1,027 research outputs found

    UnterstĂŒtzung der anspruchsgruppenzentrierten Unternehmenskommunikation im Compliance Management mit Topic Maps

    Get PDF
    Verschiedene Anspruchsgruppen tragen Forderungen an eine Organisation heran. Die Erfassung und Umsetzung der Forderungen ist essentiell. Hierzu existiert mit dem Compliance Management ein geeignetes Konzept. Dabei muss durch eine individuelle Berichterstattung die Umsetzung der Forderungen gegenĂŒber den Anspruchsgruppen. Aus diesem Grund mĂŒssen angepasste Versionen der Berichtsinhalte bereitgestellt werden, welche auf die individuellen InformationsbedĂŒrfnisse ausgerichtet sind. Andernfalls kann die Akzeptanz fĂŒr die berichteten Informationen fehlen oder auch eine Datenweitergabe an unbefugte Gruppen erfolgen. Der vorliegende Artikel beschreibt ein Konzept, welches mit einem Instrument des Semantic Webs, dem ISO Topic Maps Standard, die IKT-gestĂŒtzte Generierung von anspruchsgruppenorientierten Berichten ermöglicht und vereinfacht

    Cornforth–Evans Transition States in Stereocontrolled Allylborations of Epoxy Aldehydes

    Get PDF
    Allylboration reactions rank among the most reliable tools in organic synthesis. Herein, we report a general synthesis of trifunctionalized allylboronates and systematic investigations of their stereocontrolled transformations with substituted aldehyde substrates, in order to efficiently access diverse, highly substituted target substrates. A peculiar transition in stereocontrol was observed from the polar Felkin–Anh (PFA) to the Cornforth–Evans (CE) model for alkoxy‐ and epoxy‐substituted aldehydes. CE‐type transition states were uniformly identified as minima in advanced, DFT‐based computational studies of allylboration reactions of epoxy aldehydes, conforming well to the experimental data, and highlighting the underestimated relevance of this model. Furthermore, a mechanism‐based rationale for the substitution pattern of the epoxide was delineated that ensures high levels of stereocontrol and renders α,ÎČ‐epoxy aldehydes generally applicable substrates for target synthesis

    Photon- and pion-nucleon interactions in a unitary and causal effective field theory based on the chiral Lagrangian

    Full text link
    We present and apply a novel scheme for studying photon- and pion-nucleon scattering beyond the threshold region. Partial-wave amplitudes for the γ N\gamma\, N and πN\pi N states are obtained by an analytic extrapolation of subthreshold reaction amplitudes computed in chiral perturbation theory, where the constraints set by electromagnetic-gauge invariance, causality and unitarity are used to stabilize the extrapolation. Based on the chiral Lagrangian we recover the empirical s- and p-wave amplitudes up to energies s≃1300\sqrt{s}\simeq 1300 MeV in terms of the parameters relevant at order Q3Q^3.Comment: 76 pages, 23 figures, one additional figure, Tables 4,5 and Figure 4 are corrected, a few references and comments are added. The role of higher partial waves in pion photoproduction is clarifie

    Dynamical coupled-channel model of meson production reactions in the nucleon resonance region

    Get PDF
    A dynamical coupled-channel model is presented for investigating the nucleon resonances in the meson production reactions induced by pions and photons. The model is based on an energy-independent Hamiltonian which is derived from a set of Lagrangians by using a unitary transformation method. By applying the projection operator techniques,we derive a set of coupled-channel equations which satisfy the unitarity conditions within the channel space spanned by the considered two-particle meson-baryon states and the three-particle ππN\pi\pi N state. We present and explain in detail a numerical method based on a spline-function expansion for solving the resulting coupled-channel equations which contain logarithmically divergent one-particle-exchange driving terms resulted from the ππN\pi\pi N unitarity cut. We show that this driving term can generate rapidly varying structure in the reaction amplitudes associated with the unstable particle channels. It also has large effects in determining the two-pion production cross sections. Our results indicate that cautions must be taken to interpret the N∗N^* parameters extracted from using models which do not include ππN\pi\pi N cut effects.Comment: 73 pages, 20 figure

    Proton-proton scattering above 3 GeV/c

    Get PDF
    A large set of data on proton-proton differential cross sections, analyzing powers and the double polarization parameter A_NN is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3 GeV/c to 50 GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the rho, omega, f_2, and a_2 trajectories and single Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model.Comment: 16 pages, 19 figures; revised version accepted for publication in EPJ

    Vector meson production and nucleon resonance analysis in a coupled-channel approach for energies m_N < sqrt(s) < 2 GeV I: pion-induced results and hadronic parameters

    Full text link
    We present a nucleon resonance analysis by simultaneously considering all pion- and photon-induced experimental data on the final states gamma N, pi N, 2 pi N, eta N, K Lambda, K Sigma, and omega N for energies from the nucleon mass up to sqrt(s) = 2 GeV. In this analysis we find strong evidence for the resonances P_{31}(1750), P_{13}(1900), P_{33}(1920), and D_{13}(1950). The omega N production mechanism is dominated by large P_{11}(1710) and P_{13}(1900) contributions. In this first part, we present the results of the pion-induced reactions and the extracted resonance and background properties with emphasis on the difference between global and purely hadronic fits.Comment: 54 pages, 26 figures, discussion extended, typos corrected, references updated, to appear in Phys. Rev.

    A Phenomenological Description of (\pi^{-}\Delta^{++}) Photo- and Electroproduction in Nucleon Resonance Region

    Full text link
    The (\pi^{-}\Delta^{++}) production on the nucleon by real and virtual photons is discussed as initial step in a simple model approach for the two pion photo- and electroproduction on the nucleon, with emphasis on nucleon resonance excitation which is of interest for new facilities like TJNAF. A calculation for (\pi^{-}\Delta^{++}) channel in resonance excitation region is presented and compared to existing experimental data along with a discussion of physical effects that we find to be of relevance. The calculation is proposed as a starting basis for the investigation of (N^{*}) electromagnetic form factors using experimental data about two pion production by real and virtual photons.Comment: 36 pages, 14 figures, to be published in Nucl. Phys.
    • 

    corecore