M. Kretzschmar

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We consider a simple unstructured individual based stochastic epidemic model with contact tracing. Even in the onset of the epidemic, contact tracing implies that infected individuals do not act independent of each other. Nevertheless, it is possible to analyze the embedded non-stationary Galton-Watson process. Based upon this analysis, threshold theorems(More)
A model is derived for the description of parasitic diseases on host populations with age structure. The parasite population develops according to a linear birth-death-process. The parasites influence mortality and fertility of the hosts and are acquired with a rate depending on the mean parasite load of the host population. The model consists of a system(More)
A model is discussed for the description of parasitic diseases on host populations with age structure. The parasite population develops according to a linear multitype birth-death-process. The parasites influence mortality and fertility of the hosts and are acquired with a rate depending on the mean parasite load of the host population. The model consists(More)
[1] Solar UV emission has a profound impact on the upper terrestrial atmosphere. Because of instrumental constraints, however, solar proxies often need to be used as substitutes for the solar spectral variability. Finding proxies that properly reproduce specific spectral bands or lines is an ongoing problem. Using daily observations from 2003 to 2008 and a(More)
The scientific objectives of Solar Orbiter rely ubiquitously on EUI, its suite of solar atmosphere imaging telescopes. In the configuration discussed here, EUI includes three co-aligned High Resolution Imagers (HRI) and one Full Sun Imager (FSI). FSI and two HRIs observe in extreme ultraviolet passbands, dominated by coronal emission. Another HRI is(More)
Context. The solar irradiance in the UV is a key ingredient in space weather applications; however, because of the lack of continuous and long-term observations, various indices are still used today as surrogates for the solar spectral irradiance. Aims. As an alternative to current spectrometers we use a few radiometers with properly chosen passbands and(More)
In two recent studies, Dudok de Wit et al. (2005) and Kretzschmar et al. (2006) have shown that the solar Ultra-Violet spectrum between 25 and 195 nm can be reconstructed from the observation of a set of 6 to 10 carefully chosen spectral lines. The best set of lines, however, is application dependent. In this study, we demonstrate that a good candidate for(More)
Solar images in the ultraviolet (UV) are the key to the understanding of the highly dynamic and energetic solar atmosphere. Nowadays, several missions provide simultaneous observations in multiple wavelengths. Such multispectral images have traditionally been used as inputs to physical models. However, as the number of wavelengths steadily increases,(More)
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