On the effect of time-dependent inhomogeneous magnetic fields in electron-positron pair production

Electron-positron pair production in space- and time-dependent electromagnetic fields is investigated. Especially, the influence of a time-dependent, inhomogeneous magnetic field on the particle momenta and the total particle yield is analyzed for the first time. The role of the Lorentz invariant $\mathbf{E}^2 - \mathbf{B}^2$, including its sign and local values, in the pair creation process is emphasized.Comment: 6 pages, 5 figures; Revised version: some improvements, references updated; version will be published in Phys. Lett.

From Phase Space Representation to Amplitude Equations in a Pattern Forming Experiment

We describe and demonstrate a method to reconstruct an amplitude equation from the nonlinear relaxation dynamics in the succession of the Rosensweig instability. A flat layer of a ferrofluid is cooled such that the liquid has a relatively high viscosity. Consequently, the dynamics of the formation of the Rosensweig pattern becomes very slow. By sudden switching of the magnetic induction, the system is pushed to an arbitrary point in the phase space spanned by the pattern amplitude and the magnetic induction. Afterwards, it is allowed to relax to its equilibrium point. From the dynamics of this relaxation, we reconstruct the underlying fully nonlinear equation of motion of the pattern amplitude. The measured nonlinear dynamics serves to select the best weakly nonlinear expansion which describes this hysteretic transition.Comment: 20 pages, 12 figure

Sequences and filters of characters characterizing subgroups of compact abelian groups

Let H be a countable subgroup of the metrizable compact abelian group G and f:H -> T=R/Z a (not necessarily continuous) character of H. Then there exists a sequence (chi_n)_n of (continuous) characters of G such that lim_n chi_n(alpha) = f(alpha) for all alpha in H and (chi_n(alpha))_n does not converge whenever alpha in G\H. If one drops the countability and metrizability requirement one can obtain similar results by using filters of characters instead of sequences. Furthermore the introduced methods allow to answer questions of Dikranjan et al.Comment: laTex2e, 10 page

Public Debt and Generational Balance in Austria Lueth, Erik; Raffelhueschen, Bernd

Based on Austria's fiscal stance in 1995, we compute the generational accounts for currently living as well as future generations. The results reveal the existence of an enormous intergenerational imbalance in favor of currently living generations. Total public sector liabilities may be more than five times as high as the officially recorded level of public debt. Without any action, future generations would face life-time net taxes that are about 65 percent higher than the tax burden of a current newborn. If the government could fully and permanently retain the expenditure cutting and revenue raising effects of the 1996 fiscal consolidation package and the 1997 pension reform, then it might be able to significantly reduce the intergenerational liabilities. However, enacting both the recent tax reform 2000 and the reform of the family support scheme would increase again the fiscal imbalance and intergenerational inequity of fiscal policy in Austria.Fiscal policy, Social security, Public debt, Generational accounting

Cost-sharing in the German health care system

In Germany, cost-sharing for health care has been used as a financing mechanism since 1923. In this article, the historical development of user charges in Germany since the 1980s is presented in more detail by type of private expenditure, including direct payments, cost-sharing measures, and voluntary health insurance. This is followed by a mapping of current cost-sharing measures including a discussion of protection mechanisms and responsibility for decision-making on cost-sharing measures and a summary of national policy debates. In the final section, the results of a systematic review of the literature on the impact of cost-sharing on equity, efficiency and health outcomes in Germany are presented. -- Die Selbstbeteiligung des Patienten an den Gesundheitsversorgungskosten hat in Deutschland eine lange Tradition und geht auf das Jahr 1923 zurück. In dieser Arbeit wird die historische Entwicklung und Bedeutung von Kostenselbstbeteiligung im Gesundheitswesen seit 1980 detailliert nach Art der Gesundheitsausgaben dargestellt. Dies beinhaltet direkte Zahlungen, Kostenbeteiligung, und private Krankenversicherung. Darauf folgt eine Darstellung der derzeitigen Regelungen zur Selbstbeteiligung mit Berücksichtigung der verschiedenen Mechanismen zum Schutz vor katastrophalen Gesundheitsausgaben und der Zuständigkeit für politische und administrative Entscheidungsfindungen zur Selbstbeteiligung. Im letzten Abschnitt werden die Ergebnisse einer systematischen Literatursuche zu den Auswirkungen von Kostenbeteiligungen auf Effizienz, Gerechtigkeit und Gesundheitsstatus in Deutschland dargestellt.

How do farmers research and learn? The example of organic farmers’ experiments and innovations: A research concept

Experimenting, adapting and innovating are central features of farmers’ activities all over the world. Farmers hold valuable knowledge about their environment, they actively do experiments, and have their own research traditions. The development of organic farming systems is continually evolving through the experiments and innovations of organic farmers. So far, there has been little attempt to study the nature, characteristics, and factors associated with the experimental processes of farmers in a systematic, comprehensive way. A current research project investigates learning processes of organic farmers in Austria, Cuba and Israel through researching the multifaceted experiments they conduct and the innovations they obtain as possible results. This paper presents the research concept of the project