Multielement analysis of biological reference materials by total-reflection X-ray fluorescence and inductively coupled plasma mass spectrometry in the semiquant mode

Summary Total-reflection X-ray fluorescence (TXRF) and inductively coupled plasma mass spectrometry (ICP-MS) were used for the analysis of two biological reference materials. The quantifications were carried out after addition of one single standard element which serves as an internal standard in both cases. The results of TXRF analysis were good to satisfactory. The method is therefore suitable for fast multielement analysis, because it needs no special calibration specimens. The results of ICP-MS analysis are at least in the order of magnitude of the certified values. In some cases recoveries fit very well. For quantitative analysis, however, the use of the standard addition method or the calibration with external standards is required.     

Bernoullicity of solenoidal automorphisms and global fields

We show that ergodic automorphisms of solenoids are isomorphic to Bernoulli shifts by using the product formula for global fields. The authors gratefully acknowledge support by the Mathematical Sciences Research Institute. The first author was supported in part by NSF Grant DMS-9004253.     

An asymptotically optimal algorithm for approximating bounded analytic functions

Summary. Let be the unit disk in the complex plane and let be a compact, simply connected subset of , whose boundary is assumed to belong to the class . Let be the unit ball of the Hardy space . A linear algorithm is constructed for approximating functions in . The algorithm is based on sampling functions in the Fejer points of and it produces the error Here denotes the space of continuous functions on and is the Green capacity of with respect to . Moreover it is shown that the algorithm is asymptotically optimal in the sense of -widths. Received July 7, 1994     

Size of the Detection Area of a Phase-Doppler Anemometer for reflecting and refracting particles

Measurements of particle size distributions in multi-phase flows with a phase-Doppler anemometer yield incorrect results if polydisperse particles are investigated. For weighting biased size distributions, different in situ methods, requiring the size of the detection area, are known, but all of these weighting procedures are restricted to very small measuring volumes if off-axis instrument configurations are considered. Moreover, the weighting functions have some disadvantages in the case of poor statistics in single size classes or the results are not suitable for determining the size of the detection area for particles which are larger than the beam waist. Therefore, the intention in this work was to measure the size of the detection area for different kinds of monodisperse particles, different instrument configurations and varied instrument sensitivities experimentally and to develop an improved weighting procedure that copes with the above difficulties. The application of the results obtained from the investigations with monodisperse particles to measured particle size distributions and volume flux densities of polydisperse water droplets in a spray cone of an atomizer confirms the applicability of this weighting procedure. It is still restricted to directed flows, perpendicular to the fringes.     

Completeness of the (LB)-spacesV C(X)

Dedicated to Professor H. G. Tillmann on the occasion of his 65th birthday     

A note on a P ≠ NP result for a restricted class of real machines

For a class of real machines using only linear functionals as computations and equality-tests, we show that the classes P and NP differ.