@article{AbelCelaniVergenietal.2001, author = {Abel, Markus and Celani, A. and Vergeni, D. and Vulpiani, A.}, title = {Front propagation in laminar flows}, year = {2001}, abstract = {The Problem of front propagation in flowing media is addressed for laminar velocity fields in two dimensions. Three representative cases are discussed: stationary cellular flow, stationary shear flow, and percolating flow. Production terms of Fisher-Kolmogorov-Petrovskii-Piskunov type and of Arrhenius type are considered under the assumption of no feedback of the concentration on the velocity. Numerical simulations of advection-reaction-diffusion equations have been performed by an algorithm based on discrete-time maps. The results show a generic enhancement of the speed of front propagation by the underlying flow. For small molecular diffusivity, the front speed Vf depends on the typical flow velocity U as a power law with an exponent depending on the topological properties of the flow, and on the ratio of reactive and advective time scales. For open-streamline flows we find always Vf~U, whereas for cellular flows we observe Vf~U1/4 for fast advection and Vf~U3/4 for slow advection.}, language = {en} } @article{AfshaarvahidHeuerMenzeletal.2001, author = {Afshaarvahid, Shahraam and Heuer, Axel and Menzel, Ralf and Munch, Jesper}, title = {Temporal structure of stimulated-Brillouin-scattering reflectivity considering transversal-mode development}, year = {2001}, language = {en} } @article{AhlersZillmerPikovskij2001, author = {Ahlers, Volker and Zillmer, R{\"u}diger and Pikovskij, Arkadij}, title = {Lyapunov exponents in disordered chaotic systems : avoided crossing and level statistics}, year = {2001}, abstract = {The behavior of the Lyapunov exponents (LEs) of a disordered system consisting of mutually coupled chaotic maps with different parameters is studied. The LEs are demonstrated to exhibit avoided crossing and level repulsion, qualitatively similar to the behavior of energy levels in quantum chaos. Recent results for the coupling dependence of the LEs of two coupled chaotic systems are used to explain the phenomenon and to derive an approximate expression for the distribution functions of LE spacings. The depletion of the level spacing distribution is shown to be exponentially strong at small values. The results are interpreted in terms of the random matrix theory.}, language = {en} } @article{AnishchenkoVadivasovaKopeikinetal.2001, author = {Anishchenko, Vadim S. and Vadivasova, T. E. and Kopeikin, A. S. and Kurths, J{\"u}rgen and Strelkova, G. I.}, title = {Effect of noise on the relaxation to an invariant probability measure of nonhyperbolic chaotic attractors}, year = {2001}, language = {en} } @article{AudenaertEisertJaneetal.2001, author = {Audenaert, Katrien and Eisert, Jens and Jane, E. and Plenio, M. B. and Virmani, S. and Moor, B. D.}, title = {The asymptotic relative entropy of entanglement}, year = {2001}, abstract = {We present an analytical formula for the asymptotic relative entropy of entanglement for Werner states of arbitrary dimensionality. We then demonstrate its validity using methods from convex optimization. This is the first case in which the value of a subadditive entanglement measure has been obtained in the asymptotic limit. This formula also gives the sharpest known upper bound on the distillable entanglement of these states.}, language = {en} } @article{AvilovLepeshovPietschetal.2001, author = {Avilov, Anatoly S. and Lepeshov, G. G. and Pietsch, Ullrich and Tsirelson, Vladimir G.}, title = {Multipole analysis of the electron density and electrostatic potential in Germanium by high-resolution electron diffraction}, issn = {0022-3697}, year = {2001}, language = {en} } @book{BackhausSchoen2001, author = {Backhaus, Udo and Sch{\"o}n, Lutz-Helmut}, title = {Physik plus : Kl. 8, [Hauptbd.], Gymnasium Nordrhein-Westfalen}, editor = {Mikelskis, Helmut and Wilke, Hans-Joachim}, publisher = {Volk und Wissen Verl.}, address = {Berlin}, isbn = {3-06-020840-9}, pages = {136 S.}, year = {2001}, language = {de} } @article{BeckStielLeupoldetal.2001, author = {Beck, Michael and Stiel, H. and Leupold, Dieter and Winter, Bernd and Pop, D. and Vogt, U. and Spitz, Christian}, title = {Evaluation of the energetic position of the lowest excited singlet state of ß-carotene by NEXAFS and photoemission spectroscopy}, year = {2001}, language = {en} } @phdthesis{Becker2001, author = {Becker, Thomas}, title = {3D-Spektroskopie hintergrundkontaminierter Einzelobjekte in Galaxien der lokalen Gruppe}, pages = {110 S.}, year = {2001}, language = {de} } @article{BergstedtHornMichelskisetal.2001, author = {Bergstedt, Christel and Horn, Martin Erik and Michelskis, Helmut and Winter, Rolf}, title = {Energie}, series = {Naturwissenschaften : Biologie, Chemie, Physik}, volume = {8}, journal = {Naturwissenschaften : Biologie, Chemie, Physik}, publisher = {Volk-und-Wissen-Verl.}, address = {Berlin}, isbn = {3-06-020935-9}, pages = {64 S.}, year = {2001}, language = {de} } @phdthesis{Buchsteiner2001, author = {Buchsteiner, Alexandra}, title = {Untersuchung ultrad{\"u}nner azobenzenhaltiger Filme mittels dielektischer Spektroskopie : Einfluß molekularer und suoramolekularer Parameter auf den Photoisomerisierungsprozeß}, pages = {103 S.}, year = {2001}, language = {de} } @phdthesis{Chen2001, author = {Chen, Yen-Chih}, title = {Charakterisierung der Defektstruktur von Metalloberfl{\"a}chen mittels induzierter Phasen{\"a}nderungen fl{\"u}ssikristalliner Filme}, pages = {130 S.}, year = {2001}, language = {de} } @article{ChristliebGreenWisotzkietal.2001, author = {Christlieb, N. and Green, P. J. and Wisotzki, Lutz and Reimers, Dieter}, title = {The stellar content of the Hamburg/ESO survey : II. a large, homogeneously-selected sample of high latitude carbon stars}, year = {2001}, language = {en} } @article{ChristliebWisotzkiReimers2001, author = {Christlieb, N. and Wisotzki, Lutz and Reimers, Dieter}, title = {Mining the digital Hamburg / ESO objective prism survey}, isbn = {3-540-42468-7}, year = {2001}, language = {en} } @article{ChristliebWisotzkiReimersetal.2001, author = {Christlieb, N. and Wisotzki, Lutz and Reimers, Dieter and Homeier, D. and Koester, D. and Heber, Ulrich}, title = {The stellar content of the Hamburg/ESO survey : I. Automated selection of DA white dwarfs}, year = {2001}, abstract = {We describe automatic procedures for the selection of DA white dwarfs in the Hamburg/ESO objective-prism survey (HES). For this purpose, and the selection of other stellar objects (e.g., metal-poor stars and carbon stars), a flexible, robust algorithm for detection of stellar absorption and emission lines in the digital spectra of the HES was developed. Broad band (U-B, B-V) and intermediate band (Str{\"o}mgren c_1) colours can be derived directly from HES spectra, with precisions of sigma U-B=0.092 mag; sigma B-V=0.095 mag; sigma c_1=0.15 mag. We describe simulation techniques that allow one to convert model or slit spectra to HES spectra. These simulated objective-prism spectra are used to determine quantitative selection criteria, and for the study of selection functions. We present an atlas of simulated HES spectra of DA and DB white dwarfs. Our current selection algorithm is tuned to yield maximum efficiency of the candidate sample (minimum contamination with non-DAs). DA candidates are selected in the B-V versus U-B and c_1 versus W_lambda (Hbeta +Hgamma +Hdelta ) parameter spaces. The contamination of the resulting sample with hot subdwarfs is expected to be as low as ~ 8\%, while there is essentially no contamination with main sequence or horizontal branch stars. We estimate that with the present set of criteria, ~ 80\% of DAs present in the HES database are recovered. A yet higher degree of internal completeness could be reached at the expense of higher contamination. However, the external completeness is limited by additional losses caused by proper motion effects and the epoch differences between direct and spectral plates used in the HES. Based on observations collected at the European Southern Observatory, La Silla and Paranal, Chile.}, language = {en} } @article{DavaasambuuDanielStahnetal.2001, author = {Davaasambuu, Jav and Daniel, A. and Stahn, Jochen and Pietsch, Ullrich}, title = {Harmonic and anharmonic thermal vibrations in cubic ZnSe}, issn = {0044-2968}, year = {2001}, language = {en} } @article{DavaasambuuDanielStahnetal.2001, author = {Davaasambuu, Jav and Daniel, A. and Stahn, Jochen and Pietsch, Ullrich}, title = {Comparison of experimental and theoretical valence charge densites in cubic ZnSe}, issn = {0022-3697}, year = {2001}, language = {en} } @phdthesis{Demircan2001, author = {Demircan, Ayhan}, title = {Numerische Untersuchungen zur thermischen Konvektion in einer elektrisch leitenden Fl{\"u}ssigkeitsschicht}, pages = {109 S.}, year = {2001}, language = {de} } @article{DemircanSeehafer2001, author = {Demircan, Ayhan and Seehafer, Norbert}, title = {Dynamos in rotating and nonrotating convection in the form of asymmetric squares}, year = {2001}, abstract = {We study the dynamo properties of asymmetric square patterns in Boussinesq Rayleigh-B'enard convection in a plane horizontal layer. Cases without rotation and with weak rotation about a vertical axis are considered. There exist different types of solutions distinguished by their symmetry, among them such with flows possessing a net helicity and being capable of kinematic dynamo action in the presence as well as in the absence of rotation. In the nonrotating case these flows are, however, always only kinematic, not nonlinear dynamos. Nonlinearly the back-reaction of the magnetic field then forces the solution into the basin of attraction of a roll pattern incapable of dynamo action. But with rotation added parameter regions are found where the Coriolis force counteracts the Lorentz force in such a way that the asymmetric squares are also nonlinear dynamos.}, language = {en} } @article{DemircanSeehafer2001, author = {Demircan, Ayhan and Seehafer, Norbert}, title = {Nonlinear square patterns in Rayleigh-Benard convection}, year = {2001}, abstract = {We numerically investigate nonlinear asymmetric square patterns in a horizontal convection layer with up-down reflection symmetry. As a novel feature we find the patterns to appear via the skewed varicose instability of rolls. The time-independent nonlinear state is generated by two unstable checkerboard (symmetric square) patterns and their nonlinear interaction. As the bouyancy forces increase the interacting modes give rise to bifurcations leading to a periodic alternation between a nonequilateral hexagonal pattern and the square pattern or to different kinds of standing oscillations.}, language = {en} }