TY - JOUR A1 - Abel, Markus A1 - Celani, A. A1 - Vergeni, D. A1 - Vulpiani, A. T1 - Front propagation in laminar flows N2 - 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. Y1 - 2001 UR - http://www.stat.physik.uni-potsdam.de/~markus/papers/PRE64-46307-1.pdf ER - TY - JOUR A1 - Afshaarvahid, Shahraam A1 - Heuer, Axel A1 - Menzel, Ralf A1 - Munch, Jesper T1 - Temporal structure of stimulated-Brillouin-scattering reflectivity considering transversal-mode development Y1 - 2001 ER - TY - JOUR A1 - Ahlers, Volker A1 - Zillmer, Rüdiger A1 - Pikovskij, Arkadij T1 - Lyapunov exponents in disordered chaotic systems : avoided crossing and level statistics N2 - 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. Y1 - 2001 ER - TY - JOUR A1 - Anishchenko, Vadim S. A1 - Vadivasova, T. E. A1 - Kopeikin, A. S. A1 - Kurths, Jürgen A1 - Strelkova, G. I. T1 - Effect of noise on the relaxation to an invariant probability measure of nonhyperbolic chaotic attractors Y1 - 2001 ER - TY - JOUR A1 - Audenaert, Katrien A1 - Eisert, Jens A1 - Jane, E. A1 - Plenio, M. B. A1 - Virmani, S. A1 - Moor, B. D. T1 - The asymptotic relative entropy of entanglement N2 - 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. Y1 - 2001 ER - TY - JOUR A1 - Avilov, Anatoly S. A1 - Lepeshov, G. G. A1 - Pietsch, Ullrich A1 - Tsirelson, Vladimir G. T1 - Multipole analysis of the electron density and electrostatic potential in Germanium by high-resolution electron diffraction Y1 - 2001 SN - 0022-3697 ER - TY - BOOK A1 - Backhaus, Udo A1 - Schön, Lutz-Helmut ED - Mikelskis, Helmut ED - Wilke, Hans-Joachim T1 - Physik plus : Kl. 8, [Hauptbd.], Gymnasium Nordrhein-Westfalen Y1 - 2001 SN - 3-06-020840-9 PB - Volk und Wissen Verl. CY - Berlin ER - TY - JOUR A1 - Beck, Michael A1 - Stiel, H. A1 - Leupold, Dieter A1 - Winter, Bernd A1 - Pop, D. A1 - Vogt, U. A1 - Spitz, Christian T1 - Evaluation of the energetic position of the lowest excited singlet state of ß-carotene by NEXAFS and photoemission spectroscopy Y1 - 2001 ER - TY - THES A1 - Becker, Thomas T1 - 3D-Spektroskopie hintergrundkontaminierter Einzelobjekte in Galaxien der lokalen Gruppe Y1 - 2001 ER - TY - JOUR A1 - Bergstedt, Christel A1 - Horn, Martin Erik A1 - Michelskis, Helmut A1 - Winter, Rolf T1 - Energie JF - Naturwissenschaften : Biologie, Chemie, Physik Y1 - 2001 SN - 3-06-020935-9 VL - 8 PB - Volk-und-Wissen-Verl. CY - Berlin ER - TY - THES A1 - Buchsteiner, Alexandra T1 - Untersuchung ultradünner azobenzenhaltiger Filme mittels dielektischer Spektroskopie : Einfluß molekularer und suoramolekularer Parameter auf den Photoisomerisierungsprozeß Y1 - 2001 ER - TY - THES A1 - Chen, Yen-Chih T1 - Charakterisierung der Defektstruktur von Metalloberflächen mittels induzierter Phasenänderungen flüssikristalliner Filme Y1 - 2001 ER - TY - JOUR A1 - Christlieb, N. A1 - Green, P. J. A1 - Wisotzki, Lutz A1 - Reimers, Dieter T1 - The stellar content of the Hamburg/ESO survey : II. a large, homogeneously-selected sample of high latitude carbon stars Y1 - 2001 ER - TY - JOUR A1 - Christlieb, N. A1 - Wisotzki, Lutz A1 - Reimers, Dieter T1 - Mining the digital Hamburg / ESO objective prism survey Y1 - 2001 SN - 3-540-42468-7 ER - TY - JOUR A1 - Christlieb, N. A1 - Wisotzki, Lutz A1 - Reimers, Dieter A1 - Homeier, D. A1 - Koester, D. A1 - Heber, Ulrich T1 - The stellar content of the Hamburg/ESO survey : I. Automated selection of DA white dwarfs N2 - 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 (Strömgren 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. Y1 - 2001 ER - TY - JOUR A1 - Davaasambuu, Jav A1 - Daniel, A. A1 - Stahn, Jochen A1 - Pietsch, Ullrich T1 - Harmonic and anharmonic thermal vibrations in cubic ZnSe Y1 - 2001 SN - 0044-2968 ER - TY - JOUR A1 - Davaasambuu, Jav A1 - Daniel, A. A1 - Stahn, Jochen A1 - Pietsch, Ullrich T1 - Comparison of experimental and theoretical valence charge densites in cubic ZnSe Y1 - 2001 SN - 0022-3697 ER - TY - THES A1 - Demircan, Ayhan T1 - Numerische Untersuchungen zur thermischen Konvektion in einer elektrisch leitenden Flüssigkeitsschicht Y1 - 2001 ER - TY - JOUR A1 - Demircan, Ayhan A1 - Seehafer, Norbert T1 - Dynamos in rotating and nonrotating convection in the form of asymmetric squares N2 - 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. Y1 - 2001 ER - TY - JOUR A1 - Demircan, Ayhan A1 - Seehafer, Norbert T1 - Nonlinear square patterns in Rayleigh-Benard convection N2 - 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. Y1 - 2001 UR - http://www.edpsciences.com/articles/euro/full/2001/02/6376/6376.html ER - TY - JOUR A1 - Dominis, Dijana A1 - Butler, Keith A1 - Simon, Klaus A1 - Clausen, Jens Viggo A1 - Pritchard, John T1 - Magellanic clouds' binaries as distance indicators Y1 - 2001 SN - 0934-4438 ER - TY - JOUR A1 - Eichhorn, Holger A1 - Bruce, Duncan W. A1 - Guillon, D. A1 - Gallani, Jean Louis A1 - Fischer, Thomas A1 - Stumpe, Joachim A1 - Geue, Thomas T1 - Metal ion mediated mesomorphism and thin film behaviour of amphitropic tetraazaporphyrin complexes Y1 - 2001 ER - TY - THES A1 - Eisert, Jens T1 - Entanglement in quantum information theory Y1 - 2001 ER - TY - JOUR A1 - Eisert, Jens A1 - Briegel, Hans J. T1 - Schmidt measure as a tool for quantifying multiparicle entanglement N2 - We present a measure of quantum entanglement which is capable of quantifying the degree of entanglement of a multi-partite quantum system. This measure, which is based on a generalization of the Schmidt rank of a pure state, is defined on the full state space and is shown to be an entanglement monotone, that is, it cannot increase under local quantum operations with classical communication and under mixing. For a large class of mixed states this measure of entanglement can be calculated exactly, and it provides a detailed classification of mixed states. Y1 - 2001 ER - TY - JOUR A1 - Eisert, Jens A1 - Briegel, Hans J. T1 - Quantification of Multi-Particle Entanglement Y1 - 2001 ER - TY - JOUR A1 - Elling, B. A1 - Pinnow, M. A1 - Danz, Rudi A1 - Wegener, Michael A1 - Wirges, werner A1 - Gerhard, Reimund T1 - Coating of porous polytetrafluoroethylene films with other polymers for electret applications Y1 - 2001 SN - 0-7803-7053-8 ER - TY - THES A1 - Feudel, Fred T1 - Bifurcations and pattern formation in spatially extended systems Y1 - 2001 ER - TY - JOUR A1 - Feudel, Fred A1 - Rüdiger, Sten A1 - Seehafer, Norbert T1 - Bifurcation phenomena and dynamo effect in electrically conducting fluids N2 - Electrically conducting fluids in motion can act as self-excited dynamos. The magnetic fields of celestial bodies like the Earth and the Sun are generated by such dynamos. Their theory aims at modeling and understanding both the kinematic and dynamic aspects of the underlying processes. Kinematic dynamo models, in which for a prescribed flow the linear induction equation is solved and growth rates of the magnetic field are calculated, have been studied for many decades. But in order to get consistent models and to take into account the back-reaction of the magnetic field on the fluid motion, the full nonlinear system of the magnetohydrodynamic (MHD) equations has to be studied. It is generally accepted that these equations, i.e. the Navier-Stokes equation (NSE) and the induction equation, provide a theoretical basis for the explanation of the dynamo effect. The general idea is that mechanical energy pumped into the fluid by heating or other mechanisms is transferred to the magnetic field by nonlinear interactions. For two special helical flows which are known to be effective kinematic dynamos and which can be produced by appropriate external mechanical forcing, we review the nonlinear dynamo properties found in the framework of the full MHD equations. Specifically, we deal with the ABC flow (named after Arnold, Beltrami and Childress) and the Roberts flow (after G.~O. Roberts). The appearance of generic dynamo effects is demonstrated. Applying special numerical bifurcation-analysis techniques to high-dimensional approximations in Fourier space and varying the Reynolds number (or the strength of the forcing) as the relevant control parameter, qualitative changes in the dynamics are investigated. We follow the bifurcation sequences until chaotic states are reached. The transitions from the primary flows with vanishing magnetic field to dynamo-active states are described in particular detail. In these processes the stagnation points of the flows and their heteroclinic connections play a promoting role for the magnetic field generation. By the example of the Roberts flow we demonstrate how the break up of the heteroclinic lines after the primary bifurcation leads to a complicated intersection of stable and unstable manifolds forming a chaotic web which is in turn correlated with the spatial appearance of the dynamo. Y1 - 2001 ER - TY - JOUR A1 - Frübing, Peter A1 - Blischke, D. A1 - Salah Khalil, M. A1 - Gerhard, Reimund T1 - Complete relaxation map of polyethylene : filler-induced chemical modifications as dielectric probes Y1 - 2001 ER - TY - JOUR A1 - Frübing, Peter A1 - Blischke, D. A1 - Salah Khalil, M. A1 - Gerhard, Reimund T1 - Dielectric relaxations in titanium-dioxide-filled polyethylene: Filler-induced chemical modifications of the polymer provide the dipolar response Y1 - 2001 SN - 0-7803-7053-8 ER - TY - JOUR A1 - Gil-Merino, Rodrigo A1 - Goicoechea, Luis Julian A1 - Serra-Ricart, M. A1 - Oscoz, Alejandro A1 - Alcalde, D. A1 - Mediavilla, E. T1 - Short time-scale fluctuations in the difference light curves of QSO 0957+561A,B: microlensing or noise? N2 - From optical R-band data of the double quasar QSO 0957+561A,B, we made two new difference light curves (with an overlap of about 330d between the time-shifted light curve for the A image and the magnitude-shifted light curve for the B image). We observed noisy behaviours around the zero line and no short time-scale events (with a duration of months), where the term `event' refers to a prominent feature that may be a result of microlensing or another source of variability. Only one event lasting two weeks and rising -33mmag was found. Measured constraints on the possible microlensing variability can be used to obtain information on the granularity of the dark matter in the main lensing galaxy and the size of the source. In addition, one can also test the ability of the observational noise to cause the rms averages and the local features of the difference signals. We focused on this last issue. The combined photometries were related to a process consisting of an intrinsic signal plus a Gaussian observational noise. The intrinsic signal has been assumed to be either a smooth function (polynomial), a smooth function plus a stationary noise process, or a correlated stationary process. Using these three pictures without microlensing, we derived some models totally consistent with the observations. We finally discussed the sensitivity of our telescope (at Teide Observatory) to several classes of microlensing variability. Y1 - 2001 ER - TY - JOUR A1 - Goicoechea, Luis Julian A1 - Gil-Merino, Rodrigo A1 - Serra-Ricart, M. A1 - Mediavilla, E. A1 - Oscoz, Alejandro A1 - Alcalde, D. T1 - The nature of dark matter in elliptical (cD) galaxies : main lens galaxy of Q0957+561 Y1 - 2001 SN - 1-583-81074-9 ER - TY - JOUR A1 - Goicoechea, Luis Julian A1 - Gil-Merino, Rodrigo A1 - Serra-Ricart, M. A1 - Oscoz, Alejandro A1 - Alcalde, D. A1 - Mediavilla, E. T1 - IAC gravitational lenses monitoring program : difference signals from 2.5 years of QSO 0957+561 observations Y1 - 2001 SN - 0-7923-6974-2 ER - TY - JOUR A1 - Gowin, W. A1 - Saparin, Peter A1 - Kurths, Jürgen T1 - Bone architecture quantification: Measures of complexity compared to failure lead results Y1 - 2001 ER - TY - JOUR A1 - Gowin, W. A1 - Saparin, Peter A1 - Kurths, Jürgen A1 - Felsenberg, D. T1 - Bone Architecture assessment with Measures of Complexity Y1 - 2001 ER - TY - JOUR A1 - Greffet, Jean-Jacques A1 - Carminati, Rémi A1 - Joulain, Karl A1 - Mulet, J. P. A1 - Henkel, Carsten T1 - Coherence properties of thermal near fields : implications for nanometer-scale radiative transfer N2 - With the recent development of local (optical and thermal) probe microscopy and the advent of nanotechnology, it seems necessary to revisit the old subject of coherence properies of thermal sources of light. Concerning temporal coherence, we show that thermal sources may produce quasi-monochromatic near fields. In light of this result, the possibility of perfoming near-field solid-state spectroscopy and of designing near-field infrared sources is discussed. The problem of radiative transfer between two thermal sources held at subwavelength distance is studied. The radiative flux may be enhanced by several orders of magnitude due to the excitation of resonant surface waves, and this may occur at particular frequencies. Finally, we study the spatial coherence of thermal sources and the substantial influence of the near field. Surface waves may induce long-range spatial correlation, on a scale much larger than the wavelength. Conversely, quasi-static contributions, as well as skin-layer currents, induce arbitary small correlations. With the recent development of local (optical and thermal) probe microscopy and the advent of nanotechnology, it seems necessary to revisit the old subject of coherence of thermal fields. Y1 - 2001 ER - TY - JOUR A1 - Gregg, M. D. A1 - Schechter, P. A1 - Becker, Rolf A1 - Wisotzki, Lutz A1 - Maza, J. A1 - Laurent-Muehleisen, S. A1 - White, R. T1 - Two new high resolution surveys for lensed quasars Y1 - 2001 SN - 1-583-81074-9 ER - TY - JOUR A1 - Grenzer, Jörg A1 - Darowski, Nora A1 - Geue, Thomas A1 - Pietsch, Ullrich A1 - Daniel, A. A1 - Rennon, Siegfried A1 - Reithmaier, Johann-Peter A1 - Forchel, Alfred T1 - Strain analysis and quantum well intermixing of a laterally modulated multiquantum well system produced by focused ion beam implantation Y1 - 2001 ER - TY - JOUR A1 - Hamaciuc, E. A1 - Bruma, Maria A1 - Köpnick, Thomas A1 - Kaminorz, Yvette A1 - Schulz, Burkhard T1 - Synthesis and Study of New Silicon-containing Polyoxadiazoles N2 - A series of new poly-1,3,4-oxadiazoles has been synthesized by polycondensation reaction of hydrazine sulfate with a mixture of a dicarboxylic acid containing unsaturated bonds and a dicarboxylic acid containing silicon, by using methanesulfonic acid/phosphorus pentoxide as a reaction medium. These polymers were highly thermostable but they were only soluble in strong inorganic acids such as sulfuric or methanesulfonic ones. An alternative way was followed by using the corresponding dihydrazides containing unsaturated bonds and the corresponding diacid chloride containing silicon that reacted in N-methylpyrrolidinone (NMP) to give soluble silicon-containing unsaturated polyhydrazides, which were cyclodehydrated either by thermal or chemical treatment to give the corresponding polyoxadiazoles. Very thin coatings of polyhydrazides and polyoxadiazoles were deposited onto silicon wafers and they showed a very smooth surface, free of pinholes, when studied by atomic force microscopy (AFM). Some polyoxadiazole films showed strong blue photoluminescence. Y1 - 2001 ER - TY - JOUR A1 - Hamann, Wolf-Rainer A1 - Brown, John C. A1 - Feldmeier, Achim A1 - Oskinova, Lida T1 - On the wavelength drift of spectral features from structured hot star winds N2 - Spectral lines formed in stellar winds from OB stars are observed to exhibit profile variations. Discrete Absorption Components (DACs) show a remarkably slow wavelength drift with time. In a straightforward interpretation, this is in sharp contradiction to the steep velocity law predicted by the radiation-driven wind theory, and by semi- empirical profile fitting. In the present paper we re-discuss the interpretation of the drift rate. We show that the Co- rotating Interaction Region (CIR) model for the formation of DACs does not explain their slow drift rate as a consequence of rotation. On the contrary, the apparent acceleration of a spectral CIR feature is even higher than for the corresponding kinematical model without rotation. However, the observations can be understood by distinguishing between the velocity field of the matter flow, and the velocity law for the motion of the patterns in which the DAC features are formed. If the latter propagate upstream against the matter flow, the resulting wavelength drift mimics a much slower acceleration although the matter is moving fast. Additional to the DACs, a second type of recurrent structures is present in observed OB star spectra, the so-called modulations. In contrast to the DACs, these structures show a steep acceleration compatible with the theoretically predicted velocity law. We see only two possible consistent scenarios. Either, the wind is accelerated fast, and the modulations are formed in advected structures, while the DACs come from structures which are propagating upstream. Or, alternatively, steep and shallow velocity laws may co-exist at the same time in different spatial regions or directions of the wind. Y1 - 2001 ER - TY - JOUR A1 - Hassan, M. K. A1 - Kurths, Jürgen T1 - Transition from random to ordered fractals in fragmentation of particles in an open system Y1 - 2001 ER - TY - JOUR A1 - Hassan, M. K. A1 - Kurths, Jürgen T1 - Competitive random sequential adsorption of point and fixed-sized particles: analytical results Y1 - 2001 ER - TY - JOUR A1 - Henkel, Carsten T1 - Coherent transport N2 - We discuss the transport of matter waves in low-dimensional waveguides. Due to scattering from uncontrollable noise fields, the spatial coherence gets reduced and eventually lost. We develop a description of this decoherence process in terms of transport equations for the atomic Wigner function. We outline its derivation and discuss the special case of white noise where an analytical solution can be found. Y1 - 2001 SN - 1296-2147 ER - TY - JOUR A1 - Henkel, Carsten A1 - Pötting, Sierk T1 - Coherent transport of matter waves N2 - A transport theory for atomic matter waves in low-dimensional waveguides is outlined. The thermal fluctuation spectrum of magnetic near fields leaking out of metallic microstructures is estimated. The corresponding scattering rate for paramagnetic atoms turns out to be quite large in micrometer-sized waveguides (approx. 100/s). Analytical estimate for the heating and decoherence of a cold atom cloud are given. We finally discuss numerical and analytical results for the scattering from static potential imperfections and the ensuing spatial diffusion process. Y1 - 2001 ER - TY - THES A1 - Henkel, Oliver T1 - Prescribed Mean Curvature foliations in cosmological spacetimes with matter Y1 - 2001 ER - TY - JOUR A1 - Henneberg, Oliver A1 - Chi, Li Feng A1 - Geue, Thomas A1 - Saphiannikova, Marina A1 - Pietsch, Ullrich A1 - Rochon, Paul A1 - Natansohn, Almeria T1 - Atomic force microscopy inspection of the early state of formation of polymer surface relief grating Y1 - 2001 ER - TY - JOUR A1 - Henneberg, Oliver A1 - Geue, Thomas A1 - Saphiannikova, Marina A1 - Pietsch, Ullrich A1 - Rochon, Paul A1 - Natansohn, Almeria T1 - Formation and dynamics of polymer surface relief gratings Y1 - 2001 SN - 0378-5963 ER - TY - JOUR A1 - Herwig, Falk T1 - Internal mixing and surface abundance of [WC]-CSPN N2 - Recent advances in constructing stellar evolution models of hydrogen-deficient post-asymptotic giant branch (AGB) stars are presented. Hydrogen-deficiency can originate from mixing and subsequent convective burning of protons in the deeper layers during a thermal pulse on the post-AGB (VLTP). Dredge-up alone may also be responsible for hydrogen- deficiency of post-AGB stars. Models of the last thermal pulse on the AGB with very small envelope masses have shown efficient third dredge-up. The hydrogen content of the envelope is diluted sufficiently to produce H-deficient post-AGB stars (AFTP). Moreover, dredge-up alone may also cause H-deficiency during the Born-again phase (LTP). During the second AGB phase a convective envelope develops. A previously unknown lithium enrichment at the surface of Born-again stellar models may be used to distinguish between objects with different post-AGB evolution. The observed abundance ratios of C, O and He can be reproduced by all scenarios if an AGB starting model with inclusion of overshoot is used for the post- AGB model sequence. An appendix is devoted to the numerical methods for models of proton capture nucleosynthesis in the He-flash convection zone during a thermal pulse. Y1 - 2001 ER - TY - JOUR A1 - Hänisch, Christoph A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Threshold reduction of stimulated Brillouin scattering (SBS) using fiber loop schemes Y1 - 2001 ER - TY - JOUR A1 - Ivanov, Plamen Ch. A1 - Nuenes Amaral, Luís A. A1 - Goldberger, Ary L. A1 - Havlin, Shlomo A1 - Rosenblum, Michael A1 - Stanley, H. Eugene A1 - Struzik, Zbigniew R. T1 - From 1/f noise to multifractal cascades in heartbeat dynamics Y1 - 2001 SN - 1054-1500 ER - TY - JOUR A1 - Jahnke, Knud A1 - Kuhlbrodt, B. A1 - Örndahl, E. A1 - Wisotzki, Lutz T1 - QSO host galaxy star formation history from multicolour data Y1 - 2001 SN - 0-306-46662-7 ER - TY - JOUR A1 - Klemz, Guido A1 - Kubina, P. A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - Diode pumped high power TEM_00 Nd:YAG rod laser with birefringence compensation Y1 - 2001 ER - TY - JOUR A1 - Koesterke, Lars T1 - Spectral analyses of WR-type central stars of Planetary Nebulae N2 - So far, the evolution of post-AGB stars is not fully understood. In particular the formation of hydrogen- deficient and hydrogen-free Central Stars of Planetary Nebulae (CSPN) is unsettled. New evolution models, which allow for the consistent treatment of the physics of late thermal pulses, promise new insights to the formation of these stars. In this paper we summarize the results of non-LTE analyses of CSPN with wind. By comparing these results with the predictions of the new evolution models, open questions concerning the evolution of the stars might be answered. In addition we discuss the driving mechanism of the winds of Wolf-Rayet CSPN. New models, which account for millions of iron lines, support the assumptions that these winds are driven by radiation. Y1 - 2001 ER - TY - JOUR A1 - Koesterke, Lars A1 - Hamann, Wolf-Rainer A1 - Urrutia, Tanya T1 - Line-Profile Variability in the Wolf-Rayet Stars WR 135 and WR 111 N2 - We have obtained time-resolved observations of line-profile variations of the two Wolf-Rayet stars WR 135 and WR 111. The spectra, taken during two consecutive nights, cover a broad range from 4470 to 6590 Ang. The profile variability of the C iii emission line at 5696 Ang in WR 135 is shown in detail. The principal difficulties to constrain the velocity law from the frequency drift of discrete spectral features is discussed, emphasizing the crucial dependence on the adopted location of the line-emission region, and the possible necessity to distinguish between the motion of structures and the flow of the matter. - Full access to the observational data is provided via anonymous file transfer. Y1 - 2001 ER - TY - JOUR A1 - Koopmans, L. V. E. A1 - Bruyn, A. G. A1 - Wambsganß, Joachim A1 - Fassnacht, C. D. T1 - A radio-microlensing caustic crossing in B1600+434? N2 - First, we review the current status of the detection of strong `external' variability in the CLASS gravitational B1600+434, focusing on the 1998 VLA 8.5-GHz and 1998/9 WSRT multi-frequency observations. We show that this data can best be explained in terms of radio-microlensing. We then proceed to show some preliminary results from our new multi-frequency VLA monitoring program, in particular the detection of a strong feature (~30%) in the light curve of the lensed image which passes predominantly through the dark-matter halo of the lens galaxy. We tentatively interpret this event, which lasted for several weeks, as a radio-microlensing caustic crossing, i.e. the superluminal motion of a micro-arcsec-scale jet-component in the lensed source over a single caustic in the magnification pattern, that has been created by massive compact objects along the line-of-sight to the lensed image. Y1 - 2001 UR - http://xxx.uni-augsburg.de/pdf/astro-ph/0004285 SN - 1-538-81076-5 ER - TY - JOUR A1 - Koopmans, L. V. E. A1 - Wambsganß, Joachim T1 - On the probability of microlensing in gamma-ray burst afterglows N2 - The declining light curve of the optical afterglow of gamma-ray burst (GRB) GRB000301C showed rapid variability with one particularly bright feature at about t-t0=3.8d. This event was interpreted as gravitational microlensing by Garnavich, Loeb & Stanek and subsequently used to derive constraints on the structure of the GRB optical afterglow. In this paper, we use these structural parameters to calculate the probability of such a microlensing event in a realistic scenario, where all compact objects in the universe are associated with observable galaxies. For GRB000301C at a redshift of z=2.04, the a posteriori probability for a microlensing event with an amplitude of m>=0.95mag (as observed) is 0.7 per cent (2.7 per cent) for the most plausible scenario of a flat -dominated Friedmann- Robertson-Walker (FRW) universe with m=0.3 and a fraction f*=0.2 (1.0) of dark matter in the form of compact objects. If we lower the magnification threshold to m>=0.10mag, the probabilities for microlensing events of GRB afterglows increase to 17 per cent (57 per cent). We emphasize that this low probability for a microlensing signature of almost 1mag does not exclude that the observed event in the afterglow light curve of GRB000301C was caused by microlensing, especially in light of the fact that a galaxy was found within 2arcsec from the GRB. In that case, however, a more robust upper limit on the a posteriori probability of ~5 per cent is found. It does show, however, that it will not be easy to create a large sample of strong GRB afterglow microlensing events for statistical studies of their physical conditions on microarcsec scales. Y1 - 2001 ER - TY - JOUR A1 - Krivov, Alexander V. A1 - Banaszkiewicz, Marek T1 - Unusual origin, evolution and fate of icy ejecta from Hyperion Y1 - 2001 SN - 0032-0633 ER - TY - JOUR A1 - Krivov, Alexander V. A1 - Banaszkiewicz, Marek T1 - Dust Influx to Titan from Hyperion Y1 - 2001 SN - 0-7923-6946-7 ER - TY - JOUR A1 - Kuhlbrodt, B. A1 - Wisotzki, Lutz A1 - Jahnke, Knud T1 - Two-dimensional modeling of AGN host galaxies Y1 - 2001 SN - 0-306-46662-7 ER - TY - JOUR A1 - Kuhlbrodt, Till A1 - Titz, Sven Holger A1 - Feudel, Ulrike A1 - Rahmstorf, Stefan T1 - A simple model of seasonal open ocean convection. Part II: Labrador Sea stability and stochastic forcing N2 - Aspects of open ocean deep convection variability are explored with a two-box model. In order to place the model in a region of parameter space relevant to the real ocean, it is fitted to observational data from the Labrador Sea. A systematic fit to OWS Bravo data allows us to determine the model parameters and to locate the position of the Labrador Sea on a stability diagram. The model suggests that the Labrador Sea is in a bistable regime where winter convection can be either ?on? or ?off?, with both these possibilities being stable climate states. When shifting the surface buoyancy forcing slightly to warmer or fresher conditions, the only steady solution is one without winter convection. We then introduce short-term variability by adding a noise term to the surface temperature forcing, turning the box model into a stochastic climate model. The surface forcing anomalies generated in this way induce jumps between the two model states. These state transitions occur on the interannual to decadal timescale. Changing the average surface forcing towards more buoyant conditions lowers the frequency of convection. However, convection becomes more frequent with stronger variability in the surface forcing. As part of the natural variability, there is a non-negligible probability for decadal interruptions of convection. The results highlight the role of surface forcing variability for the persistence of convection in the ocean. Y1 - 2001 SN - 1616-7341 ER - TY - JOUR A1 - Landa, Polina S. A1 - Zaikin, Alexei A. A1 - Schimansky-Geier, Lutz T1 - Effect of the potential shape and of a Brownian particle mass on noise-induced transport Y1 - 2001 ER - TY - THES A1 - Landfester, Katharina T1 - Miniemulsions for poymerization processes and materials science Y1 - 2001 ER - TY - THES A1 - Legall, Herbert T1 - Laserspektroskopische Untersuchungen zur kollektiven Anregung in J-Aggregaten und deren Einfluß auf die nichtlinearen optischen Eigenschaften Y1 - 2001 ER - TY - BOOK A1 - Liebers, Klaus ED - Mikelskis, Helmut ED - Wilke, Hans-Joachim T1 - Physik : Kl. 7, [Hauptbd.], Regelschule Thüringen Y1 - 2001 SN - 3-06-020736-4 PB - Cornelsen CY - Berlin ER - TY - BOOK A1 - Liebers, Klaus ED - Mikelskis, Helmut ED - Wilke, Hans-Joachim T1 - Physik : Kl. 7/8, Arbeitsh., Sekundarschule Sachsen-Anhalt Y1 - 2001 SN - 3-06-020737-2 PB - Volk-und-Wissen-Verl. CY - Berlin ER - TY - BOOK A1 - Liebers, Klaus ED - Mikelskis, Helmut ED - Wilke, Hans-Joachim T1 - Physik : Kl. 7/8, [Hauptbd.], Sekundarschule Sachsen-Anhalt Y1 - 2001 SN - 3-06-020734-8 PB - Volk-und-Wissen-Verl. CY - Berlin ER - TY - BOOK A1 - Liebers, Klaus ED - Mikelskis, Klaus ED - Wilke, Hans-Joachim T1 - Physik plus : mit fächerübergreifenden Themen und Projektangeboten ; Kl. 6, Mecklenburg-Vorpommern Y1 - 2001 SN - 3-06-020628-7 PB - Volk-und-Wissen-Verl. CY - Berlin ER - TY - JOUR A1 - Lindner, A. A1 - Freese, H. A1 - Quehl, G. A1 - Reiß, D. A1 - Schiller, K. T1 - Jaynes-Cummings-model with damping at resonance Y1 - 2001 SN - 1434-6060 ER - TY - JOUR A1 - Marwan, Norbert A1 - Kurths, Jürgen T1 - Nonlinear analysis of bivariate data with cross recurrence plots N2 - We use the extension of the method of recurrence plots to cross recurrence plots (CRP) which enables a nonlinear analysis of bivariate data. To quantify CRPs, we develop further three measures of complexity mainly basing on diagonal structures in CRPs. The CRP analysis of prototypical model systems with nonlinear interactions demonstrates that this technique enables to find these nonlinear interrelations from bivariate time series, whereas linear correlation tests do not. Applying the CRP analysis to climatological data, we find a complex relationship between rainfall and El Nino data. Y1 - 2001 UR - http://arxiv.org/abs/physics/0201061 ER - TY - JOUR A1 - Marwan, Norbert A1 - Nowaczyk, Norbert R. A1 - Kurths, Jürgen A1 - Thiel, Marco T1 - Cross recurrence plot based rescaling of geological time series N2 - The rescaling of geological data series to a geological reference time series is of major interest in many investigations. For example, geophysical borehole data should be correlated to a given data series whose time scale is known in order to achieve an age-depth function or the sedimentation rate for the borehole data. Usually this synchronization is performed visually and by hand. Instead of using this wiggle matching by eye, we present the application of cross recurrence plots for such tasks. Using this method, the synchronization and rescaling of geological data to a given time scale is much easier and faster than by hand. Y1 - 2001 SN - 1029-7006 ER - TY - THES A1 - Mavanga, Gil Gabriel T1 - Entwicklung und Evaluation eines experimentell- und phänomenorientierten Optikcurriculumus für die 8. Klasse in Mosambik und Untersuchungen von Vorstellungen bei Lehrerstudenten und Schülern Y1 - 2001 ER - TY - JOUR A1 - Mellinger, Axel A1 - Wegener, Michael A1 - Wirges, Werner A1 - Gerhard, Reimund T1 - Thermally stable dynamic piezoelectricity in sandwich films of porous and non-porous amorphous fluoropolymer Y1 - 2001 ER - TY - JOUR A1 - Memola, Elisabetta A1 - Fendt, Christian A1 - Brinkmann, W. T1 - Relativistic Jets from Blazars and Microquasars Y1 - 2001 ER - TY - JOUR A1 - Menzel, Ralf T1 - Photonics : Linear and nonlinear interactions of laser light and matter Y1 - 2001 SN - 3-540-67074-2 PB - Springer CY - Berlin ER - TY - JOUR A1 - Mikelskis, Helmut T1 - Schülervorstellungen zur Bildentstehung in Mosambik Y1 - 2001 SN - 3-88064-300-8 ER - TY - JOUR A1 - Mikelskis, Helmut T1 - Rettet die Bildung! (auch die naturwissenschaftliche, versteht sich) oder Was heißt Bildung im Informationszeitalter und in der Wissensgesellschaft? Y1 - 2001 SN - 3-88064-300-8 ER - TY - JOUR A1 - Mikelskis, Helmut T1 - Learning interference optics : modelbuilding processes in holography Y1 - 2001 ER - TY - JOUR A1 - Mikelskis, Helmut T1 - Zukunftsperspektiven der Bildung im Informationszeitalter und in der Wissensgesellschaft Y1 - 2001 ER - TY - JOUR A1 - Mikelskis, Helmut A1 - Horn, Martin Erik T1 - Konzeption und Evaluation einer Unterrichtsreihe zur Holographie Y1 - 2001 SN - 3-88064-300-8 ER - TY - THES A1 - Mittler, Kay T1 - Dynamik vibronischer Festkörperlaser großer spektraler Brandbreite Y1 - 2001 ER - TY - THES A1 - Morawetz, Knut T1 - Untersuchungen zum Adsorptionsverhalten von gegenionen an Langmuir - Filmen Y1 - 2001 ER - TY - JOUR A1 - Mukhopadhyay, M. K. A1 - Datta, A. A1 - Sanyal, M. K. A1 - Geue, Thomas A1 - Pietsch, Ullrich T1 - Synchrotron Studies of Melting of Langmuir-Blodgett Films Y1 - 2001 ER - TY - JOUR A1 - Paajanen, Mika A1 - Wegener, Michael A1 - Gerhard, Reimund T1 - Charging of cellular space-charge electret films in various gas atmospheres Y1 - 2001 SN - 0-7803-7053-8 ER - TY - JOUR A1 - Paajanen, Mika A1 - Wegener, Michael A1 - Gerhard, Reimund T1 - Understanding the role of the gas in the voids during corona charging of cellular electret films : a way to enhance their piezoelectricity Y1 - 2001 ER - TY - BOOK A1 - Petters, Arlie O. A1 - Levine, Harold A1 - Wambsganß, Joachim T1 - Singularity theory and gravitational lensing T3 - Progress in mathematical physics Y1 - 2001 SN - 0-8176-3668-4 VL - 21 PB - Birkhäuser CY - Boston ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Grenzer, Jörg A1 - Geue, Thomas A1 - Neißendorfer, Frank A1 - Brezesinski, Gerald A1 - Symietz, Christian A1 - Möhwald, Helmuth A1 - Gudat, Wolfgang T1 - The energy dispersive reflectometer at BESSY II : a challenge for thin film analysis Y1 - 2001 SN - 0167- 5087 ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Stahn, Jochen A1 - Davaasambuu, Jav A1 - Pucher, Andreas T1 - Electric field induced charge density variations in partially-ionic compounds Y1 - 2001 SN - 0022-3697 ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Zeimer, Ute A1 - Hofmann, L. A1 - Grenzer, Jörg A1 - Gramlich, S. T1 - Strain induced compositional modulations in AlGaAs overlayers induced by lateral surface gratings Y1 - 2001 SN - 0272-9172 ER - TY - JOUR A1 - Pikovskij, Arkadij A1 - Neumann, Eireen T1 - Comment on "Simple approach to the creation of a strange nonchaotic attractor in any chaotic system" N2 - We address the problem of existence of strange nonchaotic attractors (SNAs) in quasiperiodically forced dynamical systems. Recently, Shuai and Wong [Phys. Rev. E 59, 5338 (1999)] suggested a universal method for constructing a SNA in an arbitrary system possessing chaos. We demonstrate here that, in general, this method fails. For arbitrary systems, it gives a SNA only in a vicinity of transition to chaos. We discuss also a special example, where the method by Shuai and Wong indeed produces a SNA. Y1 - 2001 ER - TY - JOUR A1 - Pikovskij, Arkadij A1 - Politi, Antonio T1 - Dynamic localization of Lyapunov vectors in Hamiltonian lattices Y1 - 2001 ER - TY - JOUR A1 - Pikovskij, Arkadij A1 - Popovych, Orest A1 - Maistrenko, Yu T1 - Resolving Clusters in Chaotic Ensembles of Globally Coupled Identical Oscillators N2 - Clustering in ensembles of globally coupled identical chaotic oscillators is reconsidered using a twofold approach. Stability of clusters towards "emanation" of the elements is described with the evaporation Lyapunov exponents. It appears that direct numerical simulations of ensembles often lead to spurious clusters that have positive evaporation exponents, due to a numerical trap. We propose a numerical method that surmounts the spurious clustering. We also demonstrate that clustering can be very sensitive to the number of elements in the ensemble. Y1 - 2001 ER - TY - JOUR A1 - Pikovskij, Arkadij A1 - Rosenblum, Michael T1 - Comment on "Intermittency in chaotic rotations" N2 - Lai et al. [Phys. Rev. E 62, R29 (2000)] claim that the angular velocity of the phase point moving along the chaotic trajectory in a properly chosen projection (the instantaneous frequency) is intermittent. Using the same examples, namely the Rössler and the Lorenz systems, we show the absence of intermittency in the dynamics of the instantaneous frequency.This is confirmed by demonstrating that the phase dynamics exhibits normal diffusion. We argue that the nonintermittent behavior is generic. Y1 - 2001 ER - TY - JOUR A1 - Pikovskij, Arkadij A1 - Rosenblum, Michael T1 - Detecting direction of coupling in interacting oscillators N2 - We propose a method for experimental detection of directionality of weak coupling between two self-sustained oscillators from bivariate data. The technique is applicable to both noisy and chaotic systems that can be nonidentical or even structurally different. We introduce an index that quantifies the asymmetry in coupling. Y1 - 2001 ER - TY - BOOK A1 - Pikovskij, Arkadij A1 - Rosenblum, Michael A1 - Kurths, Jürgen T1 - Synchronization : a universal concept in nonlinear sciences T3 - Cambridge nonlinear science series Y1 - 2001 SN - 0-521-59285-2 VL - 12 PB - Cambridge Univ. Press CY - Cambridge ET - 1st paperback ed., repr ER - TY - JOUR A1 - Poloucek, P. A1 - Pietsch, Ullrich A1 - Geue, Thomas A1 - Symietz, Christian A1 - Brezesinski, Gerald T1 - X-ray reflectivity analysis of thin complex Langmuir-Blodgett films Y1 - 2001 ER - TY - JOUR A1 - Popovych, Orest A1 - Maistrenko, Yu A1 - Mosekilde, Erik A1 - Pikovskij, Arkadij A1 - Kurths, Jürgen T1 - Transcritical riddling in a system of coupled maps N2 - The transition from fully synchronized behavior to two-cluster dynamics is investigated for a system of N globally coupled chaotic oscillators by means of a model of two coupled logistic maps. An uneven distribution of oscillators between the two clusters causes an asymmetry to arise in the coupling of the model system. While the transverse period-doubling bifurcation remains essentially unaffected by this asymmetry, the transverse pitchfork bifurcation is turned into a saddle-node bifurcation followed by a transcritical riddling bifurcation in which a periodic orbit embedded in the synchronized chaotic state loses its transverse stability. We show that the transcritical riddling transition is always hard. For this, we study the sequence of bifurcations that the asynchronous point cycles produced in the saddle-node bifurcation undergo, and show how the manifolds of these cycles control the magnitude of asynchronous bursts. In the case where the system involves two subpopulations of oscillators with a small mismatch of the parameters, the transcritical riddling will be replaced by two subsequent saddle-node bifurcations, or the saddle cycle involved in the transverse destabilization of the synchronized chaotic state may smoothly shift away from the synchronization manifold. In this way, the transcritical riddling bifurcation is substituted by a symmetry-breaking bifurcation, which is accompanied by the destruction of a thin invariant region around the symmetrical chaotic state. Y1 - 2001 ER - TY - JOUR A1 - Puga, E. A1 - Alcalde, D. A1 - Barrena, R. A1 - Mediavilla, E. A1 - Motta, V. A1 - Munoz, J. A. A1 - Oscoz, Alejandro A1 - Serra-Ricart, M. A1 - Gil-Merino, Rodrigo A1 - Goicoechea, Luis Julian A1 - Lewis, G. f A1 - Libbrecht, C. A1 - Moreau, O. A1 - Surdej, J. A1 - Wambsganß, Joachim T1 - Daily monitoring of the gravitational lens QSO 2237+0305 at the Nordic Optical Telescope Y1 - 2001 SN - 0-7923-6974-2 ER - TY - JOUR A1 - Raab, Corinna A1 - Kurths, Jürgen T1 - Estimation of Large-Scale Dimension Densities N2 - We propose a technique to calculate large-scale dimension densities in both higher-dimensional spatio-temporal systems and low-dimensional systems from only a few data points, where known methods usually have an unsatisfactory scaling behavior. This is mainly due to boundary and finite size effects. With our rather simple method we normalize boundary effects and get a significant correction of the dimension estimate. This straightforward approach is basing on rather general assumptions. So even weak coherent structures obtained from small spatial couplings can be detected with this method, what is impossible by using the Lyapunov-dimension density. We demonstrate the efficiency of our technique for coupled logistic maps, coupled tent maps, the Lorenz-attractor and the Roessler-attractor. Y1 - 2001 ER - TY - THES A1 - Radüge, Christian T1 - Der Mechanismus des Benetzungsschaltens von Azobenzol-modifizierten Oberflächen Y1 - 2001 ER - TY - JOUR A1 - Rakos, K. A1 - Dominis, Dijana A1 - Steindling, S. T1 - Intermediate-band photometry of a rich cluster of galaxies : A2218 N2 - This paper presents four color intermediate-band photometry of the cluster A2218 carried out using the Wise Observatory 1 m telescope. A2218 is one of the richest clusters in the Abell catalogue, with richness class 4. We find that A2218 has an unusually low fraction of blue galaxies for its redshift (z=0.171), and is populated mainly by E/S0 galaxies, while starburst systems are very scarce. The few starbursting galaxies present populate the faint end of the cluster luminosity function, close to the limiting magnitude of our observations. The difference between A2218 and other clusters at similar redshifts is very remarkable, underlining the influence of cluster richness on the evolution of its member galaxies. Y1 - 2001 UR - http://adsabs.harvard.edu/cgi-bin/nph- data_query?bibcode=2001A%26A...369..750R&db_key=AST&link_type=ARTICLE ER -