Catálogo de publicaciones - revistas

<jats:p>Quantum technology promises to revolutionize how we learn about the physical world. An experiment that processes quantum data with a quantum computer could have substantial advantages over conventional experiments in which quantum states are measured and outcomes are processed with a classical computer. We proved that quantum machines could learn from exponentially fewer experiments than the number required by conventional experiments. This exponential advantage is shown for predicting properties of physical systems, performing quantum principal component analysis, and learning about physical dynamics. Furthermore, the quantum resources needed for achieving an exponential advantage are quite modest in some cases. Conducting experiments with 40 superconducting qubits and 1300 quantum gates, we demonstrated that a substantial quantum advantage is possible with today’s quantum processors.</jats:p>

<jats:p> Many plant-associated fungi are obligate biotrophs that depend on living hosts to proliferate. However, little is known about the molecular basis of the biotrophic lifestyle, despite the impact of fungi on the environment and food security. In this work, we show that combinations of organic acids and glucose trigger phenotypes that are associated with the late stage of biotrophy for the maize pathogen <jats:italic>Ustilago maydis</jats:italic> . These phenotypes include the expression of a set of effectors normally observed only during biotrophic development, as well as the formation of melanin associated with sporulation in plant tumors. <jats:italic>U. maydis</jats:italic> and other hemibiotrophic fungi also respond to a combination of carbon sources with enhanced proliferation. Thus, the response to combinations of nutrients from the host may be a conserved feature of fungal biotrophy. </jats:p>

<jats:p>Caloric restriction (CR) prolongs life span, yet the mechanisms by which it does so remain poorly understood. Under CR, mice self-impose chronic cycles of 2-hour feeding and 22-hour fasting, raising the question of if it is calories, fasting, or time of day that is the cause of this increased life span. We show here that 30% CR was sufficient to extend the life span by 10%; however, a daily fasting interval and circadian alignment of feeding acted together to extend life span by 35% in male C57BL/6J mice. These effects were independent of body weight. Aging induced widespread increases in gene expression associated with inflammation and decreases in the expression of genes encoding components of metabolic pathways in liver from ad libitum–fed mice. CR at night ameliorated these aging-related changes. Our results show that circadian interventions promote longevity and provide a perspective to further explore mechanisms of aging.</jats:p>

<jats:p>DNA viruses are increasingly recognized as influencing marine microbes and microbe-mediated biogeochemical cycling. However, little is known about global marine RNA virus diversity, ecology, and ecosystem roles. In this study, we uncover patterns and predictors of marine RNA virus community- and “species”-level diversity and contextualize their ecological impacts from pole to pole. Our analyses revealed four ecological zones, latitudinal and depth diversity patterns, and environmental correlates for RNA viruses. Our findings only partially parallel those of cosampled plankton and show unexpectedly high polar ecological interactions. The influence of RNA viruses on ecosystems appears to be large, as predicted hosts are ecologically important. Moreover, the occurrence of auxiliary metabolic genes indicates that RNA viruses cause reprogramming of diverse host metabolisms, including photosynthesis and carbon cycling, and that RNA virus abundances predict ocean carbon export.</jats:p>

<jats:p>Realizing quantum speedup for practically relevant, computationally hard problems is a central challenge in quantum information science. Using Rydberg atom arrays with up to 289 qubits in two spatial dimensions, we experimentally investigate quantum algorithms for solving the maximum independent set problem. We use a hardware-efficient encoding associated with Rydberg blockade, realize closed-loop optimization to test several variational algorithms, and subsequently apply them to systematically explore a class of graphs with programmable connectivity. We find that the problem hardness is controlled by the solution degeneracy and number of local minima, and we experimentally benchmark the quantum algorithm’s performance against classical simulated annealing. On the hardest graphs, we observe a superlinear quantum speedup in finding exact solutions in the deep circuit regime and analyze its origins.</jats:p>

<jats:p>Early naturalists suggested that predation intensity increases toward the tropics, affecting fundamental ecological and evolutionary processes by latitude, but empirical support is still limited. Several studies have measured consumption rates across latitude at large scales, with variable results. Moreover, how predation affects prey community composition at such geographic scales remains unknown. Using standardized experiments that spanned 115° of latitude, at 36 nearshore sites along both coasts of the Americas, we found that marine predators have both higher consumption rates and consistently stronger impacts on biomass and species composition of marine invertebrate communities in warmer tropical waters, likely owing to fish predators. Our results provide robust support for a temperature-dependent gradient in interaction strength and have potential implications for how marine ecosystems will respond to ocean warming.</jats:p>

<jats:p> Infant microbiome assembly has been intensely studied in infants from industrialized nations, but little is known about this process in nonindustrialized populations. We deeply sequenced infant stool samples from the Hadza hunter-gatherers of Tanzania and analyzed them in a global meta-analysis. Infant microbiomes develop along lifestyle-associated trajectories, with more than 20% of genomes detected in the Hadza infant gut representing novel species. Industrialized infants—even those who are breastfed—have microbiomes characterized by a paucity of <jats:italic>Bifidobacterium infantis</jats:italic> and gene cassettes involved in human milk utilization. Strains within lifestyle-associated taxonomic groups are shared between mother-infant dyads, consistent with early life inheritance of lifestyle-shaped microbiomes. The population-specific differences in infant microbiome composition and function underscore the importance of studying microbiomes from people outside of wealthy, industrialized nations. </jats:p>

<jats:p>Synthetic methods that enable simultaneous control over multiple stereogenic centers are desirable for the efficient preparation of pharmaceutical compounds. Herein, we report the discovery and development of a catalyst-mediated asymmetric Michael addition/crystallization–induced diastereomer transformation of broad scope. The sequence controls three stereogenic centers, two of which are stereochemically labile. The configurational instability of 1,3-dicarbonyls and nitroalkanes, typically considered a liability in stereoselective synthesis, is productively leveraged by merging enantioselective Brønsted base organocatalysis and thermodynamic stereocontrol using a single convergent crystallization. The synthesis of useful γ-nitro β-keto amides containing three contiguous stereogenic centers is thus achieved from Michael acceptors containing two prochiral centers.</jats:p>

<jats:p>The stereoselective synthesis of molecules bearing stereogenic phosphorus(V) centers represents an enduring challenge in organic chemistry. Although stereospecific nucleophilic substitution at P(V) provides a general strategy for elaborating optically active P(V) compounds, existing methods for accessing the requisite chiral building blocks rely almost entirely on diastereocontrol using chiral auxiliaries. Catalytic, enantioselective methods for the synthesis of synthetically versatile stereogenic P(V) building blocks offer an alternative approach to stereogenic-at-P(V) targets without requiring stoichiometric quantities of chiral control elements. Here, we report an enantioselective hydrogen-bond-donor–catalyzed synthesis of aryl chlorophosphonamidates and the development of these products as versatile chiral P(V) building blocks. We demonstrate that the two leaving groups on these chlorophosphonamidates can be displaced sequentially and stereospecifically to access a wide variety of stereogenic-at-P(V) compounds featuring diverse substitution patterns.</jats:p>