Variograms and covariance functions are key tools in geostatistics. However, various properties, characterizations, and decomposition theorems have been established for covariance functions only. We present analogous results for variograms and explore the connections to covariance functions. Our ndings include criteria for covariance functions on intervals, and we apply them to exponential mode...

Two-sex populations are usually studied through frequency-dependent models that describe how sex ratio affects mating, recruitment and population growth. However, in two-sex populations, mating and recruitment should also be affected by density and by its interactions with the sex ratio. Density may have positive effects on mating (Allee effects) but negative effects on other demographic proces...

Parameter errors in orbital models can result in poor orbit determination (OD) using a traditional Kalman filter. One approach to account for these errors is to consider them in the so-called Schmidt-Kalman filter (SKF), by augmenting the state covariance matrix (CM) with additional parameter covariance rather than additively estimating these so-called “consider” parameters. This paper introduc...

A simplified version of this case appeared in Section 5 of Goldstern’s Tools for your forcing constructions [2]. This version uses the additional requirement that every forcing of the iteration adds a new real. Note that this requirement is met in most applications, but the case of forcings not adding reals has important applications as well (and not adding reals is generaly not preserved under...

Recent years have seen an enormous development in the field of medical expert systems, making it a time consuming and complicated task for physicians finding the system most capable for them. To give physicians the opportunity to get fast and easy access to a specific system, our department has developed a web site which intends to be a comprehensive source for physicians, students and other he...