Nonpharmaceutical interventions against the spread of SARS-CoV-2 in Germany included the cancellation of mass events (from March 8), closures of schools and child day care facilities (from March 16) as well as a “lockdown” (from March 23). This study attempts to assess the effectiveness of these interventions in terms of revealing their impact on infections over time. Dates of infections were estimated from official German case data by incorporating the incubation period and an empirical reporting delay. Exponential growth models for infections and reproduction numbers were estimated and investigated with respect to change points in the time series. A significant decline of daily and cumulative infections as well as reproduction numbers is found at March 8, March 10 and March 3, respectively. Further declines and stabilizations are found in the end of March. There is also a change point in new infections at April 19, but daily infections still show a negative growth. From March 19, the reproduction numbers fluctuate on a level below one. The decline of infections in early March 2020 can be attributed to relatively small interventions and voluntary behavioural changes. Additional effects of later interventions cannot be detected clearly. Liberalizations of measures from April 20 did not induce a re-increase of infections. Thus, the effectiveness of most German interventions remains questionable. Moreover, assessing of interventions is impeded by the estimation of true infection dates and the influence of test volume.

In the automatization of molecular structure elucidation, generators for constitutional and configurational isomers are indispensable tools. Sophisticated computer programs of this kind are based on a mathematical theory of the construction of discrete structures. First, we will describe the basic principles for the generation of constitutional isomers, starting with the notions of group actions and ending up with recent improvements with respect to hybridization constraints. The second part is devoted to the generation of all configurational isomers to a given structural isomer. The underlying mathematical concepts as well as the techniques for computing spatial realizations are discussed. The outlined theory is implemented in the program system MOLGEN, which provides a fast and efficient tool for structure elucidation, running under DOS, MS-Windows, OS/2, and SUN-Solaris.

Since the emerging of the "novel coronavirus" SARS-CoV-2 and the corresponding respiratory disease COVID-19, the virus has spread all over the world. In Europe, Germany is currently one of the most affected countries. In March 2020, a "lockdown" was established to contain the virus spread, including the closure of schools and child day care facilities as well as forced social distancing and bans of any public gathering. The present study attempts to analyze whether these governmental interventions had an impact on the declared aim of "flattening the curve", referring to the epidemic curve of new infections. This analysis is conducted from a regional perspective. On the level of the 412 German counties, logistic growth models were estimated based on reported cases of infections, aiming at determining the regional growth rate of infections and the point of inflection where infection rates begin to decrease and the curve flattens. All German counties exceeded the peak of new infections between the beginning of March and the middle of April. In a large majority of German counties, the epidemic curve has flattened before the social ban was established (March 23). In a minority of counties, the peak was already exceeded before school closures. The growth rates of infections vary spatially depending on the time the virus emerged. Counties belonging to states which established an additional curfew show no significant improvement with respect to growth rates and mortality. On the contrary, growth rates and mortality are significantly higher in Bavaria compared to whole Germany. The results raise the question whether social ban measures and curfews really contributed to the curve flattening. Furthermore, mortality varies strongly across German counties, which can be attributed to infections of people belonging to the “risk group”, especially residents of retirement homes.

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