Catálogo de publicaciones - revistas

<jats:title>Liquid water under Mars' southern ice cap</jats:title> <jats:p> Mars is known to host large quantities of water in solid or gaseous form, and surface rocks show clear evidence that there was liquid water on the planet in the distant past. Whether any liquid water remains on Mars today has long been debated. Orosei <jats:italic>et al.</jats:italic> used radar measurements from the Mars Express spacecraft to search for liquid water in Mars' southern ice cap (see the Perspective by Diez). They detected a 20-km-wide lake of liquid water underneath solid ice in the Planum Australe region. The water is probably kept from freezing by dissolved salts and the pressure of the ice above. The presence of liquid water on Mars has implications for astrobiology and future human exploration. </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="6401" page="490" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aar7268">490</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6401" page="448" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aau1829">448</jats:related-article> </jats:p>

<jats:title>An epitaxial route to strain</jats:title> <jats:p> Strain can have a dramatic effect on the properties of materials. Zhang <jats:italic>et al.</jats:italic> introduced a large strain in the material PbTiO <jats:sub>3</jats:sub> by growing it epitaxially in a composite with PbO. On the boundaries between the two materials, their normally different lattice constants were matched, giving rise to the strain. As a consequence, the films exhibited a very large electric polarization even in the absence of an electric field. The method may be applicable to generating other functional materials. </jats:p> <jats:p> <jats:italic>Scence</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6401" page="494" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aan2433">494</jats:related-article> </jats:p>

<jats:title>Falling from a fall in rainfall</jats:title> <jats:p> How much did rainfall have to decrease to trigger the collapse of Lowland Classic Maya civilization during the Terminal Classic Period? This collapse is a well-cited example of how past climate change—in this case, drought—can disrupt a population. Evans <jats:italic>et al.</jats:italic> measured the isotopic composition of water in Lake Chichancanab, Mexico, to quantify how much precipitation decreased during that period. Annual rainfall must have fallen by around 50% on average and by up to 70% during peak drought conditions. </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="6401" page="498" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aas9871">498</jats:related-article> </jats:p>

<jats:title>Enough but not too many stem cells</jats:title> <jats:p> In the shoot apical meristem of plants, just the right number of stem cells generates a steady supply of cells with which to build differentiated tissues. Too few stem cells, and the plant cannot grow. Too many, and growth runs amok. Zhou <jats:italic>et al.</jats:italic> analyzed the controls on stem cell proliferation. They found that the HAIRY MERISTEM proteins define a domain within which WUSCHEL (WUS) cannot work, but beyond which WUS is left free to promote stem cell proliferation. </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="6401" page="502" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aar8638">502</jats:related-article> </jats:p>

<jats:title>A channel for calcium</jats:title> <jats:p> Maintaining the correct balance of calcium concentrations between the cytosol and the mitochondria is essential for cellular physiology. A calcium-selective channel called the mitochondrial calcium uniporter (MCU) mediates calcium entry into mitochondria. Yoo <jats:italic>et al.</jats:italic> report the high-resolution structure of MCU from <jats:italic>Neurospora crassa.</jats:italic> The channel is formed by four MCU protomers with differing symmetry between the soluble and membrane domains. The structure, together with mutagenesis, suggests that two acidic rings inside the channel provide the selectivity for calcium. </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="6401" page="506" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aar4056">506</jats:related-article> </jats:p>

<jats:title>The genetics of human short stature</jats:title> <jats:p> Flores Island in Indonesia has a long history of hominin occupation, including by the extinct <jats:italic>Homo floresiensis</jats:italic> and a more recent settlement by modern humans. Furthermore, Flores has an extant population of pygmy humans, and <jats:italic>H. floresiensis</jats:italic> exhibited a diminutive adult size relative to other hominins. Tucci <jats:italic>et al.</jats:italic> examined genetic variation among 32 individuals, including 10 sequenced genomes, from a population of pygmies living close to the cave where <jats:italic>H. floresiensis</jats:italic> remains were discovered. These individuals exhibit signatures of polygenic selection explaining the short stature and have genomic content from both Neanderthals and Denisovans, but no additional archaic lineages. Thus, restricted height is under selection at this location and has evolved independently at least twice in hominins. </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="6401" page="511" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aar8486">511</jats:related-article> </jats:p>

<jats:p>A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.</jats:p>