405 research outputs found

    Afterlive: A performant code for Vlasov-Hybrid simulations

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    A parallelized implementation of the Vlasov-Hybrid method [Nunn, 1993] is presented. This method is a hybrid between a gridded Eulerian description and Lagrangian meta-particles. Unlike the Particle-in-Cell method [Dawson, 1983] which simply adds up the contribution of meta-particles, this method does a reconstruction of the distribution function ff in every time step for each species. This interpolation method combines meta-particles with different weights in such a way that particles with large weight do not drown out particles that represent small contributions to the phase space density. These core properties allow the use of a much larger range of macro factors and can thus represent a much larger dynamic range in phase space density. The reconstructed phase space density ff is used to calculate momenta of the distribution function such as the charge density ρ\rho. The charge density ρ\rho is also used as input into a spectral solver that calculates the self-consistent electrostatic field which is used to update the particles for the next time-step. Afterlive (A Fourier-based Tool in the Electrostatic limit for the Rapid Low-noise Integration of the Vlasov Equation) is fully parallelized using MPI and writes output using parallel HDF5. The input to the simulation is read from a JSON description that sets the initial particle distributions as well as domain size and discretization constraints. The implementation presented here is intentionally limited to one spatial dimension and resolves one or three dimensions in velocity space. Additional spatial dimensions can be added in a straight forward way, but make runs computationally even more costly.Comment: Accepted for publication in Computer Physics Communication

    Structural investigation of two supramolecular complexes of the eukaryotic cell

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    Preface This study is focussed on the structural investigation of large molecular assemblies such as the 26S proteasome and the translocation machinery of the outer mitochondrial membrane. It is divided in two chapters and in both parts the structural and further functional analysis is based on X-ray crystallography. Chapter 1: Structural investigation of Rpn13, the multifunctional adaptor protein of the 26S proteasome The results in chapter 1 reveal that the multifunctional adaptor protein Rpn13 acts as a novel ubiquitin receptor of the 26S proteasome and deliver structural and biophysical details of its interaction with ubiquitin and with other proteasomal subunits. The crystal structure of the ubiquitin binding domain of Rpn13 reveals the molecular architecture of a Pleckstrin Homology (PH) domain and the NMR structure of the complex with ubiquitin shows a novel ubiquitin-binding mode. Additional NMR studies and domain mapping by truncation analysis provide further insights in the domain architecture of Rpn13 and the interaction with its partners Rpn2 and Uch37. Chapter 2: Crystallographic studies of the TOM core complex Chapter 2 presents the purification and crystallization of the mitochondrial protein translocase, the TOM core complex, from Neurospora crassa. Preliminary crystallographic data lead to the determination of space group and cell dimensions. This chapter also describes various experiments to improve the diffraction quality of the crystals and the co-crystallization of TOM core complex with specific monoclonal antibody fragments. Furthermore, expression and refolding of the main component Tom40 is raised as an alternative approach in structural investigation of the TOM complex

    PICPANTHER: A simple, concise implementation of the relativistic moment implicit Particle-in-Cell method

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    A three-dimensional, parallelized implementation of the electromagnetic relativistic moment implicit particle-in-cell method in Cartesian geometry (Noguchi et. al., 2007) is presented. Particular care was taken to keep the C++11 codebase simple, concise, and approachable. GMRES is used as a field solver and during the Newton-Krylov iteration of the particle pusher. Drifting Maxwellian problem setups are available while more complex simulations can be implemented easily. Several test runs are described and the code's numerical and computational performance is examined. Weak scaling on the SuperMUC system is discussed and found suitable for large-scale production runs.Comment: 29 pages, 8 figure

    AuswÀrtige Kulturarbeit zwischen Konzeption und Umsetzung: Steuerungsprobleme in einem schwierigen Politikfeld

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    'In der deutschen auswĂ€rtigen Kulturpolitik hat sich ein Modell entwickelt, das neben politisch-administrativer Steuerung durch das AuswĂ€rtige Amt zahlreiche Mittlerorganisationen vorsieht. Diese agieren in der auswĂ€rtigen Kulturarbeit als der DurchfĂŒhrungsebene auswĂ€rtiger Kulturpolitik relativ autonom. Die Studie widmet sich dem SpannungsverhĂ€ltnis zwischen dieser Autonomie auf der einen Seite und dem Anspruch der Politik auf strategische Steuerung auf der anderen. Sie untersucht, inwiefern auswĂ€rtige Kulturpolitik außenpolitische Rahmenfunktionen fĂŒr andere Politikfelder erfĂŒllen soll, wie diese Rahmenfunktionen von den Mittlerorganisationen eingeschĂ€tzt werden, welche spezifischen Perspektiven damit einhergehen und welche Schwierigkeiten damit verbunden sind. Die Studie zeigt, dass auswĂ€rtige Kulturpolitik mit zwei grundlegenden Problemen konfrontiert ist. Das Politikfeld ist zum Ersten in hohem Maße von unverbindlichen Ziel- und Strategieformulierungen seitens der politischen Akteure aus Regierung, Administration und Parlament geprĂ€gt. Zum Zweiten fĂ€llt es den Mittlerorganisationen (nicht zuletzt aufgrund dieser Unverbindlichkeit) schwer, die Erfolge ihrer Kulturarbeit an die Politik und in die Gesellschaft zu vermitteln. Da eine grĂ¶ĂŸere Verbindlichkeit und Klarheit auf einer ĂŒbergeordneten, politisch-strategischen Ebene auswĂ€rtiger Kulturpolitik allerdings nur begrenzt herstellbar zu sein scheint, wird empfohlen, Prozesse der Koordination und Kommunikation insbesondere auf einer nachgeordneten, operativen Ebene auswĂ€rtiger Kulturarbeit zu initiieren. An konkreten ZiellĂ€ndern und Sparten orientiert, kann es den beteiligten Akteuren gelingen, hinsichtlich der gegenseitigen Erwartungen und der strategischen Ausrichtung eine grĂ¶ĂŸere Klarheit und Verbindlichkeit zu erreichen.' (Autorenreferat

    Außenkulturpolitik

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    Sport, KĂŒnste, Wissenschaft und Personenaustausch stellen zentrale - aber viel zu wenig beachtete - Aspekte der Nationalstaatlichkeit und der internationalen Politik dar. Erstmals wird in diesem Buch in einer "Theorie der Außenkulturpolitik" gezeigt, dass sich Staaten durch Kultur zugleich voneinander differenzieren wie auch in ein positives VerhĂ€ltnis zueinander treten können - und sich gerade in dieser WidersprĂŒchlichkeit reproduzieren. Auf der methodologischen Grundlage von Umberto Ecos Zeichentheorie verbindet Patrick Schreiner postklassische AnsĂ€tze der Nationalismusforschung mit poststrukturalistischen AnsĂ€tzen der Internationalen Beziehungen, um eine Theorie der Außenkulturpolitik zu entwickeln

    Außenkulturpolitik: internationale Beziehungen und kultureller Austausch

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    Sport, KĂŒnste, Wissenschaft und Personenaustausch stellen zentrale -aber viel zu wenig beachtete- Aspekte der Nationalstaatlichkeit und der internationalen Politik dar. Erstmals wird in diesem Buch in einer "Theorie der Außenkulturpolitik" gezeigt, dass sich Staaten durch Kultur zugleich voneinander differenzieren wie auch in ein positives VerhĂ€ltnis zueinander treten können - und sich gerade in dieser WidersprĂŒchlichkeit reproduzieren. Auf der methodologischen Grundlage von Umberto Ecos Zeichentheorie verbindet Patrick Schreiner postklassische AnsĂ€tze der Nationalismusforschung mit poststrukturalistischen AnsĂ€tzen der Internationalen Beziehungen, um eine Theorie der Außenkulturpolitik zu entwickeln

    Außenkulturpolitik

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    Sport, KĂŒnste, Wissenschaft und Personenaustausch stellen zentrale - aber viel zu wenig beachtete - Aspekte der Nationalstaatlichkeit und der internationalen Politik dar. Erstmals wird in diesem Buch in einer "Theorie der Außenkulturpolitik" gezeigt, dass sich Staaten durch Kultur zugleich voneinander differenzieren wie auch in ein positives VerhĂ€ltnis zueinander treten können - und sich gerade in dieser WidersprĂŒchlichkeit reproduzieren. Auf der methodologischen Grundlage von Umberto Ecos Zeichentheorie verbindet Patrick Schreiner postklassische AnsĂ€tze der Nationalismusforschung mit poststrukturalistischen AnsĂ€tzen der Internationalen Beziehungen, um eine Theorie der Außenkulturpolitik zu entwickeln

    Allegory and animals in Olive Schreiner’s Undine : A Queer Little Child (1929)

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    Written and abandoned in the 1870s, and published posthumously in 1929, Undine: A Queer Little Child has remained on the margins of Olive Schreiner (1855-1920) studies, repeatedly dismissed as a juvenile and poor antecedent to The Story of An African Farm (1883), or deemed valuable primarily for its autobiographical content. This article redresses these schematic readings by analysing how Schreiner draws on allegorical forms in order to explore aspects of her burgeoning radicalism. Focusing on one of the main allegorical thrusts of the novel, provided by the zoomorphic and anthropomorphic animal characters that descend from mythical, fairytale, and Ancient Greek philosophical origins, it investigates how the protagonist’s metaphorically significant associations with animals relate to freethinking, feminist, and anti-imperialist ideas introduced by the novel. Undine thus undermines dominant nineteenth-century models of the “primitive” human or animal as less evolutionarily developed and without political platform, which can be seen to be a liberating move when the novel is read in dialogue with Jacques Derrida’s lectures on animals, and with other recent work in postcolonial ecocriticism

    Characterizing the Urban Mine—Challenges of Simplified Chemical Analysis of Anthropogenic Mineral Residues

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    Anthropogenic mineral residues are characterized by their material complexity and heterogeneity, which pose challenges to the chemical analysis of multiple elements. However, creating an urban mine knowledge database requires data using affordable and simple chemical analysis methods, providing accurate and valid results. In this study, we assess the applicability of simplified multi-element chemical analysis methods for two anthropogenic mineral waste matrices: (1) lithium-ion battery ash that was obtained from thermal pre-treatment and (2) rare earth elements (REE)-bearing iron-apatite ore from a Swedish tailing dam. For both samples, simplified methods comprising ‘inhouse’ wet-chemical analysis and energy-dispersive Xray fluorescence (ED-XRF) spectrometry were compared to the results of the developed matrix-specific validated methods. Simplified wet-chemical analyses showed significant differences when compared to the validated method, despite proven internal quality assurance, such as verification of sample homogeneity, precision, and accuracy. Matrix-specific problems, such as incomplete digestion and overlapping spectra due to similar spectral lines (ICP-OES) or element masses (ICP-MS), can result in quadruple overestimations or underestimation by half when compared to the reference value. ED-XRF analysis proved to be applicable as semi-quantitative analysis for elements with mass fractions higher than 1000 ppm and an atomic number between Z 12 and Z 50. For elements with low mass fractions, ED-XRF analysis performed poorly and showed deviations of up to 90 times the validated value. Concerning all the results, we conclude that the characterization of anthropogenic mineral residues is prone to matrix-specific interferences, which have to be addressed with additional quality assurance measures.DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische UniversitĂ€t BerlinEC/H2020/641999/EU/ Prospecting Secondary raw materials in the Urban mine and Mining waste/ProSU
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