Detection of rubella virus in fetal and placental tissues and in the throats of neonates after serologically confirmed rubella in pregnancy

From 35 therapeutic abortions performed because rubella had occurred at 2–19 weeks of pregnancy, 120 fetal organs, 12 specimens of mixed products of conception, and 15 placentae were tested for rubella virus. Virus was isolated from 10 out of 11 fetuses (91 per cent) from women infected at 2–8 weeks, from 5 out of 8 (63 per cent) infected at 9–10 weeks, and from 2 out of 16 (13 per cent) infected at 11–19 weeks. Hybridization tests for viral RNA on 39 fetal organs from eight cases revealed infection in four additional fetuses. Virus was isolated from only 3 out of 15 aborted placentae, but hybridization tests on six placentae revealed infection in three additional specimens. Hybridization was superior to virus isolation for detecting rubella infection in products of conception and is therefore potentially the better method for examining chorionic villus biopsies. Rubella virus was isolated from the throats of 4 out of 9 infants (44 per cent) infected during the first 12 weeks of gestation, but from none of 13 infected after 17 weeks. Infants in the latter group are unlikely to infect susceptible contacts.     

Paternal expenditure is related to brood sex ratio in polygynous great reed warblers

In many polygynous animals, parents invest more heavily in individual sons than in daughters. However, it is unclear if these differences in investment are a consequence of sex differences in the demand of offspring related to sexual size dimorphism or a consequence of parental manipulation. Here, we report on parental food delivery frequency in relation to brood size and brood sex ratio in a wild population of polygynous great reed warblers Acrocephalus arundinaceus. We used the polymorphic microsatellite loci on the Z chromosome to sex chicks. We found that paternal feeding frequency (times/h per nest) increased not with brood size, but with the proportion of males in the brood, although the demand per nest was more closely related to brood size than to brood sex ratio. Additionally, the increase in rate of paternal feeding frequency in relation to the brood sex ratio was much higher than the increase in rate of nestling food demands. Maternal feeding frequency was independent of both brood size and brood sex ratio. These results strongly suggest that fathers preferentially invest in their sons. We propose that parents can afford sex-biased parental care in animals in which food provisioning is enough for all offspring to survive. Received: 22 January 1996/Accepted after revision: 30 June 1996     

Preparing future engineers for challenges of the 21st century: Sustainable engineering

The field of engineering is changing rapidly as the growing global population puts added demands on the earth's resources: engineering decisions must now account for limitations in materials and energy as well as the need to reduce discharges of wastes. This means educators must revise courses and curricula so engineering graduates are prepared for the new challenges as practicing engineers. The Center for Sustainable Engineering has been established to help faculty members accommodate such changes through workshops and new educational materials, including a free access website with peer-reviewed materials.     

Fire shapes and the adequacy of fire-spread models

It has been suggested that shapes of burned areas resulting from fires spreading under uniform fuel and meteorological conditions may be described as ellipses, double ellipses, or ovoids. The adequacy of these shapes (together with simulation outputs) as bases for fire spread models was tested by finding the best fits of each shape to maps of experimental fires and comparing the results with fits given by a rectangle (an unlikely fire shape). Each of the models (ellipse, double ellipse, ovoid, simulation model, and even the rectangle) provided adequate approximations to the fire contours used in the tests. The parameter trends found implied that the fires examined tended to become more nearly elliptical in shape and to have higher eccentricity as they grew.