Moskau und Chicago als Metropolen der Moderne: Sozialer Konflikt und gesellschaftliche Integration 1870-1914

Das WZB-Discussion Paper verwendet Georg Simmels Aufsatz „Die Großstädte und das Geistesleben“ von 1903 als Ausgangspunkt für eine vergleichende Diskussion der sozialen Frage in Moskau und Chicago in der klassischen Moderne. Der vergleichende Blick auf Russland und die USA verdeutlicht, dass die spezifische Perspektive Georg Simmels auf das Großstadtleben jenseits der europäischen Metropolen eher einer Zielvorstellung denn der Beschreibung sozialer Realitäten entsprach. Der durchschnittliche Bewohner von Moskau oder Chicago konnte sich die von Simmel gepriesene „Blasiertheit“ kaum zu eigen machen. „Hass und Kampf“ bestimmten häufig seinen Alltag. In einer segregierten Stadt musste er versuchen, Fuß zu fassen und sich zu behaupten. Das unabhängige Individuum im Sinne Georg Simmels war in diesen Metropolen nur in den Eliten anzutreffen. Eine Gesellschaft autonomer Stadtbürger war bestenfalls im Entstehen begriffen und die zahlreichen gewalttätigen Auseinandersetzungen und letztlich die russische Revolution zeigen, welch fragile Werte Frieden und Zivilität in der modernen Metropole waren. Das Papier gibt einen Überblick über die urbanen Lebenswelten der russischen und der amerikanischen Stadt und über die unterschiedlichen Versuche sozialer Reform.This WZB Discussion Paper takes Georg Simmel’s classic 1903 essay, “The Metropolis and Mental Life,” as the starting point for a comparative analysis of social issues and city reform in Moscow and Chicago in the period of classic modernity. Scrutinizing each of these cities, it becomes clear that many of Simmel’s observations about the European metropolis did not hold true in these countries. The average Muscovite or Chicagoan was hardly in a position to adopt the “blasé attitude” attributed to the average European, characterized by a kind of cool, remote, and intellectualized approach to things. To the contrary, Muscovites and Chicagoans during this period were struggling for survival in urban environments where authority was often absent or corrupt, and where physical violence shaped everyday life. The “urbane” city dweller, as described by Simmel, could only be found among elites. In densely populated, largely segregated cities with anonymous and estranged citizenries, peace and civility remained fragile, to which the upheavals of the Russian revolution and the Chicago riots dramatically testify. This paper provides an overview of everyday life in Moscow and Chicago, and considers different approaches to social reform in the United States and Russia

Lock-in detection for pulsed electrically detected magnetic resonance

We show that in pulsed electrically detected magnetic resonance (pEDMR) signal modulation in combination with a lock-in detection scheme can reduce the low-frequency noise level by one order of magnitude and in addition removes the microwave-induced non-resonant background. This is exemplarily demonstrated for spin-echo measurements in phosphorus-doped Silicon. The modulation of the signal is achieved by cycling the phase of the projection pulse used in pEDMR for the read-out of the spin state.Comment: 4 pages, 2 figure

Site-selective measurement of coupled spin pairs in an organic semiconductor

From organic electronics to biological systems, understanding the role of intermolecular interactions between spin pairs is a key challenge. Here we show how such pairs can be selectively addressed with combined spin and optical sensitivity. We demonstrate this for bound pairs of spin-triplet excitations formed by singlet fission, with direct applicability across a wide range of synthetic and biological systems. We show that the site-sensitivity of exchange coupling allows distinct triplet pairs to be resonantly addressed at different magnetic fields, tuning them between optically bright singlet (S=0) and dark triplet, quintet (S=1,2) configurations: this induces narrow holes in a broad optical emission spectrum, uncovering exchange-specific luminescence. Using fields up to 60 T, we identify three distinct triplet-pair sites, with exchange couplings varying over an order of magnitude (0.3-5 meV), each with its own luminescence spectrum, coexisting in a single material. Our results reveal how site-selectivity can be achieved for organic spin pairs in a broad range of systems.Comment: 8 pages, article, 7 pages, supporting informatio

Room Temperature Optically and Magnetically Active Edges in Phosphorene Nanoribbons

Nanoribbons - nanometer wide strips of a two-dimensional material - are a unique system in condensed matter physics. They combine the exotic electronic structures of low-dimensional materials with an enhanced number of exposed edges, where phenomena including ultralong spin coherence times, quantum confinement and topologically protected states can emerge. An exciting prospect for this new material concept is the potential for both a tunable semiconducting electronic structure and magnetism along the nanoribbon edge. This combination of magnetism and semiconducting properties is the first step in unlocking spin-based electronics such as non-volatile transistors, a route to low-energy computing, and has thus far typically only been observed in doped semiconductor systems and/or at low temperatures. Here, we report the magnetic and semiconducting properties of phosphorene nanoribbons (PNRs). Static (SQUID) and dynamic (EPR) magnetization probes demonstrate that at room temperature, films of PNRs exhibit macroscopic magnetic properties, arising from their edge, with internal fields of ~ 250 to 800 mT. In solution, a giant magnetic anisotropy enables the alignment of PNRs at modest sub-1T fields. By leveraging this alignment effect, we discover that upon photoexcitation, energy is rapidly funneled to a dark-exciton state that is localized to the magnetic edge and coupled to a symmetry-forbidden edge phonon mode. Our results establish PNRs as a unique candidate system for studying the interplay of magnetism and semiconducting ground states at room temperature and provide a stepping-stone towards using low-dimensional nanomaterials in quantum electronics.Comment: 18 pages, 4 figure

The Amino-Terminus of Nitric Oxide Sensitive Guanylyl Cyclase α1 Does Not Affect Dimerization but Influences Subcellular Localization

BACKGROUND: Nitric oxide sensitive guanylyl cyclase (NOsGC) is a heterodimeric enzyme formed by an α- and a β₁-subunit. A splice variant (C-α₁) of the α₁-subunit, lacking at least the first 236 amino acids has been described by Sharina et al. 2008 and has been shown to be expressed in differentiating human embryonic cells. Wagner et al. 2005 have shown that the amino acids 61-128 of the α₁-subunit are mandatory for quantitative heterodimerization implying that the C-α₁-splice variant should lose its capacity to dimerize quantitatively. METHODOLOGY/PRINCIPAL FINDINGS: In the current study we demonstrate preserved quantitative dimerization of the C-α₁-splice by co-purification with the β₁-subunit. In addition we used fluorescence resonance energy transfer (FRET) based on fluorescence lifetime imaging (FLIM) using fusion proteins of the β₁-subunit and the α₁-subunit or the C-α₁ variant with ECFP or EYFP. Analysis of the respective combinations in HEK-293 cells showed that the fluorescence lifetime was significantly shorter (≈0.3 ns) for α₁/β₁ and C-α₁/β₁ than the negative control. In addition we show that lack of the amino-terminus in the α₁ splice variant directs it to a more oxidized subcellular compartment. CONCLUSIONS/SIGNIFICANCE: We conclude that the amino-terminus of the α₁-subunit is dispensable for dimerization in-vivo and ex-vivo, but influences the subcellular trafficking