Catálogo de publicaciones - revistas

<jats:p> <jats:bold>Redeeming Culture.</jats:bold> American Religion in an Age of Science. JAMES GILBERT. University of Chicago Press, Chicago, 1997. x, 407 pp., illus. $28.95 or £23.25. ISBN 0-226-29320-3. </jats:p>

<jats:p> <jats:bold>Bright Galaxies, Dark Matters.</jats:bold> VERA RUBIN. AIP Press (Springer-Verlag), New York, 1996. xvi, 236 pp., illus., + plates. $29.95 or £22.95. ISBN 1-56396-231-4. Masters of Modern Physics. </jats:p>

<jats:p>After the unexpected discovery of x-rays emitted from comet C/1996 B2 (Hyakutake) with the Röntgen X-ray Satellite (ROSAT) in March 1996, x-ray emissions from comets C/1990 K1 (Levy), C/1990 N1 (Tsuchiya-Kiuchi), 45P (Honda–Mrkos–Pajdušáková), and C/1991 A2 (Arai), optically 300 to 30,000 times fainter than Hyakutake, were discovered in archival ROSAT data. These findings establish comets as a class of x-ray sources and allow their properties to be studied over a wide optical brightness range. The results indicate that charge exchange between highly charged heavy ions in the solar wind and cometary neutrals is the dominant process for the x-ray emission. Comets may thus be used as probes for monitoring the heavy-ion content of the solar wind.</jats:p>

<jats:p> STATs (signal transducers and activators of transcription) are a family of latent cytoplasmic proteins that are activated to participate in gene control when cells encounter various extracellular polypeptides. Biochemical and molecular genetic explorations have defined a single tyrosine phosphorylation site and, in a dimeric partner molecule, an Src homology 2 (SH2) phosphotyrosine-binding domain, a DNA interaction domain, and a number of protein-protein interaction domains (with receptors, other transcription factors, the transcription machinery, and perhaps a tyrosine phosphatase). Mouse genetics experiments have defined crucial roles for each known mammalian STAT. The discovery of a STAT in <jats:italic>Drosophila</jats:italic> , and most recently in <jats:italic>Dictyostelium discoideum</jats:italic> , implies an ancient evolutionary origin for this dual-function set of proteins. </jats:p>

<jats:p>Smoke particles from biomass burning can generate forcing of climate by modifying cloud microphysics and reflectance of sunlight. Cloud modification, critical to an understanding of climate change, is uncertain and variable. Satellite data over the Amazon Basin and Cerrado were analyzed for cloud reflectance and droplet size and for smoke concentration. Smoke increased cloud reflectance from 0.35 to 0.45, while reducing droplet size from 14 to 9 micrometers. The regional variability of the smoke effect was correlated to the availability of water vapor. During the 3 months of biomass burning in the dry season, the smoke-cloud forcing of climate was only −2 watts per square meter in this region, much smaller than what can be inferred from model predictions.</jats:p>