Catálogo de publicaciones - revistas

<jats:p> <jats:bold>Snakes.</jats:bold> The Evolution of Mystery in Nature. HARRY W. GREENE. Photographs by Michael and Patricia Fogden. University of California Press, Berkeley, 1997. xiv, 351 pp., illus. $45 or £35. ISBN 0-520-20014-4. </jats:p>

<jats:p> <jats:bold>Spin Choreography.</jats:bold> Basic Steps in High Resolution NMR. RAY FREEMAN. Spektrum, Oxford, UK, and University Science Books, Sausalito, CA, 1997. xii, 391 pp., illus. $58.50 or £30. ISBN 0-935702-95-4. </jats:p>

<jats:p>In plants and algae, photosystem II uses light energy to oxidize water to oxygen at a metalloradical site that comprises a tetranuclear manganese cluster and a tyrosyl radical. A model is proposed whereby the tyrosyl radical functions by abstracting hydrogen atoms from substrate water bound as terminal ligands to two of the four manganese ions. Molecular oxygen is produced in the final step in which hydrogen atom transfer and oxygen-oxygen bond formation occur together in a concerted reaction. This mechanism establishes clear analogies between photosynthetic water oxidation and amino acid radical function in other enzymatic reactions.</jats:p>

<jats:p>A digital bathymetric map of the oceans with a horizontal resolution of 1 to 12 kilometers was derived by combining available depth soundings with high-resolution marine gravity information from the Geosat and ERS-1 spacecraft. Previous global bathymetric maps lacked features such as the 1600-kilometer-long Foundation Seamounts chain in the South Pacific. This map shows relations among the distributions of depth, sea floor area, and sea floor age that do not fit the predictions of deterministic models of subsidence due to lithosphere cooling but may be explained by a stochastic model in which randomly distributed reheating events warm the lithosphere and raise the ocean floor.</jats:p>

<jats:p>Results from Active Cavity Radiometer Irradiance Monitor (ACRIM) experiments show an upward trend in total solar irradiance of 0.036 percent per decade between the minima of solar cycles 21 and 22. The trend follows the increasing solar activity of recent decades and, if sustained, could raise global temperatures. Trends of total solar irradiance near this rate have been implicated as causal factors in climate change on century to millennial time scales.</jats:p>