Flashing males win mate success

Article Abstract:

Photic playback experiments on female Photinus consimilis', Nearctic firefly, responses to simulated male bioluminescent signals show strong directional intersexual selection favouring rapid male flash rates. Females identify male flashes based on their rapidity only and mating success of males may be proportional to their flash rate. However, for successful mating the male flash rate should exceed a minimum value and the flash length must near the mean. Rapid male flashes elicit dimmer signals from females leading to a signaling dialogue, culminating in courtship and mating.

Sexual behavior, Reports, Bioluminescence, Visual evoked response, Visual evoked potentials, Fireflies

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Constraints on the Hubble constant from observations of the brightest red-giant stars in a Virgo-cluster galaxy

Article Abstract:

Elliptical galaxies in the Virgo and Fornax clusters are important in determining the Hubble constant, H(sub 0), and thus the cosmological rate of expansion. Distance calibrations for ellipticals could minimize uncertainties due to the large amount of clusters in the line of sight. Using the brightest red-giant stars is a way of establishing such distances. Direct observations of old red-giant stars are reported, in a dwarf elliptical galaxy in the Virgo cluster, ageing the Universe at no more than 12-13 billion years.

Virgo Cluster

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Flashing giants forge fluorine

Article Abstract:

Episodes of thermonuclear burning deep within red giant stars generate large quantities of the element fluorine. A. Jorissen and colleagues devised a new method of spectral analysis and found that the red giants have 30 times as much fluorine as the Sun. The red giants' plenitude of fluorine may result from a reaction sequence in which a radioactive fluorine isotope, 18F, is yielded by the combination of 14N and an alpha-particle or helium nucleus.

Stars, Fluorine

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