Some results on orbifold quotients and related objects

The quotient of a finite-dimensional Euclidean space by a finite linear group inherits different structures from the initial space, e.g. a topology, a metric and a piecewise linear structure. The question when such a quotient is a manifold leads to the study of finite groups generated by reflections and rotations, i.e. by orthogonal transformations whose fixed point subspace has codimension one or two. We classify such groups and thereby complete earlier results by M. A. Mikhaîlova from the 70s and 80s. Moreover, we show that a finite group is generated by reflections and) rotations if and only if the corresponding quotient is a Lipschitz-, or equivalently, a piecewise linear manifold (with boundary). For the proof of this statement we show in addition that each piecewise linear manifold of dimension up to four on which a finite group acts by piecewise linear homeomorphisms admits a compatible smooth structure with respect to which the group acts smoothly. This solves a challenge by Thurston and confirms a conjecture by Kwasik and Lee. In the topological category a counterexample to the above mentioned characterization is given by the binary icosahedral group. We show that this is the only counterexample up to products. In particular, we answer the question by Davis of when the underlying space of an orbifold is a topological manifold. As a corollary of our results we generalize a fixed point theorem by Steinberg on unitary reflection groups to finite groups generated by reflections and rotations. As an application thereof we answer a question by Petrunin on quotients of spheres.

State-Selective Attachment of Helium to Molecular Ions in a New Cryogenic Ion Trap

Light is the main information about the interstellar medium accessible on Earth. Based on this information one can conclude on the composition of the region where the light originates from, as well as on its history. The requirement for this is that it is possible to identify the different absorption and emission features in the spectrum and assign them to certain molecules, atoms or ions. To enable the identification of the different species, precise spectroscopic investigations of the species in the laboratory are necessary. In this work a new spectroscopic method is presented, which can be used to record pure rotational spectra of mass selected, cold, stored molecular ions. It is based on the idea of state specific attachment of helium atoms to the stored molecular ions. The new technique has been made possible through the development and recent completion of two new 22-pole ion trap instruments in the work group of Laboratory Astrophysics at the University of Cologne. These new instruments have the advantage to reach temperatures as low as 4K compared to the 10K of the predecessor instrument. These low temperatures enable the ternary attachment of helium atoms to the stored molecular ions and by this make it possible to develop this new method for pure rotational spectroscopy. According to this, this work is divided into two parts. The first part deals with the new FELion experiment that was build and characterized in the first part of the thesis. FELion is a cryogenic 22-pole ion trap apparatus, allowing to generate, mass select, store and cool down, and analyze molecular ions. The different components of the instrument, e.g. the Storage Ion Source for generating the ions or the first quadrupole mass filter, are described and characterized in this part. Besides this also the newly developed control and data acquisitions system is introduced. With this instrument the measurements presented in the second part of the work were performed. The second part deals with the new action spectroscopic method of state-selective helium attachment to the stored molecular ions. For a deeper analysis of the new technique the systems of CD+ and helium and HCO+ and helium are investigated in detail. Analytical and numerical models of the process are presented and compared to experimental results. The results of these investigations point to a seemingly very general applicability of the new method to a wide class of molecular ions. In the final part of the thesis measurements of the rotational spectrum of l-C3H+ are presented. These measurements have to be high-lighted, since it was possible for the first time in the laboratory to unambiguously measure four low-lying rotational transitions of l-C3H+. These measurements (Brünken et al. ApJL 783, L4 (2014)) enabled the reliable identification of so far unidentified emision lines observed in several regions of the interstellar medium (Pety et al. Astron. Astrophys. 548, A68 (2012), McGuire et al. The Astrophysical Journal 774, 56 (2013) and McGuire et al. The Astrophysical Journal 783, 36 (2014)).

Topics in Behavioural Economics - Information and Fairness. Revised edition

This thesis dwells upon topics in behavioural economics: information and fairness, with five research papers. The first two contributions are concerned with the extension of standard auction formats with information acquisition strategies. The third paper addresses global games framed as a speculative attack and tests theoretical predictions for risk and ambiguity. The fourth contribution deals with disclosing conflicts of interest, where one player has a monetary incentive to deceive. The last paper extends a standard model of social preferences with a second fairness dimension and studies how economic agents distort fairness norms exhibiting a self-serving bias effect.

Adolph Tidemand (1814-76) und die Konstruktion norwegischer Identität

In der Arbeit „Adolph Tidemand und die Konstruktion norwegischer Identität“ werden vier Schlüsselwerke des in Düsseldorf tätigen norwegischen Künstlers Adolph Tidemand (1814-76) neu erschlossen und gedeutet. Dabei wurde die These aufgestellt, dass das Oeuvre Tidemands, der für die Entwicklung der Genremalerei der Düsseldorfer Malerschule eine zentrale Rolle spielte und gleichzeitig einer der wichtigsten Vertreter der norwegischen Nationalromantik ist, weit über eine Kennzeichnung und Einordnung als eine volkskundlich-romantische Malerei hinausgeht. Aus der Analyse der visuellen Umsetzung seiner Rolle eines Vermittlers zwischen zwei Kulturen in seinen Bildern, mit denen er zur Konstruktion einer nationalen, norwegischen Identität beitrug, ergibt sich eine doppelte Sicht auf eine aus Deutschland vorgenommene Konstruktion der norwegischen Heimat.

O negro na construção da identidade nacional: auto e heteroimagens no romance abolicionista cubano e brasileiro

Die vorliegende Arbeit nahm sich vor, das Bild des Afroamerikaners in jeweils zwei kubanischen und brasilianischen Romanen des 19. Jahrhunderts zu analysieren: El negro Francisco, Cecilia Valdés, A escrava Isaura und O mulato. Das Hauptziel war es, zu untersuchen, wie das Bild des Afroabstammenden von den Autoren angeeignet und instrumentalisiert wurde, um Veränderungen in ihren Gesellschaften zu erzielen. Darüber hinaus, versuchte man darzustellen, wie der Afroamerikaner und seine Kultur aus dem kubanischen und brasilianischen nationalen Projekt ausgeschlossen wurden. Zunächst wurden die Haupttheorien über die Konstruktion von Auto- und Heterostereotypen vorgestellt und auf die Relevanz der Stereotypenbildung im kolonialen Kontext hingewiesen. Daraufhin wurde der historische Kontext der Sklaverei und der Abolition in Kuba und in Brasilien dargelegt. Auf diese Basis wurden die Werke analysiert. Im letzten Kapitel wurde auf die Resultate der Fragestellungen eingegangen, die die vorliegende Arbeit geleitet haben. Solche wie: Welche Bilder der Weißen und der Schwarzen wurden in den Werken kreiert? Wie positioniert sich der Autor bezüglich der Abolition und der Vermischung der Ethnien? Welche Bedeutung hatten die ethnischen Diskurse im kubanischen und brasilianischen kollektiven Gedächtnis des 19. Jahrhunderts? Es konnte gezeigt werden, dass das Bild des Afroamerikaners in den Romanen verwendet wurde, um die Zukunft der eigenen Nation zu projizieren, von der der Schwarze nur ein Teil werden könnte, wenn er die weiße Kultur und Hautfarbe annehmen würde, das heißt, wenn er sich dem Prozess eines physischen und kulturellen „branqueamento“ unterziehen würde. Die abolitionistische Narrative, auch wenn sie nach außen hin dem Schwarzen zu verteidigen scheint, trug in Wahrheit zur Fixierung und Perpetuierung der ethnischen Stereotype bei, die die Schwarzen in den marginalen Sphären der Gesellschaft verewigten und die Macht in den Händen der Weißen konsolidierten.

Die Pflicht zur Verlustübernahme im GmbH-Vertragskonzern - Erforderlichkeit und Rechtfertigung einer Analogie von § 302 AktG im GmbH-Recht -

Diese Arbeit widmet sich der Frage, ob und wie der GmbH-Vertragskonzern einem speziellen Haftungsregime unterworfen werden sollte. Anders als das Aktiengesetz - das in § 302 AktG eine Verlustübernahmepflicht der vertraglich herrschenden Konzernmutter statuiert - kennt das GmbHG kein kodifiziertes Haftungsregime des Vertragskonzerns. Die herrschende Meinung behilft sich mit einer Analogie des § 302 AktG im GmbH-Vertragskonzern. Die vorliegende Arbeit beleuchtet den Sinn und die Berechtigung dieser Analogie vor dem Hintergrund der strukturellen Unterschiede und Parallelen von Aktienrecht und GmbH-Recht.

Kinder kauft man nicht. Die politische Ökonomie von Auslandsadoptionen in Deutschland und den Vereinigten Staaten von Amerika

Bei der Adoption eines Kindes aus dem Ausland werden hohe Summen an unterschiedliche Akteure gezahlt: Adoptionsagenturen, Behörden, Vermittler, Ärzte und Waisenhäuser. In der Literatur der letzten dreißig Jahre wird daher immer wieder kritisiert, Auslandsadoptionen seien im Grunde Kinderhandel oder zumindest ein Teil der Adoptionsakteure betriebe profitorientierten Handel mit Kindern. Im Jahre 1993 veröffentlichte die Den Haager Konferenz für internationales Privatrecht das "Haager Übereinkommen für Auslandsadoptionen", das mit einem transnationalen Regime für Adoptionen mit Grenzberührung den Kinderhandel verhindern soll. Geldzahlungen verbietet es jedoch nicht. Die Dissertation untersucht, die Geschichte des Kampfes gegen Kinderhandel; die Entstehungsgeschichte des Übereinkommens; wie es Kinderhandel verhindern soll; es fragt nach den Regimestrukturen, die es etablieren, die Probleme, die es lösen und den Wirkungen, die es entfalten soll. Die theoretische und empirische Untersuchung basiert auf der Auswertung von Statistiken, Experteninterviews und Dokumentenanalysen. Die Dissertation trägt damit zur Forschung über die soziale Einbettung von ökonomischen Systemen bei, die nicht wie Märkte aufgebaut sind.

La mitificación occidental de Saladino: Un viaje por las principales literaturas románicas de los siglos XIII y XIV

This article deals with the figure Ṣalāḥ ad-Dīn, Saladino or Saladin and his reception in European cultures. It describes its function as myth which reappears in distinct shapes in relation to local realities and nevertheless also exhibits general features of the European cultural identity.

Proficiency and mechanisms of perturbation of mature T-cell homeostasis by the TCL1 family of oncogenes

In the first part of this thesis, the oncogenic potential of TCL1A family genes was comparatively evaluated by using gamma-retroviral vectors to introduce human TCL1A, MTCP1, and TML1 into hematopoietic stem cells/hematopoietic progenitor cells (HSC/HPC) of wild type mice that were transplanted into wild type recipients. TCL1A and MTCP1 recipient mice predominantly developed B-cell malignancies after a median survival of 388 days and 394 days, respectively. The presented data indicates that TCL1A and MTCP1 are oncogenes with comparable oncogenic potential and shows for the first time that MTCP1 is not only a T-cell oncogene, but is able to transform B cells as well. The third family member TML1 induced the development of immature T-cell malignancies in only a few mice. This study provides first evidence for its oncogenic function. Additionally, the transforming potential of compartment-targeted TCL1A variants was evaluated by retroviral expression of a membrane localizing myristoylated (myr-TCL1A) and a nuclear localizing (nls-TCL1A) variant. Recipients of HSC/HPC transduced with myr-TCL1A and nls-TCL1A predominantly developed B-cell malignancies after a median survival of 360 days and 349 days, respectively. There was a significantly shorter latency period for nls-TCL1A compared to the previously described generic TCL1A. Gene expression analysis revealed higher similarities between expression profiles of tumors induced by TCL1A and nls-TCL1A. Together these data implicate that TCL1A’s predominant oncogenic function might rely on its nuclear presence. The second part of this thesis aims to understand if and how TCR stimulation affects the transforming potential of TCL1A. Mature OT-1 T cells carrying monoclonal TCR’s that specifically recognize ovalbumin (OVA) were retrovirally transduced with TCL1A and repeatedly stimulated in vivo with OVA-peptides. TCR stimulated recipient mice of TCL1A transduced T cells showed a significantly accelerated leukemic outgrowth and a reduced median survival of 305 days, when compared to unstimulated recipients (417 days). These data strongly implicate a pro-leukemogenic cooperation of TCL1A and TCR signals that might be actionable in upcoming interventional designs.

El copernicanismo en las Españas del XVI y el XVII. Ciencia, filosofía y literatura.

In 1543 Nicolas Copernicus published his Revolutionibus Orbium's Coelelestium. This is the scientific work that gave birth to modern science, something thoroughly European, since scientists of different countries contributed to it: Poland, Italy, Germany, Spain, France, Holland, etc. A work that appeared in a crucial moment obviously represented the need of that time to correct the Julian calendar. A new procedure to calculate the positions of the stars was necessary for astrology and for the making of predictions that were important at that time. Our intention is to outline the history of how it was introduced in Spain at the beginning of the scientific revolution. We will not conceal that Spain has been a country that has only contributed to scientific literature in a deficient way, maybe we can offer some arguments that help to understand why this has happened.

Towards a grammar of the senses: perception in Lushese (Olussese)

The thesis presents the grammar of the Eastern African Bantu language Lushese (Olussese), spoken in Uganda, and gives information on the historical background that caused the today´s highly endangered status of the language (chapters 1 & 2). Focussing on the semantics of the verbs of perception, the thesis presents the use and meaning of various linguistic means for expressing perception in general and further for the expression of physical, sensory, emotional and cognitive experience in Lushese (chapters 3-5). The findings in Lushese provide insights of the use of language in the light of social interaction and include information on the ways cultural and social values impact the choice of linguistic means (chapter 6). With respect to the theoretical issues concerning the language of perception the data in Lushese show that the way people speak about the environment and use language to express categories of perception are rather a matter of innate cultural interpretation regarding the human body and the environment than a matter of the human body and the environment as given by biological and/or physical conditions.

Mittelneolithische Silexaustauschsysteme auf der Aldenhovener Platte und in ihrer Umgebung

In der Archäologie gibt die Untersuchung der räumlichen und zeitlichen Dimensionen von Tausch Hinweise auf die Reichweite und Entwicklung prähistorischer Wirtschaftssysteme und den damit verbundenen sozialen Kontakten. Bei der Erforschung neolithischer Gesellschaften wird Tausch – bedingt durch die archäologische Quellenlage – häufig anhand der Weitergabe lithischen Materials erforscht. In diesem Dissertationsprojekt wird die Weitergabe von Silex (Feuerstein) zwischen mittelneolithischen Siedlungen innerhalb der Kleinregion des heutigen Braunkohletagebaus zwischen Aachen und Köln untersucht. Silex diente als Rohmaterial zur Herstellung von Werkzeugen für die Jagd sowie für eine Vielzahl häuslicher, agrarischer und handwerklicher Tätigkeiten. Die untersuchten Siedlungslätze datieren in die mittelneolithischen Phasen Großgartach, Planig-Friedberg und Rössen (ca. 4900 bis 4550 v. Chr.). Ein zentraler Untersuchungsteil stellt der Vergleich zwischen den Fundplätzen im Hinblick auf die Produktion von Silexgrundformen und -werkzeugen dar. Dabei kommt unter anderem eine Faktorenanalyse zur Anwendung. Das Analyseresultat bildet die Grundlage zum Entwurf dreier Thesen, auf deren Überprüfung die darauffolgenden Untersuchungsschritte ausgelegt sind. Dabei werden die Analysen auf ein siedlungsinternes und ein überregionales Level ausgeweitet. Auf diese Weise konnten nicht nur quellenkritische Aspekte überprüft und Ergebnisse für das zentrale Untersuchungsgebiet verifiziert, sondern auch die weiträumigen Verteilungsmuster der Feuersteinweitergabe erfasst werden. In einer abschließenden interpretativen Betrachtung wurden die Tauschverhältnisse auf den verschiedenen Skalenniveaus anhand eines ethnographischen Modells nach M. Sahlins beschrieben.

Fluctuations in and out of equilibrium: Thermalization, quantum measurements and Coulomb disorder

This purely theoretical thesis covers aspects of two contemporary research fields: the non-equilibrium dynamics in quantum systems and the electronic properties of three-dimensional topological insulators. In the first part we investigate the non-equilibrium dynamics in closed quantum systems. Thanks to recent technologies, especially from the field of ultracold quantum gases, it is possible to realize such systems in the laboratory. The focus is on the influence of hydrodynamic slow modes on the thermalization process. Generic systems in equilibrium, either classical or quantum, in equilibrium are described by thermodynamics. This is characterized by an ensemble of maximal entropy, but constrained by macroscopically conserved quantities. We will show that these conservation laws slow down thermalization and the final equilibrium state can be approached only algebraically in time. When the conservation laws are violated thermalization takes place exponential in time. In a different study we calculate probability distributions of projective quantum measurements. Newly developed quantum microscopes provide the opportunity to realize new measurement protocols which go far beyond the conventional measurements of correlation functions. The second part of this thesis is dedicated to a new class of materials known as three-dimensional topological insulators. Also here new experimental techniques have made it possible to fabricate these materials to a high enough quality that their topological nature is revealed. However, their transport properties are not fully understood yet. Motivated by unusual experimental results in the optical conductivity we have investigated the formation and thermal destruction of spatially localized electron- and hole-doped regions. These are caused by charged impurities which are introduced into the material in order to make the bulk insulating. Our theoretical results are in agreement with the experiment and can explain the results semi-quantitatively. Furthermore, we study emergent lengthscales in the bulk as well as close to the conducting surface.

Identification of Genes Modulating Mitochondrial Biogenesis in Caenorhabditis elegans

Since Altmann recognized ubiquitously distributed "bioblasts" in 1890, understanding of mitochondria has evolved from "elementary organisms" living inside cells and carrying out vital functions, over the Harman's "free radical theory" in 1956, to one of the driving forces of aging and cause of multiple associated diseases impacting society today. While a tremendous amount of work has contributed to the understanding of mitochondrial biology in different model organisms, the precise molecular mechanisms of basic mitochondrial function have yet to be deciphered. By employing an RNA interference mediated screen in Caenorhabditis elegans, we identified two transcription factors: SPTF-3, a member of Sp1 family, and an uncharacterized, nematode specific W04D2.4. We propose that both proteins modulate expression of many genes with regard to mitochondrial function including mitochondrial single-stranded binding protein encoded by mtss-1, whose promoter was used as transcriptional reporter in the screen. Further, RNA sequencing data indicate that W04D2.4 indirectly regulates expression of mitochondrial DNA via control of genes functionally related to mitochondrial replication and translation machineries. We also demonstrate that from all interventions targeting cytosolic translation, MTSS-1 levels are elevated only upon knockdown of genes encoding cytosolic ribosomal proteins. Reduction of ribosomes leads to increased sptf-3 translation, most likely in an internal ribosome entry side (IRES) mediated manner, eventually inducing mtss-1 expression. Moreover, we identify a novel role for SPTF-3 in the regulation of mitochondrial unfolded stress response (UPRmt) activation, but not endoplasmatic reticulum or oxidative stress responses. Taken together, this study identifies two transcription factors previously not associated with mitochondrial biogenesis and UPRmt in C. elegans, establishing a basis for further investigation of mito-nuclear interactions.