1,192 research outputs found

    Ferromagnetic coupling of mononuclear Fe centers in a self-assembled metal-organic network on Au(111)

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    The magnetic state and magnetic coupling of individual atoms in nanoscale structures relies on a delicate balance between different interactions with the atomic-scale surrounding. Using scanning tunneling microscopy, we resolve the self-assembled formation of highly ordered bilayer structures of Fe atoms and organic linker molecules (T4PT) when deposited on a Au(111) surface. The Fe atoms are encaged in a three-dimensional coordination motif by three T4PT molecules in the surface plane and an additional T4PT unit on top. Within this crystal field, the Fe atoms retain a magnetic ground state with easy-axis anisotropy, as evidenced by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. The magnetization curves reveal the existence of ferromagnetic coupling between the Fe centers

    Cervical artery dissection: An atypical presentation with Ehlers-Danlos-like collagen pathology?

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    The authors took skin biopsies of the macroscopically normal skin of seven consecutive patients with spontaneous cervical artery dissection (SCAD). Histologically, alterations of the collagen and elastic fiber networks were found in six patients. In five, the histologic, immunohistochemical, and ultrastructural changes were similar to those usually found in Ehlers-Danlos syndrome (EDS). This suggests that SCAD is frequently associated with the dermal alterations seen in EDS

    A mitochondrial mutator plasmid that causes senescence under dietary restricted conditions

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    BACKGROUND: Calorie or dietary restriction extends life span in a wide range of organisms including the filamentous fungus Podospora anserina. Under dietary restricted conditions, P. anserina isolates are several-fold longer lived. This is however not the case in isolates that carry one of the pAL2-1 homologous mitochondrial plasmids. RESULTS: We show that the pAL2-1 homologues act as 'insertional mutators' of the mitochondrial genome, which may explain their negative effect on life span extension. Sequencing revealed at least fourteen unique plasmid integration sites, of which twelve were located within the mitochondrial genome and two within copies of the plasmid itself. The plasmids were able to integrate in their entirety, via a non-homologous mode of recombination. Some of the integrated plasmid copies were truncated, which probably resulted from secondary, post-integrative, recombination processes. Integration sites were predominantly located within and surrounding the region containing the mitochondrial rDNA loci. CONCLUSION: We propose a model for the mechanism of integration, based on innate modes of mtDNA recombination, and discuss its possible link with the plasmid's negative effect on dietary restriction mediated life span extension

    Iron porphyrin molecules on Cu(001): Influence of adlayers and ligands on the magnetic properties

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    The structural and magnetic properties of Fe octaethylporphyrin (OEP) molecules on Cu(001) have been investigated by means of density functional theory (DFT) methods and X-ray absorption spectroscopy. The molecules have been adsorbed on the bare metal surface and on an oxygen-covered surface, which shows a 2×22R45\sqrt{2}\times2\sqrt{2}R45^{\circ} reconstruction. In order to allow for a direct comparison between magnetic moments obtained from sum-rule analysis and DFT we calculate the dipolar term 77, which is also important in view of the magnetic anisotropy of the molecule. The measured X-ray magnetic circular dichroism shows a strong dependence on the photon incidence angle, which we could relate to a huge value of 77, e.g. on Cu(001) 77 amounts to -2.07\,\mbo{} for normal incidence leading to a reduction of the effective spin moment ms+7m_s + 7. Calculations have also been performed to study the influence of possible ligands such as Cl and O atoms on the magnetic properties of the molecule and the interaction between molecule and surface, because the experimental spectra display a clear dependence on the ligand, which is used to stabilize the molecule in the gas phase. Both types of ligands weaken the hybridization between surface and porphyrin molecule and change the magnetic spin state of the molecule, but the changes in the X-ray absorption are clearly related to residual Cl ligands.Comment: 17 figures, full articl

    DFTCalc: reliability centered maintenance via fault tree analysis (tool paper)

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    Reliability, availability, maintenance and safety (RAMS) analysis is essential in the evaluation of safety critical systems like nuclear power plants and the railway infrastructure. A widely used methodology within RAMS analysis are fault trees, representing failure propagations throughout a system. We present DFTCalc, a tool-set to conduct quantitative analysis on dynamic fault trees including the effect of a maintenance strategy on the system dependability

    Транспортная логистика: проблемы и перспективы развития в таможенном деле

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    Выпускная квалификационная работа посвящена исследованию транспортной логистике в таможенном деле. Целью данной работы является комплексный анализ факторов, механизмов и проблем трансформации таможенной логистики в глобальной торговой системе и обоснование направлений адаптации таможенной логистики России в условиях либерализации международной торговли. Задачи: •Понятие, виды, функции логистики •Задачи транспортной логистики •Сущность таможенной логистики •Проблемы становления таможенной логистики •Ключевые проблемы таможенной логистики •Перспективы развития таможенной логистики. Объектом исследования является процесс формирования и реализации таможенной логистики в глобальной торговой системе.The final qualifying work is devoted to the study of transport logistics in the customs business. The purpose of this work is a comprehensive analysis of the factors, mechanisms and problems of the transformation of customs logistics in the global trading system and the rationale for adapting the customs logistics of Russia in the context of the liberalization of international trade

    Distribution-based bisimulation for labelled Markov processes

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    In this paper we propose a (sub)distribution-based bisimulation for labelled Markov processes and compare it with earlier definitions of state and event bisimulation, which both only compare states. In contrast to those state-based bisimulations, our distribution bisimulation is weaker, but corresponds more closely to linear properties. We construct a logic and a metric to describe our distribution bisimulation and discuss linearity, continuity and compositional properties.Comment: Accepted by FORMATS 201
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