Catálogo de publicaciones - revistas

<jats:title>Breaking down graphene degeneracy</jats:title> <jats:p> Bilayer graphene has two layers of hexagonally arranged carbon atoms stacked on top of each other in a staggered configuration. This spatial arrangement results in degenerate electronic states: distinct states that have the same energy. Interaction between electrons can cause the states to separate in energy, and so can external fields (see the Perspective by LeRoy and Yankowitz). Kou <jats:italic>et al.</jats:italic> , Lee <jats:italic>et al.</jats:italic> , and Maher <jats:italic>et al.</jats:italic> used three distinct experimental setups that clarify different parameter regimes of bilayer graphene. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="55" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1250270">55</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="58" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1251003">58</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="61" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1252875">61</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="31" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256545">31</jats:related-article> </jats:p>

<jats:title>Gas jets block extragalactic x-rays</jats:title> <jats:p> Supermassive black holes at the heart of active galaxies produce powerful gas outflows. NGC 5548 is one such source known to sustain a persistent outflow of ionized gas. However, its associated x-ray and ultraviolet (UV) emission seem to have been suppressed in recent years. Kaastra <jats:italic>et al.</jats:italic> conducted a multiwavelength monitoring campaign throughout 2013 to characterize the system's behavior. They suggest that an additional faster jet component has been launching clumps of gas that obscure both the x-ray and UV radiation. The timing of this phenomenon indicates a source only a few light-days away from the nucleus. This proximity suggests that the outflow could be associated with a wind from the supermassive black hole's accretion disk. Even more powerful outflows could also influence their host galaxies, and this finding demonstrates how that feedback might work. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="64" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1253787">64</jats:related-article> </jats:p>

<jats:title>Carbon-carbon bonds without byproducts</jats:title> <jats:p>Environmental and cost concerns are spurring development of chemical methods that minimize byproduct formation. In this vein, Mo and Dong present a catalyst that inserts olefins such as ethylene directly into the C-H bonds of ketones. Traditional methods to form such products rely on the preliminary reaction of the ketone with a base, followed by subsequent reaction with an alkyl halide. The authors used a ligand that simultaneously activates the ketone and guides the catalytic rhodium to the right location. This approach removes the need for the other reagents and eliminates the associated halide salt byproducts.</jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="68" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254465">68</jats:related-article> </jats:p>

<jats:title>High-surface-area gas separation membranes</jats:title> <jats:p> Membranes for gas separation require a combination of high surface area and selective transport pathways. Brown <jats:italic>et al.</jats:italic> present a potentially scalable route for making high-quality gas separation membranes in a high-surface-area configuration. Using two different solvents flowing in opposite directions, a metal-organic framework material was selectively deposited within hollow polymer fibers. The membranes showed high-performance separation capabilities when tested with mixtures of hydrocarbon gases. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="72" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1251181">72</jats:related-article> </jats:p>

<jats:title>Don't leave me alone with my thoughts</jats:title> <jats:p> Nowadays, we enjoy any number of inexpensive and readily accessible stimuli, be they books, videos, or social media. We need never be alone, with no one to talk to and nothing to do. Wilson <jats:italic>et al.</jats:italic> explored the state of being alone with one's thoughts and found that it appears to be an unpleasant experience. In fact, many of the people studied, particularly the men, chose to give themselves a mild electric shock rather than be deprived of external sensory stimuli. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="75" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1250830">75</jats:related-article> </jats:p>

<jats:title>Strong winds, upwelling, and teeming shores</jats:title> <jats:p> Climate warming has produced stronger winds along some coasts, a result of growing differences in temperature and pressure between land and sea. These winds cause cold nutrient-rich seawater to rise to the surface, affecting climate and fueling marine productivity. Sydeman <jats:italic>et al.</jats:italic> examined data from the five major world regions where upwelling is occurring. Particularly in the California, Humboldt, and Benguela upwelling systems, winds have become stronger over the past 60 years. These regions represent up to a fifth of wild marine fish catches and are hot spots of biodiversity. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="77" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1251635">77</jats:related-article> </jats:p>

<jats:title>Seismic noise reveals volcanic plumbing</jats:title> <jats:p> Monitoring the way in which seismic noise passes through Earth's crust after a large earthquake can clarify how volcanoes erupt. Japan has the highest-density seismic network in the world. Brenguier <jats:italic>et al.</jats:italic> observed reductions in seismic velocity below volcanic regions of Japan from before, to the weeks and months after the 2011 Tohoku-Oki earthquake (see the Perspective by Prejean and Haney). This indicates that pressurized fluids below volcanoes can weaken in response to dynamic stress perturbations. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="80" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254073">80</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="39" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256196">39</jats:related-article> </jats:p>

<jats:title>Exploiting nervous paths already traveled</jats:title> <jats:p> The parasympathetic nervous system helps regulate the functions of many tissues and organs, including the salivary glands and the esophagus. To do so, it needs to reach throughout the body, connecting central systems to peripheral ones. Dyachuk <jats:italic>et al.</jats:italic> and Espinosa-Medina <jats:italic>et al.</jats:italic> explored how these connections are established in mice (see the Perspective by Kalcheim and Rohrer). Progenitor cells that travel along with the developing nerves can give rise to both myelinforming Schwann cells and to parasympathetic neurons. That means the interacting nerves do not have to find each other. Instead, the beginnings of the connections are laid down as the nervous system develops. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="82" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1253281">82</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="87" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1253286">87</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="32" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1257175">32</jats:related-article> </jats:p>

<jats:title>Exploiting nervous paths already traveled</jats:title> <jats:p> The parasympathetic nervous system helps regulate the functions of many tissues and organs, including the salivary glands and the esophagus. To do so, it needs to reach throughout the body, connecting central systems to peripheral ones. Dyachuk <jats:italic>et al.</jats:italic> and Espinosa-Medina <jats:italic>et al.</jats:italic> explored how these connections are established in mice (see the Perspective by Kalcheim and Rohrer). Progenitor cells that travel along with the developing nerves can give rise to both myelinforming Schwann cells and to parasympathetic neurons. That means the interacting nerves do not have to find each other. Instead, the beginnings of the connections are laid down as the nervous system develops. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="82" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1253281">82</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="87" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1253286">87</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="32" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1257175">32</jats:related-article> </jats:p>

<jats:title>The heart needs blood vessels, too</jats:title> <jats:p> For the newborn heart to grow quickly, the heart's own blood vessels must grow as well. Researchers have assumed that preexisting fetal coronary vessels expand to cause this postnatal coronary vascular growth. Instead, Tian <jats:italic>et al.</jats:italic> now show that, for the most part, brandnew blood vessels form within the neonatal heart (see the Perspective by Burns and Burns). This ability to produce new coronary blood vessels after birth may one day help researchers work out how to promote cardiovascular regeneration after injury or disease. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="90" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1251487">90</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6192" page="28" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256866">28</jats:related-article> </jats:p>