36 research outputs found
Cation ordering in ferri/ferromagnetic perovskite thin films
No full textEin großes Hindernis für die Anwendbarkeit von oxidischen Perowskiten in elektrotechnischen oder spintronischen Applikationen, ist die Größe der spezifischen Temperaturen, bei der die physikalischen Phänomene, wie Ferromagnetismus oder Hochtemperatur-Supraleitung, beobachtet werden können. Die physikalischen Eigenschaften der Perowskite zeigen eine Abhängigkeit von der Ordnung der verschiedenartigen Metallionen in mehrkomponentigen Systemen. Die Abhängigkeit ergibt sich durch den Einfluss der Metallionen auf die Elektronenkonfiguration und elastischen Verspannung innerhalb des Materials. Man spricht in diesem Zusammenhang auch von der Kontrolle der Füllung und der Bandbreite der elektronischen Bänder im Material durch die Wahl der Metallionen. Die Zielsetzung dieser Arbeit ist die Präparation und Charakterisierung von künstlich A-Platz geordneten schmal- und breitbandigen Manganat Dünnfilmen als auch von natürlich B-Platz geordneten ferro-/ferrimagnetischen doppelperowskitischen Dünnfilmen. Für die Präparation der dünnen Schichten wurde die unkonventionelle Metallorganischen Aerosol Deposition (MAD) verwendet. Es konnte gezeigt werden, dass diverse künstlich oder natürlich Kationengeordnete Perowskite mit der MAD Technologie präpariert werden können. Die lagenweise A-Platz Ordnung in Manganaten führt, über die Modulation der Gitterverspannung und der Elektronenbesetzung im eg-Band der Manganionen, zu modifizierten elektronischen und magnetischen Eigenschaften. In schmalbandigen CMR Manganaten wurde die PS und somit der CMR über die Ordnung beeinflusst, während in breitbandigen CMR Manganaten ein Weg aufgezeigt werden konnte, der zu Übergangstemperaturen TC > 370K führen kann. In geordneten, ferromagnetischen Doppelperowskiten wurde der Einfluss und die Anwesenheit von Antiphasen-Grenzen dargelegt. Über die Einführung einer aktiven Valenz-Kontrolle, konnte die Präparation von halbmetallischen, ferrimagnetischen Doppelperowskiten mit der MAD Technologie ermöglicht werden.A major obstacle to the applicability of oxide perovskites in electrical or spintronic applications
is the size of the specific temperatures at which the physical
phenomena such as ferromagnetism or high-temperature superconductivity can be observed. The physical properties of the perovskites
show a dependence on the ordering of the various metal ions in multicomponent
systems. The dependence results from the influence of the metal ions
on the electron configuration and elastic tension within the material. One
speaks in this context of the control of the filling and the width of
electronic bands in the material by the choice of metal ions.
The objective of this work was the preparation and characterization
of artificially A-site ordered narrowband and broadband manganite thin films as well as B-site ordered
ferro/ferrimagnetic double perovskite thin films. For the preparation of the thin films, the unconventional, vacuum-free,
metallorganic aerosol deposition (MAD) was used.
It was shown that various artificial or natural cation ordered
perovskites can be grown with the MAD technology. The layer by layer
A-site ordering results in manganites with modified electronic and
magnetic properties, due to the modulation of the lattice strain and
the electron occupation in the eg-band of manganese ions. In narrowband CMR manganites the PS and thus
the CMR was effected by the ordering. For broadband CMR manganites
a way was illustrated, which can lead to transition temperatures TC > 370K.
In fully ordered ferromagnetic double perovskites, the influence
and the presence of anti-phase boundaries was argued. The introduction of an active valence control enabled the preparation of half-metallic
ferrimagnetic double perovskite thin films with the MAD technology
Charakterisierung der T-Zell-Antwort auf eine intestinale Nematodeninfektion
No full textParasitische Nematoden beeinflussen gezielt die Abwehrreaktionen ihres Wirtes. Dies wird besonders während der chronischen Infektionsphase durch eine herabregulierte T-Zell-Antwort auf Parasitenantigene und andere Stimuli ersichtlich. In dieser Arbeit wurde die T-Zell-Antwort gegen einen intestinalen Nematoden untersucht. Mäuse wurden mit dem Trichostrongyliden Heligmosomoides polygyrus infiziert und in der Folge Effektor- sowie regulatorische T-Zellen (Tregs) untersucht. Subpopulationen von CD4+ T-Zellen wurden aus chronisch infizierten Mäusen isoliert und in naive Empfänger transferiert, welche nachfolgend infiziert wurden. Dabei zeigte sich, dass der Transfer von CD4+ Effektor-T-Zellen zu einer verminderten Wurmlast in den Empfängertieren führte, diese Zellen also einen partiellen Schutz gegen die Primärinfektion vermitteln. Der gleichzeitige Transfer von Tregs beeinflusste diesen Effekt nicht. Tregs allein zeigten keinerlei Einfluss auf die Wurmlast der Empfänger. Die Protektion durch Transfer von Effektor-T-Zellen kann vermutlich auf eine kleine Antigen-spezifische Population von CD4+ Zellen zurückgeführt werden. Diese Zellen wurden durch die Expression von CD40-L (CD154) nach Restimulation mit Parasitenantigen in vitro charakterisiert und enthielten einen Großteil der Zytokinproduzenten unter den CD4+ Zellen. Während diese Effektorzellen ein deutliches Th2-Zytokinprofil durch Produktion von Interleukin-4 (IL-4) und IL-13 zeigten, reagierte eine Treg-Subpopulation mit der Sekretion hoher Mengen von IL-10 auf Antigenstimulation. Diese Tregs waren durch Expression des Integrins AlphaE (CD103)Beta7 sowie CD25 und Foxp3 charakterisiert und vermittelten in vitro die stärkste Suppression anderer T-Zellen, wenn sie aus chronisch infizierten Mäusen isoliert wurden. Durch Untersuchung der zellulären Zusammensetzung von mesenterialen Lymphknoten und Milz konnte gezeigt werden, dass die Frequenz solcher regulatorischer Zellen im Verlauf der Infektion dauerhaft und überproportional zunimmt. Im Gegensatz dazu wurde am Infektionsort nur eine vorübergehende Akkumulation von Tregs (Foxp3+) während der akuten Phase der Infektion nachgewiesen. Diese Ergebnisse zeigen den Einfluss einer intestinalen Nematodeninfektion auf die Aktivität von Tregs und das Potential parasitenspezifischer CD4+ Effektor-Zellen zur Vermittlung von Schutz gegen die Infektion. Ein weiteres Projekt dieser Arbeit wahr die Verabreichung eines immunmodulatorischen Parasitenproteins, des Filariencystatins Av17, in einem Mausmodell entzündlicher Darmerkrankungen. In Mäusen wurde eine kolitisartige Entzündung durch eine Chemikalie im Trinkwasser induziert. Die regelmäßige Verabreichung von rekombinant exprimiertem Cystatin verminderte die Entzündungsreaktion signifikant. Damit konnte in dieser Arbeit gezeigt werden. dass Entzündungsreaktionen, die nicht durch den Parasiten selbst hervorgerufen werden, durch die Applikation einer einzelnen Parasitenkomponente unterdrückt werden können.Parasitic nematodes specifically modulate the immune response of their hosts. A cellular hyperreactivity, especially during the chronic phase of infection, is a distinct finding of such infections. The T cell response against an intestinal nematode was analyzed in this work. Mice were infected with the trichostrongylid Heligmosomoides polygyrus and surveyed for changes concerning effector and regulatory T cells (Tregs). Subpopulations of CD4+ T cells were isolated from chronically infected mice and adoptively transferred to naive recipients, which were subsequently infected. The Transfer of CD4+ effector cells conferred partial protection, seen as decreased worm burdens in recipients. This effect was unimpaired by simultaneous transfer of Tregs. The transfer of purified Tregs alone showed no effect on worm burdens. The protection by transfer of effector T cells was probably due to a small parasite-specific population, which was characterized by the expression of CD40-L (CD154) after antigen-restimulation. The CD154+ population contained high frequencies of cells reacting with production of the Th2 key cytokines interleukin-4 (IL-4) and IL-13. On the other hand, a subpopulation of Tregs secreted high amounts of IL-10 in response to the antigen. These Tregs were characterized by the expression of the integrin AlphaE (CD103)Beta7, as well as CD25 and Foxp3. They showed a peculiar strong suppressive efficacy on the proliferation of other T cells, especially when derived from chronically infected donors. Analyzing the cellular composition of mesenteric lymph nodes and spleens in response revealed a lasting and over-proportional increase in frequencies of these Tregs. In clear contrast, only a transient increase of Foxp3-expressing Tregs was detected at the site of infection during the acute phase. These results point out the changes Treg activity during an intestinal nematode infection and show the potential of CD4+ effector cells in mediating protection against infection. A second project of this work was the application of an immunomodulatory parasite protein, the filarial cystatin Av17, in a mouse model of inflammatory bowel disease. Mice developed an inflammatory response to a chemical applied in the drinking water. The repeated application of recombinantly expressed cystatin significantly diminished the inflammatory response. Hence, this work showed the potential of a single parasite component in suppressing inflammatory processes not caused by the parasite itself
Sustainable Leadership and Hegelian Self-Awareness
No full textThe contribution of businesses to sustainability, captured in the concept of the triple bottom line (people, profit, planet), has been given a lot of attention. One line of argument is to make sustainability mandatory via regulation, while another is to create a consciousness for questions of sustainability in the minds of managers, that is, to make managers agents of sustainability. Thus, there is debate about what behaviors, practices, and skills leaders need for positive sustainability. In recent years, scholars have attempted to develop leadership approaches (e.g., sustainable leadership, sustainability leadership) that contribute to the implementation of sustainability and positively influence sustainability practices, filling a perceived gap in the current literature. Here, connections to popular relationship-based approaches such as ethical leadership, transformational leadership, authentic leadership, and responsible leadership are also discussed. In this paper, we debate to what extent a specific leadership type is necessary to successfully lead a company into a sustainable future or whether, regardless of conceptualized behaviors, practices, and skills, it is not the core character and attitude of leaders that is crucial to changing the company culture to achieve the goal of sustainable business. This paper first outlines the existing literature on leadership approaches designed to lead to greater sustainability. It does not claim to be exhaustive but refers to the most prominent research findings. It then critically assesses these and raises questions. In the third section, we propose an alternative view of successful leadership toward positive sustainability
thin films: field enhancement and depolarization effects
No full textPolarization-dependent tip-enhanced Raman spectroscopy (TERS) was carried out on double perovskite La2CoMnO6 (LCMO) thin films to determine the contributions of the enhancement by the excitation of surface plasmon polariton and tip-induced polarization effects. Due to B-site ordering and the resulting monoclinic P12(1)/n1 structure, the spectra exhibit a strong A(g) mode around 644cm(-1) originated from (Co/Mn)O-6 stretching vibrations. The TERS contrast C, defined as the ratio of the total-field (the sum of the near field and the far field) to the far-field intensity, up to C similar to 60-110 for a cross-polarized configuration (incident light polarization perpendicular to the detected one), reveals a possible breakdown of polarization-dependent selection rules for the Raman scattering due to a tip-induced near-field depolarization component. We disentangled a significant enhancement for all observed modes in a parallel configuration with a TERS contrast of C similar to 2-5 due to general near-field amplification, strongly affected also by the film thickness. With B-site ordering and highly dielectric behavior, LCMO therefore provides an excellent test system to study TERS phenomena on oxide surfaces. Copyright (c) 2016 John Wiley & Sons, Ltd.Deutsche Forschungsgemeinschaft DFG [Sonderforschungsbereich SFB 1073
Wallace Stevens: Lyrisch Philosophieren
No full textWallace Stevens is widely regarded as an author whose poetry possesses a particularly close affinity to philosophy, which is usually taken to mean that his poems contain statements of philosophical concepts or propositions. In contrast to this, the following article examines the relation of Stevens’s poetry and philosophy with respect not to the contents of his poems but to their sequential structure. This analytic focus is motivated by the observation that the progression of the utterance in a great many of Stevens’s poems appears to be modelled on the principles of philosophical argumentation: i.e., that the poems go through a quasi-philosophical process of questioning, reflection, and cognition. As lyric poems, however, they pursue this practical process of thinking and arguing on the basis of the principles of poetic composition. The poems can thus be described as employing two different discourse types at the same time and in interaction with each other: philosophical argumentation, on the one hand, and poetic composition on the other. Accordingly, the following analyses are guided by two questions: first, what aims do the argumentations in the poems pursue and, second, how do the two discourse types interact with each other in that process? Three poems from different periods of Stevens’s poetic œuvre are used as examples: “A High-Toned Old Christian Woman” (1923), “Man Carrying Thing” (1947) and “The Plain Sense of Things” (1954)
Exploring shared understandings of future AI systems through design
No full textThe focus of this project was building shared understandings of future AI systems through design. Based on the literature study on the Explainability of AI, two main gaps were identified: the stakeholder's backgrounds are not accounted for during the design of systems and there is a need for a more holistic approach considering social and technical implications. To address these gaps, the project aimed to move from explainability to building situated understandings that accommodate multiple stakeholders' perspectives and backgrounds.A criteria for shared understandings was defined based on literature and research: functionality, relatability, situatedness, and expectations. The main design approaches chosen were speculative design and the stack from Freedom Lab. While speculative design, provided immersion and context, the stack facilitated the breakdown and analysis of system layers. A case study on residential shared mobility was chosen as the focus of the project. The stakeholders included a real estate company, municipality officials, a transport provider, and behavioral and technology researchers. The goal was to bring tensions and challenges within the system to the surface and establish a shared understanding among the stakeholders. The project involved seven participants, including direct stakeholders and external individuals, for critical discussions. The participants were interviewed to understand their current understanding, backgrounds, and future visions of the system. Insights from the interviews revealed different interpretations of shared mobility, varying stakeholder priorities, and the challenges related to behavior change and technology implementation.Four speculative artifacts were designed to surface tensions in the system. These artifacts represented future objects related to shared mobility. The participants interacted with the objects individually, followed by group discussions to explore the implications and challenges. The stack from FreedomLab was used to collect ideas and facilitate group discussions. The sessions aimed to sensitize participants to the case study, encourage their active involvement and gather their perspectives and reflections. Overall, the fostering of shared understandings of future AI systems was sought by the project through the consideration of stakeholder backgrounds, the employment of design methodologies, and the addressing of social and technical implications. The project helped shed light on three aspects. The case study of residential shared mobility, how an ideal system can be achieved, and the role of different stakeholders in this future. Reflection on the process of using speculative design and stack in combination to support each other. Finally insight into shared understandings as an approach to explainability. Design for Interactio
Two Types of Events in Border Crossing Narratives of Contemporary Travelogues
No full textThe paper analyzes border crossing in two contemporary travelogues – The Border by E. Fatland (2021) and All the Agents and Saints: Dispatches from the U.S. Borderlands by S. E. Griest (2017). Methodologically, the study relies on the framework proposed by Peter Hühn [Hühn 2011], distinguishing two types of events – the first refers to the sequential elements, changes of state, constitutive of any narration, while the second pinpoints the transformative and disruptive quality of certain changes in the story. The same actions or facts may, or may not, be interpreted as events of both types in different plots. The notion of an event thus helps the author highlight the temporal and experiential dimension of travelers’ movements across borders.
Both narratives describe borders as fluid and shiftable, emphasizing their artificial and performative nature. Fatland, whose border crossings structure her itinerary, highlights the minimal geographical and yet stunning cultural distance between different “universes”. Griest is more interested in exploring the liminality experienced by the ethnic communities whose lands the national borders cut through. Of special interest is the experience of border crossing for “undesirable” travelers such as illegal migrants.
What may be a type I event or non-event for “trusted” travelers (e.g. American citizens or Russian shoppers in Heihe) may easily mean a type II or even the final event (death) for the “undesirables” (e.g. Mexican immigrants). Thus, the status of border crossing as a type I or type II event depends on its unpredictability and inherent risks
Narrative Structures in Hagiwara's collection Tsuki ni hoeru
No full textBachelor thesis focuses on the poetry of the Japanese poet Hagiwara Sakutarō, the founding figure of modern Japanese poetry, specifically on his first poetry collection called Tsuki ni hoeru (Howling at the Moon, 1917). The goal of the thesis is to reconstruct narrative structures in the collection and to demonstrate applicability of the employed method for productive narrative analysis of this collection. The first part briefly presents the life and works of the author, an aesthetic-philosophical basis of his works and outlines its significant role in the history of Japanese literature. The second part of the thesis presents the basic terms and concepts of the model of transgeneric narrative analysis worked out by Peter Hühn and at the same time shows its limitations. The third part is trying to apply this model in the narrative analysis of selected representative poems of the examined work. The result of the thesis are the reconstructions of the narrative structures of these poems and obtained basic features of narativity in the analysis. Keywords japanese literature, Hagiwara Sakutarō, narratology, Peter Hühn, narratological analysis of lyric petr
Narrative Structures in Hagiwara's collection Tsuki ni hoeru
No full textBakalářská práce se zaměřuje na poezii japonského básníka Hagiwary Sakutaróa, zakladatelské postavy moderní japonské poezie, konkrétně na jeho první básnickou (Výt na měsíc, 1917). Cílem práce je provést aplikovatelnost použité metody pro narativní analýzu tohoto díla. První část práce stručně představuje život a dílo au nastiňuje jeho významnou roli v dějinách japonské literatury. Druhá část práce předkládá základní termíny a koncepty modelu transgenerické narativní analýzy vypracované Peterem Hühnem a současně uvádí jeho omezení. Třetí část je věnována zkoumaného díla. Výsledkem práce jsou rekonstrukce narativních struktur těchto básní a na jejich základě získané základní rysy narativity ve Klíčová slovaBachelor thesis focuses on the poetry of the Japanese poet Hagiwara Sakutarō, the founding figure of modern Japanese poetry, specifically on his first poetry collection called Tsuki ni hoeru (Howling at the Moon, 1917). The goal of the thesis is to reconstruct narrative structures in the collection and to demonstrate applicability of the employed method for productive narrative analysis of this collection. The first part briefly presents the life and works of the author, an aesthetic-philosophical basis of his works and outlines its significant role in the history of Japanese literature. The second part of the thesis presents the basic terms and concepts of the model of transgeneric narrative analysis worked out by Peter Hühn and at the same time shows its limitations. The third part is trying to apply this model in the narrative analysis of selected representative poems of the examined work. The result of the thesis are the reconstructions of the narrative structures of these poems and obtained basic features of narativity in the analysis. Keywords japanese literature, Hagiwara Sakutarō, narratology, Peter Hühn, narratological analysis of lyric petryÚstav Dálného východuInstitute of East Asian StudiesFaculty of ArtsFilozofická fakult
Interface-controlled magnetism and transport of ultrathin manganite films
No full textWe report ferromagnetic, T-C = 240 K, and metallic, T-MI = 250 K, behaviors of a three unit cell thick interface engineered lanthanum manganite film, grown by metalorganic aerosol deposition technique on SrTiO3(100) substrates. Atomically resolved electron microscopy and chemical analysis show that ultrathin manganite films start to grow with La-O layer on a strongly Mn/Ti-intermixed interface, engineered by an additional deposition of 2 u.c. of Sr-Mn-O. Such interface engineering results in a hole-doped manganite layer and stabilizes ferromagnetism and metallic conductivity down to the thickness of d = 3 u.c. The films with d = 8 u.c. demonstrate a bulk-like transport behavior with T-MI similar to T-C = 310 - 330 K. (C) 2013 American Institute of Physics
