Catálogo de publicaciones - revistas

<jats:p> The deconfined quantum critical point (DQCP) represents a paradigm shift in quantum matter studies, presenting a “beyond Landau” scenario for order-order transitions. Its experimental realization, however, has remained elusive. Using high-pressure <jats:sup>11</jats:sup> B nuclear magnetic resonance measurements on the quantum magnet SrCu <jats:sub>2</jats:sub> (BO <jats:sub>3</jats:sub> ) <jats:sub>2</jats:sub> , we here demonstrate a magnetic field–induced plaquette singlet to antiferromagnetic transition above 1.8 gigapascals at a notably low temperature, <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> ≃ 0.07 kelvin. First-order signatures of the transition weaken with increasing pressure, and we observe quantum critical scaling at the highest pressure, 2.4 gigapascals. Supported by model calculations, we suggest that these observations can be explained by a proximate DQCP inducing critical quantum fluctuations and emergent O(3) symmetry of the order parameters. Our findings offer a concrete experimental platform for investigation of the DQCP. </jats:p>

<jats:p>We investigated the effects of Facebook’s and Instagram’s feed algorithms during the 2020 US election. We assigned a sample of consenting users to reverse-chronologically-ordered feeds instead of the default algorithms. Moving users out of algorithmic feeds substantially decreased the time they spent on the platforms and their activity. The chronological feed also affected exposure to content: The amount of political and untrustworthy content they saw increased on both platforms, the amount of content classified as uncivil or containing slur words they saw decreased on Facebook, and the amount of content from moderate friends and sources with ideologically mixed audiences they saw increased on Facebook. Despite these substantial changes in users’ on-platform experience, the chronological feed did not significantly alter levels of issue polarization, affective polarization, political knowledge, or other key attitudes during the 3-month study period.</jats:p>

<jats:p> Murine intraepithelial γδ T cells include distinct tissue-protective cells selected by epithelial butyrophilin-like (BTNL) heteromers. To determine whether this biology is conserved in humans, we characterized the colonic γδ T cell compartment, identifying a diverse repertoire that includes a phenotypically distinct subset coexpressing T cell receptor Vγ4 and the epithelium-binding integrin CD103. This subset was disproportionately diminished and dysregulated in inflammatory bowel disease, whereas on-treatment CD103 <jats:sup>+</jats:sup> γδ T cell restoration was associated with sustained inflammatory bowel disease remission. Moreover, CD103 <jats:sup>+</jats:sup> Vγ4 <jats:sup>+</jats:sup> cell dysregulation and loss were also displayed by humans with germline BTNL3/BTNL8 hypomorphism, which we identified as a risk factor for penetrating Crohn’s disease (CD). Thus, BTNL-dependent selection and/or maintenance of distinct tissue-intrinsic γδ T cells appears to be an evolutionarily conserved axis limiting the progression of a complex, multifactorial, tissue-damaging disease of increasing global incidence. </jats:p>

<jats:p>Immunomodulation of lymphocytes by intestinal epithelial cells could lead to new therapies</jats:p>

<jats:p> Short tandem repeats (STRs) are enriched in eukaryotic <jats:italic>cis</jats:italic> -regulatory elements and alter gene expression, yet how they regulate transcription remains unknown. We found that STRs modulate transcription factor (TF)–DNA affinities and apparent on-rates by about 70-fold by directly binding TF DNA-binding domains, with energetic impacts exceeding many consensus motif mutations. STRs maximize the number of weakly preferred microstates near target sites, thereby increasing TF density, with impacts well predicted by statistical mechanics. Confirming that STRs also affect TF binding in cells, neural networks trained only on in vivo occupancies predicted effects identical to those observed in vitro. Approximately 90% of TFs preferentially bound STRs that need not resemble known motifs, providing a <jats:italic>cis</jats:italic> -regulatory mechanism to target TFs to genomic sites. </jats:p>

<jats:p>From surfboard-stealing sea otters to sailboat-chomping killer whales, the summer of 2023 was a landmark year of wild animal antics. Why is wildlife suddenly interacting with humans and their toys in this way? Speculation and headlines have espoused theories about learned behaviors due to enticements with food, increased intrusion, and proximity of humans in wild habitats, as well as aberrant animal responses instigated by oceanic noise or disease-related neurological disorders. However, the most honest answer is, “We don’t really know. Maybe the animals are just playing around.”</jats:p>

<jats:p>Early in August this year, a high-profile summit was held in Belém, Brazil, where the eight Amazonian countries discussed the future of the Amazon. The nations recognized that the Amazon is very close to reaching a tipping point for turning into a degraded ecosystem. The result of their discussions was the Belém Declaration, an ambitious plan to protect and conserve the Amazon forests and to support Indigenous Peoples and local communities. Concern arose, however, because they failed to agree on attaining zero deforestation by 2030 and on avoiding new explorations in the Amazon for fossil fuel. The Declaration also lacks specific and measurable indicators. The ministers of Foreign Affairs therefore have a very important role in further refining the agenda and deadlines so that the Belém Declaration can be implemented.</jats:p>

<jats:p>A feisty Sun threatens satellites and electric grids, highlighting need for better forecasts</jats:p>

<jats:p>Scheme to factor giant numbers could be more efficient than 30-year-old Shor’s algorithm</jats:p>