Gromov-Witten invariants play a crucial role in symplectic- and enumerative Geometry as well as topological String Theory. Essentially, theseinvariants are a count of (pseudo)holomorphic curves of a given genus,going through n-marked points on a symplectic manifold. In the last fewdecades, this has been a huge research topic for both physicists as well asmathematicians, and breakthroughs in calculation techniques have beenmade using Mirror Symmetry. We investigate and explicitly calculateclosed genus zero Gromov-Witten invariants of toric Calabi-Yau threefolds, namely O(−3) → P2 and the resolved conifold. This will be doneby using localization techniques, mirror symmetry and the so called diskpartition function.

Superconformal field theories (SCFTs) are an important class of quantum field theories. These SCFTs have been a significant component in exploring and comprehending the fundamental framework of quantum field theories. In the vast realm of quantum field theories, integrability plays a crucial role, providing powerful analytic tools that allow us to solve certain physical quantities exactly. In this thesis, we focus on the representation theory of the algebraic structure in six-dimensional (6D) SCFTs and investigate the intricate interplay between 6D SCFTs and integrability. To begin, we delve into the fundamental concepts of representation theory, establishing a solid foundation for our subsequent analysis. The discussion then will move on to all possible generators in the SCFTs, explaining how they are realized in terms of bosonic and fermionic oscillators. Finally, we investigate spin chains and their application in 6D SCFTs. We demonstrate that symmetry arguments derived from representation theory are not sufficient to establish the integrability of the spin chains in 6D SCFTs. This conclusion does not imply the absence of integrable systems within 6D SCFTs; rather, it suggest there are other potential methods available e.g., correlation functions, to explore the appearance of integrable systems in 6D SCFTs. / Superkonforma fältteorier (SCFTs) är en viktig klass av kvantfältteorier. Dessa SCFTs utgör en viktig komponent för att utforska och förstå det fundamentala ramverket för kvantfältteorin. Inom det stora riket av kvantfältteori spelar integrabilitet en avgörande roll, vilket tillhandahåller kraftfulla analytiska verktyg som gör att vi kan lösa vissa fysiska storheter exakt. I denna avhandling fokuserar vi på representationsteorin av den algebraiska strukturen i sexdimensionella (6D) SCFTs och undersöker det intrikat samspelet mellan 6D SCFTs och integrabilitet. Till att börja med kommer vi att fördjupa oss i de grundläggande begreppen inom representationsteori och skapa en gedigen grund för vår efterföljande analys.  Diskussionen kommer sedan att gå vidare till alla möjliga generatorer i SCFTs, och förklarar hur de realiseras i termer av bosoniska och fermioniska oscillatorer. Slutligen kommer spinnkedjor och dess tillämpningar i 6D SCFTs att undersökas. Vi kommer visa att symmetriargument som härleds från representationsteori inte är  tillräckliga för att fastställa integrerbarhet av spinnkedjor i 6D SCFTs. Denna slutsats innebär inte att integrerbara system inte existerar inom 6D SCFTs, utan föreslår att det finns andra potentiella metoder, till exempel korrelationsfunktioner, för att utforska existensen av integrerbara system i 6D SCFTs.

Nanoelectronics is a field undergoing rapid development, meaning knowledge of the materials and methods used in nano-scale systems is a driving force in the industry. Silicon is a well known material in nanoelectronics commonly used as a semiconductor and is therefore a good representative for nanomaterials in general. In this thesis work the effects of the helium and neon ions with the energies 100 keV and 200 keV respectively on surface contaminants and the bulk material of nanometer thick silicon membranes are being studied. Beyond interactions based on different incident ions, the effects are studied inboth the geometries of transmission and backscattering, giving information about the immediate effects on the surface, as well as bulk effects. Using Medium Energy Ion Scattering (MEIS), the positively charged particles on the surfaces and in the bulk of the materials, which are either sputtered or desorbed, can be detected. While the ions are different, the energies in this work are chosen to be such, that the electronic stopping power is the same, while the nuclear stopping of neon is vastly higher. From this work, it is concluded that both ions have the same qualitative effects on the membrane contaminants, consisting of hydrocarbons, which are desorbed electronically. Furthermore, neon has the effect of destructively sputtering the bulk material. A synergistic effect of electronic and nuclear deposition was also found, as quantitatively, more hydrocarbons per incident Ne+ ion were desorbed than per incident He+ ion. The change in effect based on different geometries can to a large extent be attributed to the energy loss of the ions in the material. The one change between geometries which can not be explained by energy loss in the material, is a 50% under representation of desorbed hydrogen ions in transmission geometryfor He+ incident ion. It is also concluded that the method used has the potential to be a viable, non-destructive and scalable cleaning and measuring method for contaminations on nano-scale materials, such as 2 dimensional materials. / Nanoelektronik är ett område under snabb utveckling, vilket gör kunskap kring de material som bygger upp elektroniken drivande i utvecklingen av teknologin. Kisel är ett välkänt material inom nanoteknologin då det är välanvänt som halvledare, vilket gör det till en bra representant för en mängd andra nanomaterial. I detta examensarbete undersöks de effekter som 100 keV helium- och 200 keV neonjoner har på ytföroreningar och bulkmaterial av kiselmembran i nanometertjocklek. Utöver olika jonslag undersöks även skillnaderna mellan membranets geometri i transmission och backåtspridning. Detta ger information, både om de direkta effekterna som jonerna har på materialets bestrålade yta, samt effekterna på den motsatta ytan. Genom användningen av ”Medium Energy Ion Scattering” (MEIS) kan de positivt laddade partiklarna på ytan och i bulkmaterialet, som genom elektronisk och nukleär växelverkan bryts läs, utforskas. Partiklarnas energier har valts så att den elektroniska bromsförmågan är densamma för de två partiklarna, medan den nukleära bromsförmågan skiljer sig kraftigt. Från detta arbete kan slutsatsen dras att båda joner har samma kvalitativa effekt på kiselmembranets föroreningar i form av kolväten. Dock har neon en betydlig nukleär, destruktiv effekt på bulkmaterialet. En synergistisk effekt har också kvantitativt observerats, där de elektroniska effekterna på kolväten är högre för neonjoner. De förändringar som påvisades i de olika geometrierna kan i stort förklaras av energiförlust av jonerna under passagen genom membranet. Den geometribaserade differens som inte följer förklaringen energiförlust är desorberat väte, vilket är 50 % mindre i transmissionsgeometri för heliumjoner. Den andra slutsatsen som kan dras från detta arbete är att den använda metoden har potentialen att utvecklas till en icke-destruktiv och skalbar metod för rengöring och mätning av föroreningar på nanomembran så som 2 dimensionella material.

This thesis explores and develops a simulation model for Line of Sight(LoS) Multiple-Input Multiple-Output (MIMO) systems in complex environments. The focus will be on implementing a 2 × 2-MIMO system in order to study phase differences of the received signals. The propagation of the electromagnetic waves is based on an existing wave propagation model that uses the parabolic equation approach. This work aims to deepen our understanding of a 2 × 2-MIMO systems’ behavior under various conditions, including free space propagation but also standard atmospheric and ducting environments. The results demonstrate that the parabolic equation method aligns well with theoretical expectations, validating its use for modeling MIMO systems.The findings have significant implications for optimizing the design and operation of wireless communication systems. The thesis also outlines potential future work, including empirical model verification, development of alternative models, and extension to more complex MIMO systems.

No description available.

In this master thesis we investigate implications of the Domain-Wall/Cosmology (DW/C) correspondence on one-point functions of holographic RG-flows. The thesis gives a detailed computation of linearized gauge-invariant Einstein equations in (d+1) dimensions while making the DW/C correspondence explicit. Although holographic renormalization has previously been studied on Lorentzian manifolds, we extend its study to Lorentzian domain-wall solutions with a parameter η. This parameter is introduced to easily travel from domain-walls to cosmologies in the context of the DW/C correspondence. We present the calculation of the vacuum expectation value of general scalar boundary operators of conformal weight Δ dual to a (d+1)-dimensional bulk theory, while still making the DW/C correspondence appear explicitly. Finally, we study the application of these results to holographic RG-flow solutions. In particular, the GPPZ solution is investigated in the framework of the thesis. We find that the vacuum expectation value of the scalar field is invariant under the domain-wall/cosmology correspondence.

In a celebrated series of experimental observations, starling flocks have been shown to be characterized by scale-free, long-ranged spatial correlations in their velocity fluctuations. While this is expected for velocity orientation correlations on the basis of simple symmetry-breaking arguments, the same scaling-free behaviour for speed (i.e. the absolute value of birds’ velocity) correlations cannot be explained by the same symmetry-based argument. Possible explanations so far put forward required the implicit or explicit fine-tuning of a speed control parameter. In this work we explore a different possibility, investigating the effects of the experimental discrete temporal sampling of individual bird trajectories. We argue that observed velocity may well be a time coarse-grained observable, that is, the sum over many faster course corrections taken by the bird. A simple argument shows such a time coarse-grained speed to be linked with the squared fluctuations of (soft modes) transversal velocities, which may thus acquire a long-range correlation. Our idea is numerically tested by measuring spatial correlations between coarse-grained speeds in the on-lattice equilibrium XY model and the off-lattice out-of-equilibrium Vicsek model in two dimensions. Saturation of the speed correlation length is found in the equilibrium XY model, while in the non-equilibrium Vicsek model ordered symmetry-broken phase shows scale-free behaviour with a correlation length ξ is found to be proportional to system size L. We conclude that in non-equilibrium flocking models, the temporal coarse-graining procedure is able to reproduce scale-free behaviour at system sizes which are relevant to the experimental observations. We believe that this mechanism might find applications beyond the case of starling flocks and perhaps be relevant for other experimental observations of collective motion.

Water contamination through substances called per- and polyfluoroalkyl substances (PFAS) is a worldwide problem. Being able to measure the concentrations of PFAS in water is a first step towards beating this contamination. One alternative is to use a field test kit instead of extensive lab equipment to monitor the contaminated areas. This thesis has investigated the possibility of using amine-functionalized mesoporous carbon as adsorbent to develop a detection method based on adsorbing first PFAS and then dye in aqueous solutions. The non-adsorbed dye concentrations are depending on the amount of PFAS, and hence the colour intensity in the remaining solution is proportional to PFAS concentration. Mesoporous carbon with amine functional groups were chosen as specific adsorbents for PFAS because of its large surface area and high adsorption capacity. It has been shown that some colorants would react in a similar way as PFAS on sorbents and thus can be used as an indicator for the user. In the study, the two most common PFAS, PFOA and PFOS, were studied and Rose Bengal was the dye. The adsorbent’s morphology, pore structure and pore size was verified with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen sorption before being tested. Adsorption tests were performed using different PFAS concentrations and a dye solution range in order to find three things: the detection range, the ratio powder/solution in order to see a difference, and the adsorption or saturation time for both PFAS and dye. This thesis concluded that even though the adsorbent was not as efficient as predicted, this method could be used for detecting PFAS concentrations down to at least 0.1 pg/ml and could be a possible approach for quick field tests in the future.

This thesis is about thwo papers related to extra dimensions. Paper A discusses extrinsic curvature effects, and paper B treats symmetries of supersymmetric membranes. In the part of this thesis related to paper A, we extend the theory of non-relativistic quantum particles confined to submanifolds to relativistic boson fields. We show that a Klein-Gordon field constrained to a submanifold of a Lorentzian manifold experiences an induced potential similar to the one for the Schr{\"o}dinger equation. We embedd the Schwarzschild solution and the Robertson-Walker space-time and derive the induced potentials. Possible physical consequences of these induced potentials are also discussed. The second part is related to paper B, we study the dynamics of supersymmetric membranes, which are higher dimensional generalizations of supersymmetric strings. We derive a supersymmetric analogue of a dynamical symmetry for bosonic membranes. / QC 20110427

Special relativity is a subject that attracts interest among students, but there are many things that make students experience it as difficult. As a physics teacher, it is important to both have a solid base of knowledge in physics as well as educational knowledge within the subject. You need to know what students usually struggle with, which parts to focus on to give the students a good understanding of physics, et cetera. This project is a literature study that examines special relativity in four parts. The first part of the project is a historical description of special relativity, summarizing how researchers have concluded the theory of special relativity. It consists of a series of experiments and hypotheses before Einstein tied everything together with his theory of special relativity. Then the central ideas of special relativity are described, with a focus on exercises that describe relativistic phenomena. The ideas covered in this second part are the relativity of simultaneity, time dilation, length contraction and mass and energy equivalence. The third part consists of a summary of current educational research to explore different ways to teach special relativity, according to the educational research. Many students make up their own explanations when presented with a relativistic phenomenon, that matches their Newtonian view in mechanics. It is a challenge to get students to think in a new relativistic way. A common difficulty is to move between different reference systems, which is necessary since relativistic phenomena in movement is only visible when looking at the same movement from different reference system. For the last part of the project, the Swedish curriculum and Swedish textbooks are examined. The section on relativity often begins with what students struggle most with, moving between frames of reference. Before introducing special relativity, it is useful to practice switching between different reference systems in classical mechanics, using Galilean transformations and relative motion. Another idea might be to introduce special relativity with, for example, the equivalence in mass and energy, where students do not encounter the problem with reference systems. / Speciell relativitetsteori är något som väcker nyfikenhet hos elever, men det finns mycket som gör att eleverna upplever det som svårt. Som lärare är det viktigt att ha en gedigen ämneskunskap och mycket didaktisk kunskap. Man måste ha koll på vad eleverna brukar ha svårt för, vilka delar man bör fokusera på för att eleverna ska få en bra grund, med mera. Det här projektet är en litteraturstudie som undersöker speciell relativitetsteori i gymnasieskolan i fyra delar. Första delen i projektet är en historisk beskrivning av speciell relativitetsteori, hur forskare har kommit fram till den speciella relativitetsteorin. Historiebeskrivningen består av en serie experiment och hypoteser innan Einstein knöt ihop säcken med den speciella relativitetsteorin. Sedan beskrivs de centrala idéerna inom relativitetsteori, med fokus på många exempel som beskriver relativistiska fenomen. De delar som behandlas i det här projektet är relativiteten i simultanitet, tidsdilatation, längdkontraktion samt massa- och energiekvivalens. Den tredje delen består av en sammanfattning av modern fysikdidaktisk forskning, för att ta reda på hur man kan undervisa forskningsbaserat inom speciell relativitet. Elever skapar ofta egna förklaringar till relativistiska fenomen, som stämmer bättre överens med en Newtonsk uppfattning. Att få eleverna till ett nytt relativistiskt tankesätt är en utmaning. Det som elever främst har svårt med är att gå mellan olika referenssystem, vilket är nödvändigt för att uppfatta relativistiska fenomen inom rörelse. Till sist undersöks den svenska läroplanen och svenska läroböcker. Ofta börjar avsnittet om relativitetsteori med det elever har som svårast för, att gå mellan olika referenssystem. Innan speciell relativitetsteori introduceras är det bra att öva att gå mellan olika referenssystem inom klassisk mekanik, arbeta med relativ rörelse och Galileitransformationer. En annan idé kan vara att introducera speciell relativitetsteori med till exempel ekvivalensen i massa- och energi, där eleverna inte stöter på det problemet.