1476 search hits
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Globale Verfassungen – jenseits des Nationalstaats : wie Subsysteme der Weltgesellschaft ihre eigenen Rechtsnormen schaffen
(2007)
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Gunther Teubner
- Während in den Vereinten Nationen mit mäßigem Erfolg um eine international akzeptierte Weltpolitik gerungen wird, haben sich in anderen gesellschaftlichen Bereichen längst globale vernetzte Strukturen entwickelt. Ansätze für eine Vielzahl von autonomen Zivilverfassungen, die die Welt umspannen, sind erkennbar – vom »cyberspace « bis zur Weltwirtschaft. Lassen sich mit den Grundsätzen der nationalstaatlichen Verfassungen auch die Herausforderungen angehen, die sich aus den drei aktuellen Trends – Digitalisierung, Privatisierung und globaler Vernetzung – ergeben? Ging es im 18. und 19. Jahrhundert im Nationalstaat darum, die Rechte des Einzelnen gegenüber dem Staat zu stärken und die Politik durch ihre Bindung an das Recht zu disziplinieren, so dreht es sich heute um Freisetzung und Disziplinierung ganz anderer globaler Dynamiken. Der Rechtssoziologe Prof. Dr. Gunther Teubner beschäftigt sich mit der Frage: Kann man die Traditionen der Nationalstaatsverfassung fruchtbar machen und sie zugleich so umdenken, dass sie den neuen Problemlagen gerecht werden?
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»... steht als schöpferische Persönlichkeit turmhoch über uns« : eine Annäherung an Peter Suhrkamp beim Stöbern in seinen Korrespondenzen
(2007)
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Wolfgang Schopf
- Peter Suhrkamp und sein Verlag stehen für den kulturellen Wiederaufbau: Suhrkamp erhält 1945 die erste Verlagslizenz, sein Programm prägt die geistige Identität der jungen Republik. Der Verleger wirkt im Stillen als Katalysator bei der Entstehung von Werken, er gibt Autoren die intellektuelle Heimat, in der entstehen kann, was zur literarischen Signatur Nachkriegsdeutschlands werden wird. Die Frage nach seinem Erfolgsrezept beantwortet Wolfgang Schopf mit einem Blick auf die Schätze des »Archivs der Peter Suhrkamp Stiftung an der Johann Wolfgang Goethe-Universität«.
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Münze und Geld in der antiken Welt : was Fundstücke aus zehn Jahrhunderten preisgeben
(2007)
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Hans-Markus von Kaenel
- Aus den zehn Jahrhunderten antiker Münzgeschichte gibt es Millionen an Fundmünzen. Jedes Jahr kommen zahllose Neufunde hinzu. Wozu haben Griechen, Römer, Kelten und andere Völker Münzen geprägt, und wie haben sie diese gebraucht? Wer Einsichten in staatliches Handeln, gesellschaftliche Vorstellungen und Verhaltensweisen, ökonomisches Denken sowie Kultpraktiken gewinnen will, kommt am Studium von Münzen (Numismatik) und ihres Gebrauchs als Geld (Geldgeschichte) nicht vorbei. An der Universität Frankfurt forschen Numismatiker, Archäologen, Althistoriker und Mineralogen aus neun verschiedenen Ländern über Münze und Geld in der antiken Welt.
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How specific is synchronous neuronal firing? : Poster presentation
(2007)
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Wei Wu
Gordon Pipa
- Background Synchronous neuronal firing has been discussed as a potential neuronal code. For testing first, if synchronous firing exists, second if it is modulated by the behaviour, and third if it is not by chance, a large set of tools has been developed. However, to test whether synchronous neuronal firing is really involved in information processing one needs a direct comparison of the amount of synchronous firing for different factors like experimental or behavioural conditions. To this end we present an extended version of a previously published method NeuroXidence [1], which tests, based on a bi- and multivariate test design, whether the amount of synchronous firing above the chance level is different for different factors.
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Zero-lag long-range synchronization of Hodgkin-Huxley neurons is enhanced by dynamical relaying : poster presentation
(2007)
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Raul Vicente
Gordon Pipa
Ingo Fischer
Claudio R Mirasso
- Background The synchrony hypothesis postulates that precise temporal synchronization of different pools of neurons conveys information that is not contained in their firing rates. The synchrony hypothesis had been supported by experimental findings demonstrating that millisecond precise synchrony of neuronal oscillations across well separated brain regions plays an essential role in visual perception and other higher cognitive tasks [1]. Albeit, more evidence is being accumulated in favour of its role as a binding mechanism of distributed neural responses, the physical and anatomical substrate for such a dynamic and precise synchrony, especially zero-lag even in the presence of non-negligible delays, remains unclear. Here we propose a simple network motif that naturally accounts for zero-lag synchronization for a wide range of temporal delays [3]. We demonstrate that zero-lag synchronization between two distant neurons or neural populations can be achieved by relaying the dynamics via a third mediating single neuron or population. Methods We simulated the dynamics of two Hodgkin-Huxley neurons that interact with each other via an intermediate third neuron. The synaptic coupling was mediated through alpha-functions. Individual temporal delays of the arrival of pre-synaptic potentials were modelled by a gamma distribution. The strength of the synchronization and the phase-difference between each individual pairs were derived by cross-correlation of the membrane potentials. Results In the regular spiking regime the two outer neurons consistently synchronize with zero phase lag irrespective of the initial conditions. This robust zero-lag synchronization naturally arises as a consequence of the relay and redistribution of the dynamics performed by the central neuron. This result is independent on whether the coupling is excitatory or inhibitory and can be maintained for arbitrarily long time delays (see Fig. 1). Conclusion We have presented a simple and extremely robust network motif able to account for the isochronous synchronization of distant neural elements in a natural way. As opposed to other possible mechanisms of neural synchronization, neither inhibitory coupling, gap junctions nor precise tuning of morphological parameters are required to obtain zero-lag synchronized neuronal oscillation.
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Energiediskussion Frankfurter Art : Forscher am Institut für Anorganische und Analytische Chemie entwickeln hocheffizientes Verfahren zur Herstellung von Photovoltaik-Silicium und von Wasserstoffträger-Materialien
(2007)
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Norbert Auner
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Unternehmensmitbestimmung in Deutschland : Vorteil oder Ballast im Standortwettbewerb?
(2007)
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Oliver Stettes
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The law of corporate finance in Europe : an essay
(2007)
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Theodor Baums
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Allosteric modulators of metabotropic glutamate receptors: from virtual screening to experimental validation
(2007)
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Tobias Noeske
- The goal of this thesis was to gain further insight into the binding behavior of ligands in the heptahelical domain (HD) of group I metabotropic glutamate receptors (mGluRs). This was realized by the establishment of strategies for the detection and optimization of molecules acting as non-competitive antagonists of group I mGluRs (mGluR1/5). These strategies should guarantee high diversity in the retrieved chemotypes of the detected compounds not resembling original reference molecules (“scaffold-hopping”). The detection of new scaffolds, in turn, was divided into two approaches: First the development of pharmacological assays to screen compounds at a certain target for bioactivity (here: affinity towards the allosteric recognition site of mGluR1 and mGluR5), and second the evaluation of computer assisted methods for the identification of virtual hits to be screened afterwards on the pharmacological assays established before. Promising molecules should be optimized with respect to activity/affinity and selectivity, their binding mode investigated and, finally, compared to existing lead compounds. Initially, membrane based binding assays for the HD of mGlu1 and mGlu5 receptors with enhanced throughput (shifting from 24-well plates to 96-well plates) were set up. For the mGluR1 assay the potent antagonist EMQMCM exhibited high affinity towards the binding site (Ki ~3nM), which is in accordance with published data from Mabire et al. (functional IC50 3nM). For mGluR5 the reference antagonist MPEP binds with high affinity to the receptor (binding IC50 13.8nM), which confirmed earlier findings from Anderson et al. (binding IC50 15nM). In another series of experiments the properties of rat cerebellar (mGluR1) and corticalmembranes (mGluR5) as well as of radiotracers were investigated by means of binding saturation studies and kinetic experiments. Furthermore, the influence of the solvent DMSO, necessary for compound screening of lipophilic substances, on positive and negative controls was evaluated. As the precise architecture of the HD of mGluR1 is still not known our efforts in identifying new ligands for this receptor focused on the ligand-based approach. All computer assisted methods that were applied to virtually screen large compound collections and to retrieve potential hits (“activity-enriched subsets”) acting at the heptahelical domain of mGluR1 relied on the existence of a valid dataset of reference molecules. This was realized by an initial compilation of a mGluR reference data collection comprising in total 357 entries predominantly negative but also some positive allosteric modulators for mGluR1 and mGluR5. In the next step a pharmacophore model for non-competitive mGluR1 antagonists was constructed. It was based upon six selective, potent and structurally diverse ligands. Prospective virtual screening was performed using the CATS atom-pair descriptor. The Asinex Gold-Collection was screened for each seed compound and some of the most similar compounds (according to the CATS descriptor) were ordered and tested forbinding affinity and functional activity at mGluR1. A high hit rate of approximately 26% (IC50 < 15 micro M) was yielded confirming the applicability of this method. One compound exerted functional activity below one micro molar (IC50-value of C-07:362nM ± 0.03). Moreover, non-linear principal component analysis was employed. Again the Asinex vendor database served as test database and was filtered by the pharmacophore model for mGluR1 established before. Test molecules that were adjacently located with mGluR1 antagonist references were selected. 15 compounds were tested on mGluR1 in binding and functional assays and three of them exhibited functional activity (IC50) below 15 micro M. The most potent molecule P-06 revealed an IC50-value of 1.11 micro M (± 0.41). The COBRA database comprising 5,376 structurally diverse bioactive molecules affecting various targets was encoded with the CATS descriptor and used for training two selforganizing maps (SOM). The encoded mGluR reference data collection was projected onto this map according to the SOM algorithm. This projection allowed to clearly distinguish between antagonists of mGluR1 and mGluR5 subtype. 28 compounds were ordered and tested on activity and affinity for mGluR1. They exhibited functional activity down to the sub-micro molar range (IC50-value of S-08: 744nM ± 0.29) yielding a final hit rate of 46% (<15 micro M). Then, the Asinex collection was screened using the SOM approach. For a predicted target panel including the muscarinic mACh (M1) receptor, the histamine H1-receptor and the dopamine D2/D3 receptors, the tested mGluR ligands exhibited the calculated binding pattern. This virtual screening concept might provide a basis for early recognition of potential sideeffects in lead discovery. We superimposed a set of 39 quinoline derivatives as non-competitive mGluR1 antagonists that were recently published by Mabire and co-workers. A CoMFA model (QSAR) was established and the influence of several side chains on functional activity was investigated. The coumarine derivative C-07 was obtained as a result of similarity searching. Starting from this compound a series of chemical derivatives was synthesized. This led to the discovery of potent (B-28, IC50: 58nM ± 0.008; Ki: 293nM ± 0.022) and selective (rmGluR5 IC50: 28.6 micro M) mGluR1 antagonists. From a homology model of mGluR1 we derived a potential binding mode for coumarines within the allosteric transmembrane region. Potential interacting patterns with amino acids were proposed considering the difference of the binding pockets between rat and human receptors. The proposed binding modes for quinolines (here:EMQMCM) and coumarines (here:B-04) were compared and discussed considering in particular the influence on activity of several side chains of quinolines obtained from the QSAR studies. The present studies demonstrated the applicability of ligand-based virtual screening for non-competitive antagonists of a G-protein coupled receptor, resulting in novel, potent and selective agents.
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Energy and system size dependence of Xi- and anti-Xi+ production in relativistic heavy-ion collisions at the CERN SPS
(2007)
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Michael Kosta Mitrovski
- The strong nuclear force is described by Quantum Chromodynamics (QCD), the parallel field theory to Quantum Electrodynamics (QED) that describes the electromagnetic force. It is propagated by gluons analogously to photons in the electromagnetic force, but unlike photons, which do not carry electric charge, gluons carry color, and they can self-interact. However, as individual quarks have never been observed in nature, it is postulated that the color charge itself is confined, and hence all baryons and mesons must be colorless objects. To study nuclear matter under extreme conditions, it is necessary to create hot and dense nuclear matter in the laboratory. In such conditions the confinement between quarks and gluons is cancelled (deconfinement). This state is characterized with a qusi-free behavior of quarks and gluons. The strange (s) and anti-strange (anti-s) quarks are not contained in the colliding nuclei, but are newly produced and show up in the strange hadrons in the final state. It was suggested that strange particle production is enhanced in the QGP with respect to that in a hadron gas. This enhancement is relative to a collision where a transition to a QGP phase does not take place, such as p+p collisions where the system size is very small. Therefore the energy- and system size dependence is studied to receive a picture about the initial state. In this thesis experimental results on the energy- and system size dependence of Xi hyperon production at the CERN SPS is shown. All measurements were performed with the NA49 detector at the CERN SPS. NA49 took central lead-lead collisions from 20 - 158 AGeV, minimus bias lead-lead collisions at 40 and 158 AGeV, and semi-central silicon-silicon colisions at 158 AGeV. The NA49 experiment features a large acceptance in the forward hemisphere allowing for measurements of Xi rapidity spectra. At the SPS accelerator at CERN Pb+Pb collisions are performed with beam energies to 158 AGeV. The analyzed data sets were taken in the period from 1999 to 2002. The NA49 experiment is a large acceptance hadron spectrometer, which measures charged hadrons in a wide acceptance. The main components are the four TPCs (Time Projection Chamber). The centrality of nucleon-nucleon collisions was done by measuring the not in the collision participating (spectator-) nucleons in the VETO-calorimeter. The study of strangeness is motivated by its role as a signature for the Quark Gluon Plasma. Any enhancement in the yield must be with respect to a ’normal’ yield, where a QGP is not formed. This is usually taken to mean suitably scaled p+p collisions, where the volume of the system created is too small for a QGP to occur. The results at SPS and RHIC energies show an enhancement, with the doubly strange Xi? being enhanced more than the Lambda, in accordance with the original prediction. However, the enhancement at SPS energies is higher than at RHIC energies.
