This thesis describes the construction and application of the Edinburgh/Durham Southern Galaxy Catalogue, which is a database of information on ~ 1-5 million galaxies, covering ~ 2000 deg2 of the South Galactic Cap. This catalogue is based on objective image detection and classification techniques, rather than the visual searches of photographic plates used in previous galaxy catalogues. The raw data for this project are digitised scans of 60 ESO/SERC Atlas plates using the COSMOS high-speed plate measuring machine. The quality controls employed during the production of the ESO/SERCAtlas, ensures that it is deeper and more uniform than set of plates used previously to construct a galaxy catalogue. The COSMOS machine objectively detects and parameterises ~ 2 X 105 images on each photographic plate. Image deblending software has been introduced to ensure the accurate detection and parameterisation of images in the crowded regions of compact clusters. Star-galaxy classification and photometric calibration techniques have been investigated and optimised to reduce and quantify any systematic variations that could introduce spurious structure. A classification algorithm has been used to automatically classify images over the whole range of magnitudes in the survey. Accurate intra-plate pho?tometry is possible for galaxies, because a COSMOS magnitude can be defined which is linearly related to the object magnitude. Inter-plate calibration is carried out using CCD galaxy sequences for every second field in the catalogue. Unlike global calibration techniques used previously, this arrangement of CCD?s prevents propagation of calibration errors. Statistics are given to show that the final catalogue of galaxies will be > 95% complete for bj < 20-0 with < 10% contamination by stars and that the point- to-point variation in galaxy number density, due to the combined residual systematic errors in classification and calibration, is ~ 8%. To date a mosaic of 35 plates covering a contiguous region of 1000 deg2 has been constructed. The large-scale galaxy distribution, seen in maps of this data, is dominated by two large supercluster complexes separated by ~ 15? ? 20?. Several filamentary arc structures can also be seen, with clusters distributed along them. The number- magnitude counts derived from this database show significant deviation from a no?evolution model at bj > 18-75. The variation in the amplitude of the counts across the survey cannot be accounted for by systematic variations in limiting magnitude and so is probably due large-scale clustering of galaxies. The two-point correlation functions calculated for this 35-plate mosaic confirm a break from power-law, though at larger scales (~ 20h-1 Mpc ) than previously estimated. In the context of current theories of galaxy formation, models involving standard cold dark matter with extra large-scale power would still seem to be excluded.

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Der Beitrag diskutiert die Notwendigkeit von Emotionen im futuristischen Gesellschaftsbild von Star Trek anhand der Föderationsgesellschaft und dem Borg-Kollektiv. Es wird herausgestellt, dass die Borg begründet durch ihren Willen zur Perfektion sich vollkommen einer fortgeschrittenen Technologie unterwerfen und die Individualität von einzelnen Borgdrohnen negieren. Emotionen spielen bei den Borg keine Rolle. Die Borg kann man damit als transhumanistische Staatsordnung interpretieren, die starke Parallelen zu Hobbes’ Leviathan aufweist. / The paper discusses the necessity of emotions in the futuristic concept of society in Star Trek and compares the Federation society with the Borg Collective. We show that the Borg driven by their will to achieve perfection submit to a sophisticated technology and negate the individuality of single Borg drones. In this society, emotions are irrelevant. Thus the Borg may be seen as a manifestation of transhumanism which shows certain parallels to Hobbes’ Leviathan.

Realistic star cluster simulations that dynamically evolve embedded star clusters require an accurate treatment of the stars, gas and their interaction. We present and validate a novel technique which creates an initial gas density distribution based on observational gas column density data. We consider two approaches to this technique where the first is based on randomly sampling from the original gas density distribution and the second assigns one particle to represent the gas in each observed image pixel. To create a three-dimensional distribution, we consider two estimates of cloud depth where one is a constant value and the second involves variable depths calculated using image processing techniques based on density features seen in the plane of the sky. We apply these methods to evolve the Carina region using initial stellar positions derived from the MYSTiX catalogue and gas data from the Herschel Hi-GAL survey. We evolve the stars using an N-body code and the gas using a smoothed-particle hydrodynamics code which are coupled through the AMUSE framework. We analyzed our results using dendrograms to describe the gas distribution over time and the DBSCAN clustering algorithm to track the clustering of stars over time. We model the gas using an adiabatic ideal gas equation of state and find that increasing the initial gas velocity dispersion prevents gas from accumulating and therefore could hinder future star formation. We also find that the stars, initially in subclusters spatially (not necessarily bound), tend to merge together to form one large cluster regardless of the initial conditions of the gas. It is only after the subclusters have merged that the initial conditions of the gas start to have a noticeable effect on the structure of the star cluster. Of the two approaches to our novel technique, the second approach leads to more accurate and realistic results. The second approach also has a significant effect on the stars as the subclusters merge together approximately 1 Myr earlier compared to the first approach. Therefore the choice of initial gas conditions affects the dynamical evolution of star cluster systems and being able to incorporate observational gas data leads to the increasingly accurate dynamical evolution of such systems. / Thesis / Master of Science (MSc)

An important research area in modern astrophysics is understanding how molecular clouds form stars and star clusters. These rich clusters within molecular clouds are the dominant mode of star formation in our galaxy, but we know very little about these areas of space due to incomplete observational data. The MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-Ray) project was started to create a detailed catalogue of these regions and the rich star clusters embedded within them. Once the observational data was available, the evolution of these clusters could be investigated in more detail. Current cluster simulations investigate the stars in detail but usually ignore the gas entirely which can be inaccurate, especially in gas mass dominated clusters. We use AMUSE (Astrophysical Multi-purpose Software Environment) to model embedded young clusters with stars and gas, similar to those found by the MYStIX project, and track their evolution over the first few million years of their lifespan while allowing the stars and gas to interact. We are particularly interested in non-spheroidal subclusters and how they can evolve into the spherical structures that we see today. / Thesis / Master of Science (MSc)

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In the study of pairwise sequence alignment, a clear relationship between the scoring system and assumptions about the occurrence of evolutionary events has been established in [BT86], [TKF91], [TKF92] and [TC95] by proposing an evolutionary model. To align two given sequences, one need estimate some evolutionary parameters through maximum likelihood method, and find an alignment with the maximum probability using the estimated parameters. In this thesis, we extend the above model and the maximum likelihood method to star alignment of three molecular sequences along the same line. We overcome the duplications of star alignments by defining canonical star alignments. Two star alignment algorithms, i.e. sum approach and direct alignment approach, are proposed in this thesis based on two different likelihood functions. A software system, called MLSAS (Maximum Likelihood Star Alignment System), is developed to implement the two algorithms with a friendly graphical user interface. Simulation studies show their behaviors are satisfactory for closely related sequences. A few real examples are also provided. / Thesis / Master of Engineering (ME)

This research outlines a low-cost, low-power, arc-minute accurate star tracker that is designed for use on a CubeSat. The device is being developed at the University of Texas at Austin for use on two different 3-unit CubeSat missions. The hardware consists of commercial off-the-shelf parts designed for use in industrial machine vision systems and employs a 1024x768 grey-scale charge coupled device (CCD) sensor. The software includes the three standard steps in star tracking: centroiding, star identification, and attitude determination. Centroiding algorithms were developed in-house. The star identification code was adapted from the voting method developed by Kolomenkin, et al. Attitude determination was performed using Markley's singular value decomposition method. The star tracker was then tested with internal simulated star-fields. The resulting accuracy was less than an arcminute. It was concluded that this system is a viable option for CubeSats looking to improve their attitude determination. On-orbit demonstration of the system is planned when the star tracker flies on the planned CubeSat missions in 2013 or later. Further testing with external simulated star fields and night sky tests are also planned. / text