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As an alternative to the shadow evaporation method for the preparation of ultrasmall tunnel junctions we have established the so-called self-aligned in-line technique. It was applied to the fabrication of common Al/AlO/sub x//Al-type and, for the first time, Nb/AlO/sub x//Nb-based single-electron transistors. The characterization of the samples at temperatures in the range of a few hundred millikelvins reveals charging effects (Coulomb blockade and gate modulation) of the quasiparticle current.

It is known that classical Coulomb blockade effects of SET devices are disturbed by the tunneling effects of higher order denoted as macroscopic quantum tunneling of charge (q-mqt) or co-tunneling. The influence of an external electromagnetic environment modelled by an additional impedance in the circuit on the mean q-mqt current is studied in the high-impedance limit. This is important especially for devices containing only two SET junctions, for instance the SET electrometer, where the influence of the environment on the Coulomb blockade is remarkable. It can be shown that the Coulomb blockade is only partly destroyed producing a new, lower “quantum” Coulomb blockade. This holds as well in the case of the incoherent as of the coherent q-mqt. Furthermore, a method is presented on how to regularize the logarithmic singularities in the q-mqt current using line width effects.

Emotional stress is often followed by increased susceptibility to infections. One major role in the immediate immune response to infection is played by natural killer (NK) cells. This study was designed to establish whether acute psychological stress influences cellular immune functions and to elucidate the role of endocrine parameters as potent mediators of stress induced alterations of the immune system. Forty-five first-time tandem parachutists were examined continuously for their plasma concentrations of cortisol and catecholamines from 120 min before to 60 min after jumping. Lymphocyte subsets, NK activity, and ADCC were determined 2 hr before, immediately after, and 1 hr after jumping. There was a significant increase in sympathetic-adrenal hormones during (adrenaline, noradrenaline) and shortly after jumping (cortisol). Lymphocyte subsets and the functional capacity of NK cells revealed an increase immediately after jumping followed by a decrease significantly below starting values 1 hr later. These changes were significantly correlated to plasma concentrations of noradrenaline. Thus, quick mobilization of NK cells is suggested as one major mechanism for this effective adaptation of the immune system to stress situations.

The essential part of the SET electrometer is the so-called SET transistor which consists of two serially coupled SET junctions driven by an external voltage. An external charge is influenced on the island between the two junctions. Furthermore, the influence of the electromagnetic environment is modelled by an additional impedance in the circuit. Using as well the two-state as the three-state approach, the mean-current through the double-junction, the shot-noise parameters and the charge sensitivity are calculated as a function of the driving voltage and the external charge on the island.

The ``orthodox theory'' of a single electron double junction is dealt with. It is shown that the stationary solution of the underlying master equation allows the construction of any time-dependent solution in terms of orthogonal polynomials. The approach pays off if the stationary solution becomes simple. Two special cases are considered. We use the time-dependent solution to calculate the current noise in these cases., 6 pages, 4 Postscript figures, uses epsf.sty and multicol.sty, amended computation in the high-temperature domain

The influence of the phases of tunneling matrix elements on the rate of the elastic co--tunneling at an ultrasmall normal--conducting double--junction is studied in a simple quantum--hole approach at zero temperature. The results are compared with experimental data., Comment: 8 pages, REVTeX v3.0

The non-existence of non-abelian Yang-Mills fields exhibiting the symmetry group G 5 of plane waves is proven.

Solutions of spherically symmetric state SU(3) gauge field equations without sources and with boundary conditions corresponding to localized energy are found numerically. Despite the high number of free parameters in the solutions we get by comparing the results with the appropriate SU(2) solutions a good overview over the qualitative behaviour of the corresponding SU(3) field configurations.