We compare two recent astrobiological approaches to the solution of the problem of the “Great Silence” (or Fermi’s paradox): the “rare Earth” hypothesis of Ward and Brownlee, and the phase-transition scenario of Annis. We show that they have important similarities, as far as self-selection of intelligent observers is concerned. In order to better illuminate the differences, we consider the dura...

A sequence of eight twice-daily meals, each marked with different rare earth elements, was fed to 24 Spanish goats (BW = 20.6 +/- 1.94 kg) to produce meal-based profiles of rare earth markers within segments of the gastrointestinal digesta on subsequent slaughter. Accumulative mean residence time and time delay of rare earths and segmental and accumulative mean residence times of indigestible N...

Spectrographic methods applicable to the determination of major rare earth constituents in complex mixtures are described. The specific examples discussed are the determination of yttrium and gadolinium in the concentration range of 10 to 100 per cent. The procedures involve the high current DC arc excitation of rare earth oxide sample-ceric oxide-graphite mixtures. Selected lines of cerium are...

The recent interest in the anticoagulant action of heparin has led us to seek a substance which might be similar in action but less expensive and simpler to administer. The anticoagulant effect of various rare earths given intravenously has been studied in lower animals (1, 2, 3). As far back as 1920, Esnault and Brou (4), and Grenet and Drouin (5) injected rare earths in 40 to 100 mgm. doses i...