Symmetry breaking: A tool to unveil the topology of chaotic scattering with three degrees of freedom

We shall use symmetry breaking as a tool to attack the problem of identifying the topology of chaotic scatteruing with more then two degrees of freedom. specifically we discuss the structure of the homoclinic/heteroclinic tangle and the connection between the chaotic invariant set, the scattering functions and the singularities in the cross section for a class of scattering systems with one open and two closed degrees of freedom.Comment: 13 pages and 8 figure

Zur Effizienz der Fachsprachen im Fremdsprachenunterricht

Fachsprachen gelten allgemein als relativ undurchsichtig und unzugänglich. "Fachsprachen - abnehmerorientiert" thematisiert diese Auffassung und lädt zu praktikablen Lösungsvorschlägen ein. In diesem Beitrag werden daher verschiedene Lösungsansätze vorgestellt, und zwar im Rahmen einer fachsprachlichen Effizienzhypothese. Dabei wird zunächst der allgemeine Kontext der Wissenschafts- und Fachsprachendiskussion abgesteckt. Im zweiten Teil wird dann die Struktur von Fachsprachen etwas eingehender beschrieben. Der dritte Teil des Beitrages stellt dar, welche Rolle die Medien im Fremdsprachenunterricht spielen können und welche sie in einem konkreten Programm für den fachsprachlichen Leseunterricht tatsächlich spielen. Abschließend wird - auch an Hand laufender Projekte - skizziert, welche Zukunftsperspektiven sich für die mediengestützte Fachsprachenvermittlung ergeben

Traveling Wave Fronts and Localized Traveling Wave Convection in Binary Fluid Mixtures

Nonlinear fronts between spatially extended traveling wave convection (TW) and quiescent fluid and spatially localized traveling waves (LTWs) are investigated in quantitative detail in the bistable regime of binary fluid mixtures heated from below. A finite-difference method is used to solve the full hydrodynamic field equations in a vertical cross section of the layer perpendicular to the convection roll axes. Results are presented for ethanol-water parameters with several strongly negative separation ratios where TW solutions bifurcate subcritically. Fronts and LTWs are compared with each other and similarities and differences are elucidated. Phase propagation out of the quiescent fluid into the convective structure entails a unique selection of the latter while fronts and interfaces where the phase moves into the quiescent state behave differently. Interpretations of various experimental observations are suggested.Comment: 46 pages, 11 figures. Accepted for publication in Phys. Rev.

Absorption of Ultrashort Laser Pulses in Strongly Overdense Targets

We report on the first absorption experiments of sub-10 fs high-contrast Ti:Sa laser pulses incident on solid targets. The very good contrast of the laser pulse assures the formation of a very small pre-plasma and the pulse interacts with the matter close to solid density. Experimental results indicate that p-polarized laser pulses are absorbed up to 80 percent at 80 degrees incidence angle. The simulation results of PSC PIC code clearly confirm the observations and show that the collisionless absorption works efficiently in steep density profiles

Theory of single-photon transport in a single-mode waveguide coupled to a cavity containing a two-level atom

The single-photon transport in a single-mode waveguide, coupled to a cavity embedded with a two-leval atom is analyzed. The single-photon transmission and reflection amplitudes, as well as the cavity and the atom excitation amplitudes, are solved exactly via a real-space approach. It is shown that the dissipation of the cavity and of the atom respectively affects distinctively on the transport properties of the photons, and on the relative phase between the excitation amplitudes of the cavity mode and the atom.Comment: 28 pages, 6 figures. Accepted by Physical Review A (2009

Analogue modulation characteristics of InP membrane microdisc laser for in-building networks

Using thin membrane InP microdisc lasers heterogeneously integrated on a silicon on insulator (SOI) substrate having a broadband analogue modulation bandwidth of 11 GHz, analogue direct modulation with radio data signals (64 and 256 QAM, 20M symbols/s at 5 GHz RF carrier) is demonstrated. The demonstration shows the potential of the microdisc laser as a low-energy analogue optical transmitter with error-vector magnitude penalties of 3.6 and 4.2% for 64 and 256 QAM, respectively, and the low biasing currents for both DC (4 mW) and RF (0.1 mW) signals, which are compatible with signals and currents which can be supplied by a simple CMOS driving chip