On self-dual, doubly even codes of length 32

AbstractWe give a new proof for the theorem of Conway and Pless that there are exactly five binary linear self-dual doubly even extremal codes of length 32

Dynamics of rural areas (DORA): National report - Germany

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Extendible functions and local root numbers: Remarks on a paper of R. P. Langlands

This paper refers to Langlands' big set of notes devoted to the question if the (normalized) local Hecke–Tate root number , where E is a finite separable extension of a fixed nonarchimedean local field F, and χ a quasicharacter of , can be appropriately extended to a local ε‐factor for all virtual representations ρ of the corresponding Weil group . Whereas Deligne has given a relatively short proof by using the global Artin–Weil L‐functions, the proof of Langlands is purely local and splits into two parts: the algebraic part to find a minimal set of relations for the functions Δ, such that the existence (and unicity) of will follow from these relations; and the more extensive arithmetic part to give a direct proof that all these relations are actually fulfilled. Our aim is to cover the algebraic part of Langlands' notes, which can be done completely in the framework of representations of solvable profinite groups, where two modifications of Brauer's theorem play a prominent role.Peer Reviewe

Improvement of the phase regulation between two amplifiers feeding the inputs of the 3dB combiner in the ASDEX-Upgrade ICRH system

The present ICRF system at ASDEX Upgrade uses 3dB combiners to forward the combined power of a generator pair to a single line. Optimal output performance is achieved when the voltages at the two input lines of a combiner are equal in amplitude and the phase in quadrature. If this requirement is not met, a large amount of power is lost in the dummy loads of the combiner. To minimize losses, it is paramount to reach this phase relationship in a fast and stable way. The current phase regulation system is based on analog phase locked loops circuits. The main limitation of this system is the response time: several tens of milliseconds are needed to achieve a stable state. In order to get rid of the response time limitation of the current system, a new system is proposed based on a multi-channel direct digital synthesis device which is steered by a microcontroller and a software-based controller. The proposed system has been developed and successfully tested on a test-bench. The results show a remarkable improvement in the reduction of the response times. Other significant advantages provided by the new system include greater flexibility for frequency and phase settings, lower cost and a noticeable size reduction of the system

The Centrosomal Protein Pericentrin Identified at the Basal Body Complex of the Connecting Cilium in Mouse Photoreceptors

BACKGROUND: Pericentrin (Pcnt), a conserved protein of the pericentriolar material, serves as a multifunctional scaffold for numerous proteins and plays an important role in microtubule organization. Recent studies indicate that Pcnt mutations are associated with a range of diseases including primordial dwarfism and ciliopathies. To date, three Pcnt splice variants from orthologous genes in mice and humans are known. PRINCIPAL FINDINGS: We generated a specific Pcnt antiserum detecting all known Pcnt splice variants and examined the cellular and subcellular distribution of Pcnt in ciliated tissues of the mouse, the olfactory epithelium and the retina. For the first time, we identified Pcnt and its centrosomal interaction partners at the basal body complex of mouse retinal photoreceptors. Photoreceptors are morphologically and functionally subdivided into the light sensitive outer segment and the inner segment comprising the metabolic function of the cell. The two compartments are linked via a modified, specialized, non-motile cilium, the connecting cilium. Here, Pcnt colocalized with the whole protein machinery responsible for transport processes between the two compartments. Surprisingly, photoreceptors expressed a small Pcnt splice transcript - most likely a modified variant of Pcnt S - which was not present in receptor neurons of the olfactory epithelium. CONCLUSIONS: Our findings suggest distinct functional roles of several Pcnt variants in different ciliated tissues and sensory neurons, like the olfactory epithelium and the retina of the mouse. The individual patchwork of different Pcnt splice transcripts seems to reflect the complexity of Pcnt function, an assumption corroborated by the heterogeneous clinical manifestations associated with mutations in the Pcnt gene

Modeling extracellular field potentials and the frequency-filtering properties of extracellular space

Extracellular local field potentials (LFP) are usually modeled as arising from a set of current sources embedded in a homogeneous extracellular medium. Although this formalism can successfully model several properties of LFPs, it does not account for their frequency-dependent attenuation with distance, a property essential to correctly model extracellular spikes. Here we derive expressions for the extracellular potential that include this frequency-dependent attenuation. We first show that, if the extracellular conductivity is non-homogeneous, there is induction of non-homogeneous charge densities which may result in a low-pass filter. We next derive a simplified model consisting of a punctual (or spherical) current source with spherically-symmetric conductivity/permittivity gradients around the source. We analyze the effect of different radial profiles of conductivity and permittivity on the frequency-filtering behavior of this model. We show that this simple model generally displays low-pass filtering behavior, in which fast electrical events (such as Na$^+$-mediated action potentials) attenuate very steeply with distance, while slower (K$^+$-mediated) events propagate over larger distances in extracellular space, in qualitative agreement with experimental observations. This simple model can be used to obtain frequency-dependent extracellular field potentials without taking into account explicitly the complex folding of extracellular space.Comment: text (LaTeX), 6 figs. (ps

Vorwort zu Musikgeschichte in Mittel- und Osteuropa Heft 17

Vorwor

Musikgeschichte in Mittel- und Osteuropa: Mitteilungen der internationalen Arbeitsgemeinschaft an der Universität Leipzig : in Zusammenarbeit mit den Mitgliedern der internationalen Arbeitsgemeinschaft für die Musikgeschichte in Mittel- und Osteuropa an der Universität Leipzig

Als 'Mitteilungen' dokumentieren die einzelnen Hefte die Zusammenarbeit von Musikwissenschaftlern aus den betroffenen Gebieten seit 1997