Asynchronous sampling for ultrafast experiments with low momentum compaction at the ANKA ring

A high‐repetition‐rate pump–probe experiment is presented, based on the asynchronous sampling approach. The low‐α mode at the synchrotron ANKA can be used for a time resolution down to the picosecond limit for the time‐domain sampling of the coherent THz emission as well as for hard X‐ray pump–probe experiments, which probe structural dynamics in the condensed phase. It is shown that a synchronization of better than 1 ps is achieved, and examples of phonon dynamics of semiconductors are presented.     

Anomalous self-similarity in a turbulent rapidly rotating fluid

Our velocity measurements on quasi-two-dimensional turbulent flow in a rapidly rotating annulus yield self-similar (scale-independent) probability distribution functions for longitudinal velocity differences, deltav(l) = v(x+l)-v(x). These distribution functions are strongly non-Gaussian, suggesting that the coherent vortices play a significant role. The structure functions <[deltav(l)](p)> approximately l(zeta)p exhibit anomalous scaling: zeta(p) = p / 2 rather than the expected zeta(p) = p / 3. Correspondingly, the energy spectrum is described by E(k) approximately k(-2) rather than the expected E(k) approximately k(-5/3).     

Fortschritte in der analytischen Chemie seltener Metalle

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The Mean Single Molecule Rate (mSMR) in the Analysis of Fluorescence Fluctuations: Measurements on DNA Mixtures of Defined Composition

Journal of Fluorescence - We present a method for the evaluation of fluorescence fluctuations on the basis of Mandel’s Q parameter, using sampling time-dependent factorial cumulants. By...     

A robust and efficient method for solving point distance problems by homotopy

Very large nonlinear unconstrained binary optimization problems arise in a broad array of applications. Several exact or heuristic techniques have proved quite successful for solving many of these problems when the objective function is a quadratic polynomial. However, no similarly efficient methods are available for the higher degree case. Since high degree objectives are becoming increasingly important in certain application areas, such as computer vision, various techniques have been recently developed to reduce the general case to the quadratic one, at the cost of increasing the number of variables by introducing additional auxiliary variables. In this paper we initiate a systematic study of these quadratization approaches. We provide tight lower and upper bounds on the number of auxiliary variables needed in the worst-case for general objective functions, for bounded-degree functions, and for a restricted class of quadratizations. Our upper bounds are constructive, thus yielding new quadratization procedures. Finally, we completely characterize all “minimal” quadratizations of negative monomials.     

Precipitation of dissolved alkali salts and fullerenes on surfaces of doped porous matter

Standard porcelain samples burnt at different temperatures were doped with LiCl, organo-Li solutions, or with fullerene solution and then dried. The depth profiles of both Li and fullerene were determined. The distributions of the incorporated dopants strongly depend on the samples' porosity. Additional ultrasonic treatment during the diffusion process has a fatal influence on the porcelain structure, resulting in enhanced dopant uptake of the remaining sample. The surface-near shape of the depth profiles is interpreted by solvation, i.e., by precipitation of the dissolved salts or fullerenes in the surface-near zone during the drying process. It is shown that the solvation effect is important only in the case of media with high porosity.