>Magister Scientiae - MSc / Next-generation surveys of the large-scale structure of the Universe will be of great importance in allowing us to extract invaluable information about the nature of the Universe and the physical laws that govern it, at a higher precision than previously possible. In particular, they will allow us to more closely study primordial non-Gaussianity, a feature which leaves an imprint on the power spectrum of galaxies on the ultra-large scales and which acts as a powerful probe of the physics of the early Universe. To investigate the extent to which upcoming surveys will be able to improve our knowledge of primordial non-Gaussianity, we perform a forecast to predict the observational constraints on local-type primordial non-Gaussianity, as well as an extension that includes a scale dependence. We study the constraining power of a multi-tracer approach, where information from different surveys is combined to help suppress cosmic variance and break parameter degeneracies. More specifically, we consider the combination of a 21cm intensity mapping survey with each of two different photometric galaxy surveys, and also examine the effect of including CMB lensing as an additional probe. The forecast constraint from a combination of SKA1, a Euclid-like (LSST-like) survey and a CMB Stage 4 lensing experiment is (fNL) ' 0:9 (1:4) which displays a factor of 2 improvement over the case without CMB lensing, indicating that the surveys considered are indeed complementary. The constraints on the running index of the scale-dependent model are forecast as (nNL) ' 0:12 (0:22) from the same combination of surveys.

Grâce à une analyse statistique de l’équation de la Mesure des Interféromètres Radio, un schéma de pondération adaptatif est dérivé,basé sur la qualité de calibration des données d’un instrument interférométrique. Ce schéma est utilisé sur une observation d’un champ extragalactique, l’ExtendedGroth Strip, observation qui contient une source radio-vive (3C295) dans son champ de vue. Cette source est résolue avec LOFAR-VLBI ; un modèle de source est créé afin de calibrer les stations LOFAR internationales. Cela permettra d’imager le champ a une résolution comparable à celle du Hubble Space Telescope, dont des données sont disponibles pour ce champ extragalactique. / By performing a statistical analysis ofthe Radio Interferometer’s MeasurementEquation, we derive adaptivequality-based weighting schemes.These are deployed on an observationof the Extended Groth Strip,which includes a bright 3C sourcein the field of view. This source,which is resolved for LOFAR-VLBI,is modeled and used as a calibratorsource for the Extended Groth Strip.This will allow the field to be imagedwith a resolution matching the HubbleSpace Telescope’s, of which dataare available for this field.

Tvångsåtgärder inom psykiatrisk vård är vanligt förekommande och är ett omdiskuterat ämnei media,såväl som inom vården. Syftet med denna litteraturstudie var att beskriva sjuksköterskans upplevelser beträffande tvångsåtgärder inom psykiatrisk vård. Enkvalitativlitteraturstudie genomfördes med en manifest innehållsanalys, med totalt tio stycken vetenskapliga artiklar. Studien resulterade i fyra huvudkategorier med 14 subkategori;Att sjuksköterskans beslutsfattande styrdes av flera olika faktorer, att tvångsåtgärder kundemissbrukas och att dess form är ohållbar, att erfarenheter förändradeen sjuksköterskas syn och att relationerna påverkades,och att uppleva starka och svåra känslor försvårade arbetet. Resultatet skildrade känslor hos sjuksköterskan som utfört tvångsåtgärder från rädsla och skuld till lättnad när ingen kommit till skada. Debeskrev att deinte upplevde sig haandra alternativ till tvångsåtgärder att tillgå, men att det fanns en önskan och längtan till att tvångsåtgärderska eliminerashelt. Eftersom tvångsåtgärder är vanligt förkommandeinom psykiatrinbehövs ny kunskap och möjlighet till reflektioni arbetsteamet, och självreflektion,om hur sjuksköterskanska bemöta dessa situationer.

>Magister Scientiae - MSc / We are fast moving into an era where data will be the primary driving factor for discovering new unknown astronomical objects and also improving our understanding of the current rare astronomical objects. Wide field survey telescopes such as the Square Kilometer Array (SKA) and Vera C. Rubin observatory will be producing enormous amounts of data over short timescales. The Rubin observatory is expected to record ∼ 15 terabytes of data every night during its ten-year Legacy Survey of Space and Time (LSST), while the SKA will collect ∼100 petabytes of data per day. Fast, automated, and datadriven techniques, such as machine learning, are required to search for anomalies in these enormous datasets, as traditional techniques such as manual inspection will take months to fully exploit such datasets.

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Ce travail de thèse entre dans le cadre de projets nationaux et internationaux de radioastronomie d'une manière générale et en particulier dans celui de SKA (Square Kilometre Array). La conception de circuits intégrés d’applications spécifiques devient de plus en plus importante dans ce domaine. La première étape de ce travail consiste à une étude bibliographique sur les inductances actives intégrées et leurs principales applications dédiées à la radioastronomie. Cette étude a permis de faire un état de l'art. Cet état de l'art a fait ressortir que l'intégration de certaines fonctions s'avère particulièrement difficile voire impossible dès lors que l'utilisation d'une inductance est nécessaire. Ceci est essentiellement dû à la taille importante des inductances. Parmi ces fonctions, nous avons le filtrage, certains types de transceivers, le temps de retard, etc. Or ces fonctions sont très importantes dans une architecture de radiofréquence propre aux réseaux d'antennes phasées. Ce travail de thèse est donc consacré à l'étude et la conception de ces différentes fonctions à l'aide des inductances actives basées sur des topologies à gyrateurs en technologie SiGeC 0,25 μm afin de palier aux problèmes d'intégration. Une des finalités de cette thèse est aussi de montrer que la consommation de ce procédé d'intégration n’est pas si excessive pour ces applications, par rapport à l’utilisation d’inductances localisées intégrées occupant une surface importante sur le substrat. Ce dernier point sera un résultat très important pour les projets où la très haute intégration à bas coût est nécessaire, point clé de réussite des réseaux phasés denses du projet international SKA. / This thesis work is part of national and international projects of radio-astronomy in general and in particular that of the SKA (Square Kilometre Array). The design of integrated circuits for specific applications is becoming increasingly important in this field. The first step in this work is a bibliography study on integrated active reactors and their main applications dedicated to radio astronomy. This study allowed making a state of the art. This state of the art has highlighted that the integration of some functions is made especially difficult by the need to use an inductor. This is mainly due to the large size of passive inductors. These functions include the filtering function, some transceivers types, the time delay, etc. But, they are very important in radio-frequency architecture owing to phased array antennas. This thesis propose the study and design of these different functions using active inductors based on gyrators topologies in SiGeC 0.25 μm technology in order to overcome the integration problems. One of the aims of this thesis is to show that the consumption of this integration process is not so excessive for these applications, compared to the use of integrated located inductors occupying a large area on the substrate. This last point is a very important result for projects where high integration at low cost is necessary, key point of the success of dense phased array in the SKA international project.

In this project we investigate the feasibility of detecting the signatures of Pop III stars in metal poor second generation stars and in gas clouds at high redshifts. First, the nucleosynthetic yields of Pair Instability Supernova and how they are manifested in gas clouds are presented. Next, some basic quantities of radio astronomy are explained and the requirements of SKA are shown. Then, the minimum detectable hydrogen column density of SKA for gas clouds at high redhsift is calculated and after that the basic principles of spectroscopy and the requirements of the HiReS instrument of E-ELT are demonstrated. Finally, suggestions about where the observations with HiReS should focus are made.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The use of Focal Plane Arrays (FPAs) as suitable feed-structures for the Parabolic Dish Reflector antennas that are intended to form a large part of the Square Kilometre Array (SKA) is currently the topic of conversation in various SKA research groups. The simulation of these structures however, relies on intensive computational resources, which can result in very long simulation runtimes - a serious problem for antenna designers. It was the purpose of the research to investigate efficient simulation techniques, based on the Method of Moments (MoM). In this thesis, the reader will be introduced to ways of improving FPA design by using resources such as High Performance Clusters, developing efficient MoM formulations for FPAs such as the Vivaldi antenna array and by developing efficient solution techniques for the resulting MoM equations by using techniques such as the Characteristic Basis Function Method (CBFM). In addition to the above mentioned methods, the concept of distributed computing is explored as a way to further aid the antenna designer in obtaining desired results in a reasonable time and with sufficient accuracy. / AFRIKAANSE OPSOMMING: Die gebruik van Fokus Punt Samestellings (FPS) vir die voer van Paraboliese Skottel Antennas in die Square Kilometer Array (SKA), geniet tans baie aandag in verkeie navorsing-sirkels. Die analise van hierdie samestellings vereis egter intensiewe berekenings-infrastrukture, wat tot lang simulasies kan lei - ’n ernstige probleem vir antenna ontwerpers. Die doel van die skrywer se navorsing was om effektiewe simulasie metodes te ondersoek, gebaseer op die Moment Metode. In hierdie tesis, sal die leser bekendgestel word aan verskeie metodes om die ontwerp van Fokus Punt Samestellings doeltreffend te verrig; nl. die gebruik van Parallel Rekenaar Klusters, die ontwikkeling van effektiewe Moment Metode kode vir samestellings soos die Vivaldi antenna konfigurasie, asook die ontwikkeling van effektiewe oplos-metodes vir die matrikse wat deur die Moment Metode gelewer word, deur die sogenaamde Karakteristieke Basis Funksie Metode (KBFM) te gebruik. Hierby ingesluit word die konsep van verspreide numeriese berekening ondersoek, as ’n manier waarop die antenna ontwerper resultate binne ’n aanvaarbare tyd en akkuraatheid kan verkry.

Philosophiae Doctor - PhD / Next-generation galaxy surveys will usher in a new era of high precision cosmology. They will increasingly rely on the galaxy bispectrum to provide improved constraints on the key parameters of a cosmological model to percent level or even beyond. Hereby, it is imperative to understand the theory of the galaxy bispectrum to at least the same level of precision. By this, we mean to include all the general relativistic projection effects arising from observing on the past lightcone, which still remains a theoretical challenge. This is because unlike the galaxy power spectrum, the galaxy bispectrum requires these lightcone corrections at second-order. For the rst time, this PhD project looks at all the local relativistic lightcone e ects in the galaxy bispectrum for a at Friedmann-Lemaitre-Robertson-Walker Universe, giving full details on the second-order scalars, vectors and tensors. These lightcone effects are mostly Doppler and gravitational potential contributions. The vector and tensor modes are induced at second order by scalars. We focus on the squeezed shapes for the monopole of the galaxy bispectrum because non-Gaussianity of the local form shows high signatures for these triangular con gurations. In the exact squeezed limit, the contributions from the vectors and tensors vanish. These relativistic projection effects, if not included in the analysis of observations, can be mistaken for primordial non-Gaussianity. For future surveys which will probe equality scales and beyond, all the relativistic corrections will need to be considered for an accurate measurement of primordial non-Gaussianity.

>Magister Scientiae - MSc / Future radio surveys as the Square Kilometer Array (SKA) and its precursor, the "Meer" Karoo Array Telescope (MeerKAT), will map the Neutral Hydrogen (HI) in large areas of the sky using the intensity mapping (IM). HI IM is currently one of the most promising ways of accessing the Large-Scale Structure of the Universe. The distribution of matter in the Universe not only encodes its composition but also how it evolves and its initial conditions. An effect on the matter distribution that will be detected by the SKA on the post re-ionization Universe are the Baryonic Acoustic Oscillations (BAO). While it has been shown that in single dish mode the SKA can measure the BAO peak in the radial 21cm power spectrum at low redshifts, this possibility has not yet been studied in detail for the MeerKAT. In this thesis we construct a set of full sky simulations to test how well MeerKAT will be able to extract the BAO wiggles along the line of sight. These simulations are done for the frequencies corresponding to MeerKAT L-band. The maps combine the cosmological HI signal, systematic noise, cosmological foregrounds and the instrumental telescope beam. A model-independent estimator is used to extract the BAO wiggles by subtracting a smooth polynomial component from the 21cm radial power spectrum. We test with simulations if this estimator is biased and the signal to noise of the extraction. We conclude that we are able to remove contaminants and recover the cosmological HI signal while not risking the recovery of the BAO signal. We investigate the effects of varying the sky area and the observational hours on the signal to noise ratio for the BAO wiggles. We found that for a HI IM experiment using MeerKAT, the optimal sky area to detect the BAO along the line of sight is 50% of the sky. With a signal-to-noise ratio of 3.37. This can be achieved with 2000 hours of exposure time