174 research outputs found
ChatDB: Augmenting LLMs with Databases as Their Symbolic Memory
Large language models (LLMs) with memory are computationally universal.
However, mainstream LLMs are not taking full advantage of memory, and the
designs are heavily influenced by biological brains. Due to their approximate
nature and proneness to the accumulation of errors, conventional neural memory
mechanisms cannot support LLMs to simulate complex reasoning. In this paper, we
seek inspiration from modern computer architectures to augment LLMs with
symbolic memory for complex multi-hop reasoning. Such a symbolic memory
framework is instantiated as an LLM and a set of SQL databases, where the LLM
generates SQL instructions to manipulate the SQL databases. We validate the
effectiveness of the proposed memory framework on a synthetic dataset requiring
complex reasoning. The project website is available at
https://chatdatabase.github.io/
Observation of Hybrid Magnetic Skyrmion Bubbles in Fe3Sn2 Nanodisks
It is well known that there are two types of magnetic bubbles in uniaxial
magnets. Here, using Lorentz-transimission electronic microscopy magnetic
imaging, we report the direct experimental observation of 3D type-III hybrid
bubbles, which comprise N\'eel-twisted skyrmion bubbles with topological charge
Q = -1 in near-surface layers and type-II bubbles with Q = 0 in interior
layers, in Fe3Sn2 nanodisks. Using the tilted magnetic field, we further show
the controlled topological magnetic transformations of three types of bubbles
in a confined ferromagnetic nanodisk. Our observations are well reproduced
using micromagnetic simulations based on measured magnetic parameters. Our
results advance fundamental classification and understanding of magnetic
bubbles, which could propel the applications of three-dimensional magnetism.Comment: https://doi.org/10.1103/PhysRevB.107.17442
Current-Controlled Skyrmion Number in Confined Ferromagnetic Nanostripes
Skyrmions are vortex-like localized magnetic structures that possess an
integer-valued topological index known as the skyrmion number or topological
charge. Skyrmion number determines the topology-related emergent magnetism,
which is highly desirable for advanced storage and computing devices. In order
to achieve device functions, it is necessary to manipulate the skyrmion number
in confined nanostructured geometries using electrical methods. Here, we report
the reliable current-controlled operations for manipulating the skyrmion number
through reversible topological transformations between skyrmion chains and
stripe domains in confined Fe3Sn2 nanostripes. The results of micromagnetic
simulations are successful in numerically reproducing our experiments and
explaining them through the combined effect of current-induced Joule heating
and magnetic hysteresis. These findings hold the potential to advance the
development of topological spintronic devices.Comment: https://doi.org/10.1002/adfm.20230404
Fe-assisted epitaxial growth of 4-inch single-crystal transition-metal dichalcogenides on c-plane sapphire without miscut angle
Epitaxial growth and controllable doping of wafer-scale single-crystal
transition-metal dichalcogenides (TMDCs) are two central tasks for extending
Moore's law beyond silicon. However, despite considerable efforts, addressing
such crucial issues simultaneously under two-dimensional (2D) confinement is
yet to be realized. Here we design an ingenious epitaxial strategy to
synthesize record-breaking 4-inch single-crystal Fe-doped TMDCs monolayers on
industry-compatible c-plane sapphire without miscut angle. In-depth
characterizations and theoretical calculations reveal that the introduction of
Fe significantly decreases the formation energy of parallel steps on sapphire
surfaces and contributes to the edge-nucleation of unidirectional TMDCs domains
(>99%). The ultrahigh electron mobility (~86 cm2 V -1 s-1) and remarkable
on/off current ratio (~108) are discovered on 4-inch single-crystal Fe-MoS2
monolayers due to the ultralow contact resistance and perfect Ohmic contact
with metal electrodes. This work represents a substantial leap in terms of
bridging the synthesis and doping of wafer-scale single-crystal 2D
semiconductors without the need for substrate miscut, which should promote the
further device downscaling and extension of Moore's law.Comment: 17 pages, 5 figure
Biochar-mediated control of metabolites and other physiological responses in water-stressed Leptocohloa fusca
We investigated biochar-induced drought tolerance in Leptocohloa fusca (Kallar grass) by exploring the plant defense system at physiological level. L. fusca plants were exposed to drought stress (100%, 70%, and 30% field capacity), and biochar (BC), as an organic soil amendment was applied in two concentrations (15 and 30 mg kg−1 soil) to induce drought tolerance. Our results demonstrated that drought restricted the growth of L. fusca by inhibiting shoot and root (fresh and dry) weight, total chlorophyll content and photosynthetic rate. Under drought stress, the uptake of essential nutrients was also limited due to lower water supply, which ultimately affected metabolites including amino and organic acids, and soluble sugars. In addition, drought stress induced oxidative stress, which is evidenced by the higher production of reactive oxygen species (ROS) including hydrogen peroxide (H2O2), superoxide ion (O2−), hydroxyl ion (OH−), and malondialdehyde (MDA). The current study revealed that stress-induced oxidative injury is not a linear path, since the excessive production of lipid peroxidation led to the accumulation of methylglyoxal (MG), a member of reactive carbonyl species (RCS), which ultimately caused cell injury. As a consequence of oxidative-stress induction, the ascorbate–glutathione (AsA–GSH) pathway, followed by a series of reactions, was activated by the plants to reduce ROS-induced oxidative damage. Furthermore, biochar considerably improved plant growth and development by mediating metabolites and soil physio-chemical status
The Influence of Light Intensity and Leaf Movement on Photosynthesis Characteristics and Carbon Balance of Soybean
In intercropping systems shading conditions significantly impair the seed yield and quality of soybean, and rarely someone investigated the minimum amount of light requirement for soybean growth and development. Therefore, it is an urgent need to determine the threshold light intensity to ensure sustainable soybean production under these systems. An integrated approach combining morphology, physiology, biochemistry and genetic analysis was undertaken to study the light intensity effects on soybean growth and development. A pot experiment was set up in a growth chamber under increasing light intensity treatments of 100 (L100), 200 (L200), 300 (L300), 400 (L400), and 500 (L500) μmol m−2 s−1. Compared with L100, plant height, hypocotyl length, and abaxial leaf petiole angle were decreased, biomass, root:shoot ratio, and stem diameter were increased, extremum was almost observed in L400 and L500. Leaf petiole movement and leaf hyponasty in each treatment has presented a tendency to decrease the leaf angle from L500 to L100. In addition, the cytochrome content (Chl a, Chl b, Car), net photosynthetic rate, chlorophyll fluorescence values of Fv/Fm, Fv′/Fm′, ETR, ΦPSII, and qP were increased as the light intensity increased, and higher values were noted under L400. Leaf microstructure and chloroplast ultrastructure positively improved with increasing light intensity, and leaf-thickness, palisade, and spongy tissues-thickness were increased by 105, 90, and 370%, under L500 than L100. Moreover, the cross-sectional area of chloroplast (C) outer membrane and starch grains (S), and sectional area ratio (S:C) was highest under L400 and L500, respectively. Compared to L100, the content of starch granules increased by 35.5, 122.0, 157.6, and 145.5%, respectively in L400. The same trends were observed in the enzyme activity of sucrose-synthase, sucrose phosphate synthase, starch synthase, rubisco, phosphoenol pyruvate carboxykinase, and phosphoenol pyruvate phosphatase. Furthermore, sucrose synthesis-related genes were also up-regulated by increasing light intensity, and the highest seed yield and yield related parameters were recorded in the L400. Overall, these results suggested that 400 and 500 μmol m−2 s−1 is the optimum light intensity which positively changed the leaf orientation and adjusts leaf angle to perpendicular to coming light, consequently, soybean plants grow well under prevailing conditions
Genetic Evidence for an Indispensable Role of Somatic Embryogenesis Receptor Kinases in Brassinosteroid Signaling
The authors are grateful to the Arabidopsis Biological Resource Center for providing the T-DNA insertion lines discussed in this work. We thank Dr. Yanhai Yin (Iowa State University) for providing anti-BES1 antibody, Dr. Jiayang Li (Institute of Genetics and Developmental Biology, Chinese Academy of Sciences) for bri1-301 seeds, and Dr. Xing-wang Deng (Yale University) for cop1-4 and cop1-6 seeds as controls.Author Summary Brassinosteroids (BRs) are a group of plant hormones critical for plant growth and development. BRs are perceived by a cell-surface receptor complex including two distinctive receptor kinases, BRI1 and BAK1. Whereas BRI1 is a true BR-binding receptor, BAK1 does not appear to have BR-binding activity. Therefore, BAK1 is likely a co-receptor in BR signal transduction. The genetic significance of BAK1 was not clearly demonstrated in previous studies largely due to functional redundancy of BAK1 and its closely related homologues. It was not clear whether BAK1 plays an essential role or only an enhancing role in BR signaling. In this study, we identified all possible BAK1 redundant genes in the Arabidopsis thaliana genome and generated single, double, triple, and quadruple mutants. Detailed analysis indicated that, without BAK1 and its functionally redundant proteins, BR signaling is completely disrupted, largely because BRI1 has lost its ability to activate downstream components. These studies provide the first piece of loss-of-functional genetic evidence that BAK1 is indispensable to the early events of the BR signaling pathway.Yeshttp://www.plosgenetics.org/static/editorial#pee
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