Combining exchange rate forecasts: What is the optimal consensus measure?

In this paper a high-quality disaggregate database is utilized to examine whether individual forecasters produce efficient exchange rate predictions and also if the properties of the forecasts change when they are combined. The paper links a number of themes in the exchange rate literature and examines various methods of forecast combination. It is demonstrated, inter alia, that some forecasters are better than others, but that most are not as good as a naive no-change prediction. Combining forecasts adds to the accuracy of the predictions, but the gains mainly reflect the removal of systematic and unstable bias.     

The inability of nuclear dehydrogenating clostridia to oxidize bile salt hydroxyl groups

Summary In a survey of the intracellular bile salt oxidoreductase activity in fecal bacteria, 16 strains of nuclear dehydrogenating clostridia and 2 strains of non-nuclear dehydrogenatingC. paraputrificum were demonstrated unable to oxidize cholate at any of the 3 OH groups. Since nuclear dehydrogenation at the -1 and -4 position requires a 3-oxo precursor steroid, it appears that these organisms require the presence of a 3-hydroxysteroid dehydrogenating organism for nuclear dehydrogenation.This work is supported by the National Cancer Institute of Canada (IAM) and by the Cancer Research Campaign (MJH).     

Antarctic fishes survive exposure to carbon monoxide.

The extensive in vivo conversion of haemoglobin to the carbon monoxide derivative has no discernible effect on the survival of the red-blooded Antarctic fish Pagothenia bernacchii. Analysis of caudally sampled blood of cannulated specimens revealed that reconversion of carbon-monoxy haemoglobin to oxyhaemoglobin was complete within 48 hours. Thus, under stress-free conditions, haemoglobin is not necessary for survival of P. bernacchii. Red-blooded Antarctic fishes can carry oxygen necessary for routine delivery dissolved in plasma, in a similar way to the haemoglobinless Channichthyidae, although they lack the morphological and physiological adaptations which allow the latter to prosper without any haemoglobin.     

The structure of gephyrotoxin (GTX) 223AB

Summary The structure 3-butyl-5-propylindolizidine (2), tentatively assigned to a minor alkaloid in skin extracts from a number of poison frogs of the Neotropical genusDendrobates, has been confirmed and its stereochemistry determined as 5E, 9E (2d) by comparison on GC and GC-MS with the four synthetic diastereomers2a-2d.     

A synthetic attractant for the male spruce budworm mothChoristoneura fumiferana (Clem.)

Zusammenfassung Die besondere Eigenschaft desn-Octadekanitrils als Lockstoff für die männliche MotteChoristoneura fumiferana (Clem.) wurde festgestellt.     

Simultaneous monitoring by optical techniques of respiratory chain and intracellular pH in toad ventricle strip

Summary Intracellular pH and oxidative metabolism can be measured in toad ventricle strips simultaneously by the use of the pH indicator dye, neutral red, and a rapid scanning spectrophotometer. The effects of hypoxia and acidification on mechanical function are approximately additive. The decrease in tension due to slight acidification is probably through an effect on the portion of the twitch tension supported by anaerobic metabolism.Acknowledgments. This work was supported by PHS grants HL 17391, Am 17876 and HL 05208. J.-J.S. is aspirant au Fonds National de la Recherche Scientifique (Belgium).