Schwarzschild and Synge once again

We complete the historical overview about the geometry of a Schwarzschild black hole at its horizon by emphasizing the contribution made by J. L. Synge in 1950 to its clarification.Comment: 2 pages, LaTeX, submitted for publication; 2 references, one Note, and an Acknowledgement are adde

Volljährige Asylerstantragsteller in Deutschland im Jahr 2017: Sozialstruktur, Schulbesuch und Berufstätigkeit im Herkunftsland

Die Kurzanalyse 3/2018 wertet neben den Daten der Asylgeschäftsstatistik auch die Daten zur "Soziale Komponente" (sog. "SoKo"-Daten) aus und liefert Erkenntnisse über die Sozialstruktur (Geschlecht, Alter, Familienstand), den Schulbesuch sowie über die zuletzt im Herkunftsland ausgeübten Berufstätigkeiten von volljährigen Asylerstantragsstellenden im Jahr 2017. Damit schreibt sie die Ergebnisse der BAMF-Kurzanalyse 3/2017 fort. Die Teilnahme am Arbeitsmarkt stellt einen der wichtigsten Aspekte der Integration dar. Um eine gezielte Einschätzung der Potenziale, aber auch der Bedarfe und entsprechende Planungen für Fördermaßnahmen vornehmen zu können, sind Hintergrundinformationen über das Qualifikationsniveau der Asylbewerber in Deutschland von großer Bedeutung.In addition to the asylum business statistics, Brief Analysis 3/2018 also analyses data relating to the "social component" (so-called "SoKo" data) and presents findings on the social structure (gender, age, marital status), school attendance as well as the last occupation held in the countries of origin of asylum applicants of legal age in 2017. As such, it updates the findings of BAMF Brief Analysis 3/2017. Participation in the labour market constitutes one of the most important aspects of integration. Background information on the level of qualification of asylum applicants in Germany is extremely important in order to assess potentials purposefully as well as their needs and to plan corresponding support measures

Ursachen für Ertragsunterschiede in Betrieben mit unterschiedlicher Wirtschaftsweise und Betriebsstruktur in zwei Regionen Deutschlands

In this study, winter wheat yields of organic and conventional farms with and without livestock in two regions in Germany were examined, with the aim of determining yield differences between the farming systems and possible reasons for these differences. Yields were 85% higher on conventional farms, mainly due to higher nitrogen input and the positive effects of chemical plant protection. The farms in North Rhine-Westphalia achieved higher yields than the farms in Bavaria. Climate was the most important factor, as lower temperatures during winter and higher precipitation during summer in Bavaria probably negatively affected yields. Differences in yield between farms with and without livestock could only be observed for conventional farms. The high intensity of farms without livestock resulted in higher yields

A two-dimensional representation of four-dimensional gravitational waves

The Einstein equation in D dimensions, if restricted to the class of space-times possessing n = D - 2 commuting hypersurface-orthogonal Killing vectors, can be equivalently written as metric-dilaton gravity in 2 dimensions with n scalar fields. For n = 2, this results reduces to the known reduction of certain 4-dimensional metrics which include gravitational waves. Here, we give such a representation which leads to a new proof of the Birkhoff theorem for plane-symmetric space--times, and which leads to an explanation, in which sense two (spin zero-) scalar fields in 2 dimensions may incorporate the (spin two-) gravitational waves in 4 dimensions. (This result should not be mixed up with well--known analogous statements where, however, the 4-dimensional space-time is supposed to be spherically symmetric, and then, of course, the equivalent 2-dimensional picture cannot mimic any gravitational waves.) Finally, remarks on hidden symmetries in 2 dimensions are made.Comment: 12 pages, LaTeX, no figures, Int. J. Mod. Phys. D in prin

Comment on 'Stability of the semiclassical Einstein equation'

Some mathematical errors of the paper commented upon [W.-M. Suen, Phys. Rev. D 40, (1989) 315] are corrected.Comment: 3 pages, LaTeX, reprinted from Phys. Rev. D 50 (1994) 545

Comment to the paper `Conformal transformations single out a unique measure of distance'

We discuss the consequences of the incorrectness [see the Erratum in Phys. Rev D 49, 1145 (1994)] of that paper and add two related remarks. The scope of this comment is to encourage further research on: `Which of the conformally equivalent metrics is the physical one?'Comment: 4 pages, LaTeX, published in Phys. Rev. D52, 6198 (1995