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 -