1,246 research outputs found
Spin Speed and Supportedness Correlation and Evolution of Galaxy-Halo Systems
Galaxy angular momenta (spins) contain valuable cosmological information,
complementing with their positions and velocities. The baryonic spin direction
of galaxies have been probed as a reliable tracer of their host halos and the
primordial spin modes. Here we use the TNG100 simulation of the IllustrisTNG
project to study the spin magnitude correlations between dark matter, gas and
stellar components of galaxy-halo systems, and their evolutions across the
cosmic history. We find that these components generate similar initial spin
magnitudes from the same tidal torque in Lagrangian space. At low redshifts,
the gas component still traces the spin magnitude of dark matter halo and the
primordial spin magnitude. However, the traceability of stellar component
depends on the stellar mass fraction, . Our results
suggest that the galaxy baryonic spin magnitude can also serve as a tracer of
their host halo and the initial perturbations, and the similarity of their
evolution histories affects the galaxy-halo correlations.Comment: 9 pages, 7 figures, comments welcom
CoderEval: A Benchmark of Pragmatic Code Generation with Generative Pre-trained Models
Code generation models based on the pre-training and fine-tuning paradigm
have been increasingly attempted by both academia and industry, resulting in
well-known industrial models such as Codex, CodeGen, and PanGu-Coder. To
evaluate the effectiveness of these models, multiple existing benchmarks are
proposed, including only cases of generating a standalone function, i.e., a
function that may invoke or access only built-in functions and standard
libraries. However, non-standalone functions, which typically are not included
in the existing benchmarks, constitute more than 70% of the functions in
popular open-source projects, and evaluating models' effectiveness on
standalone functions cannot reflect these models' effectiveness on pragmatic
code generation scenarios.
To help bridge the preceding gap, in this paper, we propose a benchmark named
CoderEval, consisting of 230 Python and 230 Java code generation tasks
carefully curated from popular real-world open-source projects and a
self-contained execution platform to automatically assess the functional
correctness of generated code. CoderEval supports code generation tasks from
six levels of context dependency, where context refers to code elements such as
types, APIs, variables, and consts defined outside the function under
generation but within the dependent third-party libraries, current class, file,
or project. CoderEval can be used to evaluate the effectiveness of models in
generating code beyond only standalone functions. By evaluating three code
generation models on CoderEval, we find that the effectiveness of these models
in generating standalone functions is substantially higher than that in
generating non-standalone functions. Our analysis highlights the current
progress and pinpoints future directions to further improve a model's
effectiveness by leveraging contextual information for pragmatic code
generation
Searching for axion dark matter with MeerKAT Radio Telescope
Axions provide a natural and well-motivated dark matter candidate, with the
capability to convert directly to photons in the presence of an electromagnetic
field. A particularly compelling observational target is the conversion of dark
matter axions into photons in the magnetospheres of highly magnetised neutron
stars, which is expected to produce a narrow spectral peak centred at the
frequency of the axion mass. We point the MeerKAT radio telescope towards the
isolated neutron star J0806.44123 for -hours of observation and obtain
the radio spectra in the frequency range - MHz. By modelling the
conversion process of infalling axion dark matter (DM), we then compare these
spectra to theoretical expectations for a given choice of axion parameters.
Whilst finding no signal above in the data, we provide a unique
constraint on the Primakoff coupling of axion DM, at the
confidence level, in the mass range -eV. This result serves
the strongest constraint in the axion mass range -eV.Comment: 6 pages, 3 figures, accepted by Physical Review
Glt25d2 Knockout Directly Increases CD25+CD69ā but Decreases CD25āCD69+ Subset Proliferation and is Involved in Concanavalin-Induced Hepatitis
Background/Aims: The elaborate structure of the extracellular matrix (ECM) and the appropriate surface glycoforms upon it are indispensable to CD4+ T cell regulation. Methods: To explore the effects of GlcĪ±1,2GalĪ²1 glycosylation mediated by GLT25D2 (Colgalt2) for CD4+ T cell regulation, we prepared C57BL/6J Glt25d2-/- mice. In the induction of hepatitis, after concanavalin A (Con A) challenge for 6, 12, and 24 h, more extensive parenchymal injury was noted in Glt25d2-/- mice than in wild-type (WT) mice at 12 h. Immunohistochemistry and laser scanning confocal microscopy were used to detect GLT25D2 expression, and subsets of CD4+T cells was analyzed by flow cytometry. A total of 26 cytokines in serum samples were determined using Luminex technology. Results: The trend in liver injury score variation was consistent with serum alanine aminotransferase and aspartate aminotransferase levels. The levels of interleukin 4 (IL-4), IL-1Ī², IL-9, and several chemokines such as macrophage inflammatory protein-2, eotaxin, and growth-related oncogene Ī± were significantly increased in Glt25d2-/- mice compared with WT mice after Con A challenge. A further phenotype analysis of primary Glt25d2-/- CD4+ T cells showed that Glt25d2 knockout increased the frequency of the CD25+CD69- subset but decreased the frequency of the CD25-CD69+ subset after Con A challenge for 6, 12, and 24 h compared with those of WT CD4+ T cells. Activation-induced apoptosis was also significantly increased in Glt25d2-/- CD4+ T cells after Con A challenge compared with WT CD4+ T cells. Lectin microarray hybridization showed that Glt25d2 knockout increased the binding activity of Narcissus pseudonarcissus lectin to CD4+ T cells but Amaranthus caudatus lectinābinding activity was lost during Con A challenge. Conclusion: The present results suggest that collagen glycosylation mediated by GLT25D2 may regulate a subset of CD4+ T cells and be involved in the pathogenesis of Con Aāinduced hepatitis
Fine-Grained Video Retrieval With Scene Sketches
Benefiting from the intuitiveness and naturalness of sketch interaction, sketch-based video retrieval (SBVR) has received considerable attention in the video retrieval research area. However, most existing SBVR research still lacks the capability of accurate video retrieval with fine-grained scene content. To address this problem, in this paper we investigate a new task, which focuses on retrieving the target video by utilizing a fine-grained storyboard sketch depicting the scene layout and major foreground instancesā visual characteristics (e.g., appearance, size, pose, etc.) of video; we call such a task āfine-grained scene-level SBVRā. The most challenging issue in this task is how to perform scene-level cross-modal alignment between sketch and video. Our solution consists of two parts. First, we construct a scene-level sketch-video dataset called SketchVideo, in which sketch-video pairs are provided and each pair contains a clip-level storyboard sketch and several keyframe sketches (corresponding to video frames). Second, we propose a novel deep learning architecture called Sketch Query Graph Convolutional Network (SQ-GCN). In SQ-GCN, we first adaptively sample the video frames to improve video encoding efficiency, and then construct appearance and category graphs to jointly model visual and semantic alignment between sketch and video. Experiments show that our fine-grained scene-level SBVR framework with SQ-GCN architecture outperforms the state-of-the-art fine-grained retrieval methods. The SketchVideo dataset and SQ-GCN code are available in the project webpage https://iscas-mmsketch.github.io/FG-SL-SBVR/
A Novel Mechanism of Mesenchymal Stromal Cell-Mediated Protection against Sepsis: Restricting Inflammasome Activation in Macrophages by Increasing Mitophagy and Decreasing Mitochondrial ROS
Sepsis, a systemic inflammatory response to infection, is the leading cause of death in the intensive care unit (ICU). Previous studies indicated that mesenchymal stromal cells (MSCs) might have therapeutic potential against sepsis. The current study was designed to investigate the effects of MSCs on sepsis and the underlying mechanisms focusing on inflammasome activation in macrophages. The results demonstrated that the bone marrow-derived mesenchymal stem cells (BMSCs) significantly increased the survival rate and organ function in cecal ligation and puncture (CLP) mice compared with the control-grouped mice. BMSCs significantly restricted NLRP3 inflammasome activation, suppressed the generation of mitochondrial ROS, and decreased caspase-1 and IL-1Ī² activation when cocultured with bone marrow-derived macrophages (BMDMs), the effects of which could be abolished by Mito-TEMPO. Furthermore, the expression levels of caspase-1, IL-1Ī², and IL-18 in BMDMs were elevated after treatment with mitophagy inhibitor 3-MA. Thus, BMSCs exert beneficial effects on inhibiting NLRP3 inflammasome activation in macrophages primarily via both enhancing mitophagy and decreasing mitochondrial ROS. These findings suggest that restricting inflammasome activation in macrophages by increasing mitophagy and decreasing mitochondrial ROS might be a crucial mechanism for MSCs to combat sepsis
Quantum simulation of topological zero modes on a 41-qubit superconducting processor
Quantum simulation of different exotic topological phases of quantum matter
on a noisy intermediate-scale quantum (NISQ) processor is attracting growing
interest. Here, we develop a one-dimensional 43-qubit superconducting quantum
processor, named as Chuang-tzu, to simulate and characterize emergent
topological states. By engineering diagonal
Aubry-Andr-Harper (AAH) models, we experimentally
demonstrate the Hofstadter butterfly energy spectrum. Using Floquet
engineering, we verify the existence of the topological zero modes in the
commensurate off-diagonal AAH models, which have never been experimentally
realized before. Remarkably, the qubit number over 40 in our quantum processor
is large enough to capture the substantial topological features of a quantum
system from its complex band structure, including Dirac points, the energy
gap's closing, the difference between even and odd number of sites, and the
distinction between edge and bulk states. Our results establish a versatile
hybrid quantum simulation approach to exploring quantum topological systems in
the NISQ era.Comment: Main text: 6 pages, 4 figures; Supplementary: 16 pages, 14 figure
Prevalence of Stroke and Hypoperfusion in Patients With Isolated Vertigo and Vascular Risk Factors
Background and Purpose: The aim of this study was to determine the prevalence and associated factors of stroke and hypoperfusion among patients with isolated vertigo and vascular risk factors.Methods: We studied 157 patients with isolated vertigo who had undergone multimodal magnetic resonance imaging. Magnetic resonance angiography (MRA) was used to measure the diameters of vertebrobasilar arteries and to evaluate morphologic changes to vessels. Measurements obtained included length of the basilar artery and curvature index for the vertebral artery (VA). Perfusion-weighted imaging (PWI) was performed to determine relative cerebral blood flow, relative cerebral blood volume (rCBV), time to peak (TTP), and mean transit time for two mirror regions of interest (ROIs) in each map. Regional hypoperfusion of the cerebellum was considered significant when TTP and mean transit time (MTT) were present in ā„2 adjacent slices.Results: The prevalence of stroke in patients with isolated vertigo and vascular risk factors was 24.8% (n = 39). Visual assessment revealed cerebellar hypoperfusion in 57.6% (68/118) of non-stroke patients. Multivariate logistic regression indicated that diabetes mellitus (P = 0.049, OR = 2.758), VA stenosis or hypoplasia (P = 0.023, OR = 3.486), and relative TTP of cerebellum (P = 0.002, OR = 3.197) were independent risk factors for stroke and LVA curvature index (P = 0.026, OR = 2.049), VA stenosis and hypoplasia (P = 0.009, OR = 2.977) were independent risk factors for hypoperfusion.Conclusions: The prevalence of stroke and hypoperfusion is higher in patients with isolated vertigo and vascular risk factors, compared with matched controls. Potential risk factors include diabetes mellitus, VA stenosis or hypoplasia, and enlarged VA curvature index
Titanium Nitride Film on Sapphire Substrate with Low Dielectric Loss for Superconducting Qubits
Dielectric loss is one of the major decoherence sources of superconducting
qubits. Contemporary high-coherence superconducting qubits are formed by
material systems mostly consisting of superconducting films on substrate with
low dielectric loss, where the loss mainly originates from the surfaces and
interfaces. Among the multiple candidates for material systems, a combination
of titanium nitride (TiN) film and sapphire substrate has good potential
because of its chemical stability against oxidization, and high quality at
interfaces. In this work, we report a TiN film deposited onto sapphire
substrate achieving low dielectric loss at the material interface. Through the
systematic characterizations of a series of transmon qubits fabricated with
identical batches of TiN base layers, but different geometries of qubit
shunting capacitors with various participation ratios of the material
interface, we quantitatively extract the loss tangent value at the
substrate-metal interface smaller than in 1-nm disordered
layer. By optimizing the interface participation ratio of the transmon qubit,
we reproducibly achieve qubit lifetimes of up to 300 s and quality factors
approaching 8 million. We demonstrate that TiN film on sapphire substrate is an
ideal material system for high-coherence superconducting qubits. Our analyses
further suggest that the interface dielectric loss around the Josephson
junction part of the circuit could be the dominant limitation of lifetimes for
state-of-the-art transmon qubits
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