Catálogo de publicaciones - revistas

<jats:p>Embryonic development played a key role in the evolution of the mammalian ear.</jats:p>

<jats:p>A magnetic field can create tiny currents that flow continuously in an ordinary metal ring, despite its electrical resistance.</jats:p>

<jats:p>Laser pulses can be shaped to control energy transfer at the molecular scale in light-harvesting systems.</jats:p>

<jats:p>A protein heterotetramer repairs RNA cleaved by ribotoxins, and methylation protects against further ribotoxin attack.</jats:p>

<jats:title>Monsoon Cave Recordings</jats:title> <jats:p> Rocky deposits in caves in central China record the changes over time in the Asian Monsoon through the oxygen isotopic composition of the minerals from which they are formed. These deposits can be precisely dated and provide an absolute time line for climate system changes. <jats:bold> Cheng <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="248" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1177840">248</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="5950" page="240" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1179941">Severinghaus</jats:related-article> </jats:bold> ) present oxygen isotope data from speleothems collected from Sanbao Cave, China, for the three glacial terminations that occurred between 120,000 and 350,000 years ago. The data reveal variations in the amount of precipitation delivered by the Asian Monsoon over time. Comparison of the timing of these changes with corresponding changes in ice core and marine sedimentary records provides mechanistic insights into how variations in insolation affect ice sheets and ice age terminations. </jats:p>

<jats:title>Metabolite Arrays</jats:title> <jats:p> Methods suitable for the biochemical analysis of multiple metabolic pathways in mixed samples are in short supply. <jats:bold> Beloqui <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="252" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1174094">252</jats:related-article> ) report a method to sample the global metabolic state of an organism or mixture of organisms using an array of more than 1500 metabolites linked to a glass slide. The substrates are linked to the plate so that the reaction of an enzyme with one of the metabolites releases a fluorescent dye, which allows sensitive detection of the enzymatic activity. From a sample with small numbers of a mixture of bacteria, the authors were able to collect DNA, amplify it in a host bacterium, and measure its encoded metabolic activity with the array. Furthermore, by coating the substrates on nanoparticles with a specially designed linker, the authors could trap and purify enzymes that reacted with the immobilized substrate. The metabolite array may be useful in the characterization of environmental samples, in diagnostic procedures, and in enzyme discovery. </jats:p>

<jats:title>Peeking at Pathogen Response Networks</jats:title> <jats:p> Networks controlling gene expression serve as key decision-making circuits in cells, but the regulatory networks that control dynamic and specific gene expression responses to stimuli are often not well understood. This is particularly true for immune dendritic cells (DCs), which respond to pathogens by mounting elaborate transcriptional responses, and are centrally involved in infectious diseases, autoimmunity, and vaccines. <jats:bold> Amit <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="326" xlink:href="10.1126/science.1179050">257</jats:related-article> , published online 3 September) explored the transcriptional response of dendritic cells to specific classes of pathogens. The transcriptional subnetworks responsible for mammalian dendritic cell responses to different pathogens were identified, and the function of 100 regulators clarified. </jats:p>

<jats:title>Phasing-In Emission</jats:title> <jats:p> In keeping with quantum mechanics, the dynamics that ensue when molecules absorb light depend not only on the light's frequency but also its phase, which can manipulate excited state trajectories through interference. Recently, an impressive degree of control has been achieved over complex light absorbers, including proteins, by iteratively adapting the phase of a laser excitation pulse. However, the optimal pulses used are often too complicated to reveal straightforward insights into the systems being manipulated. <jats:bold> Kuroda <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="263" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1176524">263</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="5950" page="245" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1179694">Batista</jats:related-article> </jats:bold> ) applied iterative phase manipulation toward optimizing the photoemission efficiency of a macromolecular donor-acceptor system, followed by statistical analysis to isolate a fairly simple phase function underlying much of the control mechanism. Careful follow-up experiments revealed an intuitive picture of the excited state behavior. </jats:p>

<jats:title>Extending Quantum Memory</jats:title> <jats:p> Quantum information processing and communication relies on the ability to store, retrieve, and manipulate information stored in quantum memories. In most practical instances, however, the stored quantum information is fragile and susceptible to loss during readout. <jats:bold> Jiang <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="326" xlink:href="10.1126/science.1176496">267</jats:related-article> , published online 10 September) used a combination of quantum logic operations on the electronic spin of a nitrogen vacancy center in diamond to control its interactions with a nearby set of proximal nuclear spins of the carbon network. In this setup, the quantum memory of the electron spin could be made more robust. Extending the lifetime and allowing multiple readouts of the quantum memory should prove a useful technique for quantum information processing. </jats:p>

<jats:title>Normally Persistent</jats:title> <jats:p> In superconductors, currents are expected to flow persistently without dissipation. Quantum mechanics predicts that such persistent currents should also exist in normal mesoscopic metal rings. However, the predicted effect is small, which has made the detection of these currents difficult. <jats:bold> Bleszynski-Jayich <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="272" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1178139">272</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="5950" page="244" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1180577">Birge</jats:related-article> </jats:bold> ) have developed a sensitive technique based on a nanomechanical resonator. An array of aluminum rings on the end of a resonator was fabricated to monitor the shift in frequency of the resonator as the rings were threaded with quanta of magnetic-field flux, setting up currents in the rings. In agreement with a theoretical scenario put forward over a decade ago, the results could be described with a model based on non-interacting electrons. </jats:p>