The IceCube Neutrino Observatory is a cubic kilometre scale detector for high-energy neutrinos above hundreds of GeV produced in Earth’s atmosphere as well as outside our solar system whenever particles are accelerated to ultra-relativistic energies. The prompt atmospheric contribution is a result of the creation of heavy mesons with charm components in the atmosphere. Past studies from IceCube using a maximum likelihood estimation over the whole neutrino energy spectrum always reported a best-fit zero prompt contribution so far [1–5], contrary to theory [6, 7]. In this analysis we tried to measure this prompt atmospheric flux in muon neutrino event data from different IceCube releases. In contrast to past studies we performed a binned least-squares fit of the conventional atmospheric flux from data at low energies and subtracted this fit and an astrophysical flux reported by IceCube to measure a prompt contribution. Due to a lack of statistics and accessible information from data releases, our results are also compatible with a zero prompt contribution.

Training simulators are valuable tools in education of forest machine operators. One important part of the education is to learn about damages occurring due to the forest machines and how they can be avoided. Two types of damages are especially severe, soil compaction and formation of wheel ruts. Compaction reduces the amount of water and nutrients in the soil, and impedes root growth. Furthermore, water is gathered in wheel ruts, leading to transport of organic materia and heavy metals into water courses. These damages can be avoided through planning of the harvesting activities with respect to season, weather, and the conditions on the site. The main focus point is to avoid driving on wet soil, since wetness makes it more susceptible to damage.  The aim of this thesis is to investigate how this should be incorporated in a simulator. Implementations are made in Unreal Engine with AGX Dynamics for Unreal, which already has a deformable terrain called AGX Terrain. This terrain was investigated by creating two terrain materials, representing dry and wet Swedish forest soil, and driving a forwarder on them.  AGX Terrain was found to be simple to use and gave fair results, the rut depths were comparable in size with empirical results. However, it was limited in the sense that shearing was not taken into account and there was no possibility of having different material properties across the terrain. A potential solution to these problems is suggested, in which a more extensive way of computing stress propagation and the resulting damages is used. Further investigations has to be made in order to find out if this approach is of good use.

Background One of the most used treatments for hyperthyroidism, is therapy with radioactive iodine (131I), which is accumulated in the thyroid gland. To determine the activity of 131I to be administered for a certain absorbed dose, the volume of the gland is of great importance but the historically used methods for estimating the functional volume of the gland are based on large approximations. The use of SPECT images enables increased accuracy of functional volume determination. However, there is a need for more realistic phantom studies and improved image segmentation. Aim The aim of this thesis was to find a robust method for image segmentation of the thyroid gland that could adapt to various object sizes and contrasts. The aim was also to develop an accessible and flexible 3D thyroid phantom for measurements and optimisation of parameter settings. Materials and Methods Thyroid phantoms made from playdough loaded with 99mTcO4-, were placed in a neck phantom filled with 99mTcO4- solution of various concentration. SPECT and CT acquisitions of the phantoms were performed and the SPECT images were segmented using thresholding and region growing algorithms. The thresholds in the segmentation algorithms were optimised by minimisation of cost functions consisting of Dice score, against the CT-volume, and relative SPECT volume. To find thresholds that could be used on all phantom volumes and image backgrounds, two overall cost functions were optimised for high and low backgrounds respectively. The optimised thresholds were validated on another set of playdough phantoms. They were also used on a simpler plastic can phantom for comparison of the performance relative to the method used in the clinic today. Results The optimised thresholds showed a substantial divergence between the measurements, ranging from 40 to 58 % for the thresholding algorithm and from 8 to 19 % for the region growing algorithm. The overall optimised thresholds were 55 and 48 % for high and low image backgrounds for the thresholding algorithm which was selected for the validation measurements due to its lower overall cost function and high stability. The developed method indicated a higher accuracy in functional volume determination of the thyroid gland than the standard method used. Conclusions An image segmentation method for functional volume determination of the thyroid gland, that can adapt to image contrast, was developed in this thesis. The method indicates an improved accuracy for functional volume determination of thyroid glands, but more experiments would need to be conducted. The developed thyroid phantoms enable further optimisation of image segmentation parameters for various object sizes, contrasts and shapes. The results indicate that thresholds deduced from simpler phantoms may be too uncertain which might lead to overtreatment of hyperthyroidism with 131I. It was also indicated that thresholding is more suitable than region growing for image segmentation of SPECT images.

This report provides a new theoretical measure for the nonlocality of an arbitrary three-qubit pure state system similar to the method used to describe tripartite entanglement, resulting in a concept referred to as residual nonlocality, η. This report also investigates the special cases that can be encountered when using η. This method assigns a numerical value between 0 and 1 in order to indicate the degree of nonlocality between three-qubits. It was discovered that η has the characteristic of being consistently larger or equal to the value found for the residual entanglement which can provide further insights regarding the relation between nonlocality and entanglement. / I rapporten föreslås och analyseras ett nytt teoretisk mått för ickelokalitet hos tre-kvantbitsystem på ett liknande sätt till metoden som används för tredelad sammanflätningar. Detta ger en koncept som vi har valt att benämna residual ickelokalitet η. Rapporten undersöker också specialfall som kan påträffas när man använder η. Metoden som läggs fram i rapporten ger ett numeriskt värde mellan 0 och 1 för att visa graden av ickelokalitet mellan kvantbitarna. Vår undersökning visar att η kommer under alla sammanhang vara större eller lika med den graden av tredelad sammanflätning i samma system vilket kan ge en bättre förståelse av relationen mellan sammanflätning och ickelokalitet.

The goal of this thesis is to, on behalf of JB Eco Tech, investigate a novel method of interconnecting photovoltaic (PV) modules. The principle is to stick the interconnecting strings on the cells with a transparent tape instead of soldering. As a part of the assembly process, the module is laminated under heat which makes the strings stick to the PV cell. The method is going to reduce one step in the production process, replacing the soldering procedure with the lamination of the strings onto the cells. Also, the replacement of lead and silver will spare costs and the environment. To analyse the effects of the novel method on the performance of the cell, the optical properties of the module were investigated by mathematical models and Light Beam Induced Current (LBIC). Also, the electrical properties were compared to the conventional method of soldering by analysing the I-V characteristics. The experiments were done on mini modules. Although the mini module displayed a reflectance of about 5.7 – 6.0% the contribution of the tape only accounted for a maximum of 0.5%. Since the tape only covers a fraction of the cell, this reflectance is negligible. Only 3 modules were successfully analysed, and the electrical properties of the novel method did not differ from the conventional method. To solidify the later a claim a more extensive rapport has to be made. The thesis opens up a new research area where improvements to the novel method can be done. / Det här examensarbetet är gjort på uppdrag av JB Eco Tech. De har utvecklat en ny metod i produktionen av solcells moduler. Syftet med studien är att undersöka metoden som baseras på att fästa transparant tejp med en belagd koppartråd på solcellerna istället för den konventionella metoden som använder sig av lödning. Metoden kommer att reducera ett steg i produktionskedjan genom att utesluta lödningsprocessen. Processen kommer också bidra till en minskning i användandet av silver och bly vilket bidrar till en reducerad kostnad och en minskad miljöpåverkan. För att analysera effekterna av prestandan till följd av den nya metoden så analyserades de optiska egenskaperna med hjälp av matematiska modeller och Light Beam Induced Current (LBIC). De elektriska egenskaperna hos solcells modulerna jämfördes med den konventionella metoden som involverar lödning genom att analysera I-V karakteristiken för de båda metoderna. De ovannämnda experimenten utfördes på miniatyr moduler. Resultaten som erhållits visade på att modulerna hade en reflektans av 5.7 – 6.0% och att tejpen endast stod för max 0.5%. Tejpen täcker endast en bråkdel av cellen därför går det att konstatera att reflektansen som härstammar från tejpen är försumbar. Det innebar att de optiska egenskaperna inte bidrog till en signifikant påverkan på prestandan av modulerna. De elektriska egenskaperna av modulerna påvisade ingen signifikant skillnad mellan de två olika metoderna. För att säkerställa det senare antagandet krävs en utökad studie inom området. Studien har öppnat upp för nya rön som grundas på den nya metoden där det finns utrymme för förbättringar av tejpen.

This exploratory case study aimed to investigate patterns in student reasoning in statistical mechanics, in order to identify difficulties and develop ideas for future research. Upper-division undergraduate students, taking a course in statistical mechanics, were interviewed in groups. Here we present our findings regarding student difficulties in distinguishing microstates and macrostates, as well as distinguishable versus indistinguishable particles. We also present observed patterns of student reasoning about a simple, discrete system in contact with a heat bath. Our findings reveal problematic student intuitions of the high temperature limit. Several students were, however, able to transfer knowledge from a similar problem involving spin to improve their reasoning. / Denna explorativa fallstudie ämnade att undersöka mönster i studenters resonemang i statistisk mekanik, för att identifiera svårigheter och utveckla idéer för framtida forskning. Studenter i sista året på kandidatprogrammet i fysik, som läste en kurs i statistisk mekanik, intervjuades i grupper. Här presenterar vi våra fynd gällande studenters svårigheter med att skilja på mikrotillstånd och makrotillstånd, såväl som urskiljbara och ourskiljbara partiklar. Vi presenterar också observerade mönster i studenters resonemang kring ett simpelt, diskret system i kontakt med en värmereservoar. Våra fynd avslöjar problematiska intuitioner för gränsvärdet vid hög temperatur. Flera studenter kunde dock överföra kunskap från ett liknande problem, som handlade om spin, för att förbättra deras resonemang.

Due to the complex nature of phase interfaces, acquiring precise interfacial energies is usually a big challenge for both experimental measurements and computational modelings. In this thesis, we put forward an efficient route for assessing the temperature dependence of the interfacial energy using density functional theory (DFT). For our investigations, we select the Cu-Co binary system as a model with large miscibility gap. Most of the first-principles calculations presented here are carried out using the exact muffin-tin orbitals (EMTO) method in combination with the coherent potential approximation (CPA), but other alternative DFT methods are also included in the various stages of the project.The first step is to acquire an accurate thermodynamical description of the Cu-Co binary system. We assess the quality of the predicted thermodynamic properties by an effort to reproduce the phase diagram for the entire range of composition using first-principles calculations and alloy theory. The calculations are performed for the random Cu-Co alloys with face-centered cubic (fcc) structure at both ferromagnetic (FM) and paramagnetic (PM) states, depending on the composition. We demonstrate that the equilibrium volumes and magnetic states are crucial for the proper description of the magnetic entropy of the Cu-Co system at elevated temperatures. More specifically, the contribution of magnetic entropy to the free energy in the Cu-rich region obtained for the PM state turns out to be critical. Furthermore, the adopted equilibrium volumes strongly affect the contribution of the vibrational entropy to the free energy. When all effects are properly accounted for, we find that the ab initio phase diagram of the Cu-Co system agrees well with the Thermo-Calc phase diagram and the experimental observations.The Cu-Co system has a large miscibility gap. The interface between the decomposed Cu-rich and Co-rich phases plays critical roles in the precipitation nucleation and growth, therefore having huge effects on the physical and mechanical properties of the alloys. Therefore, adopting the thermodynamical properties of the bulk Cu-Co alloys successfully obtained by our ab initio calculations, we go further and investigate the interfacial properties of the Cu-Co alloys using a coherent interface model. The chemical, magnetic, and strain energy contributions to the formation energy of the interfaces are analyzed separately. We find that the chemical interfacial energies generally decrease with increasing concentrations, namely when the compositions accross the interface become more homogenous. We identify a sizable contribution to the interfacial energies from the magnetic effects. The temperature dependence of the interfacial energy is estimated, to the first-order approximation, through considering how the equilibrium compositions of the two phases vary at different temperatures. Our results show that the temperature dependence of the interfacial energy originates primarily from the temperature-induced increase of the mutual solubility of the alloy constituents and the loss of the magnetic long range order near the Curie temperature. Our ab initio results are compared with the experimental data as well as with those extracted from Thermo-Calc modeling. The present thesis provides an atomic-level description of the bulk and interfacial properties of the Cu-Co binary system using quantum mechanics simulations. This approach is believed to be useful for a complete thermodynamical description of other similar immiscible alloy systems as well from first-principles. / På grund av fasgränssnittens komplexa karaktär är det vanligtvis en stor utmaning att få exakta gränssnittsenergier för både experimentella mätningar och beräkningsmodeller. I denna avhandling presenterar vi en effektiv väg för att bedöma temperaturberoendet för gränssnittsenergin med hjälp av densitetsfunktionell teori (DFT) i ett modellsystem, Cu-Co-legeringar. Våra första principberäkningar är baserade på den exakta muffins-tennorbitalmetoden (EMTO) i kombination med den koherenta potential-approximationen (CPA).Det första steget är att skaffa en noggrann termodynamisk beskrivning för det binära systemet. Vi bedömer kvaliteten på de förutsagda termodynamiska egenskaperna genom ett försök att reproducera fasdiagrammet för hela kompositionen med hjälp av första principberäkningar och legeringsteori. Beräkningarna utförs för de slumpmässiga Cu-Co-legeringarna med ansiktscentrerad kubisk (fcc) struktur vid både ferromagnetiska (FM) och paramagnetiska (PM) tillstånd, beroende på sammansättningen. Vi visar att jämviktsvolymer och magnetiska tillstånd är avgörande för en korrekt beskrivning av den magnetiska entropin i Cu-Co-systemet vid förhöjda temperaturer. Närmare bestämt visar sig den magnetiska entropins bidrag till den fria energin i den Cu-rika regionen som erhålls vid PM-tillståndet vara kritisk. Vidare påverkar de antagna jämviktsvolymerna starkt vibrationsentropins bidrag till den fria energin. När alla effekter är korrekt redovisade kommer vi fram till att ab initio fasdiagrammet för Cu-Co-systemet överensstämmer väl med experimentellt resultat.Cu-Co-systemet har ett stort blandningsgap. Gränssnittet mellan de sönderdelade Cu-rika och Co-rika faserna spelar en avgörande roll för nederbördskärnbildning och tillväxt och har därför enorma effekter på legeringarnas fysiska och mekaniska egenskaper. Här, med de termodynamiska egenskaperna hos bulk-Cu-Co-legeringarna framgångsrikt erhållna med våra ab initio-tillvägagångssätt, går vi vidare och undersöker gränssnittsegenskaperna för Cu-Co-legeringarna med en koherent gränssnittsmodell. De kemiska, magnetiska och stamenergibidragen till gränssnittets bildningsenergi analyseras separat. Vi finner att de kemiska gränssnittsenergierna generellt minskar med ökande koncentrationer, nämligen när kompositionerna över gränssnittet blir mer homogena. Vi identifierar ett betydande bidrag till gränssnittsenergierna från de magnetiska effekterna. Temperaturberoendet för gränssnittsenergin uppskattas, till första ordningens approximation, genom att överväga hur jämviktskompositionerna i de två faserna varierar vid olika temperaturer. Våra resultat visar att temperaturberoendet för gränssnittsenergin främst härrör från den temperaturinducerade ökningen av legeringskomponenternas ömsesidiga löslighet och förlusten av magnetisk långdistansordning nära Curie-temperaturen. Våra ab initio resultat jämförs med experimentella data såväl som med de som extraherats från Thermo-Calc-modellering.Föreliggande avhandling ger en atomnivåbeskrivning av bulk- och gränssnittsegenskaper hos Cu-Co-binära systemet med hjälp av kvantemekaniska simuleringar, vilket antas vara användbart för en fullständig termodynamisk beskrivning av liknande icke-blandbara legeringssystem med exakta initieringsmetoder.

Quantum computers are being developed to solve certain problems faster than classical computers. Instead of using classical bits, they use quantum bits (qubits) that utilize quantum effects. At Chalmers University of Technology, researchers have already built a quantum chip consisting of two superconducting transmon qubits and are trying to build systems with more qubits. To assist in that process, they make numerical simulations of the quantum systems. However, these simulations face an intrinsic computational limitation: the Hilbert space of the system grows exponentially with the number of qubits. In order to mitigate the problem: the simulations should be made as efficient as possible, by applying certain approximations, while still obtaining accurate results. The aim of this project is to compare several of these approximations, to see how accurate they are and how fast they run on a classical computer. This is done by modelling the qubits as quantum anharmonic oscillators and testing several cases: varying the energy levels of the qubits, increasing the number of qubits, and testing the rotating-wave approximation (RWA). These cases were tested by implementing two-qubit gates on the system. The simulations were all made using the Python library QuTiP. The results show that one should simulate using at least one energy level higher than the maximum energy level required for the gate to function. For larger systems, the RWA will make a big difference in simulation times, while still giving relatively accurate results. When using the RWA, the number of levels used does not seem to affect the results significantly and one could therefore use the lowest possible energy levels that can simulate the system.

In this essay, we have investigated how students in year 2 of primary school understand, perceive and think about the phenomenon of gravity. We have used semi-structured interviews, individually and in pairs, and let the students make their thoughts visible with graphic representation in the form of drawn arrows before and after a practical activity. The current syllabus states that students at the end of year 3 should be able to talk about the phenomenon of gravity (Skolverket, 2019). The results from our study show that students in the early years of primary school have varying perceptions and understandings of gravity. It is not uncommon for students to have misconceptions about such an abstract physical phenomenon as gravity. Our study has shown that students' graphic representation reflects and clarifies students' understanding of gravity. Furthermore, the study confirms that all students who participated in the study can talk about gravity, but that a couple of students needed supportive teaching first. Another result is that students' graphical representation of gravity follows movement direction. We want to recommend teachers of younger students in primary school to emphasize and talk about concepts in physics. We also recommend to use semiotic resources such as drawing arrows and artifacts, in our study we used a solder, to make the phenomenon of gravity visible and thus improve students' understanding. The essay was conducted at a primary school in a medium-sized city in Sweden. The participants were 12 students, divided into 6 couples, who participated after we received the parents' and students' consent. / I det här examensarbetet har vi undersökt hur elever i grundskolans årskurs 2 förstår, uppfattar och tänker om fenomenet tyngdkraft. Vi har använt semistrukturerade intervjuer, individuellt och parvis, samt låtit eleverna synliggöra sina tankar med grafisk representation i form av ritade pilar före och efter laborativ undervisning. Aktuell kursplan säger att elever i slutet av årskurs 3 ska kunna samtala om fenomenet tyngdkraft. Av resultatet från vår studie framgår att elever i grundskolans tidiga år har varierande uppfattning och förståelse om tyngdkraft. Det är inte ovanligt att eleverna har felaktiga föreställningar eller missuppfattningar om ett, för yngre elever, så abstrakt fysikaliskt fenomen som tyngdkraft. Det har i vår studie visats sig att elevers grafiska representation speglar och förtydligar elevernas förståelse av tyngdkraft. Vidare bekräftar studien att alla elever som deltagit i studien kan samtala om tyngdkraft men att ett par elever behövde stödjande undervisning först. Ytterligare ett resultat är att eleverna genomgående ritar tyngdkraftens riktning pilar, åt samma håll som föremålets rörelseriktning. Vi vill rekommendera lärare till yngre elever i grundskolan att lyfta och samtala om begrepp inom fysiken och nyttja semiotiska resurser som ritade pilar och artefakt, i vår studie använde vi ett lod, för att synliggöra fenomenet tyngdkraft och på så sätt förbättra elevernas förståelse. Undersökningen genomfördes på en grundskola i en medelstor stad i Sverige. Deltagarna var 12 elever, indelade i 6 par, som deltog efter att vi fått föräldrarnas och elevernas medgivande.

The radiotherapy clinics in Sweden have been without a functioning national platform consisting of dose data from patients undergoing radiotherapy. A national collaboration between clinics will improve the quality of radiotherapy since clinics will be able to compare dose data from treatment plans between clinics. It will also help and improve future researches in radiotherapy. A new national quality registry for radiotherapy in Sweden is under development and is located on the INCA platform. The aim of this study is to do a quality assurance of the INCA registry. The data stored in the registry are calculated from the treatment plans stored locally at the clinics. The quality assurance of the registry is done by creating a program run by Python code and by using Streamlit as the graphical user interface. The program takes dose and volume data from the dose volume histograms located in treatment plans from the INCA database and compares it with the dose and volume data from the local clinics' treatment planning system. The different treatment planning systems considered in the program are Oncentra(Elekta, Sweden), Eclipse(Varian, U.S.), RayStation(RaySearch Laboratories, Sweden) and Monaco(Electa, Sweden). The compared absorbed doses are the dose to 99% of the structure volume(D99%), D98%, D50%, D2% and D1%. The program generates how much the INCA data differs from the TPS data in percent and is named QARS(Quality Assurance of the Radiotherapy Database in Sweden). A verification of the created program and a preliminary evaluation is done on a limited dataset containing three patient groups(prostate patients, lung patients and head and neck patients) with five patients in each group. The dataset is run through the program with patient data from both Oncentra and Eclipse. The result indicates that all the near-maximum doses, D2% and D1% in INCA are very close to their corresponding TPS dose. There is a more noticeable difference in the near-minimum doses, D99% and D98% but also for some D50% where the difference seems to increase in larger structure volumes with very low doses and in very small structure volumes, smaller than 0.01 cm3. It is compared how well INCA agrees with Oncentra and Eclipse respectively and it is clear that Eclipse has a smaller difference to INCA than Oncentra for structures with very small volumes and larger structures with low doses. To summarise the study, it generates a program for quality assurance of the national quality registry for radiotherapy in Sweden which hopefully can help improve the quality of radiotherapy and help future researches in the field.