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<jats:title>Vesta to the Core</jats:title> <jats:p> Vesta is one of the largest bodies in the main asteroid belt. Unlike most other asteroids, which are fragments of once larger bodies, Vesta is thought to have survived as a protoplanet since its formation at the beginning of the solar system (see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6104" page="203" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1228328">Binzel</jats:related-article> , published online 20 September). Based on data obtained with the Gamma Ray and Neutron Detector aboard the Dawn spacecraft, <jats:bold> Prettyman <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="242" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1225354">242</jats:related-article> , published online 20 September) show that Vesta's reputed volatile-poor regolith contains substantial amounts of hydrogen delivered by carbonaceous chondrite impactors. Observations of pitted terrain on Vesta obtained by Dawn's Framing Camera and analyzed by <jats:bold> Denevi <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="246" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1225374">246</jats:related-article> , published online 20 September), provide evidence for degassing of volatiles and hence the presence of hydrated materials. Finally, paleomagnetic studies by <jats:bold> Fu <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="238" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1225648">238</jats:related-article> ) on a meteorite originating from Vesta suggest that magnetic fields existed on the surface of the asteroid 3.7 billion years ago, supporting the past existence of a magnetic core dynamo. </jats:p>

<jats:title>Rise and Subside</jats:title> <jats:p> Earth's surface tends to deform as magmatic fluids rise toward the surface from below, usually manifesting itself in uplift of continental crust. <jats:bold>Fialko and Pearse</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="250" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1226358">250</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6104" page="207" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1228953">Brooks</jats:related-article> </jats:bold> ), however, show that subsidence, or widespread sinking, accompanies uplift when magma rises. Satellite measurements reveal that the massive Altipano-Puna magma body in the central Andes balloons upward, causing subsidence around the region of uplift, resembling a sombrero. Melting of surrounding rocks as the magma rises likely withdraws material and causes the subsidence. </jats:p>

<jats:title>Embryonic Cell Sorting and Movement</jats:title> <jats:p> Differential cell adhesion has long been thought to drive cell sorting. <jats:bold> Maître <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="253" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1225399">253</jats:related-article> , published online 23 August) show that cell sorting in zebrafish gastrulation is triggered by differences in the ability of cells to modulate cortex tension at cell-cell contacts, thereby controlling contact expansion. Cell adhesion functions in this process by mechanically coupling the cortices of adhering cells at their contacts, allowing cortex tension to control contact expansion. In zebrafish epiboly the enveloping cell layer (EVL)—a surface epithelium formed at the animal pole of the gastrula—gradually spreads over the entire yolk cell to engulf it at the end of gastrulation. <jats:bold> Behrndt <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="257" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1224143">257</jats:related-article> ) show that an actomyosin ring connected to the epithelial margin triggers EVL spreading both by contracting around its circumference and by generating a pulling force through resistance against retrograde actomyosin flow. </jats:p>

<jats:title>Embryonic Cell Sorting and Movement</jats:title> <jats:p> Differential cell adhesion has long been thought to drive cell sorting. <jats:bold> Maître <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="253" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1225399">253</jats:related-article> , published online 23 August) show that cell sorting in zebrafish gastrulation is triggered by differences in the ability of cells to modulate cortex tension at cell-cell contacts, thereby controlling contact expansion. Cell adhesion functions in this process by mechanically coupling the cortices of adhering cells at their contacts, allowing cortex tension to control contact expansion. In zebrafish epiboly the enveloping cell layer (EVL)—a surface epithelium formed at the animal pole of the gastrula—gradually spreads over the entire yolk cell to engulf it at the end of gastrulation. <jats:bold> Behrndt <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="257" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1224143">257</jats:related-article> ) show that an actomyosin ring connected to the epithelial margin triggers EVL spreading both by contracting around its circumference and by generating a pulling force through resistance against retrograde actomyosin flow. </jats:p>

<jats:title>Feeling the Light</jats:title> <jats:p> There has been a link missing in our understanding of the biochemical signaling mechanism initiated when photons are absorbed by rhodopsin in the photoreceptor cells of <jats:italic>Drosophila</jats:italic> eyes. Photoisomerization of rhodopsin activates a heterotrimeric guanine nucleotide—binding protein which leads to activation of phospholipase C. But how phospholipase C activates the transient receptor potential (TRP) or the transient receptor potential–like (TRPL) ion channels that produce the rest of the cellular response has been unclear. <jats:bold>Hardie and Franze</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="260" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1222376">260</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6104" page="200" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1229909">Liman</jats:related-article> </jats:bold> ) propose that there is a physical mechanism at work. Atomic force microscopy revealed light-induced contractions of photoreceptor cells. Consistent with a physical coupling mechanism, manipulations of the membrane altered responses of the photoreceptor cells to light. Thus, physical changes in the membrane appear to couple phospholipase C activity to the opening of mechanosensitive TRP and TRPL channels. </jats:p>

<jats:title>Cheat Control</jats:title> <jats:p> In quorum-sensing induction, a <jats:italic>Pseudomonas aeruginosa</jats:italic> population growing on a single carbon source, such as casein, will reach a density where the levels of signaling molecules they collectively secrete triggers the cells to synthesize and secrete proteases to digest the casein. However, it is metabolically costly to secrete proteases, and the system is prone to mutant “cheats.” These cheats do not respond to quorum sensing and do not go to the cost of synthesizing protease, but they do profit from the breakdown products that allow all the cells—cheats and cooperators alike—to grow. <jats:bold> Dandekar <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="264" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1227289">264</jats:related-article> ) found that quorum signaling–insensitive <jats:italic>P. aeruginosa</jats:italic> cheats could not synthesize nucleotide hydrolase and were thus unable to grow if casein was replaced by adenosine. This allowed cooperators to outgrow the cheats, leading to a stable equilibrium between cheats and cooperators. This principle of regulation may be applicable to other bacterial quorum-sensing systems and might be exploited in the development of drugs that disrupt bacterial cooperation. </jats:p>

<jats:title>Mobile Phone “Hot Spots”</jats:title> <jats:p> An obstacle to developing effective national malaria control programs is a lack of understanding of human movements, which are an important component of disease transmission. As mobile phones have become increasingly ubiquitous, it is now possible to collect individual-level, longitudinal data on human movements on a massive scale. <jats:bold> Wesolowski <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="267" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1223467">267</jats:related-article> ) analyzed mobile phone call data records representing the travel patterns of 15 million mobile phone owners in Kenya over the course of a year. This was combined with a detailed malaria risk map, to estimate malaria parasite movements across the country that could be caused by human movement. This information enabled detailed analysis of parasite sources and sinks between hundreds of local settlements. Estimates were compared with hospital data from Nairobi to show that local pockets of transmission likely occur around the periphery of Nairobi, accounting for locally acquired cases, contrary to the accepted idea that there is no transmission in the capital. </jats:p>

<jats:title>The Right Choice?</jats:title> <jats:p> So-called irrational decisions made by humans are popular fodder for “believe it or not” stories. But what's actually happening when we make choices that do not seem to be justifiable on purely economic or logical grounds? Presumably, we are not simply making errors; instead, our choices may reflect an internal bias that we are not aware of. <jats:bold>Wimmer and Shohamy</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="270" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1223252">270</jats:related-article> ) show how the hippocampus can instill an unconscious bias in valuations, whereby an object that is not highly valued on its own, increases in value when it becomes implicitly associated with a truly high-value object. As a consequence, we then end up preferring the associated object over a neutral object of equal objective value while not really knowing why. </jats:p>

<jats:p>The show includes the evolution of development, the human mutation rate, publishing patterns, and more.</jats:p>

<jats:p>On this, the 60th anniversary of Beihang University (formerly known as the Beijing University of Aeronautics and Astronautics, or BUAA), we visit some of the achievements of this prestigious Chinese institution in all manner of research fields related to air, land, sea, and space travel. Each of the schools featured in this booklet showcases their latest innovations, discoveries, and research in many and varied science and engineering disciplines. These scientists and engineers are particularly adept at generating designs that are biologically inspired, borrowing the best systems from nature and applying them to create more effective technologies for human use.</jats:p> <jats:p>From the nanoscale to the macroscale, advances being made at Beihang University are pushing the boundaries of what we can achieve, moving us toward what will be.</jats:p>