Catálogo de publicaciones - revistas

<jats:p>Forests are human-dominated ecosystems. Many of the seemingly lightly managed or unmanaged forests are actually in use for agroforestry or for hunting and gathering. Agroforestry does reduce biodiversity, but it can also act as an effective buffer to forest clearance and conversion to other land uses, which present the greatest threat to forested ecosystems. In forests used for logging, whole-landscape management is crucial. Here, emphasis is placed on areas of intensive use interspersed with areas for conservation and catchment purposes. Management strategies for sustainable forestry are being developed, but there is a need for further interaction among foresters, ecologists, community representatives, social scientists, and economists.</jats:p>

<jats:p> <jats:bold>Metapopulation Biology.</jats:bold> Ecology, Genetics, and Evolution. ILKKA HANSKI and MICHAEL R. GILPIN, Eds. Academic Press, San Diego, 1996. xvi, 512 pp., illus. $89.95 or £65. ISBN 0-12-323445-x. </jats:p> <jats:p> <jats:bold>Metapopulations and Wildlife Conservation.</jats:bold> DALE R. McCULLOUGH, Ed. Island Press, Washington, DC, 1996. xii, 429 pp., illus. $55, ISBN 1-55963-457-x; paper, $28, ISBN 1-55963-458-8. Based on a symposium, Albuquerque, NM, Sept. 1994. </jats:p>

<jats:p> <jats:bold>How Science Takes Stock.</jats:bold> A History of Meta-Analysis. MORTON HUNT. Russell Sage Foundation, New York, 1997. xii, 210 pp., illus. $29.95 or £24. ISBN 0-87154-389-3. </jats:p>

<jats:p>Because the Internet is a public good and its numerous users are not charged in proportion to their use, it appears rational for individuals to consume bandwidth greedily while thinking that their actions have little effect on the overall performance of the Internet. Because every individual can reason this way, the whole Internet's performance can degrade considerably, which makes everyone worse off. An analysis of the congestions created by such dilemmas predicts that they are intermittent in nature with definite statistical properties leading to short-lived spikes in congestion. Internet latencies were measured over a wide range of conditions and locations and were found to confirm these predictions, thus providing a possible microscopic mechanism for the observed intermittent congestions of the Internet.</jats:p>

<jats:p> Knowledge of the production history of cosmogenic nuclides, which is needed for geological and archaeological dating, has been uncertain. Measurements of chlorine-36/chlorine ( <jats:sup>36</jats:sup> Cl/Cl) ratios in fossil packrat middens from Nevada that are radiocarbon-dated between about 38 thousand years ago (ka) and the present showed that <jats:sup>36</jats:sup> Cl/Cl ratios were higher by a factor of about 2 before ∼11 ka. This raises the possibility that cosmogenic production rates just before the close of the Pleistocene were up to 50% higher than is suggested by carbon-14 calibration data. The discrepancy could be explained by addition of low–carbon-14 carbon dioxide to the atmosphere during that period, which would have depressed atmospheric radiocarbon activity. Alternatively, climatic effects on <jats:sup>36</jats:sup> Cl deposition may have enhanced the <jats:sup>36</jats:sup> Cl/Cl ratios. </jats:p>