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Die Korrespondenz zwischen Alexander von Humboldt und Karl Kreil war umfangreich und betraf den Erdmagnetismus. Aber heute ist nur noch ein einziger Brief im Original bekannt. Dieser Brief, den Kreil am 3. September 1836 Alexander von Humboldt zukommen ließ, stimmt inhaltlich und teilweise wortwörtlich mit dem Brief überein, den Kreil nur einen Tag später, am 4. September 1836, an Carl Friedrich Gauß schickte. Vier Briefe von Kreil an Humboldt wurden in den „Annalen der Physik und Chemie“ publiziert, eine nicht allzu große Anzahl weiterer Briefe an Humboldt wurde in der biographischen Literatur über Kreil und in Briefen Kreils an Koller und Gauß erwähnt. Aber nicht nur die lückenhafte und bruchstückhaft bekannte Korrespondenz zwischen Humboldt und Kreil, die bis 1851 reicht, gibt Aufschluss über die Beziehungen, sondern von besonderer Bedeutung ist des Weiteren der Bestand an Kreiliana in der Bibliothek Humboldts. Es handelt sich um neun Werke Kreils, das letzte aus dem Jahr 1856. Nachweisbare Kontakte zwischen Kreil und Humboldt fanden also mit Sicherheit mindestens bis zu diesem Jahr statt!
El Ensayo sobre la geografía de las plantas de Alexander von Humboldt ha trascendido como una de sus principales propuestas científicas, fundamento de lo que se conoce hoy como “biogeografía”. El origen de este concepto es difuso hasta el momento de la publicación simultánea de su obra en París y en Tübingen, en 1807. El presente artículo propone contrastar la primera versión manuscrita de este ensayo, elaborada en 1803 en Guayaquil y luego leída en 1805 en el Institut National de Paris, con la obra contemporánea del neogranadino Francisco José de Caldas, con quien convivió en Quito en el primer semestre de 1802.
La référence à Colomb est un lieu commun de la biographie humboldtienne. Humboldt lui-même le souligne particulièrement dans son Examen critique, en y ajoutant une dimension autobiographique. La contribution analyse, dans une perspective philologique, le matériel et les formes de mise en scène avec lesquelles une vie est représentée au travers d'une autre.
Ein unveröffentlichter Brief Alexander von Humboldts an den Buchhändler Jean-Georges Treuttel
(2016)
In der Lilly Library der Indiana University befindet sich ein kurzer unveröffentlichter Brief Alexander von Humboldts an den Buchhändler und Autor Jean-Georges Treuttel. Dieser Artikel unternimmt den Versuch, den historisch-bibliographischen Kontext des Briefes herzustellen und ihn in Humboldts wissenschaftliches Schaffen einzuordnen.
The LEA (late embryogenesis abundant) proteins COR15A and COR15B from Arabidopsis thaliana are intrinsically disordered under fully hydrated conditions, but obtain α-helical structure during dehydration, which is reversible upon rehydration. To understand this unusual structural transition, both proteins were investigated by circular dichroism (CD) and molecular dynamics (MD) approaches. MD simulations showed unfolding of the proteins in water, in agreement with CD data obtained with both HIS-tagged and untagged recombinant proteins. Mainly intramolecular hydrogen bonds (H-bonds) formed by the protein backbone were replaced by H-bonds with water molecules. As COR15 proteins function in vivo as protectants in leaves partially dehydrated by freezing, unfolding was further assessed under crowded conditions. Glycerol reduced (40%) or prevented (100%) unfolding during MD simulations, in agreement with CD spectroscopy results. H-bonding analysis indicated that preferential exclusion of glycerol from the protein backbone increased stability of the folded state.
The interaction of water with α-alumina (i.e. α-Al2O3) surfaces is important in a variety of applications and a useful model for the interaction of water with environmentally abundant aluminosilicate phases. Despite its significance, studies of water interaction with α-Al2O3 surfaces other than the (0001) are extremely limited. Here we characterize the interaction of water (D2O) with a well defined α-Al2O3(1[1 with combining macron]02) surface in UHV both experimentally, using temperature programmed desorption and surface-specific vibrational spectroscopy, and theoretically, using periodic-slab density functional theory calculations. This combined approach makes it possible to demonstrate that water adsorption occurs only at a single well defined surface site (the so-called 1–4 configuration) and that at this site the barrier between the molecularly and dissociatively adsorbed forms is very low: 0.06 eV. A subset of OD stretch vibrations are parallel to this dissociation coordinate, and thus would be expected to be shifted to low frequencies relative to an uncoupled harmonic oscillator. To quantify this effect we solve the vibrational Schrödinger equation along the dissociation coordinate and find fundamental frequencies red-shifted by more than 1500 cm−1. Within the context of this model, at moderate temperatures, we further find that some fraction of surface deuterons are likely delocalized: dissociatively and molecularly absorbed states are no longer distinguishable.
In this work, three ligands produced from amino acids were synthesized and used to produce five bis- and PEPPSI-type palladium–NHC complexes using a novel synthesis route from sustainable starting materials. Three of these complexes were used as precatalysts in the aqueous-phase Suzuki–Miyaura coupling of various substrates displaying high activity. TEM and mercury poisoning experiments provide evidence for Pd-nanoparticle formation stabilized in water.
The synthesis and photophysical properties of two new FRET pairs based on coumarin as a donor and DBD dye as an acceptor are described. The introduction of a bromo atom dramatically increases the two-photon excitation (2PE) cross section providing a 2PE-FRET system, which is also suitable for 2PE-FLIM.
The aim of this study was to develop a one-step synthesis of gold nanotriangles (NTs) in the presence of mixed phospholipid vesicles followed by a separation process to isolate purified NTs. Negatively charged vesicles containing AOT and phospholipids, in the absence and presence of additional reducing agents (polyampholytes, polyanions or low molecular weight compounds), were used as a template phase to form anisotropic gold nanoparticles. Upon addition of the gold chloride solution, the nucleation process is initiated and both types of particles, i.e., isotropic spherical and anisotropic gold nanotriangles, are formed simultaneously. As it was not possible to produce monodisperse nanotriangles with such a one-step procedure, the anisotropic nanoparticles needed to be separated from the spherical ones. Therefore, a new type of separation procedure using combined polyelectrolyte/micelle depletion flocculation was successfully applied. As a result of the different purification steps, a green colored aqueous dispersion was obtained containing highly purified, well-defined negatively charged flat nanocrystals with a platelet thickness of 10 nm and an edge length of about 175 nm. The NTs produce promising results in surface-enhanced Raman scattering.
Optical biosensors based on porous silicon were fabricated by metal assisted chemical etching. Thereby double layered porous silicon structures were obtained consisting of porous pillars with large pores on top of a porous silicon layer with smaller pores. These structures showed a similar sensing performance in comparison to electrochemically produced porous silicon interferometric sensors.
In Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy X-Ray photons are used to excite tightly bound core electrons to low-lying unoccupied orbitals of the system. This technique offers insight into the electronic structure of the system as well as useful structural information. In this work, we apply NEXAFS to two kinds of imidazolium based ionic liquids ([CnC1im]+[NTf2]- and [C4C1im]+[I]-). A combination of measurements and quantum chemical calculations of C K and N K NEXAFS resonances is presented. The simulations, based on the transition potential density functional theory method (TP-DFT), reproduce all characteristic features observed by the experiment. Furthermore, a detailed assignment of resonance features to excitation centers (carbon or nitrogen atoms) leads to a consistent interpretation of the spectra.
Herein we present an efficient synthesis of a biomimetic probe with modular construction that can be specifically bound by the mannose binding FimH protein – a surface adhesion protein of E. coli bacteria. The synthesis combines the new and interesting DBD dye with the carbohydrate ligand mannose via a Click reaction. We demonstrate the binding to E. coli bacteria over a large concentration range and also present some special characteristics of those molecules that are of particular interest for the application as a biosensor. In particular, the mix-and-measure ability and the very good photo-stability should be highlighted here.
Die vorgelegte Dissertation präsentiert wissenschaftliche Ergebnisse, die in der Zeit vom Dezember 2012 bis August 2016, erarbeitet wurden. Der zentrale Inhalt der Arbeit ist die Simulation von Röntgenabsorptionsprozessen von verschiedenen Systemen in kondensierter Phase. Genauer gesagt, werden Nahkantenabsorptions- (NEXAFS) sowie Röntgenphotoelektronenspektren (XPS) berechnet. In beiden Fällen wird ein Röntgenphoton von einem molekularen System absorbiert. Aufgrund der hohen Photonenenergie wird ein stark gebundenes kernnahes Elektron angeregt. Bei der XPS gelangt dieses mit einer zu messenden kinetischen Energie in Kontinuumszustände. In Abhängigkeit der eingestrahlten Photonenenergie und der kinetischen Energie des austreten Elektrons, kann die Bindungsenergie berechnet werden, welche die zentrale Größe der XPS ist. Im Falle der NEXAFS-Spektroskopie wird das kernnahe Elektron in unbesetzte gebundene Zustände angeregt. Die zentrale Größe ist die Absorption als Funktion der eingestrahlten Photonenenergie. Das erste Kapitel meiner Arbeit erörtert detailliert die experimentellen Methoden sowie die daraus gewonnenen charakteristischen Größen.
Die experimentellen Spektren zeigen oft viele Resonanzen, deren Interpretation aufgrund fehlender Referenzmaterialien schwierig ist. In solchen Fällen bietet es sich an, die Spektren mittels quantenchemischer Methoden zu simulieren. Der dafür erforderliche mathematisch-physikalische Methodenkatalog wird im zweiten Kapitel der Arbeit erörtert.
Das erste von mir untersuchte System ist Graphen. In experimentellen Arbeiten wurde die Oberfläche mittels Bromplasma modifiziert. Die im Anschluss gemessenen NEXAFS-Spektren unterscheiden sich maßgeblich von den Spektren der unbehandelten Oberfläche. Mithilfe periodischer DFT-Rechnungen wurden verschiedene Gitterdefekte sowie bromierte Systeme untersucht und die NEXAFS-Spektren simuliert. Mittels der Simulationen können die Beiträge verschiedener Anregungszentren analysiert werden. Die Berechnungen erlauben den Schluss, dass Gitterdefekte maßgeblich für die entstandenen Veränderungen verantwortlich sind.
Polyvinylalkohol (PVA) wurde als zweites System behandelt. Hierbei sollte untersucht werden, wie groß der Einfluss der Molekularbewegung auf die Verbreiterung der Peaks im XP-Spektrum ist. Des Weiteren wurde untersucht, wie groß der Einfluss von intermolekularen Wechselwirkungen auf die Peakpositionen und Peakverbreiterung ist. Für die Berechnung dieses Systems wurde eine Kombination aus molekulardynamischen und quantenchemischen Methoden verwendet. Als Strukturen dienten Oligomermodelle, die unter dem Einfluss eines (ab initio) Potentials propagiert wurden. Entlang der erstellten Trajektorie wurden Schnappschüsse der Geometrien extrahiert und für die Berechnung der XP-Spektren verwendet. Die Spektren werden bereits mithilfe klassischer Molekulardynamik sehr gut reproduziert. Die erhaltenen Peakbreiten sind verglichen mit dem Experiment allerdings zu klein. Die Hauptursache der Peakverbreiterung ist die Molekularbewegung. Intermolekulare Wechselwirkungen verschieben die Peakpositionen um 0.6 eV zu kleineren Anregungsenergien.
Im dritten Teil der Arbeit stehen die NEXAFS-Spektren von ionischen Flüssigkeiten (ILs) im Fokus. Die experimentell gefundenen Spektren zeigen eine komplexe Struktur mit vielen Resonanzen. In der Arbeit wurden zwei ILs untersucht. Als Geometrien verwenden wir Clustermodelle, die aus experimentellen Kristallstrukturen extrahiert wurden. Die berechneten Spektren erlauben es, die Resonanzen den Anregungszentren zuzuordnen. Außerdem kann eine erstmals gemessene Doppelresonanz simuliert und erklärt werden. Insgesamt kann die Interpretation der Spektren mithilfe der Simulation signifikant erweitert werden.
In allen Systemen wurde zur Berechnung des NEXAFS-Spektrums eine auf Dichtefunktionaltheorie basierende Methode verwendet (die sogenannte Transition-Potential Methode). Gängige wellenfunktionsbasierte Methoden, wie die Konfigurationswechselwirkung mit Einfachanregungen (CIS), zeigen eine starke Blauverschiebung, wenn als Referenz eine Hartree-Fock Slaterdeterminante verwendet wird. Wir zeigen, dass die Verwendung von kernnah-angeregten Determinanten sowohl das resultierende Spektrum als auch die Anregungsenergien deutlich verbessert. Des Weiteren werden auch Referenzen aus Dichtefunktionalrechnungen getestet. Zusätzlich werden auch Referenzen mit gebrochenen Besetzungszahlen für kernnahe Elektronen verwendet. In der Arbeit werden die Resultate der verschiedenen Referenzen miteinander verglichen. Es zeigt sich, dass Referenzen mit gebrochenen Besetzungszahlen das Spektrum nicht weiter verbessern. Der Einfluss der verwendeten Elektronenstrukturmethode ist eher gering.
Surface-enhanced Raman scattering (SERS) is a promising tool to obtain rich chemical information about analytes at trace levels. However, in order to perform selective experiments on individual molecules, two fundamental requirements have to be fulfilled. On the one hand, areas with high local field enhancement, so-called “hot spots”, have to be created by positioning the supporting metal surfaces in close proximity to each other. In most cases hot spots are formed in the gap between adjacent metal nanoparticles (NPs). On the other hand, the analyte has to be positioned directly in the hot spot in order to profit from the highest signal amplification. The use of DNA origami substrates provides both, the arrangement of AuNPs with nm precision as well as the ability to bind analyte molecules at predefined positions. Consequently, the present cumulative doctoral thesis aims at the development of a novel SERS substrate based on a DNA origami template. To this end, two DNA-functionalized gold nanoparticles (AuNPs) are attached to one DNA origami substrate resulting in the formation of a AuNP dimer and thus in a hot spot within the corresponding gap. The obtained structures are characterized by correlated atomic force microscopy (AFM) and SERS imaging which allows for the combination of structural and chemical information.
Initially, the proof-of principle is presented which demonstrates the potential of the novel approach. It is shown that the Raman signal of 15 nm AuNPs coated with dye-modified DNA
(dye: carboxytetramethylrhodamine (TAMRA)) is significantly higher for AuNP dimers arranged on a DNA origami platform in comparison to single AuNPs. Furthermore, by attaching single TAMRA molecules in the hot spot between two 5 nm AuNPs and optimizing the size of the AuNPs by electroless gold deposition, SERS experiments at the few-molecule level are presented. The initially used DNA origami-AuNPs design is further optimized in many respects. On the one hand, larger AuNPs up to a diameter of 60 nm are used which are additionally treated with a silver enhancement solution to obtain Au-Ag-core-shell NPs. On the other hand, the arrangement of both AuNPs is altered to improve the position of the dye molecule within the hot spot as well as to decrease the gap size between the two particles. With the optimized design the detection of single dye molecules (TAMRA and cyanine 3 (Cy3)) by means of SERS is demonstrated. Quantitatively, enhancement factors up to 10^10 are estimated which is sufficiently high to detect single dye molecules.
In the second part, the influence of graphene as an additional component of the SERS substrate is investigated. Graphene is a two-dimensional material with an outstanding combination of electronical, mechanical and optical properties. Here, it is demonstrated that
single layer graphene (SLG) replicates the shape of underlying non-modified DNA origami
substrates very well, which enables the monitoring of structural alterations by AFM imaging.
In this way, it is shown that graphene encapsulation significantly increases the structural
stability of bare DNA origami substrates towards mechanical force and prolonged exposure
to deionized water.
Furthermore, SLG is used to cover DNA origami substrates which are functionalized with a
40 nm AuNP dimer. In this way, a novel kind of hybrid material is created which exhibits
several advantages compared to the analogue non-covered SERS substrates. First, the fluorescence background of dye molecules that are located in between the AuNP surface and SLG is efficiently reduced. Second, the photobleaching rate of the incorporated dye molecules is decreased up to one order of magnitude. Third, due to the increased photostability of the investigated dye molecules, the performance of polarization-dependent series measurements on individual structures is enabled. This in turn reveals extensive information about the dye molecules in the hot spot as well as about the strain induced within the graphene lattice.
Although SLG can significantly influence the SERS substrate in the aforementioned ways, all
those effects are strongly related to the extent of contact with the underlying AuNP dimer.
Physikalische Hydrogele gewinnen derzeit als Zellsubstrate zunehmend an Interesse, da Viskoelastizität oder Stressrelaxation ein bedeutender Parameter in der Mechanotransduktion ist, der bisher vernachlässigt wurde. In dieser Arbeit wurden multi-funktionelle Polyurethane entworfen, die über einen neuartigen Gelierungsmechanismus physikalische Hydrogele bilden. In Wasser bilden die anionischen Polyurethane spontan Aggregate, welche durch elektrostatische Abstoßung in Lösung gehalten werden. Eine schnelle Gelierung kann von hier aus durch Ladungsabschirmung erreicht werden, wodurch die Aggregation voranschreitet und ein Netzwerk ausgebildet wird. Dies kann durch die Zugabe von verschiedenen Säuren oder Salzen geschehen, sodass sowohl saure (pH 4 - 5) als auch pH-neutrale Hydrogele erhalten werden können. Während konventionelle Hydrogele auf Polyurethan-Basis in der Regel durch toxische isocyanat-haltige Präpolymere hergestellt werden, eignet sich der hier beschriebene physikalische Gelierungsmechanismus für in situ Anwendungen in sensitiven Umgebungen. Sowohl Härte als auch Stressrelaxation der Hydrogele können unabhängig voneinander über einen breiten Bereich eingestellt werden. Darüberhinaus zeichnen sich die Hydrogele durch exzellente Stressregeneration aus.
Luhmann in da Contact Zone
(2016)
Our aim in this contribution is to productively engage with the abstractions and complexities of Luhmann’s conceptions of society from a postcolonial perspective, with a particular focus on the explanatory powers of his sociological systems theory when it leaves the realms of Europe and ventures to describe regions of the global South. In view of its more recent global reception beyond Europe, our aim is to thus – following the lead of Dipesh Chakrabarty – provincialize Luhmann’s system theory especially with regard to its underlying assumptions about a global “world society”. For these purposes, we intend to revisit Luhmann in the post/colonial contact zone: We wish to reread Luhmann in the context of spaces of transcultural encounter where “global designs and local histories” (Mignolo), where inclusion into and exclusion from “world society” (Luhmann) clash and interact in intricate ways. The title of our contribution, ‘Luhmann in da Contact Zone’ is deliberately ambiguous: On the one hand, we of course use ‘Luhmann’ metonymically, as representative of a highly complex theoretical design. We shall cursorily outline this design with a special focus on the notion of a singular, modern “world society”, only to confront it with the epistemic challenges of the contact zone. On the other hand, this critique will also involve the close observation of Niklas Luhman as a human observer (a category which within the logic of systems theory actually does not exist) who increasingly transpires in his late writings on exclusion in the global South. By following this dual strategy, we wish to trace an increasing fracture between one Luhmann and the other, between abstract theoretical design and personalized testimony. It is by exploring and measuring this fracture that we hope to eventually be able to map out the potential of a possibly more productive encounter between systems theory and specific strands of postcolonial theory for a pluritopic reading of global modernity.
Recollecting Bones
(2016)
In the same “guarded, roundabout and reticent way” which Lindsay Barrett invokes for Australian conversations about imperial injustice, Germans, too, must begin to more systematically explore, in Paul Gilroy’s words, “the connections and the differences between anti-semitism and anti-black and other racisms and asses[s] the issues that arise when it can no longer be denied that they interacted over a long time in what might be seen as Fascism’s intellectual, ethical and scientific pre-history” (Gilroy 1996: 26). In the meantime, we need to care for the dead. We need to return them, first, from the status of scientific objects to the status of ancestral human beings, and then progressively, and proactively, as close as possible to the care of those communities from whom they were stolen.
Kleine Kosmopolitismen
(2016)
Postcolonial Justice
(2016)
Postcolonial Piracy
(2016)
Media piracy is a contested term in the academic as much as the public debate. It is used by the corporate industries as a synonym for the theft of protected media content with disastrous economic consequences. It is celebrated by technophile elites as an expression of freedom that ensures creativity as much as free market competition. Marxist critics and activists promote flapiracy as a subversive practice that undermines the capitalist world system and its structural injustices. Artists and entrepreneurs across the globe curse it as a threat to their existence, while many use pirate infrastructures and networks fundamentally for the production and dissemination of their art. For large sections of the population across the global South, piracy is simply the only means of accessing the medial flows of a progressively globalising planet.
Reflections of Lusáni Cissé
(2016)
Sexual Aggression Victimization and Perpetration among Male and Female College Students in Chile
(2016)
Evidence on the prevalence of sexual aggression among college students is primarily based on studies from Western countries. In Chile, a South American country strongly influenced by the Catholic Church, little research on sexual aggression among college students is available. Therefore, the purpose of the present study was to examine the prevalence of sexual aggression victimization and perpetration since the age of 14 (the legal age of consent) in a sample of male and female students aged between 18 and 29 years from five Chilean universities (N = 1135), to consider possible gender differences, and to study the extent to which alcohol was involved in the reported incidents of perpetration and victimization. Sexual aggression victimization and perpetration was measured with a Chilean Spanish version of the Sexual Aggression and Victimization Scale (SAV-S), which includes three coercive strategies (use or threat of physical force, exploitation of an incapacitated state, and verbal pressure), three victim-perpetrator constellations (current or former partners, friends/acquaintances, and strangers), and four sexual acts (sexual touch, attempted sexual intercourse, completed sexual intercourse, and other sexual acts, such as oral sex). Overall, 51.9% of women and 48.0% of men reported at least one incident of sexual victimization, and 26.8% of men and 16.5% of women reported at least one incident of sexual aggression perpetration since the age of 14. For victimization, only few gender differences were found, but significantly more men than women reported sexual aggression perpetration. A large proportion of perpetrators also reported victimization experiences. Regarding victim-perpetrator relationship, sexual aggression victimization and perpetration were more common between persons who knew each other than between strangers. Alcohol use by the perpetrator, victim, or both was involved in many incidents of sexual aggression victimization and perpetration, particularly among strangers. The present data are the first to provide a systematic and detailed picture of sexual aggression among college students in Chile, including victimization and perpetration reports by both men and women and confirming the critical role of alcohol established in past research from Western countries.
Rapidly uplifting coastlines are frequently associated with convergent tectonic boundaries, like subduction zones, which are repeatedly breached by giant megathrust earthquakes. The coastal relief along tectonically active realms is shaped by the effect of sea-level variations and heterogeneous patterns of permanent tectonic deformation, which are accumulated through several cycles of megathrust earthquakes. However, the correlation between earthquake deformation patterns and the sustained long-term segmentation of forearcs, particularly in Chile, remains poorly understood. Furthermore, the methods used to estimate permanent deformation from geomorphic markers, like marine terraces, have remained qualitative and are based on unrepeatable methods. This contrasts with the increasing resolution of digital elevation models, such as Light Detection and Ranging (LiDAR) and high-resolution bathymetric surveys.
Throughout this thesis I study permanent deformation in a holistic manner: from the methods to assess deformation rates, to the processes involved in its accumulation. My research focuses particularly on two aspects: Developing methodologies to assess permanent deformation using marine terraces, and comparing permanent deformation with seismic cycle deformation patterns under different spatial scales along the M8.8 Maule earthquake (2010) rupture zone. Two methods are developed to determine deformation rates from wave-built and wave-cut terraces respectively. I selected an archetypal example of a wave-built terrace at Santa Maria Island studying its stratigraphy and recognizing sequences of reoccupation events tied with eleven radiocarbon sample ages (14C ages). I developed a method to link patterns of reoccupation with sea-level proxies by iterating relative sea level curves for a range of uplift rates. I find the best fit between relative sea-level and the stratigraphic patterns for an uplift rate of 1.5 +- 0.3 m/ka.
A Graphical User Interface named TerraceM® was developed in Matlab®. This novel software tool determines shoreline angles in wave-cut terraces under different geomorphic scenarios. To validate the methods, I select test sites in areas of available high-resolution LiDAR topography along the Maule earthquake rupture zone and in California, USA. The software allows determining the 3D location of the shoreline angle, which is a proxy for the estimation of permanent deformation rates. The method is based on linear interpolations to define the paleo platform and cliff on swath profiles. The shoreline angle is then located by intersecting these interpolations. The
accuracy and precision of TerraceM® was tested by comparing its results with previous assessments, and through an experiment with students in a computer lab setting at the University
of Potsdam.
I combined the methods developed to analyze wave-built and wave-cut terraces to assess regional patterns of permanent deformation along the (2010) Maule earthquake rupture. Wave-built terraces are tied using 12 Infra Red Stimulated luminescence ages (IRSL ages) and shoreline angles in wave-cut terraces are estimated from 170 aligned swath profiles. The comparison of coseismic slip, interseismic coupling, and permanent deformation, leads to three areas of high permanent uplift, terrace warping, and sharp fault offsets. These three areas correlate with regions of high slip and low coupling, as well as with the spatial limit of at least eight historical megathrust ruptures (M8-9.5). I propose that the zones of upwarping at Arauco and Topocalma reflect changes in frictional properties of the megathrust, which result in discrete boundaries for the propagation of mega earthquakes.
To explore the application of geomorphic markers and quantitative morphology in offshore areas I performed a local study of patterns of permanent deformation inferred from hitherto unrecognized drowned shorelines at the Arauco Bay, at the southern part of the (2010) Maule earthquake rupture zone. A multidisciplinary approach, including morphometry, sedimentology, paleontology, 3D morphoscopy, and a landscape Evolution Model is used to recognize, map, and assess local rates and patterns of permanent deformation in submarine environments. Permanent deformation patterns are then reproduced using elastic models to assess deformation rates of an active submarine splay fault defined as Santa Maria Fault System. The best fit suggests a reverse structure with a slip rate of 3.7 m/ka for the last 30 ka. The register of land level changes during the earthquake cycle at Santa Maria Island suggest that most of the deformation may be accrued through splay fault reactivation during mega earthquakes, like the (2010) Maule event. Considering a recurrence time of 150 to 200 years, as determined from historical and geological observations, slip between 0.3 and 0.7 m per event would be required to account for the 3.7 m/ka millennial slip rate. However, if the SMFS slips only every ~1000 years, representing a few megathrust earthquakes, then a slip of ~3.5 m per event would be required to account for the long- term rate. Such event would be equivalent to a magnitude ~6.7 earthquake capable to generate a local tsunami.
The results of this thesis provide novel and fundamental information regarding the amount of permanent deformation accrued in the crust, and the mechanisms responsible for this accumulation at millennial time-scales along the M8.8 Maule earthquake (2010) rupture zone. Furthermore, the results of this thesis highlight the application of quantitative geomorphology and the use of repeatable methods to determine permanent deformation, improve the accuracy of marine terrace assessments, and estimates of vertical deformation rates in tectonically active coastal areas. This is vital information for adequate coastal-hazard assessments and to anticipate realistic earthquake and tsunami scenarios.
Seit der Einführung von Antibiotika in die medizinische Behandlung von bakteriellen Infektionskrankheiten existiert ein Wettlauf zwischen der Evolution von Bakterienresistenzen und der Entwicklung wirksamer Antibiotika. Während bis in die 80er Jahre verstärkt an neuen Antibiotika geforscht wurde, gewinnen multiresistente Keime heute zunehmend die Oberhand. Um einzelne Pathogene erfolgreich nachzuweisen und zu bekämpfen, ist ein grundlegendes Wissen über den Erreger unumgänglich. Bakterielle Proteine, die bei einer Infektion vorrangig vom Immunsystem prozessiert und präsentiert werden, könnten für die Entwicklung von Impfstoffen oder gezielten Therapeutika nützlich sein. Auch für die Diagnostik wären diese immundominanten Proteine interessant. Allerdings herrscht ein Mangel an Wissen über spezifische Antigene vieler pathogener Bakterien, die eine eindeutige Diagnostik eines einzelnen Erregers erlauben würden.
Daher wurden in dieser Arbeit vier verschiedene Humanpathogene mittels Phage Display untersucht: Neisseria gonorrhoeae, Neisseria meningitidis, Borrelia burgdorferi und Clostridium difficile. Hierfür wurden aus der genomischen DNA der vier Erreger Bibliotheken konstruiert und durch wiederholte Selektion und Amplifikation, dem sogenannten Panning, immunogene Proteine isoliert. Für alle Erreger bis auf C. difficile wurden immunogene Proteine aus den jeweiligen Bibliotheken isoliert. Die identifizierten Proteine von N. meningitidis und B. burgdorferi waren größtenteils bekannt, konnten aber in dieser Arbeit durch Phage Display verifiziert werden. Für N. gonorrhoeae wurden 21 potentiell immunogene Oligopeptide isoliert, von denen sechs Proteine als neue zuvor unbeschriebene Proteine mit immunogenem Charakter identifiziert wurden. Von den Phagen-präsentierten Oligopeptide der 21 immunogenen Proteine wurden Epitopmappings mit verschiedenen polyklonalen Antikörpern durchgeführt, um immunogene Bereiche näher zu identifizieren und zu charakterisieren. Bei zehn Proteinen wurden lineare Epitope eindeutig mit drei polyklonalen Antikörpern identifiziert, von fünf weiteren Proteinen waren Epitope mit mindestens einem Antikörper detektierbar. Für eine weitere Charakterisierung der ermittelten Epitope wurden Alaninscans durchgeführt, die eine detaillierte Auskunft über kritische Aminosäuren für die Bindung des Antikörpers an das Epitop geben.
Ausgehend von dem neu identifizierten Protein mit immunogenem Charakter NGO1634 wurden 26 weitere Proteine aufgrund ihrer funktionellen Ähnlichkeit ausgewählt und mithilfe bioinformatischer Analysen auf ihre Eignung zur Entwicklung einer diagnostischen Anwendung analysiert. Durch Ausschluss der meisten Proteine aufgrund ihrer Lokalisation, Membrantopologie oder unspezifischen Proteinsequenz wurden scFv-Antikörper gegen acht Proteine mittels Phage Display generiert und anschließend als scFv-Fc-Fusionsantikörper produziert und charakterisiert.
Die hier identifizierten Proteine und linearen Epitope könnten einen Ansatzpunkt für die Entwicklung einer diagnostischen oder therapeutischen Anwendung bieten. Lineare Epitopsequenzen werden häufig für die Impfstoffentwicklung eingesetzt, sodass vor allem die in dieser Arbeit bestimmten Epitope von Membranproteinen interessante Kandidaten für weitere Untersuchungen in diese Richtung sind. Durch weitere Untersuchungen könnten möglicherweise unbekannte Virulenzfaktoren entdeckt werden, deren Inhibierung einen entscheidenden Einfluss auf Infektionen haben könnten.
Diese Arbeit zu Grunde liegenden Forschung zielte darauf ab, neue schmelzbare Acrylnitril-Copolymere zu entwickeln. Diese sollten im Anschluss über ein Schmelzspinnverfahren zur Chemiefaser geformt und im letzten Schritt zur Carbonfaser konvertiert werden. Zu diesem Zweck wurden zunächst orientierende Untersuchungen an unterschiedlichen Copolymeren des Acrylnitril aus Lösungspolymerisation durchgeführt. Die Untersuchungen zeigten, dass elektrostatische Wechselwirkungen besser als sterische Abschirmung dazu geeignet sind, Schmelzbarkeit unterhalb der Zersetzungstemperatur von Polyacrylnitril zu bewirken. Aus der Vielzahl untersuchter Copolymere stellten sich jene mit Methoxyethylacrylat (MEA) als am effektivsten heraus. Für diese Copolymere wurden sowohl die Copolymerisationsparameter bestimmt als auch die grundlegende Kinetik der Lösungspolymerisation untersucht. Die Copolymere mit MEA wurden über Schmelzspinnen zur Faser umgeformt und diese dann untersucht. Hierbei wurden auch Einflüsse verschiedener Parameter, wie z.B. die der Molmasse, auf die Fasereigenschaften und -herstellung untersucht. Zuletzt wurde ein Heterophasenpolymerisationsverfahren zur Herstellung von Copolymeren aus AN/MEA entwickelt; dadurch konnten die Materialeigenschaften weiter verbessert werden. Zur Unterdrückung der thermoplastischen Eigenschaften der Fasern wurde ein geeignetes Verfahren entwickelt und anschließend die Konversion zu Carbonfasern durchgeführt.
Intermontane valley fills
(2016)
Sedimentary valley fills are a widespread characteristic of mountain belts around the world. They transiently store material over time spans ranging from thousands to millions of years and therefore play an important role in modulating the sediment flux from the orogen to the foreland and to oceanic depocenters. In most cases, their formation can be attributed to specific fluvial conditions, which are closely related to climatic and tectonic processes. Hence, valley-fill deposits constitute valuable archives that offer fundamental insight into landscape evolution, and their study may help to assess the impact of future climate change on sediment dynamics.
In this thesis I analyzed intermontane valley-fill deposits to constrain different aspects of the climatic and tectonic history of mountain belts over multiple timescales. First, I developed a method to estimate the thickness distribution of valley fills using artificial neural networks (ANNs). Based on the assumption of geometrical similarity between exposed and buried parts of the landscape, this novel and highly automated technique allows reconstructing fill thickness and bedrock topography on the scale of catchments to entire mountain belts.
Second, I used the new method for estimating the spatial distribution of post-glacial sediments that are stored in the entire European Alps. A comparison with data from exploratory drillings and from geophysical surveys revealed that the model reproduces the measurements with a root mean squared error (RMSE) of 70m and a coefficient of determination (R2) of 0.81. I used the derived sediment thickness estimates in combination with a model of the Last Glacial Maximum (LGM) icecap to infer the lithospheric response to deglaciation, erosion and deposition, and deduce their relative contribution to the present-day rock-uplift rate. For a range of different lithospheric and upper mantle-material properties, the results suggest that the long-wavelength uplift signal can be explained by glacial isostatic adjustment with a small erosional contribution and a substantial but localized tectonic component exceeding 50% in parts of the Eastern Alps and in the Swiss Rhône Valley. Furthermore, this study reveals the particular importance of deconvolving the potential components of rock uplift when interpreting recent movements along active orogens and how this can be used to constrain physical properties of the Earth’s interior.
In a third study, I used the ANN approach to estimate the sediment thickness of alluviated reaches of the Yarlung Tsangpo River, upstream of the rapidly uplifting Namche Barwa massif. This allowed my colleagues and me to reconstruct the ancient river profile of the Yarlung Tsangpo, and to show that in the past, the river had already been deeply incised into the eastern margin of the Tibetan Plateau. Dating of basal sediments from drill cores that reached the paleo-river bed to 2–2.5 Ma are consistent with mineral cooling ages from the Namche Barwa massif, which indicate initiation of rapid uplift at ~4 Ma. Hence, formation of the Tsangpo gorge and aggradation of the voluminous valley fill was most probably a consequence of rapid uplift of the Namche Barwa massif and thus tectonic activity.
The fourth and last study focuses on the interaction of fluvial and glacial processes at the southeastern edge of the Karakoram. Paleo-ice-extent indicators and remnants of a more than 400-m-thick fluvio-lacustrine valley fill point to blockage of the Shyok River, a main tributary of the upper Indus, by the Siachen Glacier, which is the largest glacier in the Karakoram Range. Field observations and 10Be exposure dating attest to a period of recurring lake formation and outburst flooding during the penultimate glaciation prior to ~110 ka. The interaction of Rivers and Glaciers all along the Karakorum is considered a key factor in landscape evolution and presumably promoted headward erosion of the Indus-Shyok drainage system into the western margin of the Tibetan Plateau.
The results of this thesis highlight the strong influence of glaciation and tectonics on valley-fill formation and how this has affected the evolution of different mountain belts. In the Alps valley-fill deposition influenced the magnitude and pattern of rock uplift since ice retreat approximately 17,000 years ago. Conversely, the analyzed valley fills in the Himalaya are much older and reflect environmental conditions that prevailed at ~110 ka and ~2.5 Ma, respectively. Thus, the newly developed method has proven useful for inferring the role of sedimentary valley-fill deposits in landscape evolution on timescales ranging from 1,000 to 10,000,000 years.
Introduction: Adequate cognitive function in patients is a prerequisite for successful implementation of patient education and lifestyle coping in comprehensive cardiac rehabilitation (CR) programs. Although the association between cardiovascular diseases and cognitive impairments (CIs) is well known, the prevalence particularly of mild CI in CR and the characteristics of affected patients have been insufficiently investigated so far.
Methods: In this prospective observational study, 496 patients (54.5 ± 6.2 years, 79.8% men) with coronary artery disease following an acute coronary event (ACE) were analyzed. Patients were enrolled within 14 days of discharge from the hospital in a 3-week inpatient CR program. Patients were tested for CI using the Montreal Cognitive Assessment (MoCA) upon admission to and discharge from CR. Additionally, sociodemographic, clinical, and physiological variables were documented. The data were analyzed descriptively and in a multivariate stepwise backward elimination regression model with respect to CI.
Results: At admission to CR, the CI (MoCA score < 26) was determined in 182 patients (36.7%). Significant differences between CI and no CI groups were identified, and CI group was associated with high prevalence of smoking (65.9 vs 56.7%, P = 0.046), heavy (physically demanding) workloads (26.4 vs 17.8%, P < 0.001), sick leave longer than 1 month prior to CR (28.6 vs 18.5%, P = 0.026), reduced exercise capacity (102.5 vs 118.8 W, P = 0.006), and a shorter 6-min walking distance (401.7 vs 421.3 m, P = 0.021) compared to no CI group. The age- and education-adjusted model showed positive associations with CI only for sick leave more than 1 month prior to ACE (odds ratio [OR] 1.673, 95% confidence interval 1.07–2.79; P = 0.03) and heavy workloads (OR 2.18, 95% confidence interval 1.42–3.36; P < 0.01).
Conclusion: The prevalence of CI in CR was considerably high, affecting more than one-third of cardiac patients. Besides age and education level, CI was associated with heavy workloads and a longer sick leave before ACE.
Die Empirie des beginnenden 21. Jahrhunderts weist mehr autoritäre Regime aus als am Ende des 20. Jahrhunderts angenommen. Die gegenwärtige Autoritarismusforschung versucht die Fortdauer dieses Regimetyps in Hinblick auf die politischen Institutionen zu erklären – dabei bleiben politische Akteure, die nicht zum Herrschaftszentrum gehören, außen vor.
Das vorliegende Projekt untersucht die Rolle und Funktion politischer Opposition in autoritären Regimen. Es wird davon ausgegangen, dass sich an der Opposition eine signifikante Charakteristik autoritärer Regime manifestiert. Das akteurszentrierte Projekt ist der qualitativ orientierten Politikwissenschaft zuzurechnen und verknüpft das Autoritarismuskonzept von Juan Linz mit klassischen Ansätzen der Oppositionsforschung und macht diese Theorien für die gegenwärtige Autoritarismusforschung nutzbar.
Die eigens entwickelte elitenorientierte Oppositionstypologie wird am Beispiel Kenias im Zeitraum 1990-2005 angewendet. Die Oppositionsgruppen werden im Institutionengefüge autoritärer Regime verortet und ihr politisches Agieren in den Dimensionen Handlungsstatus, Handlungsüberzeugung und Handlungsstrategie analysiert. Unter Beachtung der historisch gewachsenen regionalen und kulturellen Spezifika wird angenommen, dass generelle, Regionen übergreifende Aussagen zur Opposition in autoritären Regimen getroffen werden können: Kein Oppositionstyp kann allein einen Herrschaftswechsel bewirken. Der Wechsel bzw. die Fortdauer der Herrschaft hängt von der Dominanz bestimmter Oppositionstypen im Oppositionsgeflecht sowie der gleichzeitigen Schwäche anderer Oppositionstypen ab.
Durch die konzeptionelle Beschäftigung mit Opposition sowie deren empirische Erschließung soll ein substantieller Beitrag für die notwendige Debatte um autoritäre Regime im 21. Jahrhundert geleistet werden.
The Earth’s shallow subsurface with sedimentary cover acts as a waveguide to any incoming wavefield. Within the framework of my thesis, I focused on the characterization of this shallow subsurface within tens to few hundreds of meters of sediment cover. I imaged the seismic 1D shear wave velocity (and possibly the 1D compressional wave velocity). This information is not only required for any seismic risk assessment, geotechnical engineering or microzonation activities, but also for exploration and global seismology where site effects are often neglected in seismic waveform modeling.
First, the conventional frequency-wavenumber (f - k) technique is used to derive the dispersion characteristic of the propagating surface waves recorded using distinct arrays of seismometers in 1D and 2D configurations. Further, the cross-correlation technique is applied to seismic array data to estimate the Green’s function between receivers pairs combination assuming one is the source and the other the receiver. With the consideration of a 1D media, the estimated cross-correlation Green’s functions are sorted with interstation distance in a virtual 1D active seismic experiment. The f - k technique is then used to estimate the dispersion curves. This integrated analysis is important for the interpretation of a large bandwidth of the phase velocity dispersion curves and therefore improving the resolution of the estimated 1D Vs profile.
Second, the new theoretical approach based on the Diffuse Field Assumption (DFA) is used for the interpretation of the observed microtremors H/V spectral ratio. The theory is further extended in this research work to include not only the interpretation of the H/V measured at the surface, but also the H/V measured at depths and in marine environments. A modeling and inversion of synthetic H/V spectral ratio curves on simple predefined geological structures shows an almost perfect recovery of the model parameters (mainly Vs and to a lesser extent Vp). These results are obtained after information from a receiver at depth has been considered in the inversion.
Finally, the Rayleigh wave phase velocity information, estimated from array data, and the H/V(z, f) spectral ratio, estimated from a single station data, are combined and inverted for the velocity profile information. Obtained results indicate an improved depth resolution in comparison to estimations using the phase velocity dispersion curves only. The overall estimated sediment thickness is comparable to estimations obtained by inverting the full micortremor H/V spectral ratio.
We study the interplay between analysis on manifolds with singularities and complex analysis and develop new structures of operators based on the Mellin transform and tools for iterating the calculus for higher singularities. We refer to the idea of interpreting boundary value problems (BVPs) in terms of pseudo-differential operators with a principal symbolic hierarchy, taking into account that BVPs are a source of cone and edge operator algebras. The respective cone and edge pseudo-differential algebras in turn are the starting point of higher corner theories. In addition there are deep relationships between corner operators and complex analysis. This will be illustrated by the Mellin symbolic calculus.
Transmorphic
(2016)
Defining Graphical User Interfaces (GUIs) through functional abstractions can reduce the complexity that arises from mutable abstractions. Recent examples, such as Facebook's React GUI framework have shown, how modelling the view as a functional projection from the application state to a visual representation can reduce the number of interacting objects and thus help to improve the reliabiliy of the system. This however comes at the price of a more rigid, functional framework where programmers are forced to express visual entities with functional abstractions, detached from the way one intuitively thinks about the physical world.
In contrast to that, the GUI Framework Morphic allows interactions in the graphical domain, such as grabbing, dragging or resizing of elements to evolve an application at runtime, providing liveness and directness in the development workflow. Modelling each visual entity through mutable abstractions however makes it difficult to ensure correctness when GUIs start to grow more complex. Furthermore, by evolving morphs at runtime through direct manipulation we diverge more and more from the symbolic description that corresponds to the morph. Given that both of these approaches have their merits and problems, is there a way to combine them in a meaningful way that preserves their respective benefits?
As a solution for this problem, we propose to lift Morphic's concept of direct manipulation from the mutation of state to the transformation of source code. In particular, we will explore the design, implementation and integration of a bidirectional mapping between the graphical representation and a functional and declarative symbolic description of a graphical user interface within a self hosted development environment. We will present Transmorphic, a functional take on the Morphic GUI Framework, where the visual and structural properties of morphs are defined in a purely functional, declarative fashion. In Transmorphic, the developer is able to assemble different morphs at runtime through direct manipulation which is automatically translated into changes in the code of the application. In this way, the comprehensiveness and predictability of direct manipulation can be used in the context of a purely functional GUI, while the effects of the manipulation are reflected in a medium that is always in reach for the programmer and can even be used to incorporate the source transformations into the source files of the application.
The visceral protein transthyretin (TTR) is frequently affected by oxidative post-translational protein modifications (PTPMs) in various diseases. Thus, better insight into structure-function relationships due to oxidative PTPMs of TTR should contribute to the understanding of pathophysiologic mechanisms. While the in vivo analysis of TTR in mammalian models is complex, time- and resource-consuming, transgenic Caenorhabditis elegans expressing hTTR provide an optimal model for the in vivo identification and characterization of drug-mediated oxidative PTPMs of hTTR by means of matrix assisted laser desorption/ionization – time of flight – mass spectrometry (MALDI-TOF-MS). Herein, we demonstrated that hTTR is expressed in all developmental stages of Caenorhabditis elegans, enabling the analysis of hTTR metabolism during the whole life-cycle. The suitability of the applied model was verified by exposing worms to D-penicillamine and menadione. Both drugs induced substantial changes in the oxidative PTPM pattern of hTTR. Additionally, for the first time a covalent binding of both drugs with hTTR was identified and verified by molecular modelling.
Variations in the distribution of mass within an orogen may lead to transient sediment storage, which in turn might affect the state of stress and the level of fault activity. Distinguishing between different forcing mechanisms causing variations of sediment flux and tectonic activity, is therefore one of the most challenging tasks in understanding the spatiotemporal evolution of active mountain belts.
The Himalayan mountain belt is one of the most significant Cenozoic collisional mountain belt, formed due to collision between northward-bound Indian Plate and the Eurasian Plate during the last 55-50 Ma. Ongoing convergence of these two tectonic plates is accommodated by faulting and folding within the Himalayan arc-shaped orogen and the continued lateral and vertical growth of the Tibetan Plateau and mountain belts adjacent to the plateau as well as regions farther north. Growth of the Himalayan orogen is manifested by the development of successive south-vergent thrust systems. These thrust systems divide the orogen into different morphotectonic domains. From north to south these thrusts are the Main Central Thrust (MCT), the Main Boundary Thrust (MBT) and the Main Frontal Thrust (MFT). The growing topography interacts with moisture-bearing monsoonal winds, which results in pronounced gradients in rainfall, weathering, erosion and sediment transport toward the foreland and beyond. However, a fraction of this sediment is trapped and transiently stored within the intermontane valleys or ‘dun’s within the lower-elevation foothills of the range. Improved understanding of the spatiotemporal evolution of these sediment archives could provide a unique opportunity to decipher the triggers of variations in sediment production, delivery and storage in an actively deforming mountain belt and support efforts to test linkages between sediment volumes in intermontane basins and changes in the shallow crustal stress field. As sediment redistribution in mountain belts on timescales of 102-104 years can effect cultural characteristics and infrastructure in the intermontane valleys and may even impact the seismotectonics of a mountain belt, there is a heightened interest in understanding sediment-routing processes and causal relationships between tectonism, climate and topography. It is here at the intersection between tectonic processes and superposed climatic and sedimentary processes in the Himalayan orogenic wedge, where my investigation is focused on. The study area is the intermontane Kangra Basin in the northwestern Sub-Himalaya, because the characteristics of the different Himalayan morphotectonic provinces are well developed, the area is part of a region strongly influenced by monsoonal forcing, and the existence of numerous fluvial terraces provides excellent strain markers to assess deformation processes within the Himalayan orogenic wedge. In addition, being located in front of the Dhauladhar Range the region is characterized by pronounced gradients in past and present-day erosion and sediment processes associated with repeatedly changing climatic conditions. In light of these conditions I analysed climate-driven late Pleistocene-Holocene sediment cycles in this tectonically active region, which may be responsible for triggering the tectonic re-organization within the Himalayan orogenic wedge, leading to out-of-sequence thrusting, at least since early Holocene.
The Kangra Basin is bounded by the MBT and the Sub-Himalayan Jwalamukhi Thrust (JMT) in the north and south, respectively and transiently stores sediments derived from the Dhauladhar Range. The Basin contains ~200-m-thick conglomerates reflecting two distinct aggradation phases; following aggradation, several fluvial terraces were sculpted into these fan deposits. 10Be CRN surface exposure dating of these terrace levels provides an age of 53.4±3.2 ka for the highest-preserved terrace (AF1); subsequently, this surface was incised until ~15 ka, when the second fan (AF2) began to form. AF2 fan aggradation was superseded by episodic Holocene incision, creating at least four terrace levels. We find a correlation between variations in sediment transport and ∂18O records from regions affected by the Indian Summer Monsoon (ISM). During strengthened ISMs sand post-LGM glacial retreat, aggradation occurred in the Kangra Basin, likely due to high sediment flux, whereas periods of a weakened ISM coupled with lower sediment supply coincided with renewed re-incision.
However, the evolution of fluvial terraces along Sub-Himalayan streams in the Kangra sector is also forced by tectonic processes. Back-tilted, folded terraces clearly document tectonic activity of the JMT. Offset of one of the terrace levels indicates a shortening rate of 5.6±0.8 to 7.5±1.0 mm.a-1 over the last ~10 ka. Importantly, my study reveals that late Pleistocene/Holocene out-of-sequence thrusting accommodates 40-60% of the total 14±2 mm.a-1 shortening partitioned throughout the Sub-Himalaya. Importantly, the JMT records shortening at a lower rate over longer timescales hints towards out-of-sequence activity within the Sub-Himalaya. Re-activation of the JMT could be related to changes in the tectonic stress field caused by large-scale sediment removal from the basin. I speculate that the deformation processes of the Sub-Himalaya behave according to the predictions of critical wedge model and assume the following: While >200m of sediment aggradation would trigger foreland-ward propagation of the deformation front, re-incision and removal of most of the stored sediments (nearly 80-85% of the optimum basin-fill) would again create a sub-critical condition of the wedge taper and trigger the retreat of the deformation front.
While tectonism is responsible for the longer-term processes of erosion associated with steepening hillslopes, sediment cycles in this environment are mainly the result of climatic forcing. My new 10Be cosmogenic nuclide exposure dates and a synopsis of previous studies show the late Pleistocene to Holocene alluvial fills and fluvial terraces studied here record periodic fluctuations of sediment supply and transport capacity on timescales of 1000-100000 years. To further evaluate the potential influence of climate change on these fluctuations, I compared the timing of aggradation and incision phases recorded within remnant alluvial fans and terraces with continental climate archives such as speleothems in neighboring regions affected by monsoonal precipitation. Together with previously published OSL ages yielding the timing of aggradation, I find a correlation between variations in sediment transport with oxygen-isotope records from regions affected by the Indian Summer Monsoon (ISM). Accordingly, during periods of increased monsoon intensity (transitions from dry and cold to wet and warm periods – MIS4 to MIS3 and MIS2 to MIS1) (MIS=marine isotope stage) and post-Last Glacial Maximum glacial retreat, aggradation occurred in the Kangra Basin, likely due to high sediment flux. Conversely, periods of weakened monsoon intensity or lower sediment supply coincide with re-incision of the existing basin-fill.
Finally, my study entails part of a low-temperature thermochronology study to assess the youngest exhumation history of the Dhauladhar Range. Zircon helium (ZHe) ages and existing low-temperature data sets (ZHe, apatite fission track (AFT)) across this range, together with 3D thermokinematic modeling (PECUBE) reveals constraints on exhumation and activity of the range-bounding Main Boundary Thrust (MBT) since at least mid-Miocene time. The modeling results indicate mean slip rates on the MBT-fault ramp of ~2 – 3 mm.a-1 since its activation. This has lead to the growth of the >5-km-high frontal Dhauladhar Range and continuous deep-seated exhumation and erosion. The obtained results also provide interesting constraints of deformation patterns and their variation along strike. The results point towards the absence of the time-transient ‘mid-crustal ramp’ in the basal decollement and
duplexing of the Lesser Himalayan sequence, unlike the nearby regions or even the central Nepal domain. A fraction of convergence (~10-15%) is accommodated along the deep-seated MBT-ramp, most likely merging into the MHT. This finding is crucial for a rigorous assessment of the overall level of tectonic activity in the Himalayan morphotectonic provinces as it contradicts recently-published geodetic shortening estimates. In these studies, it has been proposed that the total Himalayan shortening in the NW Himalaya is accommodated within the Sub-Himalaya whereas no tectonic activity is assigned to the MBT.
Interplay of coupling and common noise at the transition to synchrony in oscillator populations
(2016)
There are two ways to synchronize oscillators: by coupling and by common forcing, which can be pure noise. By virtue of the Ott-Antonsen ansatz for sine-coupled phase oscillators, we obtain analytically tractable equations for the case where both coupling and common noise are present. While noise always tends to synchronize the phase oscillators, the repulsive coupling can act against synchrony, and we focus on this nontrivial situation. For identical oscillators, the fully synchronous state remains stable for small repulsive coupling; moreover it is an absorbing state which always wins over the asynchronous regime. For oscillators with a distribution of natural frequencies, we report on a counter-intuitive effect of dispersion (instead of usual convergence) of the oscillators frequencies at synchrony; the latter effect disappears if noise vanishes.
Editorial (Dr. Roswitha Lohwaßer) ; Schon im Studium von gelingenden Schulen lernen (Jannis Andresen, Jakob Erichsen) ; Wie ein Funke überspringt (Laura Zrenner) ; Lerneffekte unter der Lupe (Ariane Faulian) ; Die Lernreise als Ultima Ratio? (Leroy Großmann) ; Die Lernreise als Schulperspektive (Laura Zrenner) ; Teamgeist gefragt (Cornelia Brückner) ; Wunschberuf Lehrerin (Robin Miska) ; Gelebte Integration (Cornelia Brückner) ; Souverän Führen im Unterricht (Dr. Helga Breuninger, Marina Rottig, Prof. Dr. Wilfried Schley) ; Was lernen Lehramtsstudierende durch ein videogestütztes Klassenmanagement-Training? (Dr. Janine Neuhaus, Mirko Wendland)
This thesis is focused on the study and the exact simulation of two classes of real-valued Brownian diffusions: multi-skew Brownian motions with constant drift and Brownian diffusions whose drift admits a finite number of jumps.
The skew Brownian motion was introduced in the sixties by Itô and McKean, who constructed it from the reflected Brownian motion, flipping its excursions from the origin with a given probability. Such a process behaves as the original one except at the point 0, which plays the role of a semipermeable barrier. More generally, a skew diffusion with several semipermeable barriers, called multi-skew diffusion, is a diffusion everywhere except when it reaches one of the barriers, where it is partially reflected with a probability depending on that particular barrier. Clearly, a multi-skew diffusion can be characterized either as solution of a stochastic differential equation involving weighted local times (these terms providing the semi-permeability) or by its infinitesimal generator as Markov process.
In this thesis we first obtain a contour integral representation for the transition semigroup of the multiskew Brownian motion with constant drift, based on a fine analysis of its complex properties. Thanks to this representation we write explicitly the transition densities of the two-skew Brownian motion with constant drift as an infinite series involving, in particular, Gaussian functions and their tails.
Then we propose a new useful application of a generalization of the known rejection sampling method. Recall that this basic algorithm allows to sample from a density as soon as one finds an - easy to sample - instrumental density verifying that the ratio between the goal and the instrumental densities is a bounded function. The generalized rejection sampling method allows to sample exactly from densities for which indeed only an approximation is known. The originality of the algorithm lies in the fact that one finally samples directly from the law without any approximation, except the machine's.
As an application, we sample from the transition density of the two-skew Brownian motion with or without constant drift. The instrumental density is the transition density of the Brownian motion with constant drift, and we provide an useful uniform bound for the ratio of the densities. We also present numerical simulations to study the efficiency of the algorithm.
The second aim of this thesis is to develop an exact simulation algorithm for a Brownian diffusion whose drift admits several jumps. In the literature, so far only the case of a continuous drift (resp. of a drift with one finite jump) was treated. The theoretical method we give allows to deal with any finite number of discontinuities. Then we focus on the case of two jumps, using the transition densities of the two-skew Brownian motion obtained before. Various examples are presented and the efficiency of our approach is discussed.
Understanding the role of natural climate variability under the pressure of human induced changes of climate and landscapes, is crucial to improve future projections and adaption strategies. This doctoral thesis aims to reconstruct Holocene climate and environmental changes in NE Germany based on annually laminated lake sediments. The work contributes to the ICLEA project (Integrated CLimate and Landscape Evolution Analyses). ICLEA intends to compare multiple high-resolution proxy records with independent chronologies from the N central European lowlands, in order to disentangle the impact of climate change and human land use on landscape development during the Lateglacial and Holocene. In this respect, two study sites in NE Germany are investigated in this doctoral project, Lake Tiefer See and palaeolake Wukenfurche. While both sediment records are studied with a combination of high-resolution sediment microfacies and geochemical analyses (e.g. µ-XRF, carbon geochemistry and stable isotopes), detailed proxy understanding mainly focused on the continuous 7.7 m long sediment core from Lake Tiefer See covering the last ~6000 years. Three main objectives are pursued at Lake Tiefer See: (1) to perform a reliable and independent chronology, (2) to establish microfacies and geochemical proxies as indicators for climate and environmental changes, and (3) to trace the effects of climate variability and human activity on sediment deposition.
Addressing the first aim, a reliable chronology of Lake Tiefer See is compiled by using a multiple-dating concept. Varve counting and tephra findings form the chronological framework for the last ~6000 years. The good agreement with independent radiocarbon dates of terrestrial plant remains verifies the robustness of the age model. The resulting reliable and independent chronology of Lake Tiefer See and, additionally, the identification of nine tephras provide a valuable base for detailed comparison and synchronization of the Lake Tiefer See data set with other climate records. The sediment profile of Lake Tiefer See exhibits striking alternations between well-varved and non-varved sediment intervals. The combination of microfacies, geochemical and microfossil (i.e. Cladocera and diatom) analyses indicates that these changes of varve preservation are caused by variations of lake circulation in Lake Tiefer See. An exception is the well-varved sediment deposited since AD 1924, which is mainly influenced by human-induced lake eutrophication. Well-varved intervals before the 20th century are considered to reflect phases of reduced lake circulation and, consequently, stronger anoxic conditions. Instead, non-varved intervals indicate increased lake circulation in Lake Tiefer See, leading to more oxygenated conditions at the lake ground. Furthermore, lake circulation is not only influencing sediment deposition, but also geochemical processes in the lake. As, for example, the proxy meaning of δ13COM varies in time in response to changes of the oxygen regime in the lake hypolinion. During reduced lake circulation and stronger anoxic conditions δ13COM is influenced by microbial carbon cycling. In contrast, organic matter degradation controls δ13COM during phases of intensified lake circulation and more oxygenated conditions. The varve preservation indicates an increasing trend of lake circulation at Lake Tiefer See after ~4000 cal a BP. This trend is superimposed by decadal to centennial scale variability of lake circulation intensity. Comparison to other records in Central Europe suggests that the long-term trend is probably related to gradual changes in Northern Hemisphere orbital forcing, which induced colder and windier conditions in Central Europe and, therefore, reinforced lake circulation. Decadal to centennial scale periods of increased lake circulation coincide with settlement phases at Lake Tiefer See, as inferred from pollen data of the same sediment record. Deforestation reduced the wind shelter of the lake, which probably increased the sensitivity of lake circulation to wind stress. However, results of this thesis also suggest that several of these phases of increased lake circulation are additionally reinforced by climate changes. A first indication is provided by the comparison to the Baltic Sea record, which shows striking correspondence between major non-varved intervals at Lake Tiefer See and bioturbated sediments in the Baltic Sea. Furthermore, a preliminary comparison to the ICLEA study site Lake Czechowskie (N central Poland) shows a coincidence of at least three phases of increased lake circulation in both lakes, which concur with periods of known climate changes (2.8 ka event, ’Migration Period’ and ’Little Ice Age’). These results suggest an additional over-regional climate forcing also on short term increased of lake circulation in Lake Tiefer See.
In summary, the results of this thesis suggest that lake circulation at Lake Tiefer See is driven by a combination of long-term and short-term climate changes as well as of anthropogenic deforestation phases. Furthermore, the lake circulation drives geochemical cycles in the lake affecting the meaning of proxy data. Therefore, the work presented here expands the knowledge of climate and environmental variability in NE Germany. Furthermore, the integration of the Lake Tiefer See multi-proxy record in a regional comparison with another ICLEA side, Lake Czechowskie, enabled to better decipher climate changes and human impact on the lake system. These first results suggest a huge potential for further detailed regional comparisons to better understand palaeoclimate dynamics in N central Europe.
Services that operate over the Internet are under constant threat of being exposed to fraudulent use. Maintaining good user experience for legitimate users often requires the classification of entities as malicious or legitimate in order to initiate countermeasures. As an example, inbound email spam filters decide for spam or non-spam. They can base their decision on both the content of each email as well as on features that summarize prior emails received from the sending server. In general, discriminative classification methods learn to distinguish positive from negative entities. Each decision for a label may be based on features of the entity and related entities. When labels of related entities have strong interdependencies---as can be assumed e.g. for emails being delivered by the same user---classification decisions should not be made independently and dependencies should be modeled in the decision function. This thesis addresses the formulation of discriminative classification problems that are tailored for the specific demands of the following three Internet security applications. Theoretical and algorithmic solutions are devised to protect an email service against flooding of user inboxes, to mitigate abusive usage of outbound email servers, and to protect web servers against distributed denial of service attacks.
In the application of filtering an inbound email stream for unsolicited emails, utilizing features that go beyond each individual email's content can be valuable. Information about each sending mail server can be aggregated over time and may help in identifying unwanted emails. However, while this information will be available to the deployed email filter, some parts of the training data that are compiled by third party providers may not contain this information. The missing features have to be estimated at training time in order to learn a classification model. In this thesis an algorithm is derived that learns a decision function that integrates over a distribution of values for each missing entry. The distribution of missing values is a free parameter that is optimized to learn an optimal decision function.
The outbound stream of emails of an email service provider can be separated by the customer IDs that ask for delivery. All emails that are sent by the same ID in the same period of time are related, both in content and in label. Hijacked customer accounts may send batches of unsolicited emails to other email providers, which in turn might blacklist the sender's email servers after detection of incoming spam emails. The risk of being blocked from further delivery depends on the rate of outgoing unwanted emails and the duration of high spam sending rates. An optimization problem is developed that minimizes the expected cost for the email provider by learning a decision function that assigns a limit on the sending rate to customers based on the each customer's email stream.
Identifying attacking IPs during HTTP-level DDoS attacks allows to block those IPs from further accessing the web servers. DDoS attacks are usually carried out by infected clients that are members of the same botnet and show similar traffic patterns. HTTP-level attacks aim at exhausting one or more resources of the web server infrastructure, such as CPU time. If the joint set of attackers cannot increase resource usage close to the maximum capacity, no effect will be experienced by legitimate users of hosted web sites. However, if the additional load raises the computational burden towards the critical range, user experience will degrade until service may be unavailable altogether. As the loss of missing one attacker depends on block decisions for other attackers---if most other attackers are detected, not blocking one client will likely not be harmful---a structured output model has to be learned. In this thesis an algorithm is developed that learns a structured prediction decoder that searches the space of label assignments, guided by a policy.
Each model is evaluated on real-world data and is compared to reference methods. The results show that modeling each classification problem according to the specific demands of the task improves performance over solutions that do not consider the constraints inherent to an application.
Der Klimawandel
(2016)
Was ist Gerechtigkeit? Wie könnten gerechte Regelungen aussehen für die Katastrophen und Leiden, die der Klimawandel auslöst bzw. auslösen wird? Diese sind häufig ungerecht, weil sie oft deutlich stärker diejenigen treffen, die am wenigsten zur Klimaveränderung beigetragen haben.
Doch was genau verstehen wir unter dem Schlagwort: ‚Klimawandel‘? Und kann dieser wirklich den Menschen direkt treffen? Ein kurzer naturwissenschaftlicher Abriss klärt hier die wichtigsten Fragen.
Da es sich hierbei um eine philosophische Arbeit handelt, muss zunächst geklärt werden, ob der Mensch überhaupt die Ursache von so etwas sein kann wie z.B. der Klimaerwärmung. Robert Spaemanns These dazu ist, dass der Mensch durch seinen freien Willen mit seinen Einzelhandlungen das Weltgeschehen verändern kann. Hans Jonas fügt dem hinzu, dass wir durch diese Fähigkeit, verantwortlich sind für die gewollten und ungewollten Folgen unserer Handlungen.
Damit wäre aus naturwissenschaftlicher Sicht (1. Teil der Arbeit) und aus philosophischer Sicht (Anfang 2. Teil) geklärt, dass der Mensch mit größter Wahrscheinlichkeit die Ursache des Klimawandels ist und diese Verursachung moralische Konsequenzen für ihn hat.
Ein philosophischer Gerechtigkeitsbegriff wird aus der Kantischen Rechts- und Moralphilosophie entwickelt, weil diese die einzige ist, die dem Menschen überhaupt ein Recht auf Rechte zusprechen kann. Diese entspringt der transzendentalen Freiheitsfähigkeit des Menschen, weshalb jedem das Recht auf Rechte absolut und immer zukommt. Gleichzeitig mündet Kants Philosophie wiederum in dem Freiheitsgedanken, indem Gerechtigkeit nur existiert, wenn alle Menschen gleichermaßen frei sein können.
Was heißt das konkret? Wie könnte Gerechtigkeit in der Realität wirklich umgesetzt werden? Die Realisierung schlägt zwei Grundrichtungen ein. John Rawls und Stefan Gosepath beschäftigen sich u.a. eingehend mit der prozeduralen Gerechtigkeit, was bedeutet, dass gerechte Verfahren gefunden werden, die das gesellschaftliche Zusammenleben regeln. Das leitende Prinzip hierfür ist vor allem: ein Mitbestimmungsrecht aller, so dass sich im Prinzip alle Bürger ihre Gesetze selbst geben und damit frei handeln.
In Bezug auf den Klimawandel steht die zweite Ausrichtung im Vordergrund – die distributive oder auch Verteilungs-Gerechtigkeit. Materielle Güter müssen so aufgeteilt werden, dass auch trotz empirischer Unterschiede alle Menschen als moralische Subjekte anerkannt werden und frei sein können.
Doch sind diese philosophischen Schlussfolgerungen nicht viel zu abstrakt, um auf ein ebenso schwer fassbares und globales Problem wie den Klimawandel angewendet zu werden? Was könnte daher eine Klimagerechtigkeit sein?
Es gibt viele Gerechtigkeitsprinzipien, die vorgeben, eine gerechte Grundlage für die Klimaprobleme zu bieten wie z.B. das Verursacherprinzip, das Fähigkeitsprinzip oder das Grandfathering-Prinzip, bei dem die Hauptverursacher nach wie vor am meisten emittieren dürfen (dieses Prinzip leitete die bisherigen internationalen Verhandlungen).
Das Ziel dieser Arbeit ist, herauszufinden, wie die Klimaprobleme gelöst werden können, so dass für alle Menschen unter allen Umständen die universellen Menschenrechte her- und sichergestellt werden und diese frei und moralisch handeln können.
Die Schlussfolgerung dieser Arbeit ist, dass Kants Gerechtigkeitsbegriff durch eine Kombination des Subsistenzemissions-Rechts, des Greenhouse-Development-Rights-Principles (GDR-Prinzip) und einer internationalen Staatlichkeit durchgesetzt werden könnte.
Durch das Subsistenzemissions-Recht hat jeder Mensch das Recht, so viel Energie zu verbrauchen und damit zusammenhängende Emissionen zu produzieren, dass er ein menschenwürdiges Leben führen kann. Das GDR-Prinzip errechnet den Anteil an der weltweiten Gesamtverantwortung zum Klimaschutz eines jeden Landes oder sogar eines jeden Weltbürgers, indem es die historischen Emissionen (Klimaschuld) zu der jetzigen finanziellen Kapazität des Landes/ des Individuums (Verantwortungsfähigkeit) hinzuaddiert. Die Implementierung von internationalen Gremien wird verteidigt, weil es ein globales, grenzüberschreitendes Problem ist, dessen Effekte und dessen Verantwortung globale Ausmaße haben.
Ein schlagendes Argument für fast alle Klimaschutzmaßnahmen ist, dass sie Synergien aufweisen zu anderen gesellschaftlichen Bereichen aufweisen wie z.B. Gesundheit und Armutsbekämpfung, in denen auch noch um die Durchsetzung unserer Menschenrechte gerungen wird.
Ist dieser Lösungsansatz nicht völlig utopisch?
Dieser Vorschlag stellt für die internationale Gemeinschaft eine große Herausforderung dar, wäre jedoch die einzig gerechte Lösung unserer Klimaprobleme. Des Weiteren wird an dem Kantischen Handlungsgrundsatz festgehalten, dass das ewige Streben auf ideale Ziele hin, die beste Verwirklichung dieser durch menschliche, fehlbare Wesen ist.
Protektiver Effekt von 6-Shogaol, Ellagsäure und Myrrhe auf die intestinale epitheliale Barriere
(2016)
Viele bioaktive Pflanzeninhaltsstoffe bzw. Pflanzenmetabolite besitzen antiinflammatorische Eigenschaften. Diese versprechen ein hohes Potential für den Einsatz in der Phytotherapie bzw. Prävention von chronisch-entzündlichen Darmerkrankungen (CED). Eine intestinale Barrieredysfunktion ist ein typisches Charakteristikum von CED Patienten, die dadurch an akuter Diarrhoe leiden.
In dieser Arbeit werden die Pflanzenkomponenten 6-Shogaol, Ellagsäure und Myrrhe an den intestinalen Kolonepithelzellmodellen HT-29/B6 und Caco-2 auf ihr Potential hin, die intestinale Barriere zu stärken bzw. eine Barrieredysfunktion zu verhindern, untersucht. Hauptschwerpunkt der Analysen ist die parazelluläre Barrierefunktion und die Regulation der dafür entscheidenden Proteinfamilie der Tight Junctions (TJs), der Claudine.
Die Barrierefunktion wird durch Messung des transepithelialen Widerstands (TER) und der Fluxmessung in der Ussing-Kammer bestimmt. Dazu werden die HT-29/B6- und Caco-2-Monolayer mit den Pflanzenkomponenten (6-Shogaol, Ellagsäure, Myrrhe), dem proinflammatorischen Zytokin TNF-α oder der Kombination von beiden Subsztanzen für 24 oder 48 h behandelt. Außerdem wurden zur weiteren Charakterisierung die Expression sowie die Lokalisation der für die parazelluläre Barriere relevanten Claudine, die TJ-Ultrastruktur und verschiedene Signalwege analysiert.
In Caco-2-Monolayern führten Ellagsäure und Myrrhe, nicht aber 6-Shogaol, allein zu einem TER-Anstieg bedingt durch eine verringerte Permeabilität für Natriumionen. Myrrhe verminderte die Expression des Kationenkanal-bildenden TJ-Proteins Claudin-2 über die Inhibierung des PI3K/Akt-Signalweges, während Ellagsäure die Expression der TJ-Proteine Claudin-4 und -7 reduzierte. Alle Pflanzenkomponenten schützten in den Caco-2-Zellen vor einer TNF-α-induzierten Barrieredysfunktion.
An den HT-29/B6-Monolayern änderte keine der Pflanzenkomponenten allein die Barrierefunktion. Die HT-29/B6-Zellen reagierten auf TNF-α mit einer deutlichen Verminderung des TER und einer erhöhten Fluoreszein-Permeabilität. Die TER-Abnahme war durch eine PI3K/Akt-vermittelte gesteigerte Claudin-2-Expression sowie eine NFκB-vermittelte Umverteilung des abdichtenden TJ-Proteins Claudin-1 gekennzeichnet. 6-Shogaol konnte den TER-Abfall partiell hemmen sowie die PI3K/Akt-induzierte Claudin-2-Expression und die NFκB-bedingte Claudin-1-Umverteilung verhindern. Ebenso inhibierte Myrrhe, nicht aber Ellagsäure, den TNF-α-induzierten TER-Abfall. Dabei konnte Myrrhe zwar den Claudin-2-Expressionsanstieg und die Claudin-1-Umverteilung unterbinden, jedoch weder die NFκB- noch die PI3K/Akt-Aktivierung hemmen. Diese Arbeit zeigt, dass auch STAT6 an dem Claudin-2-Expressionsanstieg durch
TNF-α in HT-29/B6-Zellen beteiligt ist. So wurde durch Myrrhe die TNF-α-induzierte Phosphorylierung von STAT6 und die erhöhte Claudin-2-Expression inhibiert.
Die Ergebnisse deuten darauf hin, dass die Pflanzenkomponenten 6-Shogaol, Ellagsäure und Myrrhe mit unterschiedlichen Mechanismen stärkend auf die Barriere einwirken. Zur Behandlung von intestinalen Erkrankungen mit Barrieredysfunktion könnten daher Kombinationspräparate aus verschiedenen Pflanzen effektiver sein als Monopräparate.
Gene expression describes the process of making functional gene products (e.g. proteins or special RNAs) from instructions encoded in the genetic information (e.g. DNA). This process is heavily regulated, allowing cells to produce the appropriate gene products necessary for cell survival, adapting production as necessary for different cell environments. Gene expression is subject to regulation at several levels, including transcription, mRNA degradation, translation and protein degradation. When intact, this system maintains cell homeostasis, keeping the cell alive and adaptable to different environments. Malfunction in the system can result in disease states and cell death. In this dissertation, we explore several aspects of gene expression control by analyzing data from biological experiments. Most of the work following uses a common mathematical model framework based on Markov chain models to test hypotheses, predict system dynamics or elucidate network topology. Our work lies in the intersection between mathematics and biology and showcases the power of statistical data analysis and math modeling for validation and discovery of biological phenomena.
Das Ziel der Doktorarbeit war die Entwicklung und Evaluation eines skillsbasierten primären Präventionsprogramms (Mainzer Schultraining zur Essstörungsprävention (MaiStep)) für partielle und manifeste Essstörungen. Dabei wurde die Wirksamkeit durch einen primären (Reduktion vorhandener Essstörungssymptome) und sekundären (assoziierte Psychopathologie) Zielparameter 3 und 12 Monate nach Durchführung des Trainings überprüft. Innerhalb der randomisiert kontrollierten Studie gab es zwei Interventionsgruppe und eine aktive Kontrollgruppe. 1.654 Jugendliche (weiblich/männlich: 781/873; mittleres Alter: 13.1±0.7; BMI: 20.0±3.5) konnten für die Studie, an zufällig ausgewählten Schulen in Rheinland-Pfalz, rekrutiert werden. Die Entwicklung des Präventionsprogramms basiert auf einem systematischen Literaturreview von 63 wissenschaftlichen Studien über die Prävention von Essstörungen im Kindes- und Jugendalter. Eine Interventionsgruppe wurde durch Psychologinnen/Psychologen und eine zweite durch Lehrkräfte angeleitet. Das in der aktiven Kontrollgruppe durchgeführte Sucht- bzw. Stresspräventionsprogramm wurde durch Lehrkräfte geleitet. MaiStep zeigte zur 3-Monatskatamnese keine signifikanten Effekte im Vergleich zur aktiven Kontrollgruppe. Allerdings zeigten sich nach 12 Monaten multiple signifikante Effekte zwischen den Interventions- und der aktiven Kontrollgruppe. Im Rahmen der Analyse des primären Parameters wurden in den Interventionsgruppen signifikant weniger Jugendliche mit einer partiellen Anorexia nervosa (CHI²(2) = 8.74, p = .01**) und/oder partiellen Bulimia nervosa (CHI²(2) = 7.25, p = .02*) gefunden. Im Rahmen der sekundären Zielparameter zeigten sich signifikante Veränderungen in Subskalen des Eating Disorder Inventory (EDI-2) Schlankheitsstreben (F (2, 355) = 3.94, p = .02*) und Perfektionismus (F (2, 355) = 4.19, p = .01**) sowie dem Body Image Avoidance Questionnaire (BIAQ) (F (2, 525) = 18.79, p = .01**) zwischen den Interventions- und der aktiven Kontrollgruppe. MaiStep kann somit als erfolgreiches Programm zur Reduktion von partiellen Essstörungen für die Altersgruppe der 13- 15-jährigen bezeichnet werden. Trotz unterschiedlicher Wirkmechanismen zeigten sich die Lehrkräfte im Vergleich zu den Psychologinnen/Psychologen ebenso erfolgreich in der Durchführung.
Trial registration MaiStep is registered at the German Clinical Trials Register (DRKS00005050).
Das Wissen um die lokale Struktur von Seltenen Erden Elementen (SEE) in silikatischen und aluminosilikatischen Schmelzen ist von fundamentalem Interesse für die Geochemie der magmatischen Prozesse, speziell wenn es um ein umfassendes Verständnis der Verteilungsprozesse von SEE in magmatischen Systemen geht. Es ist allgemein akzeptiert, dass die SEE-Verteilungsprozesse von Temperatur, Druck, Sauerstofffugazität (im Fall von polyvalenten Kationen) und der Kristallchemie kontrolliert werden. Allerdings ist wenig über den Einfluss der Schmelzzusammensetzung selbst bekannt. Ziel dieser Arbeit ist, eine Beziehung zwischen der Variation der SEE-Verteilung mit der Schmelzzusammensetzung und der Koordinationschemie dieser SEE in der Schmelze zu schaffen.
Dazu wurden Schmelzzusammensetzungen von Prowatke und Klemme (2005), welche eine deutliche Änderung der Verteilungskoeffizienten zwischen Titanit und Schmelze ausschließlich als Funktion der Schmelzzusammensetzung zeigen, sowie haplogranitische bzw. haplobasaltische Schmelzzusammensetzungen als Vertreter magmatischer Systeme mit La, Gd, Yb und Y dotiert und als Glas synthetisiert. Die Schmelzen variierten systematisch im Aluminiumsättigungsindex (ASI), welcher bei den Prowatke und Klemme (2005) Zusammensetzungen einen Bereich von 0.115 bis 0.768, bei den haplogranitischen Zusammensetzungen einen Bereich von 0.935 bis 1.785 und bei den haplobasaltischen Zusammensetzungen einen Bereich von 0.368 bis 1.010 abdeckt. Zusätzlich wurden die haplogranitischen Zusammensetzungen mit 4 % H2O synthetisiert, um den Einfluss von Wasser auf die lokale Umgebung von SEE zu studieren. Um Informationen über die lokalen Struktur von Gd, Yb und Y zu erhalten wurde die Röntgenabsorptionsspektroskopie angewendet. Dabei liefert die Untersuchung der Feinstruktur mittels der EXAFS-Spektroskopie (engl. Extended X-Ray Absorption Fine Structure) quantitative Informationen über die lokale Umgebung, während RIXS (engl. resonant inelastic X-ray scattering), sowie die daraus extrahierte hoch aufgelöste Nahkantenstruktur, XANES (engl. X-ray absorption near edge structure) qualitative Informationen über mögliche Koordinationsänderungen von La, Gd und Yb in den Gläsern liefert. Um mögliche Unterschiede der lokalen Struktur oberhalb der Glastransformationstemperatur (TG) zur Raumtemperatur zu untersuchen, wurden exemplarisch Hochtemperatur Y-EXAFS Untersuchungen durchgeführt.
Für die Auswertung der EXAFS-Messungen wurde ein neu eingeführter Histogramm-Fit verwendet, der auch nicht-symmetrische bzw. nichtgaußförmige Paarverteilungsfunktionen beschreiben kann, wie sie bei einem hohen Grad der Polymerisierung bzw. bei hohen Temperaturen auftreten können. Die Y-EXAFS-Spektren für die Prowatke und Klemme (2005) Zusammensetzungen zeigen mit Zunahme des ASI, eine Zunahme der Asymmetrie und Breite der Y-O Paarverteilungsfunktion, welche sich in sich in der Änderung der Koordinationszahl von 6 nach 8 und einer Zunahme des Y-O Abstand um 0.13Å manifestiert. Ein ähnlicher Trend lässt sich auch für die Gd- und Yb-EXAFS-Spektren beobachten. Die hoch aufgelösten XANESSpektren für La, Gd und Yb zeigen, dass sich die strukturellen Unterschiede zumindest halb-quantitativ bestimmen lassen. Dies gilt insbesondere für Änderungen im mittleren Abstand zu den Sauerstoffatomen. Im Vergleich zur EXAFS-Spektroskopie liefert XANES jedoch keine Informationen über die Form und Breite von Paarverteilungsfunktionen. Die Hochtemperatur EXAFS-Untersuchungen von Y zeigen Änderungen der lokalen Struktur oberhalb der Glasübergangstemperatur an, welche sich vordergründig auf eine thermisch induzierte Erhöhung des mittleren Y-O Abstandes zurückführen lassen. Allerdings zeigt ein Vergleich der Y-O Abstände für Zusammensetzungen mit einem ASI von 0.115 bzw. 0.755, ermittelt bei Raumtemperatur und TG, dass der im Glas beobachtete strukturelle Unterschied entlang der Zusammensetzungsserie in der Schmelze noch stärker ausfallen kann, als bisher für die Gläser angenommen wurde.
Die direkte Korrelation der Verteilungsdaten von Prowatke und Klemme (2005) mit den strukturellen Änderungen der Schmelzen offenbart für Y eine lineare Korrelation, wohingegen Yb und Gd eine nicht lineare Beziehung zeigen. Aufgrund seines Ionenradius und seiner Ladung wird das 6-fach koordinierte SEE in den niedriger polymerisierten Schmelzen bevorzugt durch nicht-brückenbildende Sauerstoffatome koordiniert, um stabile Konfigurationen zu bilden. In den höher polymerisierten Schmelzen mit ASI-Werten in der Nähe von 1 ist 6-fache Koordination nicht möglich, da fast nur noch brückenbildende Sauerstoffatome zur Verfügung stehen. Die Überbindung von brückenbildenden Sauerstoffatomen um das SEE wird durch Erhöhung der Koordinationszahl und des mittleren SEE-O Abstandes ausgeglichen. Dies bedeutet eine energetisch günstigere Konfiguration in den stärker depolymerisierten Zusammensetzungen, aus welcher die beobachtete Variation des Verteilungskoeffizienten resultiert, welcher sich jedoch für jedes Element stark unterscheidet. Für die haplogranitischen und haplobasaltischen Zusammensetzungen wurde mit Zunahme der Polymerisierung auch eine Zunahme der Koordinationszahl und des durchschnittlichen Bindungsabstands, einhergehend mit der Zunahme der Schiefe und der Asymmetrie der Paarverteilungsfunktion, beobachtet. Dies impliziert, dass das jeweilige SEE mit Zunahme der Polymerisierung auch inkompatibler in diesen Zusammensetzungen wird. Weiterhin zeigt die Zugabe von Wasser, dass die Schmelzen depolymerisieren, was in einer symmetrischeren Paarverteilungsfunktion resultiert, wodurch die Kompatibilität wieder zunimmt.
Zusammenfassend zeigt sich, dass die Veränderungen der Schmelzzusammensetzungen in einer Änderung der Polymerisierung der Schmelzen resultieren, die dann einen signifikanten Einfluss auf die lokale Umgebung der SEE hat. Die strukturellen Änderungen lassen sich direkt mit Verteilungsdaten korrelieren, die Trends unterscheiden sich aber stark zwischen leichten, mittleren und schweren SEE. Allerdings konnte diese Studie zeigen, in welcher Größenordnung die Änderungen liegen müssen, um einen signifikanten Einfluss auf den Verteilungskoeffizenten zu haben. Weiterhin zeigt sich, dass der Einfluss der Schmelzzusammensetzung auf die Verteilung der Spurenelemente mit Zunahme der Polymerisierung steigt und daher nicht vernachlässigt werden darf.
In complement to the well-established zwitterionic monomers 3-((2-(methacryloyloxy)ethyl)dimethylammonio)propane-1-sulfonate (“SPE”) and 3-((3-methacrylamidopropyl)dimethylammonio)propane-1-sulfonate (“SPP”), the closely related sulfobetaine monomers were synthesized and polymerized by reversible addition-fragmentation chain transfer (RAFT) polymerization, using a fluorophore labeled RAFT agent. The polyzwitterions of systematically varied molar mass were characterized with respect to their solubility in water, deuterated water, and aqueous salt solutions. These poly(sulfobetaine)s show thermoresponsive behavior in water, exhibiting upper critical solution temperatures (UCST). Phase transition temperatures depend notably on the molar mass and polymer concentration, and are much higher in D2O than in H2O. Also, the phase transition temperatures are effectively modulated by the addition of salts. The individual effects can be in parts correlated to the Hofmeister series for the anions studied. Still, they depend in a complex way on the concentration and the nature of the added electrolytes, on the one hand, and on the detailed structure of the zwitterionic side chain, on the other hand. For the polymers with the same zwitterionic side chain, it is found that methacrylamide-based poly(sulfobetaine)s exhibit higher UCST-type transition temperatures than their methacrylate analogs. The extension of the distance between polymerizable unit and zwitterionic groups from 2 to 3 methylene units decreases the UCST-type transition temperatures. Poly(sulfobetaine)s derived from aliphatic esters show higher UCST-type transition temperatures than their analogs featuring cyclic ammonium cations. The UCST-type transition temperatures increase markedly with spacer length separating the cationic and anionic moieties from 3 to 4 methylene units. Thus, apparently small variations of their chemical structure strongly affect the phase behavior of the polyzwitterions in specific aqueous environments.
Water-soluble block copolymers were prepared from the zwitterionic monomers and the non-ionic monomer N-isopropylmethacrylamide (“NIPMAM”) by the RAFT polymerization. Such block copolymers with two hydrophilic blocks exhibit twofold thermoresponsive behavior in water. The poly(sulfobetaine) block shows an UCST, whereas the poly(NIPMAM) block exhibits a lower critical solution temperature (LCST). This constellation induces a structure inversion of the solvophobic aggregate, called “schizophrenic micelle”. Depending on the relative positions of the two different phase transitions, the block copolymer passes through a molecularly dissolved or an insoluble intermediate regime, which can be modulated by the polymer concentration or by the addition of salt. Whereas, at low temperature, the poly(sulfobetaine) block forms polar aggregates that are kept in solution by the poly(NIPMAM) block, at high temperature, the poly(NIPMAM) block forms hydrophobic aggregates that are kept in solution by the poly(sulfobetaine) block. Thus, aggregates can be prepared in water, which switch reversibly their “inside” to the “outside”, and vice versa.
In this thesis we use integral-field spectroscopy to detect and understand of Lyman α (Lyα) emission from high-redshift galaxies.
Intrinsically the Lyα emission at λ = 1216 Å is the strongest recombination line from galaxies. It arises from the 2p → 1s transition in hydrogen. In star-forming galaxies the line is powered by ionisation of the interstellar gas by hot O- and B- stars. Galaxies with star-formation rates of 1 - 10 Msol/year are expected to have Lyα luminosities of 42 dex - 43 dex (erg/s), corresponding to fluxes ~ -17 dex - -18 dex (erg/s/cm²) at redshifts z~3, where Lyα is easily accessible with ground-based telescopes. However, star-forming galaxies do not show these expected Lyα fluxes. Primarily this is a consequence of the high-absorption cross-section of neutral hydrogen for Lyα photons σ ~ -14 dex (cm²). Therefore, in typical interstellar environments Lyα photons have to undergo a complex radiative transfer. The exact conditions under which Lyα photons can escape a galaxy are poorly understood.
Here we present results from three observational projects. In Chapter 2, we show integral field spectroscopic observations of 14 nearby star-forming galaxies in Balmer α radiation (Hα, λ = 6562.8 Å). These observations were obtained with the Potsdam Multi Aperture Spectrophotometer at the Calar-Alto 3.5m Telescope}. Hα directly traces the intrinsic Lyα radiation field. We present Hα velocity fields and velocity dispersion maps spatially registered onto Hubble Space Telescope Lyα and Hα images. From our observations, we conjecture a causal connection between spatially resolved Hα kinematics and Lyα photometry for individual galaxies. Statistically, we find that dispersion-dominated galaxies are more likely to emit Lyα photons than galaxies where ordered gas-motions dominate. This result indicates that turbulence in actively star-forming systems favours an escape of Lyα radiation.
Not only massive stars can power Lyα radiation, but also non-thermal emission from an accreting super-massive black hole in the galaxy centre. If a galaxy harbours such an active galactic nucleus, the rate of hydrogen-ionising photons can be more than 1000 times higher than that of a typical star-forming galaxy. This radiation can potentially ionise large regions well outside the main stellar body of galaxies. Therefore, it is expected that the neutral hydrogen from these circum-galactic regions shines fluorescently in Lyα. Circum-galactic gas plays a crucial role in galaxy formation. It may act as a reservoir for fuelling star formation, and it is also subject to feedback processes that expel galactic material. If Lyα emission from this circum-galactic medium (CGM) was detected, these important processes could be studied in-situ around high-z galaxies. In Chapter 3, we show observations of five radio-quiet quasars with PMAS to search for possible extended CGM emission in the Lyα line. However, in four of the five objects, we find no significant traces of this emission. In the fifth object, there is evidence for a weak and spatially quite compact Lyα excess at several kpc outside the nucleus. The faintness of these structures is consistent with the idea that radio-quiet quasars typically reside in dark matter haloes of modest masses. While we were not able to detect Lyα CGM emission, our upper limits provide constraints for the new generation of IFS instruments at 8--10m class telescopes.
The Multi Unit Spectroscopic Explorer (MUSE) at ESOs Very Large Telescopeis such an unique instrument. One of the main motivating drivers in its construction was the use as a survey instrument for Lyα emitting galaxies at high-z. Currently, we are conducting such a survey that will cover a total area of ~100 square arcminutes with 1 hour exposures for each 1 square arcminute MUSE pointing. As a first result from this survey we present in Chapter 5 a catalogue of 831 emission-line selected galaxies from a 22.2 square arcminute region in the Chandra Deep Field South. In order to construct the catalogue, we developed and implemented a novel source detection algorithm -- LSDCat -- based on matched filtering for line emission in 3D spectroscopic datasets (Chapter 4). Our catalogue contains 237 Lyα emitting galaxies in the redshift range 3 ≲ z ≲ 6. Only four of those previously had spectroscopic redshifts in the literature. We conclude this thesis with an outlook on the construction of a Lyα luminosity function based on this unique sample (Chapter 6).
In order to evade detection by network-traffic analysis, a growing proportion of malware uses the encrypted HTTPS protocol. We explore the problem of detecting malware on client computers based on HTTPS traffic analysis. In this setting, malware has to be detected based on the host IP address, ports, timestamp, and data volume information of TCP/IP packets that are sent and received by all the applications on the client. We develop a scalable protocol that allows us to collect network flows of known malicious and benign applications as training data and derive a malware-detection method based on a neural networks and sequence classification. We study the method's ability to detect known and new, unknown malware in a large-scale empirical study.
Meter and syntax have overlapping elements in music and speech domains, and individual differences have been documented in both meter perception and syntactic comprehension paradigms. Previous evidence insinuated but never fully explored the relationship that metrical structure has to syntactic comprehension, the comparability of these processes across music and language domains, and the respective role of individual differences. This dissertation aimed to investigate neurocognitive entrainment to meter in music and language, the impact that neurocognitive entrainment had on syntactic comprehension, and whether individual differences in musical expertise, temporal perception and working memory played a role during these processes.
A theoretical framework was developed, which linked neural entrainment, cognitive entrainment, and syntactic comprehension while detailing previously documented effects of individual differences on meter perception and syntactic comprehension. The framework was developed in both music and language domains and was tested using behavioral and EEG methods across three studies (seven experiments). In order to satisfy empirical evaluation of neurocognitive entrainment and syntactic aspects of the framework, original melodies and sentences were composed. Each item had four permutations: regular and irregular metricality, based on the hierarchical organization of strong and weak notes and syllables, and preferred and non-preferred syntax, based on structurally alternate endings. The framework predicted — for both music and language domains — greater neurocognitive entrainment in regular compared to irregular metricality conditions, and accordingly, better syntactic integration in regular compared to irregular metricality conditions. Individual differences among participants were expected for both entrainment and syntactic processes.
Altogether, the dissertation was able to support a holistic account of neurocognitive entrainment to musical meter and its subsequent influence on syntactic integration of melodies, with musician participants. The theoretical predictions were not upheld in the language domain with musician participants, but initial behavioral evidence in combination with previous EEG evidence suggest that perhaps non-musician language EEG data would support the framework’s predictions. Musicians’ deviation from hypothesized results in the language domain were suspected to reflect heightened perception of acoustic features stemming from musical training, which caused current ‘overly’ regular stimuli to distract the cognitive system. The individual-differences approach was vindicated by the surfacing of two factors scores, Verbal Working Memory and Time and Pitch Discrimination, which in turn correlated with multiple experimental data across the three studies.
Over the last decades, the world’s population has been growing at a faster rate, resulting in increased urbanisation, especially in developing countries. More than half of the global population currently lives in urbanised areas with an increasing tendency. The growth of cities results in a significant loss of vegetation cover, soil compaction and sealing of the soil surface which in turn results in high surface runoff during high-intensity storms and causes the problem of accelerated soil water erosion on streets and building grounds. Accelerated soil water erosion is a serious environmental problem in cities as it gives rise to the contamination of aquatic bodies, reduction of ground water recharge and increase in land degradation, and also results in damages to urban infrastructures, including drainage systems, houses and roads. Understanding the problem of water erosion in urban settings is essential for the sustainable planning and management of cities prone to water erosion. However, in spite of the vast existence of scientific literature on water erosion in rural regions, a concrete understanding of the underlying dynamics of urban erosion still remains inadequate for the urban dryland environments.
This study aimed at assessing water erosion and the associated socio-environmental determinants in a typical dryland urban area and used the city of Windhoek, Namibia, as a case study. The study used a multidisciplinary approach to assess the problem of water erosion. This included an in depth literature review on current research approaches and challenges of urban erosion, a field survey method for the quantification of the spatial extent of urban erosion in the dryland city of Windhoek, and face to face interviews by using semi-structured questionnaires to analyse the perceptions of stakeholders on urban erosion.
The review revealed that around 64% of the literatures reviewed were conducted in the developed world, and very few researches were carried out in regions with extreme climate, including dryland regions. Furthermore, the applied methods for erosion quantification and monitoring are not inclusive of urban typical features and they are not specific for urban areas. The reviewed literature also lacked aspects aimed at addressing the issues of climate change and policies regarding erosion in cities. In a field study, the spatial extent and severity of an urban dryland city, Windhoek, was quantified and the results show that nearly 56% of the city is affected by water erosion showing signs of accelerated erosion in the form of rills and gullies, which occurred mainly in the underdeveloped, informal and semi-formal areas of the city. Factors influencing the extent of erosion in Windhoek included vegetation cover and type, socio-urban factors and to a lesser extent slope estimates. A comparison of an interpolated field survey erosion map with a conventional erosion assessment tool (the Universal Soil Loss Equation) depicted a large deviation in spatial patterns, which underlines the inappropriateness of traditional non-urban erosion tools to urban settings and emphasises the need to develop new erosion assessment and management methods for urban environments. It was concluded that measures for controlling water erosion in the city need to be site-specific as the extent of erosion varied largely across the city.
The study also analysed the perceptions and understanding of stakeholders of urban water erosion in Windhoek, by interviewing 41 stakeholders using semi-structured questionnaires. The analysis addressed their understanding of water erosion dynamics, their perceptions with regards to the causes and the seriousness of erosion damages, and their attitudes towards the responsibilities for urban erosion. The results indicated that there is less awareness of the process as a phenomenon, instead there is more awareness of erosion damages and the factors contributing to the damages. About 69% of the stakeholders considered erosion damages to be ranging from moderate to very serious. However, there were notable disparities between the private householders and public authority groups. The study further found that the stakeholders have no clear understanding of their responsibilities towards the management of the control measures and payment for the damages. The private householders and local authority sectors pointed fingers at each other for the responsibilities for erosion damage payments and for putting up prevention measures. The reluctance to take responsibility could create a predicament for areas affected, specifically in the informal settlements where land management is not carried out by the local authority and land is not owned by the occupants.
The study concluded that in order to combat urban erosion, it is crucial to understand diverse dynamics aggravating the process of urbanisation from different scales. Accordingly, the study suggests that there is an urgent need for the development of urban-specific approaches that aim at: (a) incorporating the diverse socio-economic-environmental aspects influencing erosion, (b) scientifically improving natural cycles that influence water storages and nutrients for plants in urbanised dryland areas in order to increase the amount of vegetation cover, (c) making use of high resolution satellite images to improve the adopted methods for assessing urban erosion, (d) developing water erosion policies, and (e) continuously monitoring the impact of erosion and the influencing processes from local, national and international levels.
In the interest of producing functional catalysts from sustainable building-blocks, 1, 3-dicarboxylate imidazolium salts derived from amino acids were successfully modified to be suitable as N-Heterocyclic carbene (NHC) ligands within metal complexes. Complexes of Ag(I), Pd(II), and Ir(I) were successfully produced using known procedures using ligands derived from glycine, alanine, β-alanine and phenylalanine. The complexes were characterized in solid state using X-Ray crystallography, which allowed for the steric and electronic comparison of these ligands to well-known NHC ligands within analogous metal complexes.
The palladium complexes were tested as catalysts for aqueous-phase Suzuki-Miyaura cross-coupling. Water-solubility could be induced via ester hydrolysis of the N-bound groups in the presence of base. The mono-NHC–Pd complexes were seen to be highly active in the coupling of aryl bromides with phenylboronic acid; the active catalyst of which was determined to be mostly Pd(0) nanoparticles. Kinetic studies determined that reaction proceeds quickly in the coupling of bromoacetophenone, for both pre-hydrolyzed and in-situ hydrolysis catalyst dissolution. The catalyst could also be recycled for an extra run by simply re-using the aqueous layer.
The imidazolium salts were also used to produce organosilica hybrid materials. This was attempted via two methods: by post-grafting onto a commercial organosilica, and co-condensation of the corresponding organosilane. The co-condensation technique harbours potential for the production of solid-support catalysts.