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In model building and model evaluation, cross-validation is a frequently used resampling method. Unfortunately, this method can be quite time consuming. In this article, we discuss an approximation method that is much faster and can be used in generalized linear models and Cox' proportional hazards model with a ridge penalty term. Our approximation method(More)
Uptake of 134Cs, 137Cs and 40K is determined by gamma-ray spectroscopy for samples of fungi and humus. For these samples also the stable Cs content is determined by atomic absorption spectrophotometry. The fungi resorpted only the alkali metals and none of the other fission products from the Chernobyl accident. The measurements show a large variation in(More)
Introduction In a time when astronauts orbit the Earth and visit the Moon, and mankind has brought vehicles to Mars and telescopes into orbit, we seldom realise that we have penetrated the Earth by only 10km, a distance smaller than we commute daily to our work or equivalent to the cruising altitude of airplanes. Consequently we know, except from seismic(More)
The use of multiple testing procedures in the context of gene-set testing is an important but relatively underexposed topic. If a multiple testing method is used, this is usually a standard familywise error rate (FWER) or false discovery rate (FDR) controlling procedure in which the logical relationships that exist between the different (self-contained)(More)
We present a novel multiple testing method for testing null hypotheses that are structured in a directed acyclic graph (DAG). The method is a top-down method that strongly controls the familywise error rate and can be seen as a generalization of Meinshausen's procedure for tree-structured hypotheses. Just as Meinshausen's procedure, our proposed method can(More)
A breadboard 4.5 K helium sorption cooler for use in vibration-sensitive space missions was developed and successfully tested. This type of cooler has no moving parts and is, therefore, essentially vibration-free. The absence of moving parts also simplifies scaling down of the cooler to small sizes, and it contributes to achieving a very long lifetime. In(More)
In Third World countries chloroquine phosphate syrup is frequently prepared with chloroform as a preservative. Because of the toxic side effects of chloroform the suitability of a number of possible alternatives were investigated. If the chloroquine phosphate syrup is prepared as such, the combination of sorbic acid (1.5 g/l) and citric acid (2 g/l) is(More)
We present a multiple testing method for hypotheses that are ordered in space or time. Given such hypotheses, the elementary hypotheses as well as regions of consecutive hypotheses are of interest. These region hypotheses not only have intrinsic meaning but testing them also has the advantage that (potentially small) signals across a region are combined in(More)