Catálogo de publicaciones - revistas

<jats:title>An impact with a dash of volcanism</jats:title> <jats:p> Around the time of the end-Cretaceous mass extinction that wiped out dinosaurs, there was both a bolide impact and a large amount of volcanism. Hull <jats:italic>et al.</jats:italic> ran several temperature simulations based on different volcanic outgassing scenarios and compared them with temperature records across the extinction event. The best model fits to the data required most outgassing to occur before the impact. When combined with other lines of evidence, these models support an impact-driven extinction. However, volcanic gases may have played a role in shaping the rise of different species after the extinction event. </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="6475" page="266" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aay5055">266</jats:related-article> </jats:p>

<jats:title>A finer record of biodiversity</jats:title> <jats:p> We have pressing, human-generated reasons to explore the influence of environmental change on biodiversity. Looking into the past can not only inform our understanding of this relationship but also help us to understand current change. Paleontological records depend on fossil availability and predictive modeling, however, and thus tend to give us a picture with large temporal jumps, millions of years wide. Such a scale makes it difficult to truly understand the action of environmental forces on ecological processes. Enabled by a supercomputer, Fan <jats:italic>et al.</jats:italic> used machine learning to analyze a large marine Paleozoic dataset, creating a record with time intervals of only ∼26,000 years (see the Perspective by Wagner). This fine-scale resolution revealed new events and important details of previously described patterns. </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="6475" page="272" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aax4953">272</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6475" page="249" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aba4348">249</jats:related-article> </jats:p>

<jats:title>Magnetic energy release in a solar flare</jats:title> <jats:p> Solar flares are bright flashes and associated eruptions of plasma from the Sun that are thought to be powered by violent rearrangement of the magnetic fields near sunspots. Fleishman <jats:italic>et al.</jats:italic> observed a bright solar flare with a microwave interferometer, allowing them to map the magnetic field in the solar corona and monitor how it changed during the flare. They found a large drop in the local field strength over 2 minutes, releasing enough magnetic energy to power the entire solar flare. Determining the origin of this energy will help to predict how strong future solar flares may be and their potential space weather impacts on Earth. </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="6475" page="278" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aax6874">278</jats:related-article> </jats:p>

<jats:title>Sourcing nitrogen from nitromethane</jats:title> <jats:p> Nitromethane is produced in bulk quantities for use as a solvent. Its applications as a reagent have focused mainly on the acidity of the methyl protons en route to modifying the carbon center. Liu <jats:italic>et al.</jats:italic> now report an alternative protocol that activates the nitrogen center to produce an aminating agent. An in situ reductive reaction with triflic anhydride, formic acid, and acetic acid yields an acetylated hydroxylamine, characterized by mass spectrometry. This nitrogen donor conveniently transforms a variety of ketones and aldehydes into amides. </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="6475" page="281" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aay9501">281</jats:related-article> </jats:p>

<jats:title>Spin-charge entanglement</jats:title> <jats:p> Many physical properties follow characteristic scaling laws near quantum critical points, which are associated with phase transitions at absolute zero temperature. The material YbRh <jats:sub>2</jats:sub> Si <jats:sub>2</jats:sub> has an antiferromagnetic quantum critical point, where spin-related properties are expected to follow such a scaling. Unexpectedly, Prochaska <jats:italic>et al.</jats:italic> found that charge fluctuations follow a critical scaling as well. The researchers fabricated high-quality thin films of YbRh <jats:sub>2</jats:sub> Si <jats:sub>2</jats:sub> and used transmission spectroscopy to measure the optical conductivity of the film and infer the scaling. Their findings point to a highly entangled state of charge and spin, which may also be responsible for the strangemetal phase in this material. </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="6475" page="285" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aag1595">285</jats:related-article> </jats:p>

<jats:title>Enhancing optical nonlinearity</jats:title> <jats:p> Intense pulses of light interacting with a dielectric material can induce optical nonlinear behavior, whereby the frequency of the output light can be doubled or tripled or excited to even higher harmonics of the input light. Usually this interaction is weak and occurs over many thousands of wavelengths, typically requiring the combination of bulk volumes of material with a confining cavity. Using a mechanism of light confinement called bound states in the continuum, Koshelev <jats:italic>et al.</jats:italic> show that enhanced second-harmonic generation can be obtained in nanoscale subwavelength cylinders of a dielectric material. The results on these optical nanoantennas offer a platform for developing integrated nonlinear nanophotonic devices. </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="6475" page="288" related-article-type="in-this-issue" vol="367" xlink:href="10.1126/science.aaz3985">288</jats:related-article> </jats:p>