An examination of factors contributing to delphi accuracy

Three experiments examined the accuracy in the Delphi method. The first experiment assessed the accuracy of group predictions over 1-, 2- and 3- month time spans. Results indicated that predictions derived from the group were more accurate than those of 95 per cent of the individual panelists, but did not exceed in accuracy the best panelists. Experiment 2 evaluated the gross contributions of polling and feedback to Delphi accuracy. The manipulations did not improve the group's ability to forecast the probabilities of the occurrence of events, but did decrease the error in predicting when the events would occur. Experiment 3 separated the effects of polling and feedback as determinants of accuracy. Neither manipulation improved the accuracy of the group's predictions of whether an event would occur. The effect of iterated polling was to reduce the group's error in predicting the time course for those scenarios that did occur.     

Survival variability and population density in fish populations

To understand the processes that regulate the abundance and persistence of wild populations is a fundamental goal of ecology and a prerequisite for the management of living resources. Variable abundance data, however, make the demonstration of regulation processes challenging. A previously overlooked aspect in understanding how populations are regulated is the possibility that the pattern of variability--its strength as a function of population size--may be more than 'noise', thus revealing much about the characteristics of population regulation. Here we show that patterns in survival variability do provide evidence of regulation through density. Using a large, global compilation of marine, anadromous and freshwater fisheries data, we examine the relationship between the variability of survival and population abundance. The interannual variability in progeny survival increases at low adult abundance in an inversely density-dependent fashion. This pattern is consistent with models in which density dependence enters after the larval stage. The findings are compatible with very simple forms of density dependence: even a linear increase of juvenile mortality with adult density adequately explains the results. The model predictions explain why populations with strong regulation may experience large increases in variability at low densities. Furthermore, the inverse relationship between survival variability and the strength of density dependence has important consequences for fisheries management and recovery, and population persistence or extinction.     

Multiple regions within 8q24 independently affect risk for prostate cancer

After the recent discovery that common genetic variation in 8q24 influences inherited risk of prostate cancer, we genotyped 2,973 SNPs in up to 7,518 men with and without prostate cancer from five populations. We identified seven risk variants, five of them previously undescribed, spanning 430 kb and each independently predicting risk for prostate cancer (P = 7.9 x 10(-19) for the strongest association, and P < 1.5 x 10(-4) for five of the variants, after controlling for each of the others). The variants define common genotypes that span a more than fivefold range of susceptibility to cancer in some populations. None of the prostate cancer risk variants aligns to a known gene or alters the coding sequence of an encoded protein.     

Biodiversity hotspots for conservation priorities

Conservationists are far from able to assist all species under threat, if only for lack of funding. This places a premium on priorities: how can we support the most species at the least cost? One way is to identify 'biodiversity hotspots' where exceptional concentrations of endemic species are undergoing exceptional loss of habitat. As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth. This opens the way for a 'silver bullet' strategy on the part of conservation planners, focusing on these hotspots in proportion to their share of the world's species at risk.     

Characterization of the yeast HSP60 gene coding for a mitochondrial assembly factor

The hsp60 protein isolated from the protozoan Tetrahymena thermophila is induced in response to heat stress and is a member of an immunologically conserved family represented in Escherichia coli and in mitochondria of plants and animals. We report here the cloning and characterization of a nuclear gene, HSP60, which codes for the hsp60 homologue from the yeast Saccharomyces cerevisiae. Nucleotide sequence analysis revealed that yeast hsp60 is related to the groEL protein of E. coli and the RUBISCO-binding protein (RBP) of chloroplasts. HSP60 was found to be the genetic locus of the conditional-lethal mutation described by Cheng et al., which at non-permissive temperature is defective in the assembly of several different multisubunit complexes in mitochondria. These data are consistent with the hypothesis that the groEL-related proteins serve an evolutionarily conserved function as accessory factors facilitating the folding and/or association of individual subunits of multimeric protein complexes.     

Evoked release of 5-HT and NEFA from the hypothalamus of the conscious monkey during thermorégulation

Zusammenfassung Unterkühlungsexperimente mit Affen zeigen einen Anstieg des 5-HT-Gehaltes in der Durchströmungsflüssigkeit des vorderen Hypothalamus. Erwärmung der Tiere ergab 2–4fachen Anstieg eines NEFA-ähnlichen Stoffes.

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Supported in part by U.S. Office of Naval Research Contract No. N00014-67-A-0226-0003, Grant No. GB 7906 from the National Science Foundation and a grant from the Wallace Laboratories. The authors are indebted to P.Cuezon, J. E.Evans and R. B.Holman for their valuable assistance.     

Ethanol preference in rats with a prior history of acetaldehyde self-administration

Summary Peripherally self-injected acetaldehyde in interaction with environmental and nutritional variables significantly enhances alcohol drinking in rats and suggests an involvement of acetaldehyde in voluntary alcohol intake.