W. Kuehn

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The three-dimensional biogeochemical model ECOHAM was applied to the Northwest European Shelf (47141 0 –63153 0 N, 1515 0 W–13155 0 E) for the years 1993–1996. Nitrogen budgets were calculated for the years 1995 and 1996 for the inner shelf region, the North Sea (511,725 km 2). Simulated temperatures as well as nitrate, oxygen, and chlorophyll(More)
A charged particle modifies the structure of the surrounding medium: examples include a proton in ice, an ion in a DNA molecule, an electron at an interface, or an electron in an organic or inorganic crystal. In turn, the medium acts back on the particle. In a polar or ionic solid, a free electron distorts the crystal lattice, displacing the atoms from(More)
Based on a sample of 1.31×10^{9}  J/ψ events collected with the BESIII detector, an amplitude analysis of the isospin-violating decays η^{'}→π^{+}π^{-}π^{0} and η^{'}→π^{0}π^{0}π^{0} is performed. A significant P-wave contribution from η^{'}→ρ^{±}π^{∓} is observed for the first time in η^{'}→π^{+}π^{-}π^{0}. The branching fraction is determined to be(More)
We present a measurement of the azimuthal asymmetries of two charged pions in the inclusive process e^{+}e^{-}→ππX, based on a data set of 62  pb^{-1} at the center-of-mass energy of 3.65 GeV collected with the BESIII detector. These asymmetries can be attributed to the Collins fragmentation function. We observe a nonzero asymmetry, which increases with(More)
The two-photon transition c ð3686Þ ! J=c is studied in a sample of 1:06 Â 10 8 c ð3686Þ decays collected by the BESIII detector. The branching fraction is measured to be ð3:1 AE 0:6ðstatÞ þ0:8 À1:0 ðsystÞÞ Â 10 À4 using J=c ! e þ e À and J=c ! þ À decays, and its upper limit is estimated to be 4:5 Â 10 À4 at the 90% confidence level. This work represents(More)
Using 1.09×10^{9} J/ψ events collected by the BESIII experiment in 2012, we study the J/ψ→γη^{'}π^{+}π^{-} process and observe a significant abrupt change in the slope of the η^{'}π^{+}π^{-} invariant mass distribution at the proton-antiproton (pp[over ¯]) mass threshold. We use two models to characterize the η^{'}π^{+}π^{-} line shape around 1.85 (More)
Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider at center-of-mass energies of sqrt[s]=4.23, 4.26, and 4.36 GeV, we observe e(+)e(-)→π(0)π(0)hc for the first time. The Born cross sections are measured and found to be about half of those of e(+)e(-)→π(+)π(-)hc within less than 2σ. In the π(0)hc mass spectrum,(More)