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Summary The evolution of vocal signals can be constrained by a host of factors including habitat effects on sound propagation, morphology of sound-producing structures and phylogenetic relationships among species. Here, we asked whether auditory sensitivity over a broad range of frequencies correlates with the spectral content of conspecific vocalizations, or whether it is constrained by the overall structure of vocalizations, habitat effects on sound propagation or relatedness among species. We studied nine New World sparrows (Passeriformes: Emberizidae) including three open-habitat species, three scrub-like habitat species and three forest species. For each habitat, one species had pure-trilled songs, another had tonal songs and another had complex songs with tones, trills and amplitude-modulated buzzes. As predicted by the acoustic adaptation hypothesis, song spectral properties (specifically frequency and entropy) had the highest values in open-habitat species and the lowest values in forest species. Based on our results from song analyses, and the sender–receiver matching hypothesis, we predicted that open-habitat species would be more sensitive to high-frequency sounds compared to forest species. Contrary to this prediction, habitat and high-frequency song content had little effect on audiogram shape. Song type, however, had a strong effect, with species that produce complex songs showing higher sensitivity to high-frequency sounds than all other species. Our results suggest that the use of song frequency by receivers depends on song structure and not necessarily on song spectral content. Therefore, our current understanding of how signal-processing mechanisms should match signal properties appears to be too simple. When thinking about the evolution of signal-processing mechanisms, the multidimensionality of signals, and how the different dimensions can interact, should be considered.

An alcohol-rich product obtained by Fischer-Tropsch synthesis at 160–175° and 150 lb./sq. in. (gauge), in the presence of a cobalt catalyst has been examined. It was found that n-primary alcohols constituted 40% by weight of the organic liquid products (oil, spirit and organic matter in the water) and 92·4% of the total oxygenated products. The proportions of acids and carbonyl compounds were, therefore, markedly lower than those reported to be present in an iron-catalyst product of the Hydrocol type. The proportion of methanol present was very low, ethanol was present in the largest proportion and the proportions of the alcohols higher than propanol decreased with increasing carbon number. The proportion of propanol was less than that of butanol or pentanol so that the carbon-number distribution curve for the alcohols showed a marked inflexion in the C3-C4 region, which is not shown by the published distribution curve for the alcohols in the Hydrocol product. From a study of the relative rates of decomposition of a series of n-primary alcohols at 150° in the presence of hydrogen and a cobalt catalyst, it was possible to plot a curve relating alcohol stability and carbon number. This curve resembled the distribution curve in showing a low value for C1, a maximum at C2 and a marked inflexion in the C3-C4 region, suggesting that the individual alcohols are present in the products of synthesis in proportions which are determined, at least in part, by their relative stabilities under the synthesis conditions. It is considered that the alcohol distribution curve is of a form which would be predicted if the mechanism of alcohol formation involved step-wise addition of methylene radicals to one end of a growing chain terminated by a hydroxymethylene radical, and if the survival of the alcohols was controlled by their relative stabilities. From a consideration of the observed results and of those reported by other workers in the field, it is concluded that there is a balance of evidence in favour of the view that alcohols are the precursors of hydrocarbons in the synthesis.

The activity of catalysts prepared by sintering alkali-impregnated mill scale increases with reduction in mean particle size over the range 10–50 B.S. sieve sizes. It is also increased by lowering the temperature of reduction in hydrogen from 450° (the temperature normally used for activating fused iron catalysts) to 350° or 300°, and by prolonged extraction with water, either before or after reduction. The effect of extraction is enhanced by reduction in particle size; the effects of lowering the reduction temperature and of extraction with water are approximately additive. The beneficial effect of extraction with water is believed to be due to the removal of alkali-metal salts of impurity elements in the mill scale and to the decomposition of alkali-metal ferrites formed during the sintering process. In a fixed-bed synthesis test using an extracted mill-scale catalyst, a gas conversion of 70% was maintained for 66 days at a gas space velocity of 540 h.−1, 30 atm. pressure and a constant temperature of 230. The empirical equation described by R. B. Anderson et al. for expressing the activity of iron catalysts has been found to be applicable to mill-scale catalysts over a wide range of experimental conditions, provided that the value for E (the apparent over-all energy of activation) appropriate to the H2/CO ratio of the feed gas is employed.

An enzyme-linked immunosorbent assay (ELISA) for the screening of brucellosis in reindeer was developed. The assay, which utilizes s-LPS from Brucella abortus as antigen and biotin-labelled rabbit antibody to reindeer immunoglobulin as detecting antibody, has a high specificity and sensitivity, as indicated in a validation with sera from reindeer cultured positive for Brucella suis biovar 4 and sera from reindeer free of brucellosis.

Mutations in the Drosophila variable nurse cells (vnc) gene result in female sterility and oogenesis defects, including egg chambers with too many or too few nurse cells. We show that vnc corresponds to Arrest Defective1 (Ard1) and encodes the catalytic subunit of NatA, the major N-terminal acetyl-transferase complex. While N-terminal acetylation is one of the most prevalent covalent protein modifications in eukaryotes, analysis of its role in development has been challenging since mutants that compromise NatA activity have not been described in any multicellular animal. Our data show that reduced ARD1 levels result in pleiotropic oogenesis defects including abnormal cyst encapsulation, desynchronized cystocyte division, disrupted nurse cell chromosome dispersion, and abnormal chorion patterning, consistent with the wide range of predicted NatA substrates. Furthermore, we find that loss of Ard1 affects cell survival/proliferation and is lethal for the animal, providing the first demonstration that this modification is essential in higher eukaryotes.

Mit einem Hochdruckkaskadenbogen wird der spektrale Emissionskoeffizient von Argon in Abhangigkeit von dem Druck (1, 4, 7 und 12 at) und der Temperatur experimentell ermittelt und mit dem theoretisch bestimmten Emissionskoeffizienten verglichen. Fur das Rekombinationskontinuum ergibt sieh eine unbefriedigende Ubereinstimmung von Theorie und Experiment. Aus dem Verhaltnis der Kontinuums- zur Linienintensitat werden Aussagen uber den Verlauf der effektiven Ionisierungsspannungserniedrigung fur das Kontinuum gemacht. Die Korrekturfaktoren § fur das Rekombinationskontinuum, die die Abweichung des klassisch-korrespondenzmasig vom quantenmechanisch berechneten Emissionskoeffizienten angeben, werden fur drei Wellenlangen experimentell bestimmt.

The preparation of lubricating oils by the AlCl2 polymerisation of the olefines present in the primary product obtained by atmospheric pressure synthesis from carbon monoxide and hydrogen (ratio 1 :2) over a cobalt catalyst has been carried out in 2-gallon batches. The effect of varying temperature, catalyst and boiling range of starting material on the reaction and its products is described. The oils obtained possess properties which approximate to the requirements of the Air Ministry Specification D.T.D. 109 for aircraft lubricants in all respects except the increase in viscosity on oxidation. It was found possible to overcome this disability subjecting the oils to a carefully controlled hydrogenation in the presence of molybdenum disulphide.