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Fire prone Mediterranean-type vegetation systems like those in the Mediterranean Basin and South-Western Australia are global hot spots for plant species diversity. To ensure management programs act to maintain these highly diverse plant communities, it is necessary to get a profound understanding of the crucial mechanisms of coexistence. In the current literature several mechanisms are discussed. The objective of my thesis is to systematically explore the importance of potential mechanisms for maintaining multi-species, fire prone vegetation by modelling. The model I developed is spatially-explicit, stochastic, rule- and individual-based. It is parameterised on data of population dynamics collected over 18 years in the Mediterranean-type shrublands of Eneabba, Western Australia. From 156 woody species of the area seven plant traits have been identified to be relevant for this study: regeneration mode, annual maximum seed production, seed size, maximum crown diameter, drought tolerance, dispersal mode and seed bank type. Trait sets are used for the definition of plant functional types (PFTs). The PFT dynamics are simulated annual by iterating life history processes. In the first part of my thesis I investigate the importance of trade-offs for the maintenance of high diversity in multi-species systems with 288 virtual PFTs. Simulation results show that the trade-off concept can be helpful to identify non-viable combinations of plant traits. However, the Shannon Diversity Index of modelled communities can be high despite of the presence of ‘supertypes’. I conclude, that trade-offs between two traits are less important to explain multi-species coexistence and high diversity than it is predicted by more conceptual models. Several studies show, that seed immigration from the regional seed pool is essential for maintaining local species diversity. However, systematical studies on the seed rain composition to multi-species communities are missing. The results of the simulation experiments, as presented in part two of this thesis, show clearly, that without seed immigration the local species community found in Eneabba drifts towards a state with few coexisting PFTs. With increasing immigration rates the number of simulated coexisting PFTs and Shannon diversity quickly approaches values as also observed in the field. Including the regional seed input in the model is suited to explain more aggregated measures of the local plant community structure such as species richness and diversity. Hence, the seed rain composition should be implemented in future studies. In the third part of my thesis I test the sensitivity of Eneabba PFTs to four different climate change scenarios, considering their impact on both local and regional processes. The results show that climate change clearly has the potential to alter the number of dispersed seeds for most of the Eneabba PFTs and therefore the source of the ‘immigrants’ at the community level. A classification tree analysis shows that, in general, the response to climate change was PFT-specific. In the Eneabba sand plains sensitivity of a PFT to climate change depends on its specific trait combination and on the scenario of environmental change i.e. development of the amount of rainfall and the fire frequency. This result emphasizes that PFT-specific responses and regional process seed immigration should not be ignored in studies dealing with the impact of climate change on future species distribution. The results of the three chapters are finally analysed in a general discussion. The model is discussed and improvements and suggestions are made for future research. My work leads to the following conclusions: i) It is necessary to support modelling with empirical work to explain coexistence in species-rich plant communities. ii) The chosen modelling approach allows considering the complexity of coexistence and improves the understanding of coexistence mechanisms. iii) Field research based assumptions in terms of environmental conditions and plant life histories can relativise the importance of more hypothetic coexistence theories in species-rich systems. In consequence, trade-offs can play a lower role than predicted by conceptual models. iv) Seed immigration is a key process for local coexistence. Its alteration because of climate change should be considered for prognosis of coexistence. Field studies should be carried out to get data on seed rain composition.
In this paper we discuss how Alexander von Humboldt conceived a past to New Spain in his Political Essay on New Spain (1811) and how this text was, in turn, appropriated by the Mexican historiography during the 19th century.
In order to do so, we analyze how the Prussian drew from American sources, particularly from the text of the Jesuit Francisco Javier Clavijero, written shortly before. We also study Humboldt’s conceptions of text and of history, highlighting the place of the indigenous in the composition of his reasoning. Finally, we give examples of how the Mexican nationalist historiography read and reinterpreted the Political Essay.
Die Mannheimer Risikokinderstudie untersucht die psychische Entwicklung und ihre Störungen bei Kindern mit unterschiedlich ausgeprägten Risiken mit dem Ziel, Empfehlungen für die Verbesserung der Prävention, Früherkennung und Frühbehandlung von psychischen Störungen bei Kindern abzuleiten. Dazu begleitet sie eine Kohorte von anfangs 384 Kindern in ihrer Entwicklung von der Geburt bis zum Erwachsenenalter. Die Erhebungen fanden in regelmäßigen Abständen statt, beginnend im Alter von 3 Monaten, mit 2 Jahren, 4;6, 8, 11, 15, 19, 22, 23 und 25 Jahren. Geplant ist eine weitere Erhebung mit ca. 30 Jahren.
TBS-TK Rezension
(2018)
Die finanzgeschichtlichen Untersuchungen sind überwiegend auf Geld konzentriert, Naturalien wurden vernachlässigt oder ausgeblendet. Die vorliegende Arbeit bezieht die Naturalien konsequent mit ein. Nur so ist eine Analyse der Domänenwirtschaft in ihrer Bedeutung für die Staatsfinanzen möglich. Der Erkenntnisfortschritt liegt in der konsequenten Berücksichtigung der Naturalien durch Umrechnung in Geldwerte. Nicht zu leisten ist der Anteil der domänenwirtschaftlichen Erträge am Gesamthaushalt des hessischen Territorialstaates, auch ist die Vermarktung der Überschüsse der Ämter quellenbedingt nicht zu ermitteln. Die Ämterfinanzen zeigen einen Rahmen für domänenwirtschaftliche Staatsfinanzierung auf, dass bei Verzicht auf militärische Aktionen der frühmoderne Territorialstaat domänenwirtschaftlich zu finanzieren war.
Die vorliegende Untersuchung kann aufzeigen, dass der domänenwirtschaftliche Rahmen für die Finanzierung eines Territorialstaates ausreichte, wenn er auf militärische Aktivitäten und Abenteuer verzichtete. In dieser Studie werden erstmalig umfassende statistische Erhebungen der unteren staatlichen Ebene, das Landbuch und das Ämterbuch ausgewertet, die bisher nur von Kersten Krüger ediert waren. Die vorliegende Arbeit ist in die Staatsfinanzierung auf der Stufe der Domänenwirtschaft einzuordnen. Landgraf Wilhelm IV. von Hessen-Kassel war einer der letzten, der es geschafft hatte, seinen Staat domänenwirtschaftlich mit den Einnahmen aus den Naturalien zu finanzieren. Als Domänenstaat wird ein Staat bezeichnet, der auf den ordentlichen Einkünften aus Liegenschaften und Landbesitz beruht. Es wird in dieser Arbeit der domänenwirtschaftliche Rahmen für die Staatsfinanzen berechnet. Das bedeutet, dass die Zentralfinanzen nicht berücksichtigt sind.
Es konnte gezeigt werden, dass, obwohl Landgraf Wilhelm IV. über ein kleineres Territorium als sein Vater, Landgraf Philipp der Großmütige, verfügte, die Gesamtüberschüsse höher waren. Das war seiner klugen Politik zu verdanken und seinen Bemühungen, ständig die Ämterfinanzen zu verbessern. Wilhelm IV. konsolidierte seinen Staat und konnte über domänenwirtschaftliche Einnahmen aus den Ämtern seinen Staat finanzieren. Das gelang ihm, da er erstens seinen Staat ordentlich verwaltete und zweitens keine Kriege führte. Landgraf Wilhelm IV. verabscheute den Krieg. Er sagte über den Krieg: „es ist kain abscheulicher ding auf erden als ein krieg“.
Aldehyde oxidases (AOXs) (E.C. 1.2.3.1) are molybdoflavo-enzymes belonging to the xanthine oxidase (XO) family. AOXs in mammals contain one molybdenum cofactor (Moco), one flavin adenine dinucleotide (FAD) and two [2Fe-2S] clusters, the presence of which is essential for the activity of the enzyme. Human aldehyde oxidase (hAOX1) is a cytosolic enzyme mainly expressed in the liver. hAOX1is involved in the metabolism of xenobiotics. It oxidizes aldehydes to their corresponding carboxylic acids and hydroxylates N-heterocyclic compounds. Since these functional groups are widely present in therapeutics, understanding the behaviour of hAOX1 has important implications in medicine. During the catalytic cycle of hAOX1, the substrate is oxidized at Moco and electrons are internally transferred to FAD via the FeS clusters. An electron acceptor juxtaposed to the FAD receives the electrons and re-oxidizes the enzyme for the next catalytic cycle. Molecular oxygen is the endogenous electron acceptor of hAOX1 and in doing so it is reduced and produces reactive oxygen species (ROS) including hydrogen peroxide (H2O2) and superoxide (O2.-). The production of ROS has patho-physiological importance, as ROS can have a wide range of effects on cell components including the enzyme itself.
In this thesis, we have shown that hAOX1 loses its activity over multiple cycles of catalysis due to endogenous ROS production and have identified a cysteine rich motif that protects hAOX1 from the ROS damaging effects. We have also shown that a sulfido ligand, which is bound at Moco and is essential for the catalytic activity of the enzyme, is vulnerable during turnover. The ROS produced during the course of the reaction are also able to remove this sulfido ligand from Moco. ROS, in addition, oxidize particular cysteine residues. The combined effects of ROS on the sulfido ligand and on specific cysteine residues in the enzyme result in its inactivation. Furthermore, we report that small reducing agents containing reactive sulfhydryl groups, in a selective manner, inactivate some of the mammalian AOXs by modifying the sulfido ligand at Moco. The mechanism of ROS production by hAOX1 is another scope that has been investigated as part of the work in this thesis. We have shown that the ratio of type of ROS, i.e. hydrogen peroxide (H2O2) and superoxide (O2.-), produced by hAOX1 is determined by a particular position on a flexible loop that locates in close proximity of FAD. The size of the cavity at the ROS producing site, i.e. the N5 position of the FAD isoalloxazine ring, kinetically affects the amount of each type of ROS generated by hAOX1. Taken together, hAOX1 is an enzyme with emerging importance in pharmacological and medical studies, not only due to its involvement in drug metabolism, but also due to ROS production which has physiological and pathological implications.
The urge of light utilization in fabrication of materials is as encouraging as challenging. Steadily increasing energy consumption in accordance with rapid population growth, is requiring a corresponding solution within the same rate of occurrence speed. Therefore, creating, designing and manufacturing materials that can interact with light and in further be applicable as well as disposable in photo-based applications are very much under attention of researchers. In the era of sustainability for renewable energy systems, semiconductor-based photoactive materials have received great attention not only based on solar and/or hydrocarbon fuels generation from solar energy, but also successful stimulation of photocatalytic reactions such as water splitting, pollutant degradation and organic molecule synthesisThe turning point had been reached for water splitting with an electrochemical cell consisting of TiO2-Pt electrode illuminated by UV light as energy source rather than an external voltage, that successfully pursued water photolysis by Fujishima and Honda in 1972. Ever since, there has been a great deal of interest in research of semiconductors (e.g. metal oxide, metal-free organic, noble-metal complex) exhibiting effective band gap for photochemical reactions. In the case of environmental friendliness, toxicity of metal-based semiconductors brings some restrictions in possible applications. Regarding this, very robust and ‘earth-abundant’ organic semiconductor, graphitic carbon nitride has been synthesized and successfully applied in photoinduced applications as novel photocatalyst. Properties such as suitable band gap, low charge carrier recombination and feasibility for scaling up, pave the way of advance combination with other catalysts to gather higher photoactivity based on compatible heterojunction.
This dissertation aims to demonstrate a series of combinations between organic semiconductor g-CN and polymer materials that are forged through photochemistry, either in synthesis or in application. Fabrication and design processes as well as applications performed in accordance to the scope of thesis will be elucidated in detail. In addition to UV light, more attention is placed on visible light as energy source with a vision of more sustainability and better scalability in creation of novel materials and solar energy based applications.
The microscopic origin of ultrafast demagnetization, i.e. the quenching of the magnetization of a ferromagnetic metal on a sub-picosecond timescale after laser excitation, is still only incompletely understood, despite a large body of experimental and theoretical work performed since the discovery of the effect more than 15 years ago. Time- and element-resolved x-ray magnetic circular dichroism measurements can provide insight into the microscopic processes behind ultrafast demagnetization as well as its dependence on materials properties. Using the BESSY II Femtoslicing facility, a storage ring based source of 100 fs short soft x-ray pulses, ultrafast magnetization dynamics of ferromagnetic NiFe and GdTb alloys as well as a Au/Ni layered structure were investigated in laser pump – x-ray probe experiments. After laser excitation, the constituents of Ni50Fe50 and Ni80Fe20 exhibit distinctly different time constants of demagnetization, leading to decoupled dynamics, despite the strong exchange interaction that couples the Ni and Fe sublattices under equilibrium conditions. Furthermore, the time constants of demagnetization for Ni and Fe are different in Ni50Fe50 and Ni80Fe20, and also different from the values for the respective pure elements. These variations are explained by taking the magnetic moments of the Ni and Fe sublattices, which are changed from the pure element values due to alloying, as well as the strength of the intersublattice exchange interaction into account. GdTb exhibits demagnetization in two steps, typical for rare earths. The time constant of the second, slower magnetization decay was previously linked to the strength of spin-lattice coupling in pure Gd and Tb, with the stronger, direct spin-lattice coupling in Tb leading to a faster demagnetization. In GdTb, the demagnetization of Gd follows Tb on all timescales. This is due to the opening of an additional channel for the dissipation of spin angular momentum to the lattice, since Gd magnetic moments in the alloy are coupled via indirect exchange interaction to neighboring Tb magnetic moments, which are in turn strongly coupled to the lattice. Time-resolved measurements of the ultrafast demagnetization of a Ni layer buried under a Au cap layer, thick enough to absorb nearly all of the incident pump laser light, showed a somewhat slower but still sub-picosecond demagnetization of the buried Ni layer in Au/Ni compared to a Ni reference sample. Supported by simulations, I conclude that demagnetization can thus be induced by transport of hot electrons excited in the Au layer into the Ni layer, without the need for direct interaction between photons and spins.
Тезисы
(2016)
1. Die Produzenten eines Schulbuchs 2. Erwartungen an Schulbücher 3. Schulbuchzulassung 4. Einschätzung der Lehrerinnen und Lehrer 5. Verlegerische Herausforderungen durch den Wandel des Schulbuchs 6. Herausforderungen des Informationszeitalters 7. Das Schulbuch für den Geographieunterricht - Ein "heimlicher" Lehrplan?
The spider mite Tetranychus urticae Koch and the aphid Myzus persicae (Sulzer) both infest a number of economically significant crops, including tomato (Solanurn lycopersicum). Although used for decades to control pests, the impact of green lacewing larvae Chrysoperla carnea (Stephens) on plant biochemistry was not investigated. Here, we used profiling methods and targeted analyses to explore the impact of the predator and herbivore(s)-predator interactions on tomato biochemistry. Each pest and pest -predator combination induced a characteristic metabolite signature in the leaf and the fruit thus, the plant exhibited a systemic response. The treatments had a stronger impact on non-volatile metabolites including abscisic acid and amino acids in the leaves in comparison with the fruits. In contrast, the various biotic factors had a greater impact on the carotenoids in the fruits. We identified volatiles such as myrcene and alpha-terpinene which were induced by pest -predator interactions but not by single species, and we demonstrated the involvement of the phytohormone abscisic acid in tritrophic interactions for the first time. More importantly, C. carnea larvae alone impacted the plant metabolome, but the predator did not appear to elicit particular defense pathways on its own. Since the presence of both C. carnea larvae and pest individuals elicited volatiles which were shown to contribute to plant defense, C. carnea larvae could therefore contribute to the reduction of pest infestation, not only by its preying activity, but also by priming responses to generalist herbivores such as T urticae and M. persicae. On the other hand, the use of C. carnea larvae alone did not impact carotenoids thus, was not prejudicial to the fruit quality. The present piece of research highlights the specific impact of predator and tritrophic interactions with green lacewing larvae, spider mites, and aphids on different components of the tomato primary and secondary metabolism for the first time, and provides cues for further in-depth studies aiming to integrate entomological approaches and plant biochemistry.
Computerspiele sind wichtige und zugleich besondere geschichtskulturelle Quellen. Sie prägen in zunehmendem Maße die Vorstellungen, die wir uns von historischen Gesellschaften und Ereignissen machen. Der Geschichtsunterricht, der sich auch die Befähigung zu einem kritischen Umgang mit geschichtskulturellen Angeboten zum Ziel setzt, muss sich entsprechend mit diesen auseinandersetzen. Eine Möglichkeit, wie dies im Rahmen formaler Unterrichtsprozesse und unter Berücksichtigung der Besonderheiten dieses Mediums geschehen kann, ist Thema des folgenden Beitrags.
Vergangenheit ist vergangen, Geschichte wird gemacht. An diesem Konstruktionsprozess sind nicht nur die historischen Akteur:innen und deren Quellen, sondern in besonderem Maße auch die Historiker:innen, die sich mit diesen auseinandersetzen, beteiligt. Sie sind es, die die Quellen erst zum Sprudeln bringen. Was dabei zutage tritt, ist somit in hohem Maße von den Forschenden selbst, von ihren Vorannahmen und Methoden aber auch von ihren sozialen, kulturellen und biografischen Prägungen abhängig. Das hier vorgestellte Prozessmodell versucht, diese als Einflussfaktoren zu fassen und sichtbar zu machen, um auf dieser Basis eine erweiterte wissenschaftliche (Selbst-)Reflexion zu ermöglichen.
S(t)imulated Moralities?
(2020)
Videospiele konfrontieren die Spielenden mit moralischen Settings, die es handelnd zu bewältigen gilt und in die diese emotional involviert werden. Auf diese Weise ermöglichen sie nicht nur Erfahrungen mit den Konsequenzen eigenen Handelns in gegebenen, teils komplexen Kontexten, sondern auch mit (der eigenen) Emotionalität als Teil von Entscheidungsprozessen. Diese Erfahrungen können gezielt für eine ethische Reflexion in einem erfahrungsbasierten und handlungsorientierten Unterricht genutzt werden, um sich so der Komplexität realweltlicher Dilemmata anzunähern.
Nicht nur der Lauf der Geschichte verändert sich, sondern auch Geschichtswissenschaft und -unterricht. An die Stelle des Auswendiglernens vorgegebener historischer Erzählungen trat im Laufe der Zeit zunehmend die Befähigung zu deren Dekonstruktion. Dafür müssen allerdings die Entstehungsbedingungen (geschichts-)wissenschaftlicher Erkenntnisse nachvollzogen werden können. Eine Möglichkeit, dies auf spielerische Art und Weise, aber auch auf Augenhöhe mit Lehrkräften und Historiker*innen zu tun, bieten Open-World- Spiele wie HORIZON ZERO DAWN (2017).