135 research outputs found
Scene Graph Modification as Incremental Structure Expanding
A scene graph is a semantic representation that expresses the objects,
attributes, and relationships between objects in a scene. Scene graphs play an
important role in many cross modality tasks, as they are able to capture the
interactions between images and texts. In this paper, we focus on scene graph
modification (SGM), where the system is required to learn how to update an
existing scene graph based on a natural language query. Unlike previous
approaches that rebuilt the entire scene graph, we frame SGM as a graph
expansion task by introducing the incremental structure expanding (ISE). ISE
constructs the target graph by incrementally expanding the source graph without
changing the unmodified structure. Based on ISE, we further propose a model
that iterates between nodes prediction and edges prediction, inferring more
accurate and harmonious expansion decisions progressively. In addition, we
construct a challenging dataset that contains more complicated queries and
larger scene graphs than existing datasets. Experiments on four benchmarks
demonstrate the effectiveness of our approach, which surpasses the previous
state-of-the-art model by large margins.Comment: In COLING 2022 as a long paper. Code and data available at
https://github.com/THU-BPM/SG
Two-dimensional germanium islands with Dirac signature on Ag2Ge surface alloy
Two-dimensional (2D) Dirac materials have attracted intense research efforts
due to their promise for applications ranging from field-effect transistors and
low-power electronics to fault-tolerant quantum computation. One key challenge
is to fabricate 2D Dirac materials hosting Dirac electrons. Here, monolayer
germanene is successfully fabricated on a Ag2Ge surface alloy. Scanning
tunneling spectroscopy measurements revealed a linear energy dispersion
relation. The latter was supported by density functional theory calculations.
These results demonstrate that monolayer germanene can be realistically
fabricated on a Ag2Ge surface alloy. The finding opens the door to exploration
and study of 2D Dirac material physics and device applications
B7DC/PDL2 Promotes Tumor Immunity by a PD-1âindependent Mechanism
B7H1 (PDL1) and B7DC (PDL2) are two new members of the B7 family that can interact with PD-1, a putative negative regulator for immune function. Recent studies have provided evidence for inhibitory functions of both members via PD-1. Meanwhile, compelling evidence exists for costimulatory function of both members. Here we demonstrate that expression of B7DC on the tumor cells promotes CD8 T cellâmediated rejection of tumor cells, at both the induction and effector phase of antitumor immunity. Moreover, B7DC binds to PD-1(â/â) cells and enhances T cell killing in a PD-1âindependent mechanism. Our results demonstrate a novel pathway for B7DC to promote tumor immunity and may reconcile the apparently contradictory findings on the function of B7DC
WISDOM Project -- XV. Giant Molecular Clouds in the Central Region of the Barred Spiral Galaxy NGC 5806
We present high spatial resolution ( pc) Atacama Large
Millimeter/sub-millimeter Array CO(2-1) observations of the central
region of the nearby barred spiral galaxy NGC 5806. NGC 5806 has a highly
structured molecular gas distribution with a clear nucleus, a nuclear ring and
offset dust lanes. We identify spatially- and spectrally-resolved giant
molecular clouds (GMCs). These clouds have comparable sizes ()
and larger gas masses, observed linewidths () and
gas mass surface densities than those of clouds in the Milky Way disc. The size
-- linewidth relation of the clouds is one of the steepest reported so far
(), the clouds are on
average only marginally bound (with a mean virial parameter
), and high velocity dispersions
are observed in the nuclear ring. These behaviours are likely due to bar-driven
gas shocks and inflows along the offset dust lanes, and we infer an inflow
velocity of kms and a total molecular gas mass inflow rate
of M yr into the nuclear ring. The observed internal
velocity gradients of the clouds are consistent with internal turbulence. The
number of clouds in the nuclear ring decreases with azimuthal angle downstream
from the dust lanes without clear variation of cloud properties. This is likely
due to the estimated short lifetime of the clouds ( Myr), which
appears to be mainly regulated by cloud-cloud collision and/or shear processes.
Overall, it thus seems that the presence of the large-scale bar and gas inflows
to the centre of NGC 5806 affect cloud properties.Comment: Accepted for publication in MNRAS, 20 pages, 16 figure
WISDOM project -- XVI. SMBH mass in the early-type galaxies NGC0612, NGC1574, and NGC4261 from CO dynamical modelling
We present a CO dynamical estimate of the mass of the super-massive black
hole (SMBH) in three nearby early-type galaxies: NGC0612, NGC1574 and NGC4261.
Our analysis is based on Atacama Large Millimeter/submillimeter Array (ALMA)
Cycle 3-6 observations of the CO(2-1) emission line with spatial
resolutions of pc (). We detect disc-like CO
distributions on scales from pc (NGC1574 and NGC4261) to
kpc (NGC0612). In NGC0612 and NGC1574 the bulk of the gas is
regularly rotating. The data also provide evidence for the presence of a
massive dark object at the centre of NGC1574, allowing us to obtain the first
measure of its mass, M
(1 uncertainty). In NGC4261, the CO kinematics is clearly dominated by
the SMBH gravitational influence, allowing us to determine an accurate black
hole mass of M (
uncertainty). This is fully consistent with a previous CO dynamical estimate
obtained using a different modelling technique. Signs of non-circular gas
motions (likely outflow) are also identified in the inner regions of NGC4261.
In NGC0612, we are only able to obtain a (conservative) upper limit of M. This has likely to be ascribed to the
presence of a central CO hole (with a radius much larger than that of the SMBH
sphere of influence), combined with the inability of obtaining a robust
prediction for the CO velocity curve. The three SMBH mass estimates are overall
in agreement with predictions from the relation.Comment: Main text: 20 pages, 14 Figures; Appendix: 7 pages, 6 Figures.
Accepted for publication in MNRAS on 2023 March 2
A fundamental plane of black hole accretion at millimetre wavelengths
We report the discovery of the âmm fundamental plane of black hole accretionâ, which is a tight correlation between the nuclear 1 mm luminosity (LÎœ, mm), the intrinsic 2â10 keV X-ray luminosity (LX, 2â10) and the supermassive black hole (SMBH) mass (MBH) with an intrinsic scatter (Ïint) of 0.40 dex. The plane is found for a sample of 48 nearby galaxies, most of which are low-luminosity active galactic nuclei. Combining these sources with a sample of high-luminosity (quasar-like) nearby AGN, we show that the plane still holds. We also find that MBH correlates with LÎœ, mm at a highly significant level, although such correlation is less tight than the mm fundamental plane (Ïint = 0.51 dex). Crucially, we show that spectral energy distribution (SED) models for both advection-dominated accretion flows (ADAFs) and compact jets can explain the existence of these relations, which are not reproduced by the standard torus-thin accretion disc models usually associated to quasar-like AGN. The ADAF models reproduces the observed relations somewhat better than those for compact jets, although neither provides a perfect fit. Our findings thus suggest that radiatively inefficient accretion processes such as those in ADAFs or compact (and thus possibly young) jets may play a key role in both low- and high-luminosity AGN. This mm fundamental plane also offers a new, rapid method to (indirectly) estimate SMBH masses
Effects of different wheat bran fermentation sources on growth performance, nutrient digestibility, serum antioxidant capacity and fecal microbiota in growing pigs
The present study aimed to evaluate the application of different wheat bran fermentation sources in growing pigs. A total of 320 pigs (43â±â0.21âkg), were randomly allocated to 5 groups in a 21-d trial. The control group was fed a basal diet (CON) containing raw wheat bran, and the other four treatments were fed the diets in which the raw wheat bran in the basal diet was substituted with Aspergillus niger (WBA), Bacillus licheniformis (WBB), Candida utilis (WBC), and Lactobacillus plantarum (WBL) fermented wheat bran, respectively. The results showed that compared to the CON group, the crude fiber and pH values were decreased (pâ<â0.05), while the gross energy (GE), crude protein (CP), and lactic acid values were increased (pâ<â0.05) in all the wheat bran fermented by different strains. Compared with other treatments, feeding B. licheniformis fermented wheat bran had higher final weight, average daily gain, as well as lower feed-to-gain ratio. Compared with CON group, pigs fed with fermented wheat bran diets had higher dry matter, CP, and GE availability, serum total protein, albumin and superoxide dismutase levels, and fecal Lactobacillus counts, as well as lower malondialdehyde level and fecal Escherichia coli count. Collectively, our findings suggested that feeding fermented wheat bran, especially B. licheniformis fermented wheat bran, showed beneficial effects on the growth performance, nutrient digestibility, serum antioxidant capacity, and the gut microbiota structure of growing pigs
Nonlinear Dynamics of Silicon Nanowire Resonator Considering Nonlocal Effect
In this work, nonlinear dynamics of silicon nanowire resonator considering nonlocal effect has been investigated. For the first time, dynamical parameters (e.g., resonant frequency, Duffing coefficient, and the damping ratio) that directly influence the nonlinear dynamics of the nanostructure have been derived. Subsequently, by calculating their response with the varied nonlocal coefficient, it is unveiled that the nonlocal effect makes more obvious impacts at the starting range (from zero to a small value), while the impact of nonlocal effect becomes weaker when the nonlocal term reaches to a certain threshold value. Furthermore, to characterize the role played by nonlocal effect in exerting influence on nonlinear behaviors such as bifurcation and chaos (typical phenomena in nonlinear dynamics of nanoscale devices), we have calculated the Lyapunov exponents and bifurcation diagram with and without nonlocal effect, and results shows the nonlocal effect causes the most significant effect as the device is at resonance. This work advances the development of nanowire resonators that are working beyond linear regime
WISDOM Project - XXI. Giant molecular clouds in the central region of the barred spiral galaxy NGC 613: a steep size - linewidth relation
NGC 613 is a nearby barred spiral galaxy with a nuclear ring. Exploiting high spatial resolution (â20 pc) Atacama Large Millimetre/submillimetre Array 12CO(1â0) observations, we study the giant molecular clouds (GMCs) in the nuclear ring and its vicinity, identifying 158 spatially and spectrally resolved GMCs. The GMC sizes (Rc) are comparable to those of the clouds in the Milky Way (MW) disc, but their gas masses, observed linewidths (Ïobs,los), and gas mass surface densities are larger. The GMC sizeâlinewidth relation (â
â ) is steeper than that of the clouds of the MW disc and centre, and the GMCs are on average only marginally gravitationally bound (with a mean virial parameter â©Î±obs,virâȘ â 1.7). We discuss the possible origins of the steep sizeâlinewidth relation and enhanced observed linewidths of the clouds and suggest that a combination of mechanisms such as stellar feedback, gas accretion, and cloudâcloud collisions, as well as the gas inflows driven by the large-scale bar, may play a role
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