@article{HeninPetitRohwetteretal.2011, author = {Henin, Stefano and Petit, Yannick and Rohwetter, Philipp and Stelmaszczyk, Kamil and Hao, Zuoqiang and Nakaema, Walter Morinobu and Vogel, Andreas and Pohl, Tobias and Schneider, Friedhelm and Kasparian, J{\´e}r{\^o}me and Weber, Konradin and W{\"o}ste, Ludger and Wolf, Jean-Pierre}, title = {Field measurements suggest the mechanism of laser-assisted water condensation}, series = {Nature Communications}, volume = {2}, journal = {Nature Communications}, number = {1}, publisher = {Springer Nature}, issn = {2041-1723}, doi = {10.1038/ncomms1462}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-52439}, year = {2011}, abstract = {Because of the potential impact on agriculture and other key human activities, efforts have been dedicated to the local control of precipitation. The most common approach consists of dispersing small particles of dry ice, silver iodide, or other salts in the atmosphere. Here we show, using field experiments conducted under various atmospheric conditions, that laser filaments can induce water condensation and fast droplet growth up to several μm in diameter in the atmosphere as soon as the relative humidity exceeds 70\%. We propose that this effect relies mainly on photochemical formation of p.p.m.-range concentrations of hygroscopic Hno3, allowing efficient binary Hno3-H2o condensation in the laser filaments. Thermodynamic, as well as kinetic, numerical modelling based on this scenario semiquantitatively reproduces the experimental results, suggesting that particle stabilization by Hno3 has a substantial role in the laser-induced condensation.}, subject = {Kondensation}, language = {en} } @article{PetitHeninKasparianetal.2011, author = {Petit, Y. and Henin, S. and Kasparian, J. and Wolf, J. P. and Rohwetter, P. and Stelmaszczyk, K. and Hao, Z. Q. and Nakaema, W. M. and W{\"o}ste, L. and Vogel, A. and Pohl, T. and Weber, Konradin}, title = {Influence of pulse duration, energy, and focusing on laser-assisted water condensation}, series = {Applied Physics Letters}, volume = {98}, journal = {Applied Physics Letters}, number = {4}, publisher = {AIP Publishing}, issn = {0003-6951}, doi = {10.1063/1.3546172}, year = {2011}, abstract = {We investigate the influence of laser parameters on laser-assisted water condensation in the atmosphere. Pulse energy is the most critical parameter. Nanoparticle generation depends linearly on energy beyond the filamentation threshold. Shorter pulses are more efficient than longer ones with saturation at ∼1.5 ps. Multifilamenting beams appear more efficient than strongly focused ones in triggering the condensation and growth of submicronic particles, while polarization has a negligible influence on the process. The data suggest that the initiation of laser-assisted condensation relies on the photodissociation of the air molecules rather than on their photoionization.}, language = {en} } @article{PetrarcaHeninStelmaszczyketal.2011, author = {Petrarca, M. and Henin, S. and Stelmaszczyk, K. and Bock, S. and Kraft, S. and Schramm, U. and Vaneph, C. and Vogel, A. and Kasparian, J. and Sauerbrey, R. and Weber, Konradin and W{\"o}ste, L. and Wolf, J.-P.}, title = {Multijoule scaling of laser-induced condensation in air}, series = {Applied Physics Letters}, volume = {99}, journal = {Applied Physics Letters}, number = {14}, publisher = {AIP Publishing}, issn = {0003-6951}, doi = {10.1063/1.3646397}, year = {2011}, abstract = {Using 100 TW laser pulses, we demonstrate that laser-induced nanometric particle generation in air increases much faster than the beam-averaged incident intensity. This increase is due to a contribution from the photon bath, which adds up with the previously identified one from the filaments and becomes dominant above 550 GW/cm2. It appears related to ozone formation via multiphoton dissociation of the oxygen molecules and demonstrates the critical need for further increasing the laser energy in view of macroscopic effects in laser-induced condensation.}, language = {en} } @article{NehrBohnFuchsetal.2011, author = {Nehr, Sascha and Bohn, Birger and Fuchs, Hendrik and Hofzumahaus, Andreas and Wahner, Andreas}, title = {HO2 formation from the OH + benzene reaction in the presence of O2}, series = {Physical Chemistry Chemical Physics}, volume = {13}, journal = {Physical Chemistry Chemical Physics}, number = {22}, publisher = {Royal Society of Chemistry (RSC)}, issn = {1463-9076}, doi = {10.1039/c1cp20334g}, year = {2011}, language = {en} } @article{FuchsBohnHofzumahausetal.2011, author = {Fuchs, H. and Bohn, Birger and Hofzumahaus, A. and Holland, F. and Lu, K. D. and Nehr, Sascha and Rohrer, F. and Wahner, A.}, title = {Detection of HO2 by laser-induced fluorescence: calibration and interferences from RO2 radicals}, series = {Atmospheric Measurement Techniques}, volume = {4}, journal = {Atmospheric Measurement Techniques}, number = {6}, publisher = {Copernicus}, issn = {1867-8548}, doi = {10.5194/amt-4-1209-2011}, pages = {1209 -- 1225}, year = {2011}, abstract = {Abstract. HO2 concentration measurements are widely accomplished by chemical conversion of HO2 to OH including reaction with NO and subsequent detection of OH by laser-induced fluorescence. RO2 radicals can be converted to OH via a similar radical reaction sequence including reaction with NO, so that they are potential interferences for HO2 measurements. Here, the conversion efficiency of various RO2 species to HO2 is investigated. Experiments were conducted with a radical source that produces OH and HO2 by water photolysis at 185 nm, which is frequently used for calibration of LIF instruments. The ratio of HO2 and the sum of OH and HO2 concentrations provided by the radical source was investigated and was found to be 0.50 ± 0.02. RO2 radicals are produced by the reaction of various organic compounds with OH in the radical source. Interferences via chemical conversion from RO2 radicals produced by the reaction of OH with methane and ethane (H-atom abstraction) are negligible consistent with measurements in the past. However, RO2 radicals from OH plus alkene- and aromatic-precursors including isoprene (mainly OH-addition) are detected with a relative sensitivity larger than 80 \% with respect to that for HO2 for the configuration of the instrument with which it was operated during field campaigns. Also RO2 from OH plus methyl vinyl ketone and methacrolein exhibit a relative detection sensitivity of 60 \%. Thus, previous measurements of HO2 radical concentrations with this instrument were biased in the presence of high RO2 radical concentrations from isoprene, alkenes or aromatics, but were not affected by interferences in remote clean environment with no significant emissions of biogenic VOCs, when the OH reactivity was dominated by small alkanes. By reducing the NO concentration and/or the transport time between NO addition and OH detection, interference from these RO2 species are suppressed to values below 20 \% relative to the HO2 detection sensitivity. The HO2 conversion efficiency is also smaller by a factor of four, but this is still sufficient for atmospheric HO2 concentration measurements for a wide range of conditions.}, language = {en} } @article{CurcicStollWeigandetal.2011, author = {Curcic, Michael and Stoll, Hermann and Weigand, Markus and Sackmann, Vitalij and Juellig, Patrick and Kammerer, Matthias and Noske, Matthias and Sproll, Markus and Van Waeyenberge, Bartel and Vansteenkiste, Arne and Woltersdorf, Georg and Tyliszczak, Tolek and Sch{\"u}tz, Gisela}, title = {Magnetic vortex core reversal by rotating magnetic fields generated on micrometer length scales}, series = {physica status solidi (b)}, volume = {248}, journal = {physica status solidi (b)}, number = {10}, publisher = {Wiley}, issn = {0370-1972}, doi = {10.1002/pssb.201147208}, pages = {2317 -- 2322}, year = {2011}, abstract = {AbstractUnidirectional switching of the magnetic vortex core can be achieved in micron-sized ferromagnetic platelets by excitation of the gyrotropic mode of the vortex structure with in-plane rotating magnetic fields. Circulating fields with a switchable sense of rotation (clockwise, CW or counter clockwise, CCW) have been generated on a micrometer length scale at frequencies up to 1 GHz by two orthogonal electric RF currents with 90° phase shift flowing through crossed but not isolated striplines. Decoupling of these currents is realized by balanced symmetric RF sources. The amplitudes of the rotating magnetic fields and their spatial distributions are calculated and the stripline geometry is discussed. By taking advantage of this technique, unidirectional vortex core reversal by excitation with CW or CCW rotating magnetic fields has been observed by time resolved scanning transmission X-ray microscopy. An area with reversed magnetization, the "dip," was observed near the vortex core before vortex core reversal.}, language = {en} } @article{KammererWeigandCurcicetal.2011, author = {Kammerer, Matthias and Weigand, Markus and Curcic, Michael and Noske, Matthias and Sproll, Markus and Vansteenkiste, Arne and Van Waeyenberge, Bartel and Stoll, Hermann and Woltersdorf, Georg and Back, Christian H. and Schuetz, Gisela}, title = {Magnetic vortex core reversal by excitation of spin waves}, series = {Nature Communications}, volume = {2}, journal = {Nature Communications}, number = {1}, publisher = {Springer Nature}, issn = {2041-1723}, doi = {10.1038/ncomms1277}, year = {2011}, language = {en} } @article{ZimmermannNeumannCeliketal.2011, author = {Zimmermann, Peter and Neumann, Anna and {\c{C}}elik, Fatma and Kindler, Heinz}, title = {Sexuelle Gewalt gegen Kinder in Familien - Ein Forschungs{\"u}berblick}, series = {Sexuologie. Zeitschrift f{\"u}r Sexualmedizin, Sexualtherapie und Sexualwissenschaft}, volume = {18}, journal = {Sexuologie. Zeitschrift f{\"u}r Sexualmedizin, Sexualtherapie und Sexualwissenschaft}, number = {34}, publisher = {Deutsche Gesellschaft f{\"u}r Sexualmedizin, Sexualtherapie und Sexualwissenschaft}, issn = {0944-7105}, doi = {10.61387/S.2011.34.16}, pages = {119 -- 142}, year = {2011}, language = {de} } @article{JohanningBraunEiteneueretal.2011, author = {Johanning, M. and Braun, Alexander and Eiteneuer, D. and Paape, C. and Balzer, Christoph and Neuhauser, W. and Wunderlich, C.}, title = {Resonance-enhanced isotope-selective photoionization of YbI for ion trap loading}, series = {Applied Physics B}, volume = {103}, journal = {Applied Physics B}, number = {2}, publisher = {Springer Nature}, issn = {1432-0649}, doi = {10.1007/s00340-011-4502-7}, pages = {327 -- 338}, year = {2011}, language = {en} } @article{StuhrmannHuberKaes2011, author = {Stuhrmann, Bj{\"o}rn and Huber, Florian and K{\"a}s, Josef}, title = {Robust organizational principles of protrusive biopolymer networks in migrating living cells}, series = {Plos One}, volume = {6}, journal = {Plos One}, number = {1}, publisher = {Public Library of Science (PLoS)}, issn = {1932-6203}, doi = {10.1371/journal.pone.0014471}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-34901}, year = {2011}, abstract = {Cell migration is associated with the dynamic protrusion of a thin actin-based cytoskeletal extension at the cell front, which has been shown to consist of two different substructures, the leading lamellipodium and the subsequent lamellum. While the formation of the lamellipodium is increasingly well understood, organizational principles underlying the emergence of the lamellum are just beginning to be unraveled. We report here on a 1D mathematical model which describes the reaction-diffusion processes of a polarized actin network in steady state, and reproduces essential characteristics of the lamellipodium-lamellum system. We observe a steep gradient in filament lengths at the protruding edge, a local depolymerization maximum a few microns behind the edge, as well as a differential dominance of the network destabilizer ADF/cofilin and the stabilizer tropomyosin. We identify simple and robust organizational principles giving rise to the derived network characteristics, uncoupled from the specifics of any molecular implementation, and thus plausibly valid across cell types. An analysis of network length dependence on physico-chemical system parameters implies that to limit array treadmilling to cellular dimensions, network growth has to be truncated by mechanisms other than aging-induced depolymerization, e.g., by myosin-associated network dissociation at the transition to the cell body. Our work contributes to the analytical understanding of the cytoskeletal extension's bisection into lamellipodium and lamellum and sheds light on how cells organize their molecular machinery to achieve motility.}, language = {en} }