Laser Based Techniques for Ultra Trace Isotope Production, Spectroscopy and Detection

A variety of research activities in the field of fundamental and applied nuclear physics has evolved in the last years using resonantly tuned radiation from powerful lasers. The technique of resonance ionization spectroscopy has delivered outstanding results and found broad acceptance in the last years as a particularly efficient and highly selective method for rare and exotic radioisotope studies. It is used for production, spectroscopy and detection of these species and provides complete isobaric, high isotopic and even some isomeric selection, which altogether is needed for on-line investigation of short lived species far off stability as well as for ultra trace determination. Good overall efficiency pushes the experimental limits of detection in elemental trace analysis down to below 10⁶ atoms per sample, and additionally isotopic selectivity as high as 3 × 10¹² has been demonstrated. The widespread potential of resonance ionization techniques is discussed, focusing on the experimental arrangements for applications in selective on-line isotope production, spectroscopy of rare radioisotopes and ultra trace determination of radiotoxic isotopes like ²³⁸Pu to ²⁴⁴Pu, ^135,137Cs, ^89,90Sr or ⁴¹Ca in environmental, technical and biomedical samples.     

High density digital recording on 4 mm metal particle and Ba-ferrite tapes

In this study we compare the recording performance of 4 mm metal particle (MP) and Ba-ferrite (BF) tapes using helical scan digital audio tape (DAT) mechanisms and heads. At low bit densities the MP tapes have higher output signal and SNR compared with the BF tapes, but at high bit densities the reverse is true. This superior recording performance of the BF tapes, along with their immunity to environmental corrosion, recommends them as the media of choice for 4 mm data recording applications.     

Polynomial time approximation schemes for general multiprocessor job shop scheduling

We study preemptive and non-preemptive versions of the general multiprocessor job shop scheduling problem: Given a set of n tasks each consisting of at most μ ordered operations that can be processed on different (possibly all) subsets of m machines with different processing times, compute a schedule (preemptive or non-preemptive, depending on the model) with minimum makespan where operations belonging to the same task have to be scheduled according to the specified order. We propose algorithms for both preemptive and non-preemptive variants of this problem that compute approximate solutions of any positive ε accuracy and run in O(n) time for any fixed values of m, μ, and ε. These results include (as special cases) many recent developments on polynomial time approximation schemes for scheduling jobs on unrelated machines, multiprocessor tasks, and classical open, flow and job shops.     

On the existence of soliton solutions to quasilinear Schrödinger equations

Variational techniques are applied to prove the existence of standing wave solutions for quasilinear Schr?dinger equations containing strongly singular nonlinearities which include derivatives of the second order. Such equations have been derived as models of several physical phenomena. The nonlinearity here corresponds to the superfluid film equation in plasma physics. Direct methods of the calculus of variations and minimax methods like the Mountain Pass Theorem are used. The difficulties introduced by the nonconvex functional are substantially different from the semilinear case. Received: 21 March 2000 / Accepted: 23 February 2001 / Published online: 25 June 2001     

Analytische isoelektrische Fraktionierung der N-Acetyl-β-d-hexosaminidasen

A microanalytical technique is described for the electrofocused resolution of proteins and subsequent quantitation of their enzymatic activities. Protein samples (0.5–10 mg) were extracted from 50 mg of various human tissues or from 5 ml venous blood with sufficient enzymatic activity to hydrolyze 0.01 μM p-nitrophenyl-N-acetyl-β-d-glucosaminide per min at 37°C. Using this technique the activities of the human N-acetyl-β-d-hexosaminidases were investigated, thereby providing a useful tool for the clinical diagnosis of Tay-Sachs disease.     

Isotachophoretische Bestimmung der B-Vitamine im ng-Bereich unter Verwendung kationischer Spacerionen

Ohne Zusammenfassung

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Isotachophoretic determination of vitamins B in the ng-range using kationic spacer ions