Protein-protein interactions build large networks which are essential in understanding complex diseases. Due to limitations of experimental methodology there are problems with large amounts of false negative and positive interactions; and a large gap in the amount of known interactions and structurally determined interactions. By using computational methods these problems can be alleviated. In this thesis the quality of a newly developed pipeline (InterPred) were investigated for its ability to generate coarse interaction models and score them. This ability was investigated by performing docking experiments in Rosetta on models generated in InterPred. The results suggest that InterPred is highly successful in generating good starting points for docking proteins in silico and to distinguish the quality of models.

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Synthesis of the CCA end of essential tRNAs is performed either by CCA-adding enzymes or as a collaboration between enzymes restricted to CC- and A-incorporation. While the occurrence of such tRNA nucleotidyltransferases with partial activities seemed to be restricted to Bacteria, the first example of such split CCA-adding activities was reported in Schizosaccharomyces pombe. Here, we demonstrate that the choanoflagellate Salpingoeca rosetta also carries CC- and A-adding enzymes. However, these enzymes have distinct evolutionary origins. Furthermore, the restricted activity of the eukaryotic CC-adding enzymes has evolved in a different way compared to their bacterial counterparts. Yet, the molecular basis is very similar, as highly conserved positions within a catalytically important flexible loop region are missing in the CC-adding enzymes. For both the CC-adding enzymes from S. rosetta as well as S. pombe, introduction of the loop elements from closely related enzymes with full activity was able to restore CCA-addition, corroborating the significance of this loop in the evolution of bacterial as well as eukaryotic tRNA nucleotidyltransferases. Our data demonstrate that partial CC- and A-adding activities in Bacteria and Eukaryotes are based on the same mechanistic principles but, surprisingly, originate from different evolutionary events.

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L'orbite gravitationnelle d'une comète est affectée par la sublimation de la glace d'eau, un des principaux composants du noyau, lorsqu'elle s'approche du Soleil. Ce dégazage anisotrope produit une force dite non-gravitationnelle qui modifie de façon significative l'orbite de la comète. L'amplitude des perturbations dépend de plusieurs paramètres qui peuvent être contraints par différents types d'observations telles que les observations astrométriques et photométriques ou encore les taux de production d'eau observés en radio astronomie. Jusqu'à maintenant, la modélisation de ces effets est essentiellement fondée sur un modèle empirique défini dans les années 70 par Marsden et al. (1973) utilisant un dégazage isotrope. Dans cette thèse, j'ai développé une nouvelle approche de la physique du problème des forces non-gravitationnelles faisant intervenir différents paramètres physiques tels que les position et vitesse initiales de la comète, son activité, la direction de l'axe de rotation, la masse du noyau et donc sa densité si son volume est connu, paramètre essentiel pour la compréhension de la formation des comètes. J'ai ainsi pu déduire leur valeur par ajustement d'orbite et de données photométriques. Ce travail a été appliqué à deux comètes : 19P/Borrelly pour le développement et la validation ma méthode, et 67P/Churyumov-Gerasimenko la cible de la mission spatiale européenne Rosetta dont la connaissance de la masse est primordiale.

Several Langmuir probe voltage sweeps by a model of the ESA spacecraft Rosetta was simulated in a plasma with solar wind parameters using the ESA open source software SPIS 5. The simulations were carried out to in- vestigate the features of the spacecraft’s environment in the solar wind and the effect of photoemission from the spacecraft surface on the measurements made by the Langmuir probes on board Rosetta. We report a best fit to an existing probe sweep result in the solar wind near the Earth at 1 AU from 9 Nov 2009 for a 4 million particle simulation in SPIS of an 8 V positively charged spacecraft with the following parameters: Tph = 2 eV, Te = 12 eV, Ti = 5 eV, ne = 5 cm−3. We also report that the spacecraft is shielding the Langmuir probes on Rosetta from plasma electrons, and particularly low energy electrons. In one instance, this blocking is shown to lead to an over- estimation of solar wind electron temperature by 12% and underestimate the plasma density by 24% by the Langmuir Probe for a +10 V charged spacecraft in ne= 5 cm−3, Te = 12 eV solar wind. Two models used in lit- erature on photoemission, one for isotropical emission from a plane and the other for radial emission from a point, was used and compared. We report a clear preference to the approximation of a Maxwellian energy distribution of photoelectrons emitted radially from a point source model with our sim- ulation result on the Langmuir Probe aboard Rosetta. We also report the solar aspect angle dependence on the plasma potential and plasma density result, which are in overall agreement with Rosetta measurements from the second Earth fly-by.

The Digital Rosetta Stone is a project developed at Leipzig University by the Chair of Digital Humanities and the Egyptological Institute/Egyptian Museum Georg Steindorff in collaboration with the British Museum and the Digital Epigraphy and Archaeology Project of the University of Florida. The aims of the project are to produce a collaborative digital edition of the Rosetta Stone, address standardization and customization issues for the scholarly community, create data that can be used by students to understand the document in terms of language and content, and produce a high-resolution 3D model of the inscription. The three versions of the text were transcribed and outputted in XML, according to the EpiDoc guidelines. Next, the versions were aligned with the Ugarit iAligner tool that supports the alignment of ancient texts with modern languages, such as English and German. All three texts were then parsed syntactically and morphologically through Treebank annotation. Finally, the project explored new 3D-digitization methodologies of the Rosetta Stone in the British Museum that enhances traditional archaeological methods and facilitates the study of the artifact. The results of this work were used in different courses in Digital Humanities, Digital Philology, and Egyptology.

The Rosetta Stone is one of the most important stone fragments in history. It is the most popular single object in London’s British Museum, has been the object of scholarly research and has had much written about it. Indeed, any account of the history of translation will at least mention the Rosetta Stone. Today, the name “Rosetta” is used metaphorically in the context of translation, foreign-language learning, and even space exploration. In the light of this, one would assume that all sources are in agreement on the facts but, surprisingly, this is not the case. This article shows that sources disagree even in the most obvious aspects, such as the material, colour, condition of the stone and, in particular, with respect to its discovery. Based on an excursion to Alexandria, Rashíd and the – in all likelihood – real discovery site in the Nile delta, this article provides facts and casts some doubt on the reliability of internet sources.

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