Catálogo de publicaciones - revistas

<jats:p>Geothermal energy production is increasing across the world, but challenges remain.</jats:p>

<jats:p> A chemical method allows the composition of oxide nanocrystals to be changed while maintaining their size and shape uniformity. <jats:named-content content-type="related-content"> [Also see Report by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="964" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234751"> Oh <jats:italic>et al.</jats:italic> </jats:related-article> ] </jats:named-content> </jats:p>

<jats:p> Identification of a surface protein in <jats:italic>Plasmodium falciparum</jats:italic> reveals how it can escape detection by the mosquito immune system. <jats:named-content content-type="related-content"> [Also see Report by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="984" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1235264"> Molina-Cruz <jats:italic>et al.</jats:italic> </jats:related-article> ] </jats:named-content> </jats:p>

<jats:p> A vaccine that protects against SIV in monkeys elicits a new kind of T cell response. <jats:named-content content-type="related-content"> [Also see Research Article by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" related-article-type="in-this-issue" xlink:href="10.1126/science.1237874"> Hansen <jats:italic>et al.</jats:italic> </jats:related-article> ] </jats:named-content> </jats:p>

<jats:p>The French Nobel laureate ushered in the field of molecular genetics by defining the regulated cellular pathway that translates DNA into proteins.</jats:p>

<jats:title>Life Versus the Volcanoes</jats:title> <jats:p> Correlating a specific triggering event, such as an asteroid impact or massive volcanism, to mass extinction events is clouded by the difficulty in precisely timing their occurrence in the geologic record. Based on rock samples collected in North America and Morocco, <jats:bold> Blackburn <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="941" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234204">941</jats:related-article> , published online 21 March) acquired accurate ages for events surrounding the mass extinction that occurred ∼201 million years ago, between the Triassic and Jurassic Periods. The timing of the disappearance of marine and land fossils and geochemical evidence of the sequential eruption of the Central Atlantic Magmatic Province imply a strong causal relationship. </jats:p>

<jats:title>Quelccaya Ice Cap</jats:title> <jats:p> Ice cores drilled in the ice sheets of Greenland and Antarctica are some of the most important sources of information about the paleoclimate of high latitudes. Comparable records from the tropics are rare, however, because there are so few locations at which long-lived, undisturbed ice can be found. <jats:bold> Thompson <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="945" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234210">945</jats:related-article> , published online 4 April) report results obtained from one of the few such sites, the Quelccaya ice cap in the Peruvian Andes. The annually resolved data, extending back 1800 years, provide a detailed chronicle of changes in the isotopic composition of the oxygen in the ice, which are related to the sea surface temperature of the water's source. Analyses of a collection of major ions such as ammonium and nitrate reveal how atmospheric circulation in the region varied over that period. Finally, the radiocarbon content of ancient plants—recently exposed by the retreat of the ice sheet—reveals that Quelccaya has not been smaller for at least six thousand years. </jats:p>

<jats:title>For Good Measure</jats:title> <jats:p> SS Cygni is a well-studied binary star system in the northern constellation Cygnus, consisting of a white dwarf that accretes matter from its companion star. <jats:bold> Miller-Jones <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="950" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1237145">950</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="932" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1238835">Schreiber</jats:related-article> </jats:bold> ) used radio observations to derive a model-independent distance to this prototypical accreting white dwarf system. The measurement places the system significantly closer than previously determined, reconciling the observed properties of SS Cygni with our current understanding of accretion theory. </jats:p>

<jats:title>A Touchy Subject</jats:title> <jats:p> The ability to hold a glass being filled with water without dropping it depends on our ability to touch objects and to know the correct pressure to exert. Thus, for robotics or artificial skin design, methods are needed for sensitive pressure detection. <jats:bold> Wu <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="952" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234855">952</jats:related-article> , published online 25 April) designed a device based on an array of zinc oxide nanowires that generate a small voltage when flexed that could be translated into a pressure signal. The device has a pressure-sensing range of up to 30 kPa, comparable to the 10 to 40 kPa range of a human finger. </jats:p>

<jats:title>The Strength of Impurities</jats:title> <jats:p> The practical strength of a material (rather than its theoretical strength) is influenced by the presence of defects between crystalline domains and the inclusion of impurities. In some cases, synergistic effects may arise where the impurity atoms segregate to the domain boundaries, although kinetic barriers may limit the extent to which the impurity atoms can order. <jats:bold> Nie <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="957" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1229369">957</jats:related-article> ) show the segregation of oversized and undersized solute atoms at coherent twin boundaries in a magnesium alloy. The minimization of strain energy drives the differently sized impurities to different twin boundaries, strengthening the material. </jats:p>