266 research outputs found

    Open Access - Informationsveranstaltung

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    Die Max-Planck-Gesellschaft hat im Oktober 2003 in der „Berlin Declaration on Open Access to Knowledge in the Sciences and Humanities“ ihre aktive Teilnahme und Unterstützung der Open Access Bewegung bekundet. Damit sind Sie als Wissenschaftler und Autoren aufgerufen, sich an Open Access zu beteiligen. Die Veranstaltung gibt Antworten auf die Fragen: Was ist Open Access? Warum sollte Autoren Open Access interessieren? Wie können Autoren Open Access unterstützen? Dabei wird in den Vorträgen auf grundlegende Ziele von Open Access, die Wahrnehmung von Autorenrechten im Rahmen der rechtlichen Möglichkeiten, die Rolle von eDoc für Open Access in der MPG eingegangen und eine in der MPG gegründete Open Access Zeitschrift - Living Reviews in Relativity - vorgestellt.Was ist Open Access? • Ziele, Berlin Declaration, Strategien des Open Access Warum sollte Sie Open Access interessieren? • Eingeschränkter Zugang aufgrund der Zeitschriftenkrise/Preise, Höherer Impact Wie können Sie Open Access unterstützen? • Publizieren in Open Access Zeitschriften, Open Access Artikel in traditionellen Zeitschriften, Fachbezogene elektronische Archive: arXiv • eDoc-Server am Fritz-Haber-Institut der MPG Was sollten Autoren bei Open Access beachten? • Autorenrechte, Verlagspolitik, Ablage von Pre- und Postprints, Aktivitäten der MPG Was können Sie darüber hinaus tun? • Mitgliedschaft im Herausgebergremium einer Zeitschrift, Gründung einer Open Access Zeitschrift (am Beispiel der Living Reviews in Relativity

    CP Violation and the Width ZbbˉZ\rightarrow b\bar{b}

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    We discuss the effect of CP-violating ZbbˉZb\bar{b}, ZbbˉGZb\bar{b}G and ZbbˉγZb\bar{b}\gamma couplings on the width Γ(ZbbˉX)\Gamma(Z\rightarrow b\bar bX). The presence of such couplings leads in a natural way to an increase of this width relative to the prediction of the standard model. Various strategies of a direct search for such CP-violating couplings by using CP-odd observables are outlined. The number of ZZ bosons required to obtain significant information on the couplings in this way is well within the reach of present LEP experiments.Comment: 18 pages, LaTeX, no figure

    Bioassay-guided isolation and identification of antimicrobial compounds from thyme essential oil by means of overpressured layer chromatography, bioautography and GC-MS

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    A simple method is described for efficient isolation of compounds having an antibacterial effect. Two thyme (Thymus vulgaris) essential oils, obtained from the market, were chosen as prospective materials likely to feature several bioactive components when examined by thin layer chromatography coupled with direct bioautography as a screening method. The newly developed infusion overpressured layer chromatographic separation method coupled with direct bioautography assured that only the active components were isolated by means of overrun overpressured layer chromatography with online detection and fractionation. Each of the 5 collected fractions represented one of the five antimicrobial essential oil components designated at the screening. The purity and the activity of the fractions were confirmed with chromatography coupled various detection methods (UV, vanillin-sulphuric acid reagent, direct bioautography). The antibacterial components were identified with GC-MS as thymol, carvacrol, linalool, diethylphthalate, and alpha-terpineol. The oil component diethyl-phthalate is an artificial compound, used as plasticizer or detergent bases in the industry. Our results support that exploiting its flexibility and the possible hyphenations, overpressured layer chromatography is especially attractive for isolation of antimicrobial components from various matrixes

    Next-Generation Phage Display: Integrating and Comparing Available Molecular Tools to Enable Cost-Effective High-Throughput Analysis

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    Background: Combinatorial phage display has been used in the last 20 years in the identification of protein-ligands and protein-protein interactions, uncovering relevant molecular recognition events. Rate-limiting steps of combinatorial phage display library selection are (i) the counting of transducing units and (ii) the sequencing of the encoded displayed ligands. Here, we adapted emerging genomic technologies to minimize such challenges. Methodology/Principal Findings: We gained efficiency by applying in tandem real-time PCR for rapid quantification to enable bacteria-free phage display library screening, and added phage DNA next-generation sequencing for large-scale ligand analysis, reporting a fully integrated set of high-throughput quantitative and analytical tools. The approach is far less labor-intensive and allows rigorous quantification; for medical applications, including selections in patients, it also represents an advance for quantitative distribution analysis and ligand identification of hundreds of thousands of targeted particles from patient-derived biopsy or autopsy in a longer timeframe post library administration. Additional advantages over current methods include increased sensitivity, less variability, enhanced linearity, scalability, and accuracy at much lower cost. Sequences obtained by qPhage plus pyrosequencing were similar to a dataset produced from conventional Sanger-sequenced transducing-units (TU), with no biases due to GC content, codon usage, and amino acid or peptide frequency. These tools allow phage display selection and ligand analysis at.1,000-fold faster rate, and reduce costs,250fol

    Palaeoproterozoic magnesite: lithological and isotopic evidence for playa/sabkha environments

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    Magnesite forms a series of 1- to 15-m-thick beds within the approximate to2.0 Ga (Palaeoproterozoic) Tulomozerskaya Formation, NW Fennoscandian Shield, Russia. Drillcore material together with natural exposures reveal that the 680-m-thick formation is composed of a stromatolite-dolomite-'red bed' sequence formed in a complex combination of shallow-marine and non-marine, evaporitic environments. Dolomite-collapse breccia, stromatolitic and micritic dolostones and sparry allochemical dolostones are the principal rocks hosting the magnesite beds. All dolomite lithologies are marked by delta C-13 values from +7.1 parts per thousand to +11.6 parts per thousand (V-PDB) and delta O-18 ranging from 17.4 parts per thousand to 26.3 parts per thousand (V-SMOW). Magnesite occurs in different forms: finely laminated micritic; stromatolitic magnesite; and structureless micritic, crystalline and coarsely crystalline magnesite. All varieties exhibit anomalously high delta C-13 values ranging from +9.0 parts per thousand to +11.6 parts per thousand and delta O-18 values of 20.0-25.7 parts per thousand. Laminated and structureless micritic magnesite forms as a secondary phase replacing dolomite during early diagenesis, and replaced dolomite before the major phase of burial. Crystalline and coarsely crystalline magnesite replacing micritic magnesite formed late in the diagenetic/metamorphic history. Magnesite apparently precipitated from sea water-derived brine, diluted by meteoric fluids. Magnesitization was accomplished under evaporitic conditions (sabkha to playa lake environment) proposed to be similar to the Coorong or Lake Walyungup coastal playa magnesite. Magnesite and host dolostones formed in evaporative and partly restricted environments; consequently, extremely high delta C-13 values reflect a combined contribution from both global and local carbon reservoirs. A C- 13-rich global carbon reservoir (delta C-13 at around +5 parts per thousand) is related to the perturbation of the carbon cycle at 2.0 Ga, whereas the local enhancement in C-13 (up to +12 parts per thousand) is associated with evaporative and restricted environments with high bioproductivity

    Detection of antibacterial activity of essential oil components by TLC-bioautography using luminescent bacteria

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    The aim of the present study was the chemical characterization of some medically relevant essential oils (tea tree, clove, cinnamon bark, thyme and eucalyptus) and the investigation of antibacterial effect of the components of these oils by use of a direct bioautographic method. Thin layer chromatography (TLC) was combined with biological detection in this process. The chemical composition of the oils was determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Eucalyptol (84.2%) was the main component of the essential oil of eucalyptus, eugenol (83.7%) of clove oil, and trans-cinnamic aldehyde (73.2%), thymol (49.9%) and terpinen-4-ol (45.8%) of cinnamon bark, thyme and tea tree oils, respectively. Antibacterial activity of the separated components of these oils, as well as their pure main components (eucalyptol, eugenol, trans-cinnamic aldehyde and thymol) was observed against the Gram-negative luminescence tagged plant pathogenic bacterium Pseudomonas syringae pv. maculicola (Psmlux) and the Gram-negative, naturally luminescent marine bacterium Vibrio fischeri. On the whole, the antibacterial activity of the essential oils could be related to their main components, but the minor constituents may be involved in this process. Trans-cinnamic aldehyde and eugenol were the most active compounds in TLC-bioautography. The sensitivity of TLC-bioautographic method can be improved with using luminescent test bacteria. This method is more cost-effective and provides more reliable results in comparison with conventional microbiological methods, e.g. disc-diffusion technique

    How to Measure Chromo-magnetic Vacuum Background Field in e+ejetse^{+}e^{-}\to jets, Hadron-Hadron and Nucleus-Nucleus Collisions

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    We propose a new type of the measurement which is sensitive to the QCD vacuum color-magnetic fluctuations: A measure of the axial assymetry of the hadronic final states produced in the high energy e+ee^{+}e^{-} collisions is related to the chromomagnetic vacuum field strength.Comment: 11 pages,latex,no figures,replaced,final version which takes into account criticisms of referees of Phys.Rev. Title of the paper was changed. The formula (14) was corrected, notation in formulae (12) and (13) changed. Also we added forgotten vectorial notations,corrected misspellings and improved the style and gramma

    Soft Color Interactions and Diffractive Hard Scattering at the Fermilab Tevatron

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    An improved understanding of nonperturbative QCD can be obtained by the recently developed soft color interaction models. Their essence is the variation of color string-field topologies, giving a unified description of final states in high energy interactions, e.g., diffractive and nondiffractive events in ep and ppbar. Here we present a detailed study of such models (the soft color interaction model and the generalized area law model) applied to ppbar, considering also the general problem of the underlying event including beam particle remnants. With models tuned to HERA ep data, we find a good description also of Tevatron data on production of W, beauty and jets in diffractive events defined either by leading antiprotons or by one or two rapidity gaps in the forward or backward regions. We also give predictions for diffractive J/psi production where the soft exchange mechanism produces both a gap and a color singlet ccbar state in the same event. This soft color interaction approach is also compared with Pomeron-based models for diffraction, and some possibilities to experimentally discriminate between these different approaches are discussed.Comment: 35 pages, 15 figures, uses REVTeX. Minor changes, version to appear in Phys. Rev.

    Cruise Report Poseidon 229a/b Kolbeinsey Ridge, Akureyri - Reykjavik, 22.05.1997 - 11.06.1997

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    General Subject of research: Detailed study of the shallow water hydrothermal system around Kolbeinsey and Grimsey island

    Soft Photons in Hadron-Hadron Collisions: Synchrotron Radiation from the QCD Vacuum?

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    We discuss the production of soft photons in high energy hadron-hadron collisions. We present a model where quarks and antiquarks in the hadrons emit ``synchrotron light'' when being deflected by the chromomagnetic fields of the QCD vacuum, which we assume to have a nonperturbative structure. This gives a source of prompt soft photons with frequencies ω<=300MeV\omega <= 300 MeV in the c.m. system of the collision in addition to hadronic bremsstrahlung. In comparing the frequency spectrum and rate of ``synchrotron'' photons to experimental results we find some supporting evidence for their existence. We make an exclusive--inclusive connection argument to deduce from the ``synchrotron'' effect a behaviour of the neutron electric formfactor GEn(Q2)G_E^n(Q^2) proportional to (Q2)1/6(Q^2)^{1/6} for Q2<20fm2Q^2 < 20 fm^{-2}. We find this to be consistent with available data. In our view, soft photon production in high energy hadron-hadron and lepton-hadron collisions as well as the behaviour of electromagnetic hadron formfactors for low Q2Q^2 are thus sensitive probes of the nonperturbative structure of the QCD vacuum.Comment: Heidelberg preprint HD-THEP-94-36, 31 pages, LaTeX + ZJCITE.sty (included), 12 figures appended as uuencoded compressed ps-fil
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