Catálogo de publicaciones - revistas

<jats:p> Structures of translocation intermediates reveal how transfer RNA molecules move through the ribosome during protein synthesis. <jats:named-content content-type="related-content"> [Also see Research Articles by <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/content/340/6140/1235490.full"> Tourigny <jats:italic>et al.</jats:italic> </jats:ext-link> , <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/content/340/6140/1236086.full"> Zhou <jats:italic>et al.</jats:italic> </jats:ext-link> , and <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/content/340/6140/1235970.full">Pulk and Cate</jats:ext-link> ] </jats:named-content> </jats:p>

<jats:p> Modeling the formation of regions of mass concentration may lead to new estimates of early heat flux in the Moon. <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="6140" page="1552" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1235768"> Melosh <jats:italic>et al.</jats:italic> </jats:related-article> ] </jats:named-content> </jats:p>

<jats:p>The SCY ECO mission, an IBI prize–winning module, fosters inquiry learning, collaboration, and design for ecology following a blended learning approach.</jats:p>

<jats:p> A monthly roundup of recent news and projects of <jats:italic>Science</jats:italic> 's publisher, the American Association for the Advancement of Science. </jats:p>

<jats:title>A Twist on the Capacity Crunch</jats:title> <jats:p> The rate at which data can be transmitted down optic fibers is approaching a limit because of nonlinear optical effects. Multiplexing allows data to be encoded in different modes of light such as polarization, wavelength, amplitude, and phase and to be sent down the fibers in parallel. Optical angular momentum (OAM) can provide another degree of freedom whereby the photons are given a well-defined twist or helicity. <jats:bold> Bozinovic <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="6140" page="1545" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1237861">1545</jats:related-article> ) were able to transmit high-bandwidth data using OAM modes in long lengths of optical fibers, thus providing a possible route to get yet more capacity through optic fiber networks. </jats:p>

<jats:title>Titanium Cleaver</jats:title> <jats:p> A century after its discovery, the Haber Bosch process is still used to produce ammonia from nitrogen for fertilizer. Nonetheless, the process requires high temperature and pressure, and chemists continue to look for synthetic analogs to microbial nitrogenase enzymes, which have managed to slice through the N2 triple bond under ambient conditions for millennia. Most efforts in this vein have relied on a boost from the reducing power of alkali metals. <jats:bold> Shima <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="6140" page="1549" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1238663">1549</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="6140" page="1530" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1240365">Fryzuk</jats:related-article> </jats:bold> ) instead explored the reactivity of a titanium hydride cluster, which cleanly slices through N <jats:sub>2</jats:sub> at room temperature and incorporates the separated N atoms into its framework. Though ammonia was not produced, the system offers hope in the search for mild nitrogen reduction catalysts. </jats:p>

<jats:title>Lunar Mascons Explained</jats:title> <jats:p> The origin of lunar mass concentrations (or mascons), which appear as prominent bull's-eye patterns on gravitational maps of both the near- and far side of the Moon, has been a mystery since they were originally detected in 1968. Using state-of-the-art simulation codes, <jats:bold> Melosh <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="6140" page="1552" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1235768">1552</jats:related-article> , published online 30 May; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6140" page="1535" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1238099">Montesi</jats:related-article> </jats:bold> ) developed a model to explain the formation of mascons, linking the processes of impact cratering, tectonic deformation, and volcanic extrusion. </jats:p>

<jats:title>Water at the Bottom of a Well</jats:title> <jats:p> Earthquakes generate numerous fractures as they propagate through an underground fault zone. These fractures strongly influence the way in which fluids flow in the subsurface, and the permeability of fault zones is often used as a proxy for the extent of fracturing. Following the 2008 <jats:italic>M</jats:italic> <jats:sub>w</jats:sub> 7.9 Wenchuan earthquake in central China, several wells were drilled in and around the fault zone to understand the mechanics of the earthquake. Because the bottoms of these deep boreholes were open, the water levels in the wells were sensitive to tidal forces acting on the surrounding rock. Through continuous measurements of water levels over 1.5 years, <jats:bold> Xue <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="6140" page="1555" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1237237">1555</jats:related-article> ) found that the rate at which water was pumped in and out of the borehole was proportional to the permeability of the fault zone, providing a direct way to measure the evolution of the hydrologic properties of a fault zone following a major earthquake. Permeability decreased ∼25% during that time, suggesting that fractures generated in fault zones heal relatively rapidly. </jats:p>

<jats:title>By the Sea Side</jats:title> <jats:p> The Atlantic coastal plain of North America has been thought of as a passive margin, responding mostly to the weight of deposited sediments. As a result, the fine-scale stratigraphy of the sediments has been used to infer changes in global sea level through the Cenozoic. However, recent work has shown that the coastal plain has deformed in response to flow in Earth's mantle. <jats:bold> Rowley <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="6140" page="1560" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1229180">1560</jats:related-article> , published online 16 May) used a model of flow in the mantle to show that the topography of the mid-Atlantic and Southern United States coast varied by 60 meters or more during the past 5 million years. </jats:p>

<jats:title>Borneo Paleohydrology</jats:title> <jats:p> Climate records of the last glacial cycle provide a good picture of how climate changed at high and middle latitudes, but fewer records of the tropics are available. <jats:bold> Carolin <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="6140" page="1564" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1233797">1564</jats:related-article> , published online 6 June) present data from a suite of precisely dated stalagmites from Borneo that reveal how the western tropical Pacific region behaved between 100,000 and 15,000 years ago, a period during which many abrupt climate changes occurred in other parts of the world. While the hydroclimate of Borneo changed in response to precessional forcing, it responded only weakly to the forces that produced glacial-interglacial changes in global climate. </jats:p>