Rosa J. Meijer

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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)
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)
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)
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: The giant impact hypothesis [1,2] is the cornerstone of current lunar formation research. However, recent analyses of the elemental and isotopic composition of lunar samples show degrees of similarity between Moon and Bulk Silicate Earth (BSE) that are inconsistent with hydrodynamic models of the Moon-forming giant impact showing 60-90% of the(More)
We present a data-driven modelling approach for detection of anomalies in flood defences (levees, dykes, dams, embankments) equipped with sensors. An auto-regressive linear model and feed-forward neural network were applied for modelling a transfer function between the sensors. This approach has been validated on a dike in Boston, UK—one of the pilot sites(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)
QUEST FOR A NUCLEAR GEOREACTOR R.J. de Meijer, E.R. van der Graaf and K.P. Jungmann Kernfysisch Versneller Instituut, Rijksuniversiteit Groningen Zernikelaan 25, 9747AA Groningen, the Netherlands (email correspondence: (27 november 2004) Introduction In a time when astronauts orbit the Earth and visit the Moon, and mankind has brought(More)