RHCE alleles detected after weak and/or discrepant results in automated Rh blood grouping of blood donors in Northern Germany.

Background: More than 170 weak or partial RHD alleles are currently known. A similar heterogeneity of RHCE alleles may be anticipated, but a large-scale systematic analysis of the molecular bases of altered C, c, E, and e antigenicity in European blood donors was lacking.

Study Design And Methods: Between November 2004 and October 2006, samples collected from 567,105 blood donors in the northwest of Germany were surveyed for weakened and/or discrepant serologic reaction patterns of the C, c, E, or e antigens in automated testing.

Coherence resonance in a chemical excitable system driven by coloured noise.

We investigate how the temporal correlation in excitable systems driven by external noise affects the coherence of the system's response. The coupling to the fluctuating environment is introduced via fluctuations of a bifurcation parameter that controls the local dynamics of the light-sensitive Belousov-Zhabotinsky reaction and of its numerical description, the Oregonator model. Both systems are brought from a highly incoherent regime to a coherent one by an appropriate choice of the correlation time and keeping noise variance constant.

Noise-induced wave nucleations in an excitable chemical reaction.

We study both experimentally and numerically the temporal coherence of noise-induced wave nucleations in excitable media subjected to external fluctuations with finite correlation time. The experiments are performed with the light-sensitive variant of the Belousov-Zhabotinsky (BZ) reaction forced by an exponentially correlated dichotomous fluctuating illumination. We find that there exists an optimal correlation time for which nucleations coherence reaches a maximum.

Global control of spiral wave dynamics in an excitable domain of circular and elliptical shape.

Experiments performed in a thin layer of the Belousov-Zhabotinsky solution subjected to a global feedback demonstrate the existence of the resonance attractor for meandering spiral waves within a domain of circular shape. In an elliptical domain, the resonance attractor can be destroyed due to a saddle-node bifurcation induced by a variation of the domain eccentricity. This conclusion explains the experimentally observed anchoring of spiral waves at certain points of an elliptical domain and is in good quantitative agreement with numerical data obtained for the Oregonator model.

Periodic forcing and feedback control of nonlinear lumped oscillators and meandering spiral waves.

It is shown that meandering spiral waves rotating in excitable media subjected to periodic external forcing or feedback control resemble many features of nonlinear lumped oscillators. In particular, the period shift function obtained for the Poincaré oscillator is qualitatively identical to that for spiral waves under fixed phase control. On the other hand, under one-channel feedback control, meandering spiral waves exhibit quite different dynamic regimes appearing as specific features of a distributed system.