1,027 research outputs found
UnterstĂŒtzung der anspruchsgruppenzentrierten Unternehmenskommunikation im Compliance Management mit Topic Maps
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
CornforthâEvans Transition States in Stereocontrolled Allylborations of Epoxy Aldehydes
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 FelkinâAnh (PFA) to the CornforthâEvans (CE) model for alkoxyâ and epoxyâsubstituted aldehydes. CEâtype transition states were uniformly identified as minima in advanced, DFTâbased computational studies of allylboration reactions of epoxy aldehydes, conforming well to the experimental data, and highlighting the underestimated relevance of this model. Furthermore, a mechanismâbased rationale for the substitution pattern of the epoxide was delineated that ensures high levels of stereocontrol and renders α,ÎČâepoxy 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
We present and apply a novel scheme for studying photon- and pion-nucleon
scattering beyond the threshold region. Partial-wave amplitudes for the
and 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
MeV in terms of the parameters relevant at order .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
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
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 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 parameters extracted from using models which do
not include cut effects.Comment: 73 pages, 20 figure
Proton-proton scattering above 3 GeV/c
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
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
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.
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