Catálogo de publicaciones - revistas

<jats:title>The influence of flying</jats:title> <jats:p> Although birds' eggs are generally ovoid in shape, there is considerable variation in the degree to which they are symmetrical, round, or bottom-heavy. Many hypotheses have been put forward to explain what has driven this variation, with many accepting life history or nesting explanations. Stoddard <jats:italic>et al.</jats:italic> looked at nearly 50,000 eggs from more than 1400 species from morphological, biophysical, and evolutionary perspectives and found little support for previous hypotheses (see the Perspective by Spottiswoode). Instead, their results suggest that selection for flight adaptations is most likely to be responsible for the variation. </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="6344" page="1249" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aaj1945">1249</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6344" page="1234" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aan2517">1234</jats:related-article> </jats:p>

<jats:title>Lithium gets a new ground state</jats:title> <jats:p> For the past 70 years, the lowest-energy crystal structure of lithium was believed to be a relatively complex one called the 9R structure. Ackland <jats:italic>et al.</jats:italic> show that this is incorrect. The actual lowest-energy structure for lithium is the much simpler closest-packed face-centered cubic form. In addition, <jats:sup>6</jats:sup> Li and <jats:sup>7</jats:sup> Li isotopes have crystal phase transitions at slightly different pressures and temperatures. This difference is chalked up to large quantum mechanical effects between the isotopes. Lithium is the only metal that shows this type of quantum effect and presents a challenge for theoreticians to explain. </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="6344" page="1254" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aal4886">1254</jats:related-article> </jats:p>