Catálogo de publicaciones - revistas

<jats:title>Water up</jats:title> <jats:p> Above-anvil cirrus plumes are stratospheric cloud formations that form downwind from the tops of some very strong thunderstorms. Despite their common occurrence, an adequate physical model explaining many of their features and effects does not exist. O’Neill <jats:italic>et al</jats:italic> . show that the storm supercell that extends into the stratosphere functions like a physical barrier, deflecting wind streams there like a topographic obstacle and driving a hydraulic jump downstream at the tropopause (see the Perspective by Smith). This feature triggers the intense injection of water vapor deep into the stratosphere, leading to a substantial increase in stratospheric humidity. —HJS </jats:p>

<jats:title>Prevention of compulsive cocaine taking</jats:title> <jats:p> Over time, about 20% of chronic cocaine users lose control and become addicted. There are indications that the differential efficacy of the brain serotonin (5-HT) system may be involved in the vulnerability to drug addiction. However, the relevant circuits and underlying cellular processes remain elusive. Li <jats:italic>et al</jats:italic> . discovered a synaptic mechanism in mice that underlies the modulatory role of 5-HT in reducing the likelihood of transition to compulsion and eventually addiction (see the Perspective by Miyazaki and Miyazaki). Cocaine binds to 5-HT transporters to block 5-HT reuptake. The elevated extracellular 5-HT activates 5-HT <jats:sub>1B</jats:sub> receptors and causes presynaptic depression of a projection from the orbitofrontal cortex to the dorsal striatum. These changes reduce the likelihood of inducing postsynaptic potentiation at these synapses, which ultimately drives compulsion. —PRS </jats:p>

<jats:title>Fermi nesting</jats:title> <jats:p> Correlated states have been shown to emerge in bilayer and trilayer graphene with the two-dimensional layers at just the right angle with respect to each other. Key to the enhanced importance of interactions are the so-called moiré electronic bands that form in such systems. Rickhaus <jats:italic>et al</jats:italic> . explored a related system of two graphene bilayers twisted with respect to each other. The twist angle was set so that the layer coupling was strong enough to form moiré bands but weak enough for the carrier concentration in the top and bottom bilayer to be controlled separately. Doping the top bilayer with electrons and the bottom bilayer with holes, the researchers created a correlated state with nested Fermi surfaces. —JS </jats:p>

<jats:title>Absorbingly exceptional</jats:title> <jats:p> Most oscillating systems have a resonance or multiple resonances at which they ring out and are most sensitive to excitation. In non-Hermitian systems, open systems with gain and loss, the resonances have been found to coalesce into an exceptional point when the gain and loss can be engineered. Complementing these resonant exceptional points, Wang <jats:italic>et al</jats:italic> . show that controlling the absorption of a coupled microresonator system can produce a new kind of absorbing exceptional point. They also show how these exceptional points are distinct and how systems can be engineered to exhibit new scattering behavior. —ISO </jats:p>

<jats:title>Platform for the synthesis of diverse oligos</jats:title> <jats:p> DNA is primarily viewed as a carrier of information encoded in the sequence of bases, but the chemistry of the phosphodiester backbone is crucial to oligonucleotide stability and structure. Building on previous work in synthetic P(V) phosphorothioate coupling chemistry, Huang <jats:italic>et al</jats:italic> . developed two new reagents for making phosphorodithioate- and phosphate-based linkages (see the Perspective by Virta). The authors incorporated all of these reagents into a unified P(V)-based synthesis platform capable of running at high efficiency on a commercial automated solid-phase synthesizer. They demonstrate the flexibility of this system by producing oligonucleotides with all three linkage types in specific positions. Access to such precisely constructed molecules opens new approaches to therapeutic oligonucleotide design. —MAF </jats:p>

<jats:p>A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.</jats:p>

<jats:title>Electrons see the quantum nature of light</jats:title> <jats:p> We know that light is both a wave and a particle, and this duality arises from the classical and quantum nature of electromagnetic excitations. Dahan <jats:italic>et al</jats:italic> . observed that all experiments to date in which light interacts with free electrons have been described with light considered as a wave (see the Perspective by Carbone). The authors present experimental evidence revealing the quantum nature of the interaction between photons and free electrons. They combine an ultrafast transmission electron microscope with a silicon-photonic nanostructure that confines and strengthens the interaction between the light and the electrons. The “quantum” statistics of the photons are imprints onto the propagating electrons and are seen directly in their energy spectrum. —ISO </jats:p>

<jats:p> Break <jats:italic>et al</jats:italic> . (Research Articles, 15 January 2021, eaay5731) conclude that T cell overproduction of interferon-γ causes chronic mucocutaneous candidiasis (CMC), a typical early feature of autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED). This contradicts studies implicating interleukin IL-17 and IL-22 deficiencies as a cause of CMC. We propose that Break <jats:italic>et al</jats:italic> . have focused on late-arising events rather than more common primary causes of CMC. </jats:p>

<jats:title>Defining tumor cell immune evasion</jats:title> <jats:p> Mouse models used to study cancer often lack a full immune system, allowing implantation of human tumors into the mice. By contrast, naturally evolving tumors must contend with a fully functional immune system and its destruction of some of the cells (see the Perspective by Ho and Wood). Two groups now report studies on mouse models with a fully intact immune system. Martin <jats:italic>et al</jats:italic> . started with preexisting murine tumor cell lines and examined their continued evolution in vivo, whereas Del Poggetto <jats:italic>et al</jats:italic> . examined the development of new pancreatic tumors in the context of inflammation, as is often seen in human patients. In each study, the authors found that the immune system exerted a selective pressure on cells that would give rise to tumors, promoting the survival of those that had lost expression of tumor suppressor genes or activated a specific oncogene. The findings suggest a major role for the immune system in driving tumor evolution across multiple types of cancer. —YN </jats:p>