Ethanol metabolism inDrosophila melanogaster

Summary A quantitative study of the transformation of ethanol into acetaldehyde shows that, inDrosophila melanogaster, the mitochondrial ethanol oxidizing system is not very active but that the part played by catalase appears more important than expected. For a strain without alcoholdehydrogenase, ethanol is highly toxic. The presence of acetaldehyde in the culture medium is toxic for all the strains studied. But, since even a strain without any aldehydeoxidase lives normally, the metabolic production of acetaldehyde does not seem dangerous.     

Evidence of a subsidiary atrial pacemaker in the crista terminalis of the rabbit heart

Summary The crista terminalis (CT) with musculi pectinati was isolated from the right atrium: it discharged at a frequency intermediate to that of the 2 nodes. Pacemaker action potentials were recorded from the CT deep layer fibers. The results suggest the presence of a subsidiary atrial pacemaker in the CT deep layer.     

Deficits in social behavior in autism and their modification by a synthetic adrenocorticotrophic hormone (4–9) analog

When charting the structure of the social behavior of autistic children by means of an ethologically analyzed playroom session, deficits appeared in the reciprocity of eye-contact and in the location of verbal initiatives. These deficits in social behavior were beneficially influenced by treatment with the adrenocorticotrophic hormone (4–9) analog ORG 2766.     

A multivariate approach to socio-ecological development and endocrine variance in the spotted hyaena, Crocuta crocuta Erxleben.

This investigation of the socio-ecological development and endocrine variance in the spotted hyaena, Crocuta crocuta, illustrates that the complexity of a multivariate endocrine system cannot fully be understood using the concept of a class mean (mu). Any comprehensive investigation of a multivariate endocrine system should also include an analysis of variance (sigma), as it may provide additional insights into the dynamics of an endocrine hypervolume. Mean cortisol concentrations could not differentiate between various social and reproductive categories (MANOVA); however, in males an analysis of variance (principal component analysis) indicated that the contrast between cortisol and androstenedione was the principle axis of variance once the androgen secreting ability had been accounted for. On the other hand, the same contrast was found to be the principal axis of variance in the female sub-sample, suggesting that cortisol may play a significant role in regulating the endocrine dynamics of this species, despite showing little variance in mean values among various social and reproductive categories.     

Time series multistep‐ahead predictability estimation and ranking

A predictability index was defined as the ratio of the variance of the optimal prediction to the variance of the original time series by Granger and Anderson (1976) and Bhansali (1989). A new simplified algorithm for estimating the predictability index is introduced and the new estimator is shown to be a simple and effective tool in applications of predictability ranking and as an aid in the preliminary analysis of time series. The relationship between the predictability index and the position of the poles and lag p of a time series which can be modelled as an AR(p) model are also investigated. The effectiveness of the algorithm is demonstrated using numerical examples including an application to stock prices. Copyright © 1999 John Wiley & Sons, Ltd.     

The effect of cardiac glycoside storage on growth rate and adult size in the butterflyDanaus chrysippus (L.)

Summary Danaus chrysippus grows faster and attains significantly greater size when fed as a larva on several species of Asclepiadaceae (milkweeds) containing cardiac glycosides than on one which does not.Acknowledgment. I thank Professor D. Schneider and Dr M. Boppré for sending me a sample of butterflies of Kenya stock reared in the Federal Republic of Germany.