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Start date: 2000 Ă— End date: 2009 Ă—

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Now showing 1 - 10 of 1928
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    Schlussbericht zum BMBF-Vorhaben: Compact optohybrids (CoOp), Teilvorhaben: Ionenätzverfahren fĂ¼r die Strukturierung
    (Hannover : Technische Informationsbibliothek (TIB), 2006) Schindler, Axel
    [no abstract available]
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    Polymeric monolithic materials: Syntheses, properties, functionalization and applications
    (Amsterdam : Elsevier, 2007) Buchmeiser, M.R.
    The synthetic particularities for the synthesis of polymer-based monolithic materials are summarized. In this context, monoliths prepared via thermal-, UV- or electron-beam triggered free radical polymerization, controlled TEMPO-mediated radical polymerization, polyaddition, polycondensation as well as living ring-opening metathesis polymerization (ROMP) will be covered. Particular attention is devoted to the aspects of controlling pore sizes, pore volumes and pore size distributions as well as functionalization of these supports. Finally, selected, recent applications in separation science, (bio-) catalysis and chip technology will be summarized. © 2007 Elsevier Ltd. All rights reserved.
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    Forscherverbund: German Israeli cooperation in ultrafast laser technologies (GILCULT) : Projekt: Femtosecond coherent control for nonlinear spectroscopy ; AbschluĂŸbericht
    (Hannover : Technische Informationsbibliothek (TIB), 2004) Korn, G.; Silberberg, Yaron; Zhavoronkov, Nikolay; Laarmann, Tim
    [no abstract available]
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    Resolution of symplectic cyclic orbifold singularities
    (Oberwolfach : Mathematisches Forschungsinstitut Oberwolfach, 2007) NiederkrĂ¼ger, Klaus; Pasquotto, Federica
    In this paper we present a method to obtain resolutions of symplectic orbifolds arising as quotients of pre-symplectic semi-free S1–actions. This includes, in particular, all orbifolds arising from symplectic reduction of Hamiltonian S1–manifolds at regular values, as well as all isolated cyclic orbifold singularities. As an application, we show that pre-quantisations of symplectic orbifolds are symplectically fillable by a smooth manifold.
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    The McKay conjecture for exceptional groups and odd primes
    (Oberwolfach : Mathematisches Forschungsinstitut Oberwolfach, 2007) Späth, Britta
    Let G be a simply-connected simple algebraic group over an algebraically closed field of characteristic p with a Frobenius map F : G ! G and G := GF , such that the root system is of exceptional type or G is a Suzuki-group or Steinberg’s triality group. We show that all irreducible characters of CG(S), the centraliser of S in G, extend to their inertia group in NG(S), where S is any F-stable Sylow torus of (G, F). Together with the work in [17] this implies that the McKay-conjecture is true for G and odd primes ` different from the defining characteristic. Moreover it shows important properties of the associated simple groups, which are relevant for the proof that the associated simple groups are good in the sense of Isaacs, Malle and Navarro, as defined in [15].
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    New results on the stability of quasi-static paths of a single particle system with Coulomb friction and persistent contact
    (Berlin : WeierstraĂŸ-Institut fĂ¼r Angewandte Analysis und Stochastik, 2006) Schmid, Florian; Martins, J.A.C.; Rebrova, Natalia
    In this paper we announce some new mathematical results on the stability of quasi-static paths of a single particle linearly elastic system with Coulomb friction and persistent normal contact with a flat obstacle.A quasi-static path is said to be stable at some value of the load parameter if, for some finite interval of the load parameter thereafter, the dynamic solutions behave continuously with respect to the size of the initial perturbations (as in Lyapunov stability) and to the smallness of the rate of application of the external forces, $varepsilon$ (as in singular perturbation problems). In this paper we prove sufficient conditions for stability of quasi-static paths of a single particle linearly elastic system with Coulomb friction and persistent normal contact with a flat obstacle. The present system has the additional difficulty of its non-smoothness: the friction law is a multivalued operator and the dynamic evolutions of this system may have discontinuous accelerations.
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    Simultaneous lidar observations of temperatures and waves in the polar middle atmosphere on the east and west side of the Scandinavian mountains: A case study on 19/20 January 2003
    (MĂ¼nchen : European Geopyhsical Union, 2004) Blum, U.; Fricke, K.H.; Baumgarten, G.; Schöch, A.
    Atmospheric gravity waves have been the subject of intense research for several decades because of their extensive effects on the atmospheric circulation and the temperature structure. The U. Bonn lidar at the Esrange and the ALOMAR RMR lidar at the Andøya Rocket Range are located in northern Scandinavia 250 km apart on the east and west side of the Scandinavian mountain ridge. During January and February 2003 both lidar systems conducted measurements and retrieved atmospheric temperatures. On 19/20 January 2003 simultaneous measurements for more than 7 h were possible. Although during most of the campaign time the atmosphere was not transparent for the propagation of orographically induced gravity waves, they were nevertheless observed at both lidar stations with considerable amplitudes during these simultaneous measurements. And while the source of the observed waves cannot be determined unambiguously, the observations show many characteristics of orographically excited gravity waves. The wave patterns at ALOMAR show a random distribution with time whereas at the Esrange a persistency in the wave patterns is observable. This persistency can also be found in the distribution of the most powerful vertical wavelengths. The mode values are both at about 5 km vertical wavelength, however the distributions are quite different, narrow at the Esrange with values from λz=2–6 km and broad at ALOMAR, covering λz=1–12 km vertical wavelength. In particular the difference between the observations at ALOMAR and at the Esrange can be understood by different orographic conditions while the propagation conditions were quite similar. At both stations the waves deposit energy in the atmosphere with increasing altitude, which leads to a decrease of the observed gravity wave potential energy density with altitude. The meteorological situation during these measurements was different from common winter situations. The ground winds were mostly northerlies, changed in the upper troposphere and lower stratosphere to westerlies and returned to northerlies in the middle stratosphere.
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    Towards closing the gap between hygroscopic growth and activation for secondary organic aerosol - Part 2: Theoretical approaches
    (MĂ¼nchen : European Geopyhsical Union, 2009) Wex, H.; Petters, M.D.; Carrico, C.M.; Hallbauer, E.; Massling, A.; McMeeking, G.R.; Poulain, L.; Wu, Z.; Kreidenweis, S.M.; Stratmann, F.
    We examine the hygroscopic properties of secondary organic aerosol particles generated through the reaction of α-pinene and ozone using a continuous flow reaction chamber. The water activity versus composition relationship is calculated from measurements of growth factors at relative humidities up to 99.6% and from measurements of cloud condensation nuclei activity. The observed relationships are complex, suggesting highly non-ideal behavior for aerosol water contents at relative humidities less than 98%. We present two models that may explain the observed water activity-composition relationship equally well. The first model assumes that the aerosol is a pseudo binary mixture of infinitely water soluble compounds and sparingly soluble compounds that gradually enter the solution as dilution increases. The second model is used to compute the Gibbs free energy of the aerosol-water mixture and shows that the aerosol behaves similarly to what can be expected for single compounds that contain a certain fraction of oxygenated and non-polar functional groups.
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    Magnetic quantum oscillations of diagonal conductivity in a two-dimensional conductor with a weak square superlattice modulation under conditions of the integer quantum Hall effect
    (Milton Park : Taylor & Francis, 2009) Gvozdikov, V.M.; Taut, M.
    We report on analytical and numerical studies of the magnetic quantum oscillations of the diagonal conductivity σxx in a two-dimensional conductor with a weak square superlattice modulation under conditions of the integer quantum Hall (IQHE) effect. The quantum Hall effect in such a system differs from the conventional IQHE, in which the finite width of the Landau bands is due to disorder only. The superlattice modulation potential yields a fractal splitting of the Landau levels into Hofstadter minibands. For rational flux through a unit cell, the minibands have a finite width and intrinsic dispersion relations. We consider a regime, now accessible experimentally, in which disorder does not wash out the fractal internal gap structure of the Landau bands completely. We found the following distinctions from the conventional IQHE produced by the superlattice: (i) the peaks in diagonal conductivity are split due to the Hofstadter miniband structure of Landau bands; (ii) the number of split peaks in the bunch, their positions and heights depend irregularly on the magnetic field and the Fermi energy; (iii) the gaps between the split Landau bands (and related quantum Hall plateaus) become narrower with the superlattice modulation than without it.