Durch die Vielzahl von heterogenen Informationsquellen sehen sich viele Nutzer einer kaum überschaubaren Informationsflut gegenüber. Aus diesem Grund werden durch diese Arbeit die gängigen Nachrichtenformate analysiert und der aktuelle Stand der Technik im Bereich der Nachrichtenaggregatoren dargelegt. Dabei werden diese Analysen immer mit Blick auf die Möglichkeiten einer personalisierten Filterung der Inhalte durchgeführt. Anschließend wird eine im Rahmen dieser Arbeit entstandene Infrastruktur für die Aggregation, personalisierte Filterung und kollaborative Empfehlung von Inhalten aus heterogenen Nachrichtenquellen vorgestellt. Dabei wird detailiert auf die zu Grunde liegenden Konzepte eingegangen und deren praktische Umsetzung beschrieben.

My dissertation treats the physics of ultracold gases, in particular of Bose-Einstein condensates with long-ranged interactions induced by admixing a small fraction of a Rydberg state to the atomic ground state. The resulting interaction leads to the emergence of supersolid states and to the self-trapping of a Bose-Einstein condensate.

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In view of the potential presented by information and communication technologies, this study discusses access to the photographic archives of the Historical Archive of Santa Maria using the ICA-AtoM (International Council of Archives - Access to Memory) tool available on the world wide computers, based on theoretical criteria for archival description and access to digital documents. The proposed activities are discussed from preparing the documentation to the final presentation of the information to the user. It is a scientific research of an applied nature, exploratory and qualitative approach. The research is divided into five stages: 1) preparation of documentation and literature review, 2) digitization of documents, 3) the ICA-AtoM software installation; 4) description of photographs; and 5) analysis of the results obtained by previous practical activities, in comparison with the recommendations raised in the literature review. The electronic survey instrument is available on the Internet to users in general, containing archival descriptions and the digital representative, based on existing national recommendations. It was found that it is possible to perform digital capture using low-cost, guided by the recommendations of digital preservation. Regarding the software, it was found that there are many features that enrich and facilitate the activity of archival description and presentation of information to the end user. It was concluded that each institution has its own specifications in relation to archival description of the documentary genre and their preferences in the description, however, when compared to commercial solutions, ICA-AtoM software lets you explore enormous potential for a fraction of the cost of proprietary solutions, and guided by the standards of archival description. / Tendo em vista a potencialidade apresentada pelas tecnologias de informação e comunicação, esta pesquisa discute o acesso ao acervo fotográfico do Arquivo Histórico Municipal de Santa Maria a partir do software ICA-AtoM (International Council Archives Access to Memory) disponibilizado na rede mundial de computadores, com base nos critérios teóricos arquivísticos exigidos para descrição e acesso. São discutidas as atividades propostas desde a preparação da documentação até a forma final de apresentação das informações ao usuário. É uma pesquisa científica de natureza aplicada, exploratória e de abordagem qualitativa. A pesquisa é dividida em cinco etapas: 1) preparação da documentação e revisão de literatura; 2) digitalização das fotografias; 3) instalação do software ICA-AtoM; 4) descrição das fotografias e; 5) análise dos resultados obtidos pelas atividades práticas anteriores, em confronto com as recomendações levantadas na revisão de literatura. O instrumento eletrônico de pesquisa estará disponível na internet para os usuários em geral, contendo as descrições arquivísticas e os representantes digitais, tomando por base as recomendações nacionais existentes. Constatou-se que é possível realizar a captura digital utilizando custo baixo e pautado pelas recomendações de preservação digital. Em relação ao software, verificou-se que há muitas funcionalidades que enriquecem e facilitam a atividade de descrição arquivística e apresentação das informações para o usuário final. Concluiu-se que cada instituição tem suas especificidades em relação à descrição arquivística do seu gênero documental e suas preferências na descrição, porém quando comparado com soluções comerciais, o software ICA-AtoM permite explorar enormes potencialidades por uma fração do custo das soluções proprietárias, e pautado pelas normas de descrição arquivística.

This report examines the cross sections of silver microresonators subjected to an incident light with different polarization. The microresonators had different geometries with and without broken symmetries. Cross section profiles for different microresonator configurations are interesting for the division of Material Physics, Uppsala University, when designing metamaterials to tune the optical response of the material. The goal is to form an insight of how the optical response can be tuned by choosing different geometries, varying the size and polarization of the incident light. In this project computer simulations in COMSOL were made to simulate the optical response of different microresonators. When the incident light interact with the silver microresonators plasmonic excitations is generated which in turn interacts with the light changing the phase and therefore the optical response. By increasing the radius of the disk silver microresonantors the resonance was found to shift to lower energies. For a geometry with a disk microresonator inside a ring microresonator the Fano resonances were dependent of the radius of the disk microresonator.

During the past decades, the development of laser technology has produced pulses with increasingly higher peak intensities. These can now be made such that their strength rivals, and even exceeds, the atomic potential at the typical distance of an electron from the nucleus. To understand the induced dynamics, one can not rely on perturbative methods and must instead try to get as close to the full machinery of quantum mechanics as practically possible. With increasing field strength, many exotic interactions such as magnetic, relativistic and higher order electric effects may start to play a significant role. To keep a problem tractable, only those effects that play a non-negligible role should be accounted for. In order to do this, a clear notion of their relative importance as a function of the pulse properties is needed.  In this thesis I study the interaction between atomic hydrogen and super-intense laser pulses, with the specific aim to contribute to the knowledge of the relative importance of different effects. I solve the time-dependent Schrödinger and Dirac equations, and compare the results to reveal relativistic effects. High order electromagnetic multipole effects are accounted for by including spatial variation in the laser pulse. The interaction is first described using minimal coupling. The spatial part of the pulse is accounted for by a series expansion of the vector potential and convergence with respect to the number of expansion terms is carefully checked. A significantly higher demand on the spatial description is found in the relativistic case, and its origin is explained. As a response to this demanding convergence behavior, an alternative interaction form for the relativistic case has been developed and presented. As a guide mark for relativistic effects, I use the classical concept of quiver velocity, vquiv, which is the peak velocity of a free electron in the polarization direction of a monochromatic electromagnetic plane wave that interacts with the electron. Relativistic effects are expected when vquiv reaches a substantial fraction of the speed of light c, and in this thesis I consider cases up to vquiv=0.19c. For the present cases, relativistic effects are found to emerge around vquiv=0.16c .

III-Nitride semiconductors are very promising in both electronics and optical devices. The ability of the III-Nitride semiconductors as light emitters to span the electromagnetic spectrum from deep ultraviolet light, through the entire visible region, and into the infrared part of the spectrum, is a very important feature, making this material very important in the field of light emitting devices. In fact, the blue emission from Indium Gallium Nitride (InGaN), which was awarded the 2014 Nobel Prize in Physics, is the basis of the common and important white light emitting diode (LED). Quantum dots (QDs) have properties that make them very interesting for light emitting devices for a range of different applications, such as the possibility of increasing device efficiency. The spectrally well-defined emission from QDs also allows accurate color reproduction and high-performance communication devices. The small size of QDs, combined with selective area growth allows for an improved display resolution. By control of the polarization direction of QDs, they can be used in more efficient displays as well as in traditional communication devices. The possibility of sending out entangled photon pairs is another QD property of importance for quantum key distribution used for secure communication. QDs can hold different exciton complexes, such as the neutral single exciton, consisting of one electron and one hole, and the biexciton, consisting of two excitons. The integrated PL intensity of the biexciton exhibits a quadratic dependence with respect to the excitation power, as compared to the linear power dependence of the neutral single exciton. The lifetime of the neutral exciton is 880 ps, whereas the biexciton, consisting of twice the number of charge carriers and lacks a dark state, has a considerably shorter lifetime of only 500 ps. The ratio of the lifetimes is an indication that the size of the QD is in the order of the exciton Bohr radius of the InGaN crystal making up these QDs in the InGaN QW. A large part of the studies of this thesis has been focused on InGaN QDs on top of hexagonal Gallium Nitride (GaN) pyramids, selectively grown by Metal Organic Chemical Vapor Deposition (MOCVD). On top of the GaN pyramids, an InGaN layer and a GaN capping layer were grown. From structural and optical investigations, InGaN QDs have been characterized as growing on (0001) facets on truncated GaN pyramids. These QDs exhibit both narrow photoluminescence linewidths and are linearly polarized in directions following the symmetry of the pyramids. In this work, the neutral single exciton, and the more rare negatively charged exciton, have been investigated. At low excitation power, the integrated intensity of the PL peak of the neutral exciton increases linearly with the excitation power. The negatively charged exciton, on the other hand, exhibits a quadratic power dependence, just like that of the biexciton. Upon increasing the temperature, the power dependence of the negatively charged exciton changes to linear, just like the neutral exciton. This change in power dependence is explained in terms of electrons in potential traps close to the QD escaping by thermal excitation, leading to a surplus of electrons in the vicinity of the QD. Consequently, only a single exciton needs to be created by photoexcitation in order to form a negatively charged exciton, while the extra electron is supplied to the QD by thermal excitation. Upon a close inspection of the PL of the neutral exciton, a splitting of the peak of just below 0.4 meV is revealed. There is an observed competition in the integrated intensity between these two peaks, similar to that between an exciton and a biexciton. The high energy peak of this split exciton emission is explained in terms of a remotely charged exciton. This exciton state consists of a neutral single exciton in the QD with an extra electron or hole in close vicinity of the QD, which screens the built-in field in the QD. The InGaN QDs are very small; estimated to be on the order of the exciton Bohr radius of the InGaN crystal, or even smaller. The lifetimes of the neutral exciton and the negatively charged exciton are approximately 320 ps and 130 ps, respectively. The ratio of the lifetimes supports the claim of the QD size being on the order of the exciton Bohr radius or smaller, as is further supported by power dependence results. Under the assumption of a spherical QD, theoretical calculations predict an emission energy shift of 0.7 meV, for a peak at 3.09 eV, due to the built-in field for a QD with a diameter of 1.3 nm, in agreement with the experimental observations. Studying the InGaN QD PL from neutral and charged excitons at elevated temperatures (4 K to 166 K) has revealed that the QDs are surrounded by potential fluctuations that trap charge carriers with an energy of around 20 meV, to be compared with the exciton trapping energy in the QDs of approximately 50 meV. The confinement of electrons close to the QD is predicted to be smaller than for holes, which accounts for the negative charge of the charged exciton, and for the higher probability of capturing free electrons. We have estimated the lifetimes of free electrons and holes in the GaN barrier to be 45 ps and 60 ps, in consistence with excitons forming quickly in the barrier upon photoexcitation and that free electrons and holes get trapped quickly in local potential traps close to the QDs. This analysis also indicates that there is a probability of 35 % to have an electron in the QD between the photoexcitation pulses, in agreement with a lower than quadratic power dependence of the negatively charged exciton. InN is an attractive material due to its infrared emission, for applications such as light emitters for communication purposes, but it is more difficult to grow with high quality and low doping concentration as compared to GaN. QDs with a higher In-composition or even pure InN is an interesting prospect as being a route towards increased quantum confinement and room temperature device operation. For all optical devices, p-type doping is needed. Even nominally undoped InN samples tend to be heavily n-type doped, causing problems to make pn-junctions as needed for LEDs. In our work, we present Mg-doped p-type InN films, which when further increasing the Mg-concentration revert to n-type conductivity. We have focused on the effect of the Mg-doping on the light emission properties of these films. The low Mg doped InN film is inhomogeneous and is observed to contain areas with n-type conductivity, so called n-type pockets in the otherwise p-type InN film. A higher concentration of Mg results in a higher crystalline quality and the disappearance of the n-type pockets. The high crystalline quality has enabled us to determine the binding energy of the Mg dopants to 64 meV. Upon further increase of the Mg concentration, the film reverts to ntype conductivity. The highly Mg doped sample also exhibits a red-shifted emission with features that are interpreted as originating from Zinc-Blende inclusions in the Wurtzite InN crystal, acting as quantum wells. The Mg doping is an important factor in controlling the conductivity of InN, as well as its light emission properties, and ultimately construct InN-based devices. In summary, in this thesis, both pyramidal InGaN QDs and InGaN QDs in a QW have been investigated. Novel discoveries of exciton complexes in these QD systems have been reported. Knowledge has also been gained about the challenging material InN, including a study of the effect of the Mg-doping concentration on the semiconductor crystalline quality and its light emission properties. The outcome of this thesis enriches the knowledge of the III-Nitride semiconductor community, with the long-term objective to improve the device performance of III-Nitride based light emitting devices.

Investigating and mapping fundamental processes in nature is a driving force for breakthroughs in research and technology. Doing so, requires knowledge of the smallest scales of the world. One way of performing measurements on these scales is through intense x-ray sources, which have improved greatly over the last decades. By combing these sources with state of the art optics, even higher flux densities can be reached, allowing for faster measurements and ground-breaking discoveries.  This study aims to explore the performance of polycapillary optics, when aligned to one of the most intense x-ray micro sources in the world, the liquid-metal-jet D2+. Knife edge scans were performed together with a photon-counting medipix x-ray camera to quantify focus properties such as, flux, flux density, transmission, gain and beam width. Measurements were conducted with a 20 μm source spot that was compared to a simulated 200 μm source spot, both at 260 W electron beam power. The data from vertical and horizontal scans were combined to reconstruct the 2D functionality of the polycapillary optic. The flux density were almost four times higher with the 20 μm spot compared to the simulated 200 μm spot. This result correlated with the condition for total external reflection and the local divergence. The conclusion is that the small source spot of the liquid-metal-jet source improves the efficiency of the polycapillary optic.  The efficiency could still be improved, if the deviation in the pointing accuracy could be minimized. Furthermore, the combination of liquid-metal-jet x-ray source and the polycapillary optic, achieved extremely high flux densities. This was specially compared to an x-ray source used for confocal micro XRF, where the flux was almost nine times higher with the liquid-metal-jet x-ray source. This allows for faster measurements within confocal micro XRF and other techniques demanding very high flux densities, but with low demands on beam divergence and spectral purity.

In this licentiate thesis the luminescence properties of two flexible conjugated dyes have been studied. The first, Pt1, is a platinum(II) acetylide chromophore used in optical power limiting materials. The second is a set of optical probes known as luminescent conjugated oligothiophenes (LCOs), which are used to detect and characterize the protein structures associated with amyloid diseases such as Alzheimer’s disease. MM3 and CHARMM force field parameters have been derived for the Pt1 chromophore and LCOs, respectively, based on potential energy surface references calculated at the density functional theory (DFT)/B3LYP level of theory. The parameters have been used to perform room temperature molecular dynamics simulations of the chromophores in solvent, where tetrahydrofuran was used for Pt1 and water for the LCOs. Conformationally averaged absorption spectra were obtained, based on response theory calculations at the time-dependent DFT(TDDFT)/CAM-B3LYP level of theory for a selection of structures from the simulations. For one of the LCOs, p-HTAA, force field parameters were also created describing the dominant first excited state, based on TDDFT/B3LYP reference potential energy surfaces. These were used for molecular dynamics simulations of the chromophore in the excited state, allowing the creation of an emission spectrum. A theoretically obtained Stokes shift of 112 nm could be computed based on the absorption and emission spectra, which is in good agreement with the experimental value of 124 nm. In addition, a quantum mechanics/molecular mechanics study of the effects of solvation on the absorption properties of the p-HTAA chromophore in water has been conducted, resulting in two models for including these effects in the averaged spectra. The first includes explicit water molecules in the form of point charges and polarizable dipole moments, and results in an absorption wavelength that is blueshifted by 2 nm from a high quality reference calculation. The second model involves the complete removal of the solvent as well as the ionic groups of the chromophore. The resulting absorption wavelength is blueshifted by an additional 4 nm as compared to the first model, but requires only one fifth of the computational resources.

The manufacturing of optical components, such as lenses or mirrors, consists of numeroussteps that are essential to the performance of the fnished optical system, such as the specifcation ofthe optical surface. For a longer period, the main focus has been in identifying and restricting thenegative effects of the low and high spatial frequency content of the surface. However, as technologyand optical equipment has become more advanced, the effects of the mid-spatial frequencies havebeen studied more, and continue to be a topic of research. As of now, there is still a need for methodsthat accurately predict and analyse the regime of mid-spatial frequencies, such that they can becontrolled during the specifcation phase, successfully limiting the need of post-processing steps.This work introduces a software tool, specifcally designed to approach this problem, which wasto be developed in Python as a contribution to the existing Optical Scripting Library at OHB. Byspecifying an optical component in terms of a Power Spectral Density function, together with thecontributions from different spatial frequency domains and the application of a ripple patterns, thissoftware tool can generate pseudo-random optical surfaces, which maintains the input specifcations.Furthermore, a Dynamic Link Library fle was developed, sharing the same functionality as thePython implementation, allowing for simulations using Zemax OpticStudio. Using the software tool,it was found that the relative error between input and output measurements were approximately0.78%, in terms of the Power Spectral Density Function. In addition, the result of analysing one of thetwo test cases indicate that the software tool is effective in predicting the infuence of mid-spatialfrequency errors, fulflling a previously measured predicition. The second test case proved that thesoftware tool can be used for mimicing surfaces of real measurements, holding the same specifcations.