med viss förankring till energiomvandling och energiöverföring. Vilket gör det möjligt att arbeta med ämnesövergripande undervisning gällande energibegreppet. / This study deals with the energy concept in the school subject of geography. The energy concept is complex, not least because it is treated in different contexts with different meanings. As a science teacher, you want to understand the students' learning about science concepts, also such learning that is outside their subject. The aim of the qualitative study is therefore to investigate how the energy concept is treated in the subject of geography in order to gain a deeper understanding of how science teaching and geography teaching can complement each other. Six social science teachers in middle school were interviewed about their use of the energy concept. Their statements were thematized and compared with the four key ideas about the energy concept that Duit highlights as central from a scientific perspective. Three key ideas could be identified in the teachers' descriptions of how they treat the energy concept in the subject of geography. Three themes could also be distinguished in the data. The study indicates that the energy concept is treated in the subject of geography with some base in energy transformation and energy transfer. That makes it possible to work interdisciplinary regarding the energy concept.

In many engineering applications, one is interested in structures with elastic properties which undergo deformation due to external loads. This interest has motivated a deep study of the equations underlying the deformation and how to solve them during the two last centuries. In this thesis, we propose a method that allows us to construct exact solutions to these equations. We prove that the partial differential equation governing the deformation is equivalent to the well-studied Cauchy-Riemann equation on the unit disk. Furthermore, we prove sufficient conditions for when the exact solutions to the Cauchy-Riemann equation on the unit disk can be used to construct solutions to the physical problem. We end the thesis by outlining a method for solving the elasticity equation in a general simply connected domain with a known conformal mapping to the unit disk. This method simplifies the formulas of Kolosov and Muskhelishvili, which are constructed by complex potentials in a similar, but more indirect way. It also allows us to obtain solutions in domains where standard numerical methods, such as e.g. the finite element method, proves difficult or even impossible to apply.

The search for the optimal choice of treatment time, dose and fractionation regimen is one of the major challenges in radiation therapy. Several aspects of the radiation response of tumours and normal tissues give different indications of how the parameters defining a fractionation schedule should be altered relative to each other which often results in contradictory conclusions. For example, the increased sensitivity to fractionation in late-reacting as opposed to early-reacting tissues indicates that a large number of fractions is beneficial, while the issue of accelerated repopulation of tumour cells starting at about three weeks into a radiotherapy treatment would suggest as short overall treatment time as possible. Another tumour-to-normal tissue differential relevant to the sensitivity as well as the fractionation and overall treatment time is the issue of tumour hypoxia and reoxygenation. The tumour oxygenation is one of the most influential factors impacting on the outcome of many types of treatment modalities. Hypoxic cells are up to three times as resistant to radiation as well oxygenated cells, presenting a significant obstacle to overcome in radiotherapy as solid tumours often contain hypoxic areas as a result of their poorly functioning vasculature. Furthermore, the oxygenation is highly dynamic, with changes being observed both from fraction to fraction and over a time period of weeks as a result of fast and slow reoxygenation of acute and chronic hypoxia. With an increasing number of patients treated with hypofractionated stereotactic body radiotherapy (SBRT), the clinical implications of a substantially reduced number of fractions and hence also treatment time thus have to be evaluated with respect to the oxygenation status of the tumour. The perhaps most promising tool available for the type of study aiming at determining the optimal SBRT approach with respect to fractionation is radiobiological modelling. With clinically-derived tissue-specific radiobiological parameters and well-established survival models, in silico modelling offers a wide range of opportunities to test various hypotheses with respect to time, dose, fractionation and details of the tumour microenvironment. Any type of radiobiological modelling study intended to provide a realistic representation of a clinical tumour should therefore take into account details of both the spatial and temporal tumour oxygenation. This thesis, consisting of papers I-III and a summary, presents the results of three-dimensional radiobiological modelling of the response of tumours with heterogeneous oxygenation to various radiation qualities, fractionation schemes, oxygenation levels and dynamics using different survival models. The results of this work indicate that hypoxia and its dynamics play a major role in the outcome of both photon and carbon ion radiotherapy, and that neglecting the oxygenation status of tumours treated with SBRT may compromise the treatment outcome substantially. Continued to include clinical studies on the impact of hypoxia on the treatment outcome in lung cancer patients treated with SBRT, this project will hopefully advance the evolution towards routinely incorporating functional imaging of hypoxia into treatment planning. This is ultimately expected to result in increased levels of local control with more patients being cured from their cancer.

The ultimate aim of the current study is to investigate the electron transfer from copper (Cu) to single layer graphene through a thin Cu oxide layer. Therefore the project is divided into two main parts. In the first part, single layer graphene is synthesized with chemical vapour deposition technique on a Cu foil and the grown graphene is characterized by means of Raman spectroscopy and scanning electron microscopy (SEM). We tune different experimental parameters to grow high quality graphene. We show that a pre-annealing of the Cu foil, in Varigon environment, modifies the Cu crystal grain size and that modifies the growth dynamic of the graphene. Optimum annealing time in correlation with growth time results in high Ǵ/G ratio and a narrow FWHM of Ǵ band in Raman spectrum. The second part of the project focuses on controlling the surface oxidation of Cu foil with respect to the oxide layer thickness. The surface and cross section of the oxidized Cu foil is examined by SEM and the presence of oxide layer is confirmed via energy dispersive X-ray spectroscopy (EDS) analysis. We show that the surface roughness of the oxide layer can be minimized by controlling the oxidation condition with a minimum oxide layer thickness of 18 μm. In addition the grain size of the oxide layer is getting larger with increasing the oxidation temperature. Furthermore, the oxygen concentration in the oxide layer is controlled through a controlled reduction process which is confirmed via EDS analysis. XPS spectroscopy is also used for elemental analysis as well as revealing the chemical state of the Cu oxide.

This dissertation focuses on characterization of the mesoscopic fluid film, testing its behavior in different application scenarios, including its role in near-field scanning probe microscopy imaging, contribution to the phononic mechanism in nanotribology phenomena, utilizing it as a natural environment in the study of carbohydrate-protein interactions, and harnessing it as bridge to transport ions in the fabrication of nanostructures on responsive polymer materials. Due to their high resolution and versatile applications in a variety of fields, the family of scanning probe microscopy (SPM) has found widespread acceptance as an analytical and fabrication tool. However, the working mechanism of SPM that allows maintaining the probe-sample distance constant is still controversial. At the heart the problem is a lack of precise knowledge about the nature of the probe-sample interaction. One key factor is the presence of a mesoscopic fluid-like layer that naturally forms at any surface at ambient condition in which most SPMs are operated. Its mesoscopic nature (~20 nm in thickness) results in extraordinary behavior compared to the properties of bulk liquid. For example, the effective shear viscosity of confined mesoscopic fluids is enhanced, and viscoelastic relaxation times are prolonged. Despite the wide use of SPM techniques in ambient air, the basis of their working mechanisms is still not well understood. The probe-sample interaction is monitored using a combination of tuning-fork based shear force microscopy and our recently developed near-field acoustic technique. To characterize the mesoscopic fluid film a series of experiments are performed under different conditions in order to explore the benefits of having extra probing (acoustic) technique in addition to the shear-force approach. The presence of mesoscopic fluid layers as a natural environment enables the detection of protein-carbohydrate interactions. We demonstrated the capability of our shear-force/acoustic technique to monitor the rupture of chemical bonds between carbohydrate and protein pairs. Finally, we present fabrication of nanostructures via electric-field assisted dip-pen nanolithography by exploiting the responsive feature of a particular class of polymers, where the mesoscopic fluid layer also plays an important role in pattern creation.

The magnetization dynamics in ferromagnetic materials will depend on the specific shape of the system’s energy landscape. In most systems, the energy landscapes can be approximated as paraboloids, resulting in a typical ellipti- cal precession of the magnetization. However, this model is not always appli- cable to more complex potentials, which can present exotic precessions. The aim of this project was to measure the magnetization dynamics in a system where a non-parabolic potential was expected. From the dynamics, it would then be possible to estimate the energy potential of the system. In order to measure magnetization dynamics, time-resolved MOKE (magneto-optic Kerr effect) measurements were performed using a pump-and-probe tech- nique. A permalloy (Fe20Ni80) thin film with an uniaxial in-plane anisotropy was used as a sample, presumably presenting a bistable energy potential with two close minima at certain applied external magnetic fields. By measuring one component of the magnetization in the plane of the sample, the shape of the precession in this landscape could be extracted. The results show the expected parabolic precessions at higher external fields, from which energy landscapes could be constructed. The dynamics measured at one particular field also indicate a bistable energy potential although no exotic precessions were found.