Use of the score test as a goodness-of-fit measure of the covariance structure in genetic analysis of longitudinal data

Model selection is an essential issue in longitudinal data analysis since many different models have been proposed to fit the covariance structure. The likelihood criterion is commonly used and allows to compare the fit of alternative models. Its value does not reflect, however, the potential improvement that can still be reached in fitting the data unless a reference model with the actual covariance structure is available. The score test approach does not require the knowledge of a reference model, and the score statistic has a meaningful interpretation in itself as a goodness-of-fit measure. The aim of this paper was to show how the score statistic may be separated into the genetic and environmental parts, which is difficult with the likelihood criterion, and how it can be used to check parametric assumptions made on variance and correlation parameters. Selection of models for genetic analysis was applied to a dairy cattle example for milk production.     

Physical and chemical properties of the mucin secreted by Drosera capensis

The mucin droplets secreted by the leaves of Drosera capensis consist of a 4 % aq. solution of an acidic polysaccharide containing xylose, mannose,     

The effect of ethylene on adventitious root formation in mung bean (Vigna radiata) cuttings

A promotive effect of ethylene on the formation of adventitious roots by mung bean cuttings was demonstrated using a recirculating solution culture system to apply dissolved ethylene. The number of roots increased in proportion to the length of exposure to the gas. Mean root numbers per cutting for a 4-day exposure to ethylene and an air control were 45 and 19, respectively. The tissue was most sensitive to a 24-h ethylene “pulse” 2–3 days after taking cuttings. Rooting was maximal at a concentration of 13 μl 1^?1 ethylene. The ethylene treatment inhibited the growth of roots and terminal buds. Application of Ag⁺, as silver thiosulfate, reversed the effect of ethylene on the two growth responses but had no effect on root numbers. Norbornadiene, another inhibitor of ethylene action, reversed all three ethylene responses.     

A study of the methods available for the cytochemical localization of histamine by fluorescence induced with o-phthalaldehyde or acetaldehyde

Synopsis Methods for the histochemical localization of histamine were investigated, tissues and models being exposed to vapours ofo-phthalaldehyde, acetaldehyde, or glutaraldehyde and afterwards examined by fluorescence microscopy. Acetaldehyde and glutaraldehyde induce fluorescence in histamine models, but the method is not sufficiently sensitive for use in tissues. A modification of theo-phthalaldehyde method, giving improved reliability, is described in detail and some results in rat and dog stomach are presented.