Catálogo de publicaciones - revistas

<jats:p>Does chronic drug abuse cause brain abnormalities, or do they develop before the onset of dependence?</jats:p>

<jats:p>A cave record from Peru closely matches climate patterns seen in cores from Greenland and the North Atlantic Ocean.</jats:p>

<jats:p>The universal thermodynamic functions of a superfluid formed from a fermion gas of strongly interacting lithium atoms have been measured precisely.</jats:p>

<jats:p>Super high-resolution microscopy resolves neuron dynamics in the cerebral cortex of a living mouse.</jats:p>

<jats:title>Monitoring Meiosis</jats:title> <jats:p> During meiosis, or in yeast sporulation, haploid cells are generated from diploid cells. <jats:bold> Brar <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="552" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1215110">552</jats:related-article> , published online 22 December) performed a detailed analysis of messenger RNA (mRNA) abundance and protein synthesis over the course of sporulation. The production of most proteins was tightly regulated both at the mRNA level and by translational control. An unexpected complexity was observed as the cell passed through this key developmental transition, including increases in noncanonical translation from upstream regions of known RNA transcripts, which appear to be important in translational control. </jats:p>

<jats:title>A Drop in the Ocean</jats:title> <jats:p> The concentration of atmospheric CO <jats:sub>2</jats:sub> rose by ∼80 parts per million (ppm), from ∼190 to 270 ppm, during the last deglaciation. It is widely believed that the primary source of that CO <jats:sub>2</jats:sub> was the deep Southern Ocean. <jats:bold>Burke and Robinson</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="557" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1208163">557</jats:related-article> , published online 15 December) present a 25,000-year-long record of the radiocarbon content of deep-sea corals collected from the Southern Ocean, which shows evidence of the <jats:sup>14</jats:sup> C-depletion that must have accompanied CO <jats:sub>2</jats:sub> sequestration. <jats:sup>14</jats:sup> C depletion and ocean stratification ended between 15,000 and 14,000 years ago, in a manner consistent with the transfer of large amounts of CO <jats:sub>2</jats:sub> from the deep Southern Ocean to the atmosphere. The observed <jats:sup>14</jats:sup> C drop can explain the atmospheric CO <jats:sub>2</jats:sub> rise between 17,500 and 14,500 years ago, adding support to the existing model of deglacial CO <jats:sub>2</jats:sub> dynamics. </jats:p>

<jats:title>Probing Pulsar Rotation</jats:title> <jats:p> Pulsars are strongly magnetized, rapidly rotating neutron stars. Those with periods of the order of milliseconds obtain their fast spin by accreting mass from a companion star in a binary system. <jats:bold>Tauris</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="561" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1216355">561</jats:related-article> ) combined numerical stellar evolution calculations with a model of how accretion torques act on a neutron star. During the late accretion phase of millisecond pulsars, the termination stage of mass transfer results in a loss of more than 50% of their rotational energy. This effect may explain the observed pulsar spin distributions. </jats:p>

<jats:title>Nailing Down the Superfluid Transition</jats:title> <jats:p> A gas of fermions, the class of particle that protons, neutrons, and electrons belong to, can be found in contexts as different as neutron stars and a block of metal. When the interaction between fermions is on the brink of forming fermion pairs, the thermodynamics of the gas become dependent only on the gas temperature and density. <jats:bold> Ku <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="563" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1214987">563</jats:related-article> , published online 12 January; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6068" page="549" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1218074">Zwerger</jats:related-article> </jats:bold> ) measured this universal thermodynamics with high precision in an ultracold Fermi gas, observing the predicted transition into a superfluid state through the characteristic lambda-shaped transition in the gas's specific heat. </jats:p>

<jats:title>An Iron Hand for Silicon</jats:title> <jats:p> Carbon-silicon bonds are integral to the structure of the silicone materials widely used in adhesives, cosmetics, and numerous other industrial and consumer products. Generally, platinum-based catalysts have performed best in the hydrosilylation reactions that form these bonds, but the expense of the precious metal and, in some cases, by-product formation have motivated a search for alternatives. <jats:bold> Tondreau <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="567" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1214451">567</jats:related-article> ) now show that a class of iron compounds readily catalyzes hydrosilylation of certain commercially important substrates with rates and selectivities comparable to, or even exceeding, those associated with platinum. </jats:p>

<jats:title>Monsoon Forcing</jats:title> <jats:p> Dansgaard/Oeschger (D/O) events—the sudden, millennial-scale periods of warmth that punctuate the cold climate of the Last Glacial period, and Heinrich events—cold intervals characterized by tremendous discharges of icebergs into the North Atlantic, have been observed at many locations in the Northern Hemisphere but not extensively in the Southern Hemisphere. <jats:bold> Kanner <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="570" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1213397">570</jats:related-article> , published online 12 January; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6068" page="548" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1218365">Rodbell</jats:related-article> </jats:bold> ) present a stable isotope record from the central Peruvian Andes, which represents a record of the South American Summer Monsoon from 50,000 to 16,000 years ago and which contains the signals of D/O and Heinrich events. The Southern Hemisphere monsoon displayed an antiphase relationship to Northern Hemisphere monsoon intensity at the millennial scale, and Antarctic millennial-scale climate fluctuations influenced the South American Summer Monsoon. </jats:p>