Procedure for background estimation in energy-dispersive X-ray fluorescence spectra

A method for semi-automatic background estimation in energy-dispersive x-ray fluorescence spectra is outlined. Two cubic splines were investigated and the spline called the Butland interpolant was chosen for further investigation. Prior to the calculation of the spline, peak regions are set up, and suitable knots are defined outside the peak regions. To set up the peak regions, an automatic peak-search routine and a calibration equation are used. For a given peak, the latter relates the full width at half maximum (FWHM) to the peak centre. In turn, the size of the peak regions are defined by the FWHM multiplied by a constant given by the user. The method was tested on several types of spectra. It was found that the optimal size of the peak region decreased with increasing peak density. Reproducibility tests showed that the standard deviation of the summation of counts within a peak region and after background subtraction was less than would be expected from the counting statistics.     

Stability of the Cournot process – experimental evidence

We report results of experiments designed to test the predictions of the best-reply process. In a Cournot oligopoly with four firms, the best-reply process should theoretically explode if demand and cost functions are linear. We find, however, no experimental evidence of such instability. Moreover, we find no differences between a market which theoretically should not converge to Nash equilibrium and one which should converge because of inertia. We investigate the power of several learning dynamics to explain this unpredicted stability. Received May 1997/Revised June 2002     

Zur Wasserbestimmung in Nahrungsmitteln

Ohne Zusammenfassung     

Untersuchung von Fetten

Ohne Zusammenfassung     

Representation theorems for transfinite computability and definability

 We show how Kreisel's representation theorem for sets in the analytical hierarchy can be generalized to sets defined by positive induction and use this to estimate the complexity of constructions in the theory of domains with totality. Received: 21 January 1998 / Published online: 2 September 2002     

Subject index to volume 39

Measurements of the normal component of the stray-field at the surface of small permanent magnets were performed with a vibrating pick-up loop magnetometer with high geometrical resolution. They show a structure which reveals deviations from the desired magnetization configuration. A calculation method originally developed for soft magnetic materials was extended to calculations on permanent magnets. The real demagnetization characteristic of the material is introduced into the calculation using two independent susceptibility components. Thus the magnetic surface charges, the stray-field and the magnetization configuration can be calculated.     

Hereditarily effective typestreams

We prove that the hierarchy of hereditarily effective typestreams, that are effective models of inductivly defined types, has the length of the first recursivly inaccessible ordinal. Received March 27, 1995     

The impact of the termination rule on cooperation in a prisoner’s dilemma experiment

Cooperation in prisoner’s dilemma games can usually be sustained only if the game has an infinite horizon. We analyze to what extent the theoretically crucial distinction of finite versus infinite-horizon games is reflected in the outcomes of a prisoner’s dilemma experiment. We compare three different experimental termination rules in four treatments: a known finite end, an unknown end, and two variants with a random termination rule (with a high and with a low continuation probability, where cooperation can occur in a subgame-perfect equilibrium only with the high probability). We find that the termination rules do not significantly affect average cooperation rates. Specifically, employing a random termination rule does not cause significantly more cooperation compared to a known finite horizon, and the continuation probability does not significantly affect average cooperation rates either. However, the termination rules may influence cooperation over time and end-game behavior. Further, the (expected) length of the game significantly increases cooperation rates. The results suggest that subjects may need at least some learning opportunities (like repetitions of the supergame) before significant backward induction arguments in finitely repeated game have force.