Catálogo de publicaciones - revistas

<jats:title>Taking the pulse of optimization</jats:title> <jats:p> Finding the optimum solution of multiparameter or multifunctional problems is important across many disciplines, but it can be computationally intensive. Many such problems defined as computationally difficult can be mathematically mapped onto the so-called Ising problem, which looks at finding the minimum energy configuration for an array of coupled spins. Inagaki <jats:italic>et al.</jats:italic> and McMahon <jats:italic>et al.</jats:italic> show that an optical processing approach based on a network of coupled optical pulses in a ring fiber can be used to model and optimize large-scale Ising systems. Such a scalable architecture could help to optimize solutions to a wide range of complex problems. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue pp. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="603" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah4243">603</jats:related-article> and <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="614" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah5178">614</jats:related-article> </jats:p>

<jats:title>Shaking the lattice uncovers universality</jats:title> <jats:p> Most of our knowledge of quantum phase transitions (QPTs)—which occur as a result of quantum, rather than thermal, fluctuations—comes from experiments performed in equilibrium conditions. Less is known about the dynamics of a system going through a QPT, which have been hypothesized to depend on a single time and length scale. Clark <jats:italic>et al.</jats:italic> confirmed this hypothesis in a gas of cesium atoms in an optical lattice, which was shaken progressively faster to drive the gas through a QPT. </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="6312" page="606" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf9657">606</jats:related-article> </jats:p>

<jats:title>Exotic molecule tests fundamental symmetry</jats:title> <jats:p> Spectroscopy of exotic molecules can offer insight into fundamental physics. Hori <jats:italic>et al.</jats:italic> studied the transition frequencies of an unusual helium atom in which one of the two electrons was substituted by an antiproton, the negatively charged antiparticle partner of the proton (see the Perspective by Ubachs). The antiprotonic helium was cooled down to low temperatures to allow the frequencies to be measured with high precision. The extracted mass of the antiproton (relative to the electron mass) was in good agreement with previous measurements of the proton mass. This finding is in keeping with the implications of the combined charge, parity, and time-reversal symmetry of physical laws. </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="6312" page="610" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf6702">610</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="546" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah6215">546</jats:related-article> </jats:p>

<jats:title>Taking the pulse of optimization</jats:title> <jats:p> Finding the optimum solution of multiparameter or multifunctional problems is important across many disciplines, but it can be computationally intensive. Many such problems defined as computationally difficult can be mathematically mapped onto the so-called Ising problem, which looks at finding the minimum energy configuration for an array of coupled spins. Inagaki <jats:italic>et al.</jats:italic> and McMahon <jats:italic>et al.</jats:italic> show that an optical processing approach based on a network of coupled optical pulses in a ring fiber can be used to model and optimize large-scale Ising systems. Such a scalable architecture could help to optimize solutions to a wide range of complex problems. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue pp. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="603" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah4243">603</jats:related-article> and <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="614" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah5178">614</jats:related-article> </jats:p>

<jats:title>Assessing smoke damage in cancer genomes</jats:title> <jats:p> We have known for over 60 years that smoking tobacco is one of the most avoidable risk factors for cancer. Yet the detailed mechanisms by which tobacco smoke damages the genome and creates the mutations that ultimately cause cancer are still not fully understood. Alexandrov <jats:italic>et al.</jats:italic> examined mutational signatures and DNA methylation changes in over 5000 genome sequences from 17 different cancer types linked to smoking (see the Perspective by Pfeifer). They found a complex pattern of mutational signatures. Only cancers originating in tissues directly exposed to smoke showed a signature characteristic of the known tobacco carcinogen benzo[ <jats:italic>a</jats:italic> ]pyrene. One mysterious signature was shared by all smoking-associated cancers but is of unknown origin. Smoking had only a modest effect on DNA methylation. </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="6312" page="618" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aag0299">618</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="549" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aal2114">549</jats:related-article> </jats:p>

<jats:title>Radicals push proteins beyond genes</jats:title> <jats:p> Chemically modifying proteins after their translation can expand their structural and functional roles (see the Perspective by Hofmann and Bode). Two related methods describe how to exploit free radical chemistry to form carbon-carbon bonds between amino acid residues and a selected functional group. Wright <jats:italic>et al.</jats:italic> added a wide range of functional groups to proteins containing dehydroalanine precursors, with borohydride mediating the radical chemistry. Yang <jats:italic>et al.</jats:italic> employed a similar approach, using zinc in combination with copper ions. Together, these results will be useful for introducing functionalities and labels to a wide range of proteins. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue pp. <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/content/354/6312/aag1465.full">597</jats:ext-link> and <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="623" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aah4428">623</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="553" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aai8788">553</jats:related-article> </jats:p>

<jats:title>Uranium in the deep sea</jats:title> <jats:p> The ratio of <jats:sup>234</jats:sup> U to <jats:sup>238</jats:sup> U in seawater underlies modern marine uranium-thorium geochronology, but it is difficult to establish the ratio precisely. Chen <jats:italic>et al.</jats:italic> report two <jats:sup>234</jats:sup> U/ <jats:sup>238</jats:sup> U records derived from deep-sea corals (see the Perspective by Yokoyama and Esat). The records reveal a number of important similarities to and differences from existing records of the past 30,000 years. Higher values during the most recent 10,000 years than during earlier glaciated conditions may reflect enhanced subglacial melting during deglaciation. </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="6312" page="626" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aag1015">626</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="550" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aak9817">550</jats:related-article> </jats:p>

<jats:title>Spinal cord regeneration in zebrafish</jats:title> <jats:p> Unlike humans, zebrafish can regenerate their spinal cord. Mokalled <jats:italic>et al.</jats:italic> identified a growth factor in zebrafish that helps this process (see the Perspective by Williams and He). The protein encoded by <jats:italic>ctgfa</jats:italic> ( <jats:italic>connective tissue growth factor a</jats:italic> ) is secreted after injury and encourages glial cells to form a bridge across the spinal lesion. Addition of this protein improved spinal cord repair in injured zebrafish. </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="6312" page="630" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf2679">630</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="544" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aal2112">544</jats:related-article> </jats:p>

<jats:title>Soil microbes yield insecticidal peptide</jats:title> <jats:p> The microbial peptide BT, derived from the bacterium <jats:italic>Bacillus thuringiensis</jats:italic> , is widely used to protect crops from insect pests. Schellenberger <jats:italic>et al.</jats:italic> identified another insecticidal peptide from a different soil-dwelling bacterium, <jats:italic>Pseudomonas chlororaphis</jats:italic> (see the Perspective by Tabashnik). Corn plants expressing the <jats:italic>Pseudomonas</jats:italic> peptide were protected from attack by western corn rootworm. Rootworms that were resistant to BT were susceptible to the <jats:italic>Pseudomonas</jats:italic> peptide. Addition of another insecticidal peptide diversifies the arsenal against insect pests, which may slow down the development of resistance. </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="6312" page="634" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aaf6056">634</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6312" page="552" related-article-type="in-this-issue" vol="354" xlink:href="10.1126/science.aag101">552</jats:related-article> </jats:p>

<jats:p> Neuroscientists are employing new techniques and technologies to use animal behavior as a window into brain function.For instance, researchers are teaching mice to nose-poke a touchscreen by doling out strawberry milkshakes as part ofcognitive testing. It's a light-hearted reminder of the similarity between mice and humans, perhaps—but hopes are risingthat new therapies developed using mouse models of Alzheimer's disease, for example, can be translated to humans. <jats:list list-type="bullet"> <jats:list-item> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/custom-publishing/technology-features/mouse-milkshake-behavioral-windows-brain-function">Read the Feature (Full-Text HTML)</jats:ext-link> </jats:p> </jats:list-item> <jats:list-item> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/sites/default/files/custom-publishing/documents/4NovNeuro.pdf">Read the Feature (PDF)</jats:ext-link> </jats:p> </jats:list-item> <jats:list-item> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/sites/default/files/custom-publishing/douments/4NovNewProducts.pdf">Read New Products (PDF)</jats:ext-link> </jats:p> </jats:list-item> </jats:list> </jats:p>