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Institute
In this paper an instability calculation is given for an axially symmetric gas distribution which has a differential rotation and in which a magnetic field is present. It is a generalization of similar calculations given by CHANDRASEKHAR and BEL and SCHATZMAN. The generalization becomes necessary for the study of problems of the formation of planetary systems, and star formation.
The instability conditions and the critical wave lengths are calculated for plane-wave-like disturbances. For disturbances running perpendicularly to the axis of rotation instability can occur only if the gas density exceeds a critical value which depends on the differential rotation at the considered distance only as long as pressure gradients and gradients of the magnetic field strength are negligible. If the gas density exceeds this critical value the shortest unstable wave length is proportional to the square root of vT2+vB2, where vT means the velocity of sound and vB the ALFVÉN-velocity.
For disturbances running parallel to the axis of rotation in addition to the JEANS instability a new type of instability occurs due to the simultaneous action of the magnetic field and the differential rotation; for rigid rotation this instability vanishes.
An elementary derivation of the optical potential for high energies is given. For the determination of the optical potential only the knowledge of the scattering amplitude for free nucleons and of the autocorrelation function for density fluctuations is necessary. The numerical calculation of the real- and imaginary part of the optical potential was performed using the Tabakin potential.
The often discussed question concerning the energy-momentum tensor of the electromagnetic field in matter can be answered using NOETHER'S theorem. The separation of the electromagnetic system from the mechanical system introduced here leads to the asymmetric expression for the energy momentum tensor. From covariance with respect to scale transformations one further concludes that the trace of the energy-momentum tensor vanishes.
We examine the possibility of reformulating quantum theory (QT) as a deterministic ensemble theory which (a) interprets observables as objective properties of physical systems and (b) coincides with QT in all quantitative statements. As will be demonstrated, such an Ensemble-Quantum-Theory (EQT) can only be constructed if (1) one accepts a modified observable-concept, and (2) as long as the theory of measurement is left out of account. A correct treatment of the measuring process is impossible within such an EQT. Consequently, there exist no Hidden-Variable Theories with the properties (a) and (b).
The potential energy surface has been calculated by two methods which are compared with respect to spontaneous fission. In the first one essentially the sum of the single particle energies is computed as was done in a previous paper3 while in the second one the Strutinsky technique of renormalizing to a liquid drop model has been applied. Also the half-lives for electron capture are investigated together with the predictions of the half-lives for spontaneous fission and α-decay. The results support the existence of superheavy nuclei in the regions around Z = 114 and Z = 164.
The meaning of a recently proposed formalism for quantization of interacting fields is discussed by studying the consequences of the time-dependent unitary transformation which is essential for this approach. It turns out that non-relativistic quantum electrodynamics in dipole approximation may serve as a useful, although rather singular, example for this method. In the relativistic case a different point of view is suggested in order to avoid inconsistent interpretation. It is further possible to give arguments for a reasonable choice of the unitary transformation concerned.
The nuclear charge form factgr from the high-energy elastic electron scattering on 6Li has been calculated from the modified independent-particle shell model (IPSM) wave function. The usual harmonic oscillator type IPSM wave function has been modified by the inclusion of a nucleon-nucleon correlation function which involves extra-core nucleons only. The technique is extremely simple and provides an excellent agreement with the experimental data.
Es wird das Mikrowellenspektrum von Fluorwasserstoffassoziaten im X-und K-Band bei -70 °C und 0,01 Torr gemessen und analysiert. Dazu wird ein erstelltes Frequenzprogramm für den asymmetrischen Kreisel verwendet, sowie ein Extrapolationsprogramm, das eine in der Literatur angegebene druck-und temperaturabhängige Verteilung der Fluorwasserstoffassoziate auf für Mikrowellenspektroskopie geeignete Drücke und Temperaturen umzurechnen erlaubt. Es zeigt sich, daß planare hexamere und heptamere Fluorwasserstoffassoziate vorliegen mit F-F-F-Winkeln von etwa 104° und H-F-Bindungslängen von 0,9997 Å bzw. 0,9640 Å. Die Längen der Wasserstoff brücken sind 1,4998 Å bzw. 1,6105 Å. Ein Vergleich der Bindungslängen zeigt, daß bei Anlagerung von H-F an (HF)6 eine Kontraktion der Fluorwasserstoffbindung um 3,5% und eine Dilatation der Wasserstoffbrückenbindung um 1% stattfindet. Dieses Ergebnis steht im Einklang mit der oben erwähnten Assoziatverteilung, die eine Minderung der Kettenstabilität beim Übergang von hexamerer zu heptamerer Kette erwarten läßt.