Shape dependence of correlation times in chaos-induced diffusion

A one-dimensional discrete-time chaotic system generating a diffusive process with strong correlations between successive steps is considered, as realized in brownian motion with directional persistence (observed e.g. for the motion of infusoriae). The resulting intermittency-like behavior without $\text{1}\text{?}$ spectrum may be found in many nonlinear systems with two metastable states.     

Recent progress in quantitative and high spatial resolution AES

Progress in high resolution Auger electron spectroscopy (HR-AES or scanning Auger microscopy, SAM) during the past few years is characterized by the use of efficient field emission electron sources, parallel detection capabilities and improved data acquisition, storage and processing, thus enhancing spatial resolution (to about 10 nm), signal to noise figure and quantification of elements in different chemical bonding states, e.g. by routinely using factor analysis. Optimized ion sputtering facilities, particularly sample rotation, enable depth profiling with high, depth independent resolution. The basic features of SAM are discussed with respect to EPMA (electron probe micro-analysis), emphasizing fundamental limitations and future developments.     

Decay of bcc-structure and of bond-orientational order in a fluid

The decay of an initially prepared bcc structure and the bond-orientational order (anisotropy of the first coordination shell) are studied in a non-equilibrium molecular dynamics simulation for a fluid of 1024 particles interacting with a repulsive r^-12 potential. Data are presented for pair-correlation functions and order parameters associated with an angle dependence described by cubic harmonics of the ranks 4, 6 and 8. These cubic pair-correlation functions and cubic order parameters are defined by the expansion of the pair-correlation function and of the bond orientational distribution function with respect to Cartesian tensors. The relaxation of the local anisotropy shows a pretransformational slowing down for densities approaching the freezing point.     

Zur Theorie des Abbaus von Kettenmolekülen

Zusammenfassung In der Arbeit wird eine Methode zur praktischen Anwendung der mathematischen Ergebnisse der statistischen Theorie des Abbaus vonKettenmolekülen angegeben. Ausgehend von dem Ansatz und der L?sung von R. Simha (16) wird für die Berechnung der in der mathematischen L?sung auftretenden zahlreichen Konstanten ein Schema aufgestellt. Ferner wird der Spezialfall behandelt, da der Abbau nicht bis zum Monomeren verl?uft. Au\erdem wird eine N?herungsl?sung für jene F?lle angegeben, in denen die exakte L?sung infolge des gro\en Rechenaufwandes nicht anwendbar ist. Abschlie\end wird kurz das umgekehrte Problem, die Berechnung der Abbauwahrscheinlichkeiten aus experimentell bestimmten Abbaukurven, behandelt.     

Monitoring of fluid motion in a micromixer by dynamic NMR microscopy

The velocity distribution of liquid flowing in a commercial micromixer has been determined directly by using pulsed-field gradient NMR. Velocity maps with a spatial resolution of 29 microm x 43 microm were obtained by combining standard imaging gradient units with a homebuilt rectangular surface coil matching the mixer geometry. The technique provides access to mixers and reactors of arbitrary shape regardless of optical transparency. Local heterogeneities in the signal intensity and the velocity pattern were found and serve to investigate the quality and functionality of a micromixer, revealing clogging and inhomogeneous flow distributions.