[en] The total cross section was measured in the region of the one-pion production threshold 1.079< W<1.13 GeV at pulse transfers of q² = 0.3, 0.4, 0.5 GeV², in a coincidence experiment at the Bonn synchrotron. The results show that for the nπ⁺ reaction channel, the S wave excitation nearly describes the threshold of the cross-section. p-waves components relatively close to the threshold already contribute remarkably to the cross section. The q² dependence of the axial vector form factor is well described by a dipole form with the mass parameter (1.09 +- 0.24) GeV. (orig./LH)

[en] The analysis of the structure function F² measured by the EMC in a deep inelastic muon nucleon scattering experiment is discussed in terms of perturbative QCD and higher twist contributions. The influence of mass effects and heavy quark excitation is also investigated. The averaged QCD mass scale parameter νsub(averaged MS) = 150 +- 100MeV is in agreement with the other experiments

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[en] At the German Antarctic research station (70 degrees S, 8 degrees W), long-term observations of the chemical and radio-chemical composition of atmospheric particulate matter were started in spring 1983. Based on the analysis of high-volume aerosol filters sampled continuously for nearly 5 years, concentration records of the following aerosol components are presented here: (a) major ions (sea-salt, sulfate, nitrate); (b) cosmogenic ⁷Be and terrigeneous ²¹⁰Pb; (c) trace elements (crustal Mn, heavy metal Pb). All species mentioned, with the exception of stable and radioactive Pb, show annual cycles. The maximum occurs in austral summer for ⁷Be, sulfate, and crustal Mn. For sea-salt, however, the maximum is found in local autumn, and for nitrate in local spring. In local summer, the enhanced ⁷Be to ²¹⁰Pb ratio is attributed to intenser large scale vertical mixing. The pattern of total sulfate seems to be controlled by the nss-sulfate production from marine organo-sulfur species during local summer, whereas in polar night, nss-sulfate shows very low or even negative concentration. Crustal aerosol (indicated by Mn) shows a mean summer contribution of 16 ng/SCM which exceeds the mean winter level by more than a factor of two. Based on a mean wash-out ratio of 0.27x10⁶ observed for ²¹⁰Pb bearing aerosol particles, a Pb snow concentration of 3.0 pg/g is deduced from the mean air concentration of 11 pg/SCM. (authors)

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[en] For muon-nucleon scattering experiments 24 large drift chambers planes are being built at the University of Freiburg. As the intense muon beam has to pass through the chambers, insensitive regions are constructed in the beam area by increasing the diameter of the anode wires from 20 μm to 100 μm by electroplating. Test results in a high intensity beam are presented, showing the effectiveness of the desensitising technique. (Auth.)

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[en] In recent years radiodiagnostic procedures have made spectacular advances with improvements in the diagnosis and follow-up of malignant diseases. While they can now detect lesions of a diameter of no more than 1 to 2 cm under ideal conditions, their sensitivity is often poor and their specificity inadequate. This has prompted a quest for parameters with a high sensitivity and specificity, the quantitative measurement of which should suggest the extension of a malignancy. In addition, their nature should indicate the tumor site and even organ of origin, they should be easily assayed, inexpensive and well reproducible. These parameters called tumor markers are normally assayed for in blood and/or urinary samples and have entirely different chemical structures. Some of the, e.g. CEA, AFP or beta-HCG, have meanwhile acquired a firm place in the clinical setting, while other more recent ones like CA 15-3 and C-50 will as yet have to establish their clinical usefulness. While most of the tumor markers have a poor specificity, they have been extremely useful in monitoring the success of treatment and following up of patients operated for malignancies. However, none of them have adequate sensitivity for screening purposes. The development of the hybridoma technique for obtaining monoclonal antibodies can be expected to improve their specificity. The use of such radiolabelled monoclonal antibodies shows promise for both diagnosis and treatment. (Author)

No abstract available