Catálogo de publicaciones - revistas

<jats:title>Reserving the right to stretch</jats:title> <jats:p> Retractable antennae or certain spider silks can stretch well beyond their apparent length because they have a reserve of material that lets them expand and contract over much longer distances. Grandgeorge <jats:italic>et al.</jats:italic> made nonwoven fibrous membranes by electrospinning a block copolymer with varying ratios of two components. They infused these membranes with a liquid that let the fibers buckle and fold without changing the apparent surface area. When the membranes were stretched, this material could unbuckle and slide along the membrane surface, allowing it to extend without breakage. </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="6386" page="296" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aaq0677">296</jats:related-article> </jats:p>

<jats:title>Small, smooth, and bendable diamonds</jats:title> <jats:p> If you manage to deform a diamond, it usually means you have broken it. Diamonds have very high hardness, but they do not deform elastically. This limits their usefulness for some applications. However, Banerjee <jats:italic>et al.</jats:italic> discovered that diamond nanoneedles can deform elastically after all (see the Perspective by LLorca). The key was in their small size (300 nm), which allowed for very smooth-surfaced, defect-free diamonds. The deformation was close to the theoretical limit for diamond, which opens up the potential for applications in microelectronics and drug delivery. </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="6386" page="300" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar4165">300</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6386" page="264" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aat5211">264</jats:related-article> </jats:p>

<jats:title>Images frozen in time</jats:title> <jats:p> Freezing processes involving multiple phases are common, as seen in the zone refining used to remove impurities from a crystal through the heating of a narrow region. However, it is difficult to visualize the processes as they happen. Dedovets <jats:italic>et al.</jats:italic> studied the freezing of an oil-in-water emulsion and the interaction of the oil droplets with the leading edge of the freezing water. In situ visualization of the freezing front was achieved through confocal microscopy of samples on a moving sample holder. The authors tracked the effects of solution concentration on the droplet positions and observed premelting at the interface of the droplets by using fluorescence markers. </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="6386" page="303" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar4503">303</jats:related-article> </jats:p>

<jats:title>Recurring coherence</jats:title> <jats:p> A finite isolated system should return almost to its initial state if it evolves for long enough. For a large system, “long enough” is often unfeasibly long. Rauer <jats:italic>et al.</jats:italic> found just the right conditions to observe the recurrence of the initial state in a system of two one-dimensional superfluids with thousands of atoms in each. The superfluids were initially coupled—locking their quantum mechanical phases together—and then allowed to evolve independently. After the uncoupling, the researchers observed their phases regaining coherence two more times. </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="6386" page="307" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aan7938">307</jats:related-article> </jats:p>

<jats:title>Megafaunal loss</jats:title> <jats:p> Today, it is well known that human activities put larger animals at greater risk of extinction. Such targeting of the largest species is not new, however. Smith <jats:italic>et al.</jats:italic> show that biased loss of large-bodied mammal species from ecosystems is a signature of human impacts that has been following hominin migrations since the Pleistocene. If the current trend continues, terrestrial mammal body sizes will become smaller than they have been over the past 45 million years. Megafaunal mammals have a major impact on the structure of ecosystems, so their loss could be particularly damaging. </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="6386" page="310" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aao5987">310</jats:related-article> </jats:p>

<jats:title>Transient instruction changes migration</jats:title> <jats:p> The brain neocortex is built by waves of neurons migrating from deep within the brain to the surface layers. Ohtaka-Maruyama <jats:italic>et al.</jats:italic> found that a layer of neurons that multipolar neurons encounter on their travels instructs the migrating neurons to change phenotype and direction (see the Perspective by Schinder and Lanuza). These subplate neurons form transient glutamatergic synapses with the immature migrants. This results in the migrating multipolar neurons becoming bipolar, more directed, and faster in their final migrations. </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="6386" page="313" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar2866">313</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6386" page="265" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aat4587">265</jats:related-article> </jats:p>

<jats:title>A short-term trend reversed</jats:title> <jats:p> Theory and empirical data both support the paradigm that C <jats:sub>4</jats:sub> plant species (in which the first product of carbon fixation is a four-carbon molecule) benefit less from rising carbon dioxide (CO <jats:sub>2</jats:sub> ) concentrations than C <jats:sub>3</jats:sub> species (in which the first product is a three-carbon molecule). This is because their different photosynthetic physiologies respond differently to atmospheric CO <jats:sub>2</jats:sub> concentrations. Reich <jats:italic>et al.</jats:italic> document a reversal of this pattern in a 20-year CO <jats:sub>2</jats:sub> enrichment experiment using grassland plots with each type of plant (see the Perspective by Hovenden and Newton). Over the first 12 years, biomass increased with elevated CO <jats:sub>2</jats:sub> in C <jats:sub>3</jats:sub> plots but not C <jats:sub>4</jats:sub> plots, as expected. But over the next 8 years, the pattern reversed: Biomass increased in C <jats:sub>4</jats:sub> plots but not C <jats:sub>3</jats:sub> plots. Thus, even the best-supported short-term drivers of plant response to global change might not predict long-term results. </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="6386" page="317" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aas9313">317</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6386" page="263" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aat2481">263</jats:related-article> </jats:p>

<jats:title>A strongly oxidizing Paleoproterozoic era</jats:title> <jats:p> Two billion years ago, marine sulfate concentrations were around one-third as high as modern ones, constituting an oxidizing capacity equivalent to more than 20% of that of the modern ocean-atmosphere system. Blättler <jats:italic>et al.</jats:italic> found this by analyzing a remarkable evaporite succession more than 1 billion years older than the oldest comparable deposit discovered to date. These quantitative results, for a time when only more qualitative information was previously available, provide a constraint on the magnitude and timing of early Earth's response to the Great Oxidation Event 2.3 billion years ago. </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="6386" page="320" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar2687">320</jats:related-article> </jats:p>

<jats:title>First steps of translocation elucidated</jats:title> <jats:p> Ribosomes synthesizing membrane or secretory proteins are targeted to the endoplasmic reticulum (ER) in eukaryotic cells by the signal recognition particle (SRP). Upon reaching the ER, the SRP interacts with its receptor to promote transfer of the signal sequence to the protein-conducting channel or translocon. Kobayashi <jats:italic>et al.</jats:italic> studied the ribosomal complex that forms on the ER, in which the SRP and its receptor interact to transfer the newly synthesized protein to the translocon. The observed organization of the assembly reveals the roles of multiple eukaryotic-specific protein components present in the SRP and its receptor in stabilizing the conformation that facilitates signal sequence handover. </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="6386" page="323" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar7924">323</jats:related-article> </jats:p>

<jats:title>Inherited variation contributes to autism</jats:title><jats:p>About one-quarter of genetic variants that are associated with autism spectrum disorder (ASD) are due to de novo mutations in protein-coding genes. Brandler<jats:italic>et al.</jats:italic>wanted to determine whether changes in noncoding regions of the genome are associated with autism. They applied whole-genome sequencing to ∼2600 families with at least one affected child. Children with ASD had inherited structural variants in noncoding regions from their father. Regulatory regions of some specific genes were disrupted among multiple families, supporting the idea that a component of autism risk involves inherited noncoding 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="6386" page="327" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aan2261">327</jats:related-article></jats:p>