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<jats:p>Argument and debate are common in science, yet they are virtually absent from science education. Recent research shows, however, that opportunities for students to engage in collaborative discourse and argumentation offer a means of enhancing student conceptual understanding and students’ skills and capabilities with scientific reasoning. As one of the hallmarks of the scientist is critical, rational skepticism, the lack of opportunities to develop the ability to reason and argue scientifically would appear to be a significant weakness in contemporary educational practice. In short, knowing what is wrong matters as much as knowing what is right. This paper presents a summary of the main features of this body of research and discusses its implications for the teaching and learning of science.</jats:p>

<jats:p>In yeast, the impact of gene knockouts depends on genetic background.</jats:p>

<jats:title>Triangulating to Mechanism</jats:title> <jats:p> Cellular uptake and release of a variety of substrates are mediated by secondary transporters, but no crystal structures are known for all three fundamental states of the transport cycle, which has limited explanations for their proposed mechanisms. <jats:bold> Shimamura <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="470" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1186303">470</jats:related-article> ) report a 3.8-angstrom structure of the inward-facing conformation of the bacterial sodium-benzylhydantoin transport protein, Mhp1, complementing the other two available structures. Molecular modeling for the interconversions of these structures shows a simple rigid body rotation of four helices relative to the rest of the structure in which the protein switches reversibly from outward- to inward-facing. </jats:p>

<jats:title>Breaking Convention</jats:title> <jats:p> The defining characteristics of a superconductor are symmetry of gap function, which tells us something about how pairs of electrons move through the sample, and the strength of that pairing. Together, this information gives us the highest temperature to which the superconductor can remain superconducting. In conventional superconductors the gap function is symmetric, or s-wave, and tends to have low transition temperatures. The newly discovered iron-based superconductors also have <jats:italic>s</jats:italic> -wave symmetry, but the rather high transition temperatures, in addition to other properties, indicate that they are not conventional. <jats:bold> Hanaguri <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="474" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1187399">474</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="5977" page="441" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1188927">Hoffman</jats:related-article> </jats:bold> ) use scanning tunneling microscopy to provide direct experimental confirmation of the unconventional <jats:italic>s</jats:italic> -wave pairing of the superconducting carriers in these materials. </jats:p>

<jats:title>Nanosynthesis Without a Twist</jats:title> <jats:p> The synthesis of many nanoscale materials occurs under conditions of changing saturation because generation of product decreases the concentration of reactants. <jats:bold> Morin <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="476" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1182977">476</jats:related-article> ) used a flow reactor to maintain conditions of low supersaturation during the growth of zinc oxide nanotubes and nanowires. Under these conditions, growth of the tubes was controlled by the release of stress, which prevented the torquing of the crystals along their axis. Since growth at different saturation conditions matched predictions, this looks like a promising method to develop rational and controlled synthesis of nanomaterials at large scale and low cost. </jats:p>

<jats:title>Microcapacitors for Manufacture</jats:title> <jats:p> Capacitors can store small amounts of charge, and as they can charge and discharge quickly, they work well with batteries for recovering power, such as in regenerative braking in hybrid cars. For very small power requirements, capacitors have not been competitive with microbatteries, but using monolithic carbon films to store the charge, <jats:bold> Chmiola <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="480" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1184126">480</jats:related-article> ) demonstrate the feasibility of such applications. The small pores in the carbon films are sufficiently large to allow electrolyte transport and can be made using a processing technique compatible with current chip manufacturing. Such microcapacitors can thus be integrated with electronics to make autonomous sensors or implantable devices. </jats:p>

<jats:title>Sun Stuff</jats:title> <jats:p> Comets are thought to be remnants of the Sun's protoplanetary disk; hence, they hold important clues to the processes that originated the solar system. <jats:bold> Matzel <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="483" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1184741">483</jats:related-article> , published online 25 February) present Al-Mg isotope data on a refractory particle recovered from comet Wild 2 by the NASA Stardust mission. The lack of evidence for the extinct radiogenic isotope <jats:sup>26</jats:sup> Al implies that this particle crystallized 1.7 million years after the formation of the oldest solar system solids. This observation, in turn, requires that material formed near the Sun was transported to the outer reaches of the solar system and incorporated into comets over a period of at least two million years. </jats:p>

<jats:title>Of Monsoons and Megadroughts</jats:title> <jats:p> The Asian monsoon is the weather system that has the greatest effect on the greatest number of people in the world. Naturally then, knowing better how climate change might affect the monsoon is tremendously important. One obstacle that prevents a better understanding of future behavior is a poor knowledge of its past. <jats:bold> Cook <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="486" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1185188">486</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="5977" page="437" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1188926"> <jats:bold>Wahl and Morrill</jats:bold> </jats:related-article> </jats:bold> ) help to fill this gap with a 700-year reconstruction of the monsoon from tree-ring data obtained throughout Asia. The reconstruction chronicles monsoon failures and megadroughts, as well as patterns of precipitation, and can thus be compared with other relevant climate records to allow links with sea-surface temperatures to be better understood. </jats:p>

<jats:title>Separated About Lift</jats:title> <jats:p> The uplift history of the Andes of South America is a contentious issue, with the two main hypotheses polarizing from rapid growth between roughly 10 and 7 million years ago to more gradual elevation over most of the past 40 million years. The oxygen isotopic composition of soil carbonates has been used as a proxy for altitude and to measure the timing of uplift. <jats:bold> Poulsen <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="490" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1185078">490</jats:related-article> , published online 1 April) applied a global atmospheric general circulation model to show that the oxygen isotopic composition changes seen in carbonates formed in the late Miocene were driven more by changes in the amount of precipitation than by the altitude at which the precipitation forms. Consequently, it seems that oxygen isotopes are not a reliable paleoaltimeter, and Andean uplift may not have been as precipitate as thought. </jats:p>

<jats:title>A Little Selection for a Lot of Rarity</jats:title> <jats:p> Studies on how selection works have tended to focus on the effect of a single trait. This necessarily means that rare alleles that can be acted on by selection appear to experience high levels of frequency-dependence selection. However, selection may act on multiple traits at any one time. <jats:bold>Doebeli and Ispolatov</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="494" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1187468">494</jats:related-article> ) present a theoretical framework examining how multiple rare traits can persist and potentially drive speciation. The s show that only low levels of frequency-dependent selection are needed to explain the observed high levels of allelic diversity in nature. </jats:p>