Catálogo de publicaciones - revistas

<jats:title>Another spin at the wheel</jats:title> <jats:p> The NLR (nucleotide-binding domain leucine-rich repeat) proteins are a key intracellular component of the early innate immune response to pathogens. After binding microbial ligands, assorted NLR family members assemble to form enormous signaling complexes (inflammasomes), which promote pro-inflammatory cytokine secretion and cell death. Tenthorey <jats:italic>et al.</jats:italic> used cryo-electron microscopy to visualize an assembled ligand-bound inflammasome. They find that when NAIP5 binds flagellin, it changes conformation, which triggers a rotation in monomeric NLRC4, catalyzing further NLRC4 recruitment. Steric clash results in a partially open structure, in contrast with previous descriptions of a closed symmetrical “wheel.” Furthermore, NAIP5 recognizes multiple regions of its ligand, and mutations of flagellin that allow for NAIP5 evasion compromise bacterial fitness. </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="6365" page="888" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aao1140">888</jats:related-article> </jats:p>

<jats:title>Resetting the clock on photoemission</jats:title> <jats:p> The ability to produce attosecond pulses of light provides access to some of the fastest electronic processes occurring within atoms. Tracking the temporal dynamics of the photoemission process in which an atom absorbs a high-energy photon and the electron escapes has exposed a discrepancy between the initial experimental findings and subsequent theoretical modeling. Isinger <jats:italic>et al.</jats:italic> present an ultrafast process that can account for and distinguish the different contributions to the photoemission processes in neon atoms. The findings reveal an “electron shake-up” process that may explain the discrepancy, bringing closure to a 7-year discussion. </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="6365" page="893" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aao7043">893</jats:related-article> </jats:p>

<jats:title>From spins to spirals</jats:title> <jats:p> The polarization state of light can be used in imaging applications and optical communications. Light can also be structured into vortices that carry optical angular momentum, which can be used for micromanipulation and enhancing the capacity of optical communication channels. Devlin <jats:italic>et al.</jats:italic> present a metasurface converter for optical states that transforms polarization states into optical angular momentum states. The coupling between arbitrary spin and optical angular momentum states of light in a compact planar structure may find applications in producing complex structured light fields. </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="6365" page="896" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aao5392">896</jats:related-article> </jats:p>

<jats:title>Delving deep into electronic properties</jats:title> <jats:p> The spectral function of a material, which reflects the distribution of its electronic states as a function of momentum and energy, carries a wealth of information on its properties. However, measuring the spectral function directly is tricky, particularly in systems inaccessible to surface probes or in insulators. Jang <jats:italic>et al.</jats:italic> introduce a method dubbed momentum- and energy-resolved tunneling spectroscopy, in which electrons tunnel from a probe layer to unoccupied states in a target layer deep in a heterostructure. Because the momentum and energy of the electrons are tightly controlled, the measured tunneling probability is proportional to the spectral function of the target system. </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="6365" page="901" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aam7073">901</jats:related-article> </jats:p>

<jats:title>Pairing up electrons and holes in bilayer graphene</jats:title> <jats:p> Excitons—bound pairs of electron and holes in solids—can be harnessed for optoelectronic applications. Being able to tune the exciton energy would bring functional flexibility to such devices. Although tunable excitons have been predicted to form in bilayer graphene, observing them experimentally has been difficult. Ju <jats:italic>et al.</jats:italic> used high-quality bilayer graphene samples sandwiched between layers of hexagonal boron nitride to observe excitons in this material. Exciton energy was tuned across a large range by controlling the gate voltages. </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="6365" page="907" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aam9175">907</jats:related-article> </jats:p>

<jats:title>Exotic origin for cosmic positrons</jats:title> <jats:p> Several cosmic-ray detectors have found more positrons arriving at Earth than expected. Some researchers interpret this as a signature of exotic physics, such as the annihilation of dark matter particles. Others prefer a more mundane explanation that involves positron generation at pulsars followed by diffusion to Earth. Abeysekara <jats:italic>et al.</jats:italic> detected extended emission of gamma rays around two nearby pulsars, generated by high-energy electrons and positrons. The size of the extended emission was used to calculate how far positrons generated by the pulsars diffuse through space—which turns out to be insufficient to reach Earth. The excess positrons detected on Earth must therefore have a more exotic origin than nearby pulsars. </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="6365" page="911" related-article-type="in-this-issue" vol="358" xlink:href="10.1126/science.aan4880">911</jats:related-article> </jats:p>