By the use of highly intense X-ray pulses, with durations in the scale of tenths of fs, high resolutiondiffraction images of the structures of individual macro-molecules can be obtained. To generatea self-consistent 3D-image of the structures the diffraction images of thousands of copies of thesame molecules have to be compounded. The composition relies on advanced algorithms with longcomputational times and is not always successful or even possible. Simulations of proteins in electricfields have proven that pre-orientation of molecules could yield results otherwise unobtainable.When a molecule enters the electric field it will experience an increasing field strength, i.e. a timedependent electric field, and the change in the field strength will be a function of the moleculestranslational velocity. Proteins are compounded by amino-acids. If amino-acids structures arealtered it could indicate that the structures of proteins would be altered as well. The initial objectof this project was to determine if there exists any critical molecular velocities at which the structuresof amino-acids significantly are altered. If the structures are altered the diffraction imageswill be of other structures than of those intended. The project was based on computer simulations.When approximating the plates of a capacitor as two point charges it was found that the timelapsewould be too long for the simulations intended. Instead it was asked at which field strengthsthe amino-acids would start to lose their essential structures. The amino-acids were simulated inconstant electric fields on a computer at Uppsala University. It was found that the amino-acidscould start to lose their structures in fields intended for pre-orientation of proteins. It was alsofound that the field strengths required for a change in the intramolecular forces depended on thesize of the amino-acid as well as the direction of the field in relation to the amino-acids orientation.

We review modern methods of scattering amplitude computations, beginning with color-decomposition that decomposes the amplitude into a color-dependentand a color-independent part of partial color-ordered amplitudes. We then show how a full amplitude can be described through the color-factor, propagator structure, and kinematic numerator of cubic color-ordered diagrams. The color-factors obey a Lie algebra and as such satisfy the Jacobi identity. We are able to impose the color-kinematics duality that states that the kinematic numerators also obey this identity. Because of this it is possible to write down sets of Jacobi equations for the numerator through their diagrammatic expression. These can be solved for a set of master numerators through which all other numerators can be expressed linearly. We find such solutions for the tree-level, one-loop, and two-loop diagrams for any numberof particles.

The purpose with this thesis is to see which subject-specific concepts occur in middle school physics textbooks in the solar system. The second goal of the work is to analyze how these subject-specific concepts are explained to give an understanding of the concepts. This empirical work attempts to answer two questions:• What subject-specific concepts are found about the solar system in middle school physics textbooks?• How are the subject-specific concepts of the solar system explained so that they provide an understanding of the concepts?To answer these questions, a quantitative content analysis and a qualitative text analysis were made. The methods were applied to three different Swedish middle school textbooks. The theoretical framework used in this work is subject-specific concepts, analogies, metaphors and conceptual development. Subject-specific concepts are used to define the subject-specific concepts. Analogies and metaphors are used as a pair of glasses to show how students can acquire new concepts. The theory of conceptual development was used to gain perspective on how students understand new concepts. What I found out was that the subject-specific concepts used to explain our solar system were sun, moon, planet, earth, asteroid, earth axis, solar system, celestial bodies, gravity, attraction, dwarf planets, comets and crater. The result showed that none of the textbooks used analogies. A few metaphors were used but the explanations that appeared as the most except for no use were examples and relationships. In two textbooks some subject-specific concepts had been introduced earlier several times.Keywords: Physics, textbook, explained, solar system.Nyckelord: Fysik, lärobok, förklaringar, solsystemet.

No description available.

The description of a black hole in the limit of very large number of spacetime dimensions D simplifies considerably. When D approaches infinity, the gravitational field lines of force are infinitely dispersed among the infite number of spacetime directions. This implies that outside the near-horizon region of the black hole the background spacetime will be flat, while the gravitational field will be strongly localized near the horizon. Thus, we can attempt to replace the black hole by a sphere cut off at the horizon in an empty background. In this project we attempt to obtain the physical conditions that the sphere has to meet in order to be able to reproduce the dynamics of the black hole when embedded in the empty background. This is described in the effective equation that we derive starting from the Einstein equations. Finally, we apply our results to take a look at ’black droplets’, black holes localized at the boundary of AdS and extending a finite distance into the bulk.

ChemCam, mounted on the mast of the Mars Science Laboratory (MSL) rover, uses Laser-Induced Breakdown Spectroscopy (LIBS) to perform remote-sensing science on Mars. ChemCam’s telescope is used to simultaneously focus the laser on martian rocks up to 7 meters away from the rover and collect the light emitted as the plasma plume created on the target cools down. The light is then transmitted to three spectrometers located in the body of the rover, providing spectra from which the composition of the samples is inferred on the ground. Context images of the sampled targets are captured by the Remote Micro Imager (RMI) that completes the instrument. A hardware failure that occurred a bit more than two years into the mission caused the ChemCam instrument to lose its original autofocus ability. This resulted in a degraded performance mode for several months while the ChemCam team developed a new autofocus algorithm based on the RMI images. During this period of degraded performance, several observations with different focus conditions were made on each target.  This unusual set of data provides the opportunity to study the influence of less-than-optimal focus conditions on the LIBS signal created on the target and analyzed by ChemCam. To this purpose, we look at both raw ChemCam spectra and  post-processed products used for scientific analysis to investigate how the quality of the focus influences the LIBS signal and the quantitative predictions of the composition of the observed targets.

No description available.

The MAX phase family is a set of nanolaminated, hexagonal materials typically comprised of three elements: a transition metal (M), an A-group element (A), and carbon and/or nitrogen (X). In this thesis, first-principles based methods have been used to investigate the phase stability and physical properties of a number of MAX and MAX-like phases. Most theoretical work on MAX phase stability use the constraint of 0 K conditions, due to the very high computational cost of including temperature dependent effects such as lattice vibrations and electronic excitations for all relevant competing phases in the ternary or multinary chemical space. Despite this, previous predictions of the existence of new MAX phases have to a large extent been experimentally verified. In an attempt to provide a possible explanation for this consistency, and thus help strengthen the confidence in future predictions, we have calculated the temperature dependent phase stability of Tin+1AlCn, to date the most studied MAX phases. We show that both the electronic and vibrational contribution to the Gibbs free energies of the MAX phases are  cancelled by the corresponding contributions to the Gibbs free energies of the competing phases. We further show that this is the case even when thermal expansion is considered. We have also investigated the stability of two hypothetical MAX-like phases, V2Ga2C and (Mo1-xVx)2Ga2C, motivated by a search for ways to attain new two-dimensional MAX phase derivatives, so-called MXenes. We predict that it is possible to synthesize both phases. For x≤0.25, stability of (Mo1-xVx)2Ga2C is indicated for both ordered and disordered solid solutions on the M sublattice. For x=0.5 and x≥0.75, stability is only indicated for disordered solutions. The ordered solutions are stable at temperatures below 1000 K, whereas stabilization of the disordered solutions requires temperatures of up to 2100 K, depending on the V concentration. Finally, we have investigated the electronic, vibrational, and magnetic properties of the recently synthesized MAX phase Mn2GaC. We show that the electronic band structure is anisotropic, and determine the bulk, shear, and Young’s modulus to be 157, 93, and 233 GPa, respectively, and Poisson’s ratio to be 0.25. We further predict the magnetic critical order-disorder temperature of Mn2GaC to be 660 K. We base the predictions on Monte Carlo simulations of a bilinear Heisenberg Hamiltonian constructed from magnetic exchange interaction parameters derived using two different supercell methods: the novel magnetic direct cluster averaging method (MDCA), and the Connolly-Williams method (CW). We conclude that CW is less computationally expensive than MDCA for chemically and topologically ordered phases such as Mn2GaC.

The Standard Model (SM) of particle physics describes the elementary particles that constitute matter and their interactions. The predictions of the SM have been confirmed by numerous experimental results. However, several questions of particle phenomena in the Universe remain unaddressed by the Standard Model, which suggests that the SM can be extended to a more complete theory. One approach to search for extensions of the SM is to test the predictions of the Standard Model in high precision measurements and see whether the results falsify the SM. For this reason, production of the ttZ and ttW processes at the ATLAS experiment at CERN is studied. It is investigated whether the SM gives correct predictions for these processes and how much room there is for contributions from new physics that give similar final states. Three measurements of ttZ and ttW production are performed. The first measurement is performed at 8 TeV collision energy. The next measurement uses data collected in 2015 at 13 TeV collision energy, when the production cross sections for these processes are considerably larger. The third measurement uses ten times as much data at 13 TeV collision energy. This analysis is not public at the time of writing, so only preliminary results for the expected sensitivity are presented. The new physics affecting ttZ production is parametrised in the model-independent framework of Effective Field Theory. Five effective operators that can affect ttZ production are studied and their coefficients are constrained in a fit to simulated data for the third measurement. The major background process tWZ is modelled at NLO in QCD. In order to avoid overlaps with ttZ, the Diagram Removal (DR) method is employed in two versions: one where the quantum interference is neglected (DR1) and another where it is modelled (DR2). The differences between the two predictions are explored and enter the measurement as a modelling uncertainty.

No description available.