Catálogo de publicaciones - revistas

<jats:title>A layered approach improves solar cells</jats:title> <jats:p> Perovskite films received a boost in photovoltaic efficiency through controlled formation of charge-generating films and improved current transfer to the electrodes. Zhou <jats:italic>et al.</jats:italic> lowered the defect density of the film by controlling humidity while the perovskite film formed from lead chloride and methylammonium iodide. Low-temperature processing steps allowed the use of materials that draw current out of the perovskite layer more efficiently. These and other modifications enabled a maximum cell efficiency of just over 19% and an average of 16.6%. </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="6196" page="542" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254050">542</jats:related-article> </jats:p>

<jats:title> Converting CO <jats:sub>2</jats:sub> into methanol by catalysis </jats:title> <jats:p> By hydrogenating CO <jats:sub>2</jats:sub> , scientists can transform a greenhouse gas into methanol, a desirable fuel. Graciani <jats:italic>et al.</jats:italic> cast copper in the role of the highly active catalyst for this reaction by putting copper particles on cerium oxide. The interface between the cerium oxide and the copper enables the reverse water-gas shift reaction that converts CO <jats:sub>2</jats:sub> into CO, which reacts more readily with hydrogen to make methanol. This result takes a step forward in innovating catalysts for this environmentally friendly process. </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="6196" page="546" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1253057">546</jats:related-article> </jats:p>

<jats:title>A finger on the pulse of young stars</jats:title> <jats:p> Adolescent stars quiver and quake before the onset of nuclear fusion in their cores. Zwintz <jats:italic>et al.</jats:italic> confirm theoretical predictions that the frequency of the seismic oscillations in a given star is tied to its evolutionary status (see the Perspective by Stahler and Palla). As the protostar evolves and contracts, growing hotter and denser, it pulsates faster. Though previously applied only to aging stars, asteroseismology now offers a powerful tool for discerning the ages of very young stars. The relative timing of star formation within young clusters especially benefits from this refinement, as stars there are often tagged with one blanket age. </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="6196" page="550" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1253645">550</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6196" page="514" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1257301">514</jats:related-article> </jats:p>

<jats:title>Gamma-ray novas may be garden variety</jats:title> <jats:p>When astronomers detected gamma rays from the nova V407 Cyg, an explosive mass transfer from a red giant onto a white dwarf, they found it surprising enough. They blamed the rays on strong stellar winds enabling particle acceleration. Now, the Fermi-LAT Collaboration has observed gamma rays from three more novas, all lacking the strong winds. Although the three sources vary slightly in nature, none is particularly unusual. If all novas emit gamma rays, then astronomers would expect to see the same number of novas that they did in fact see within a 5-kpc distance over 5 years.</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="6196" page="554" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1253947">554</jats:related-article> </jats:p>

<jats:title>A macroscopic view of cultural history</jats:title> <jats:p> Sociologists and anthropologists study the growth and evolution of human culture, but it is hard to measure cultural interactions on a historical time scale. Schich <jats:italic>et al.</jats:italic> developed a tool for extracting information about cultural history from simple but large sets of birth and death records. A network of cultural centers connected via the birth and death of more than 150,000 notable individuals revealed human mobility patterns and cultural attraction dynamics. Patterns of city growth over a period of 2000 years differed between countries, but the distribution of birth-to-death distances remained unchanged over more than eight centuries. </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="6196" page="558" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1240064">558</jats:related-article> </jats:p>

<jats:title>Turning large dinosaurs into small birds</jats:title> <jats:p> Most paleontologists agree that birds are descended from dinosaurs. How did such large terrestrial or aquatic animals evolve into small feathered fliers? Lee <jats:italic>et al.</jats:italic> used two large databases of theropod morphology to explore possible evolutionary patterns that may have driven this dramatic transformation (see the Perspective by Benton). They found no clear pattern of miniaturization across the entire clade of Theropoda. However, several lines of evidence suggested that the lineage leading to birds underwent sustained miniaturization. Within that lineage, body sizes decreased and species evolved faster. They also developed ecological and morphological innovations linked to smaller body sizes. </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="6196" page="562" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1252243">562</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6196" page="508" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1257633">508</jats:related-article> </jats:p>

<jats:title>How do fingers know where to grow?</jats:title> <jats:p> Most researchers today believe that each finger forms because of its unique position within the early limb bud. However, 30 years ago, developmental biologists proposed that the arrangement of fingers followed the Turing pattern, a self-organizing process during early embryo development. Raspopovic <jats:italic>et al.</jats:italic> provide evidence to support a Turing mechanism (see the Perspective by Zuniga and Zeller). They reveal that Bmp and Wnt signaling pathways, together with the gene Sox9, form a Turing network. The authors used this network to generate a computer model capable of accurately reproducing the patterns that cells follow as the embryo grows fingers. </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="6196" page="566" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1252960">566</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6196" page="516" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1257501">516</jats:related-article> </jats:p>

<jats:title>A not-so-random integration for HIV</jats:title> <jats:p> Even in the face of a cocktail of antiretroviral drugs, HIV manages to hang on. It does so by integrating its own genome into those of host cells, where it persists in a latent state. To better understand this process, Wagner <jats:italic>et al.</jats:italic> determined the sites where HIV integrated into three HIV-infected patients treated with antiretroviral drugs for more than a decade. They found an over-representation of sites where HIV integrated into genes associated with cancer and cell proliferation. Also, multiple cells in the same individual harbored the same integration sites. This suggests that integration into specific genes may drive cell proliferation and viral persistence. </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="6196" page="570" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256304">570</jats:related-article> </jats:p>

<jats:title>Parasites make it hard to fight viruses</jats:title> <jats:p> Microbial co-infections challenge the immune system—different pathogens often require different flavors of immune responses for their elimination or containment (see the Perspective by Maizels and Gause). Two teams studied what happens when parasitic worms and viruses infect mice at the same time. Reese <jats:italic>et al.</jats:italic> found that parasite co-infection woke up a dormant virus. Osborne <jats:italic>et al.</jats:italic> found that mice already infected with parasitic worms were worse at fighting off viruses. In both cases, worms skewed the immune response so that the immune cells and the molecules they secreted created an environment favorable for the worm at the expense of antiviral immunity. </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="6196" page="573" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254517">573</jats:related-article> and p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6196" page="578" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256942">578</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6196" page="517" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1258443">517</jats:related-article> </jats:p>

<jats:title>Parasites make it hard to fight viruses</jats:title> <jats:p> Microbial co-infections challenge the immune system—different pathogens often require different flavors of immune responses for their elimination or containment (see the Perspective by Maizels and Gause). Two teams studied what happens when parasitic worms and viruses infect mice at the same time. Reese <jats:italic>et al.</jats:italic> found that parasite co-infection woke up a dormant virus. Osborne <jats:italic>et al.</jats:italic> found that mice already infected with parasitic worms were worse at fighting off viruses. In both cases, worms skewed the immune response so that the immune cells and the molecules they secreted created an environment favorable for the worm at the expense of antiviral immunity. </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="6196" page="573" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1254517">573</jats:related-article> and p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6196" page="578" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1256942">578</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6196" page="517" related-article-type="in-this-issue" vol="345" xlink:href="10.1126/science.1258443">517</jats:related-article> </jats:p>