18,495 research outputs found
Influence of building collapse on pluvial and fluvial flood inundation of metro stations in central Shanghai
Urban flooding poses a significant threat to vulnerable underground infrastructure systems, such as metro stations. Building collapse induced by earthquakes alters urban building layout and coverage, consequently influencing flood inundation and propagation patterns. This study employs GPU-accelerated hydrodynamic simulation to investigate the mechanisms by which building collapse affects subsequent pluvial or fluvial flooding in the Huangpu District of Shanghai. Massive building collapse layouts are randomly generated, on which hydrodynamic simulations are performed and the inundation process of the metro stations is analyzed. The results reveal that pluvial floods are strongly influenced by localized topography distributed across the city. Consequently, building collapse has a more substantial impact on pluvial flooding when more buildings have collapsed. In contrast, fluvial floods are sensitive to the source location (e.g., location of levee breach) and the long travel route. Building collapse can either positively or negatively influence fluvial flooding by constricting or blocking the flow path. This work highlights the complex mechanism of earthquake–flood multi-hazard processes, emphasizing the importance of performing local-to-local analysis when both the hazard (e.g., individual building collapse, fluvial flood) and the hazard-bearing body (e.g., metro station) are localized. To better serve urban disaster prevention and mitigation, more efforts should be directed to developing physics-based high-resolution urban earthquake–flood simulation methods, as well as to acquiring data to drive such simulations.</p
Antioxidant and anti-inflammatory effects of rhamnazin on lipopolysaccharide-induced acute lung injury and inflammation in rats
Background: Acute Lung Injury (ALI) results into severe inflammation and oxidative stress to the pulmonary tissue. Rhamnazin is a natural flavonoid and known for its antioxidant and anti-inflammatory properties.Materials and methods: The antioxidative and anti-inflammatory properties rhamnazin were tested for protection against the acute lung injury. We investigated whether rhamnazin improves the lipopolysaccharide (LPS)-induced ALI in an animal model (rat). We also studied the probable molecular mechanism of action of rhamnazin. Rhamnazin was injected intraperitoneally (i.p.) (5, 10 and 20 mg/kg) two days before intratracheal LPS challenge (5mg/kg). The changes in lung wet-to-dry weight ratio, LDH activity, pulmonary histopathology, BALF protein concentration, MPO activity, oxidative stress, cytokine production were estimated.Results: The results showed a significant attenuation of all the inflammatory parameters and a marked improvement in the pulmonary histopathology in the animal groups pretreated with rhamnazin. The rhamnazin pretreated group also showed activation of Nrf2 pathway and attenuation of ROS such as H2O2, MDA and hydroxyl ion. These results indicated that rhamnazin could attenuate the symptoms of ALI in rats due to its strong antioxidant and anti-inflammatory properties.Conclusion: The results strongly demonstrated that rhamnazin provides protection against LPS-induced ALI. The underlying mechanisms of its anti-inflammatory action may include inhibition of Nrf2 mediated antioxidative pathway.Keywords: acute lung injury, inflammation, cytokine, BALF, flavonoi
MTR++: Multi-Agent Motion Prediction with Symmetric Scene Modeling and Guided Intention Querying
Motion prediction is crucial for autonomous driving systems to understand
complex driving scenarios and make informed decisions. However, this task is
challenging due to the diverse behaviors of traffic participants and complex
environmental contexts. In this paper, we propose Motion TRansformer (MTR)
frameworks to address these challenges. The initial MTR framework utilizes a
transformer encoder-decoder structure with learnable intention queries,
enabling efficient and accurate prediction of future trajectories. By
customizing intention queries for distinct motion modalities, MTR improves
multimodal motion prediction while reducing reliance on dense goal candidates.
The framework comprises two essential processes: global intention localization,
identifying the agent's intent to enhance overall efficiency, and local
movement refinement, adaptively refining predicted trajectories for improved
accuracy. Moreover, we introduce an advanced MTR++ framework, extending the
capability of MTR to simultaneously predict multimodal motion for multiple
agents. MTR++ incorporates symmetric context modeling and mutually-guided
intention querying modules to facilitate future behavior interaction among
multiple agents, resulting in scene-compliant future trajectories. Extensive
experimental results demonstrate that the MTR framework achieves
state-of-the-art performance on the highly-competitive motion prediction
benchmarks, while the MTR++ framework surpasses its precursor, exhibiting
enhanced performance and efficiency in predicting accurate multimodal future
trajectories for multiple agents.Comment: Accepted by IEEE Transactions on Pattern Analysis and Machine
Intelligence (TPAMI 2024). The winning approaches for the Waymo Motion
Prediction Challenge in 2022 and 202
Microbial communities and arsenic biogeochemistry at the outflow of an alkaline sulfide-rich hot spring.
Alkaline sulfide-rich hot springs provide a unique environment for microbial community and arsenic (As) biogeochemistry. In this study, a representative alkaline sulfide-rich hot spring, Zimeiquan in the Tengchong geothermal area, was chosen to study arsenic geochemistry and microbial community using Illumina MiSeq sequencing. Over 0.26 million 16S rRNA sequence reads were obtained from 5-paired parallel water and sediment samples along the hot spring's outflow channel. High ratios of As(V)/AsSum (total combined arsenate and arsenite concentrations) (0.59-0.78), coupled with high sulfide (up to 5.87 mg/L), were present in the hot spring's pools, which suggested As(III) oxidation occurred. Along the outflow channel, AsSum increased from 5.45 to 13.86 μmol/L, and the combined sulfide and sulfate concentrations increased from 292.02 to 364.28 μmol/L. These increases were primarily attributed to thioarsenic transformation. Temperature, sulfide, As and dissolved oxygen significantly shaped the microbial communities between not only the pools and downstream samples, but also water and sediment samples. Results implied that the upstream Thermocrinis was responsible for the transformation of thioarsenic to As(III) and the downstream Thermus contributed to derived As(III) oxidation. This study improves our understanding of microbially-mediated As transformation in alkaline sulfide-rich hot springs
Role of the porous structure of the bioceramic scaffolds in bone tissue engineering
The porous structure of biomaterials plays a critical role in improving the efficiency of biomaterials in tissue engineering. Here we fabricate successfully porous bioceramics with accurately controlled pore parameters, and investigate the effect of pore parameters on the mechanical property, the cell seeding proliferation and the vascularization of the scaffolds. This study shows that the porosity play an important role on the mechanical property of the scaffolds, which is affected not only by the macropores size, but also by the interconnections of the scaffolds. Larger pores are beneficial for cell growth in scaffolds. In contrast, the interconnections do not affect cell growth much. The interconnections appear to limit the number of blood vessels penatrating through adjacent pores, and both the pores size and interconnections can determine the size of blood vessels. The results may be referenced on the selective design of porous structure of biomaterials to meet the specificity of biological application
CeNiAsO: an antiferromagnetic dense Kondo lattice
A cerium containing pnictide, CeNiAsO, crystallized in the ZrCuSiAs type
structure, has been investigated by measuring transport and magnetic
properties, as well as specific heat. We found that CeNiAsO is an
antiferromagnetic dense Kondo lattice metallic compound with Kondo scale 15 K and shows an enhanced Sommerfeld coefficient of 203
mJ/molK. While no superconductivity can been observed down to 30
mK, Ce ions exhibit two successive antiferromagnetic (AFM) transitions. We
propose that the magnetic moment of Ce ion could align in the G type AFM order
below the first transition at =9.3 K, and it might be modified into the
C type AFM order below a lower transition at =7.3 K. Our results
indicate that the 3 interlayer Kondo interactions play an important role
in Ni-based Ce-containing pnictide.Comment: 13 pages, 5 figures, to appear in J. Phys.: Condens. Matte
Guided flows in coronal magnetic flux tubes
There is evidence for coronal plasma flows to break down into fragments and
to be laminar. We investigate this effect by modeling flows confined along
magnetic channels. We consider a full MHD model of a solar atmosphere box with
a dipole magnetic field. We compare the propagation of a cylindrical flow
perfectly aligned to the field to that of another one with a slight
misalignment. We assume a flow speed of 200 km/s, and an ambient magnetic field
of 30 G. We find that while the aligned flow maintains its cylindrical symmetry
while it travels along the magnetic tube, the misaligned one is rapidly
squashed on one side, becoming laminar and eventually fragmented because of the
interaction and backreaction of the magnetic field. This model could explain an
observation of erupted fragments that fall back as thin and elongated strands
and end up onto the solar surface in a hedge-like configuration, made by the
Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The
initial alignment of plasma flow plays an important role in determining the
possible laminar structure and fragmentation of flows while they travel along
magnetic channels.Comment: 11 pages, 8 figures, accepted for publication, movies available upon
request to the first autho
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