197 research outputs found
Scalable and Safe Multi-Agent Motion Planning with Nonlinear Dynamics and Bounded Disturbances
We present a scalable and effective multi-agent safe motion planner that
enables a group of agents to move to their desired locations while avoiding
collisions with obstacles and other agents, with the presence of rich
obstacles, high-dimensional, nonlinear, nonholonomic dynamics, actuation
limits, and disturbances. We address this problem by finding a piecewise linear
path for each agent such that the actual trajectories following these paths are
guaranteed to satisfy the reach-and-avoid requirement. We show that the spatial
tracking error of the actual trajectories of the controlled agents can be
pre-computed for any qualified path that considers the minimum duration of each
path segment due to actuation limits. Using these bounds, we find a
collision-free path for each agent by solving Mixed Integer-Linear Programs and
coordinate agents by using the priority-based search. We demonstrate our method
by benchmarking in 2D and 3D scenarios with ground vehicles and quadrotors,
respectively, and show improvements over the solving time and the solution
quality compared to two state-of-the-art multi-agent motion planners.Comment: Accepted at AAAI2021. 9 pages, 5 figures, 1 tabl
Sound non-reciprocity based on synthetic magnetism
Synthetic magnetism has been recently realized using spatiotemporal
modulation patterns, producing non-reciprocal steering of charge-neutral
particles such as photons and phonons. Here, we design and experimentally
demonstrate a non-reciprocal acoustic system composed of three compact cavities
interlinked with both dynamic and static couplings, in which phase-correlated
modulations induce a synthetic magnetic flux that breaks time-reversal
symmetry. Within the rotating wave approximation, the transport properties of
the system are controlled to efficiently realize large non-reciprocal acoustic
transport. By optimizing the coupling strengths and modulation phases, we
achieve frequency-preserved unidirectional transport with 45-dB isolation ratio
and 0.85 forward transmission. Our results open to the realization of acoustic
nonreciprocal technologies with high efficiency and large isolation, and offer
a route towards Floquet topological insulators for sound.Comment: 13 pages, 4 figure
The life cycle of Dermacentor nuttalli from the Qinghai-Tibetan Plateau under laboratory conditions and detection of spotted fever group Rickettsia spp.
Dermacentor nuttalli has been a focus of study because tick-borne pathogens have been widely identified in this tick from northern and southwestern China. The aim of this study was to characterize the life cycle of D. nuttalli under laboratory conditions and to detect spotted fever group (SFG) Rickettsia in the midgut and salivary glands of both field-collected and first laboratory generation adults. D. nuttalli ticks were collected in the field on the Qinghai-Tibetan Plateau from March to April 2021 and their life cycle was studied under laboratory conditions. Tick identify was molecularly confirmed, and SFG Rickettsia were detected in the midgut and salivary glands of males and females by PCR targeting different rickettsial genes. The results showed that the life cycle of D. nuttalli under laboratory conditions was completed in an average of 86.1 days. High positivity of Rickettsia spp. was detected in the midgut and salivary glands of both males (92.0%) and females (93.0%) of field-collected D. nuttalli ticks. However, a relatively lower positivity (4.0â6.0%) was detected in first laboratory generation adults. Furthermore, sequencing analysis showed that the Rickettsia sequences obtained in this study shared 98.6 to 100% nucleotide identity with Rickettsia slovaca and Rickettsia raoultii isolated from Dermacentor spp. in China. Phylogenetic analysis of Rickettsia spp. based on the gltA, ompA, ompB and sca4 genes revealed that the Rickettsia sequences obtained could be classified as belonging to R. slovaca and R. raoultii clades. This study described for the first time the life cycle of D. nuttalli from the Qinghai-Tibetan Plateau under laboratory conditions. Two species of SFG Rickettsia were detected in the midgut and salivary glands of males and females in both field-collected and first laboratory-generation adults of D. nuttalli. Our study provides new insights into pathogen detection in ticks in the Qinghai-Tibet Plateau, and the relationships among hosts, ticks, and pathogens
Enhanced Interfacial Electronic Transfer of BiVO4 Coupled with 2D gâC3N4 for Visibleâlight Photocatalytic Performance
A BiVO4/2D gâC3N4 direct dual semiconductor photocatalytic system has been fabricated via electrostatic selfâassembly method of BiVO4 microparticle and gâC3N4 nanosheet. According to experimental measurements and firstâprinciple calculations, the formation of builtâin electric field and the opposite band bending around the interface region in BiVO4/2D gâC3N4 as well as the intimate contact between BiVO4 and 2D gâC3N4 will lead to high separation efficiency of charge carriers. More importantly, the intensity of bulidâin electric field is greatly enhanced due to the ultrathin nanosheet structure of 2D gâC3N4. As a result, BiVO4/2D gâC3N4 exhibits excellent photocatalytic performance with the 93.0% Rhodamine B (RhB) removal after 40 min visible light irradiation, and the photocatalytic reaction rate is about 22.7 and 10.3 times as high as that of BiVO4 and 2D gâC3N4, respectively. In addition, BiVO4/2D gâC3N4 also displays enhanced photocatalytic performance in the degradation of tetracycline (TC). It is expected that this work may provide insights into the understanding the significant role of builtâin electric field in heterostructure and fabricating highly efficient direct dual semiconductor systems
Repurposing of posaconazole as a hedgehog/SMO signaling inhibitor for embryonal rhabdomyosarcoma therapy
Posaconazole (POS) is a novel antifungal agent, which has been repurposed as an anti-tumor drug for its potential inhibition of Hedgehog signaling pathway. Hedgehog pathway is reported to be abnormally activated in embryonal rhabdomyosarcoma (ERMS), this study aimed to reveal whether POS could inhibit Hedgehog signaling pathway in ERMS. Following POS treatment, XTT viability assay was used to determine the cell proliferation of ERMS cell lines. Protein changes related to Hedgehog signaling, cell cycle and autophagy were detected by Western blot. The cell cycle distribution was analyzed by flow cytometry. Moreover, a subcutaneous tumor mouse model of ERMS was established to assess the anti-tumor effect of POS. POS was found to inhibit tumor progression by inducing G0/G1 arrest and autophagy of RD, RMS-YM, and KYM-1 cells dose-dependently. Western blot demonstrated that POS downregulated the expressions of SMO, Gli1, c-Myc, CDK4, and CDK6, while upregulated the expressions of autophagy-related proteins. Immunofluorescence microscopy revealed a significant increase of LC3B puncta in POS-treated ERMS cells. Furthermore, POS treatment led to a significant inhibition of tumor growth in mice bearing ERMS. Our findings could provide a theoretical basis and have important clinical implications in developing POS as a promising agent against ERMS by targeting Hedgehog pathway
Light-activated ferroelectric transition in layer dependent Bi2O2Se films
Bi2O2Se has attracted intensive attention due to its potential in
electronics, optoelectronics, as well as ferroelectric applications. Despite
that, there have only been a handful of experimental studies based on ultrafast
spectroscopy to elucidate the carrier dynamics in Bi2O2Se thin films, Different
groups have reported various ultrafast timescales and associated mechanisms
across films of different thicknesses. A comprehensive understanding in
relation to thickness and fluence is still lacking. In this work, we have
systematically explored the thickness-dependent Raman spectroscopy and
ultrafast carrier dynamics in chemical vapor deposition (CVD)-grown Bi2O2Se
thin films on mica substrate with thicknesses varying from 22.44 nm down to
4.62 nm at both low and high pump fluence regions. Combining the thickness
dependence and fluence dependence of the slow decay time, we demonstrate a
ferroelectric transition in the thinner (< 8 nm) Bi2O2Se films, influenced by
substrate-induced compressive strain and non-equilibrium states. Moreover, this
transition can be manifested under highly non-equilibrium states. Our results
deepen the understanding of the interplay between the ferroelectric phase and
semiconducting characteristics of Bi2O2Se thin films, providing a new route to
manipulate the ferroelectric transition
Nitroxoline inhibits bladder cancer progression by reversing EMT process and enhancing anti-tumor immunity
Nitroxoline is considered to be an effective treatment for the urinary tract infections. Recently, it has been found to be effective against several cancers. However, few studies have examined the anti-tumor activity of nitroxoline in bladder cancer. The purpose of the study was to reveal the possible mechanisms how nitroxoline inhibited bladder cancer progression. In vitro assay, we demonstrated that nitroxoline inhibited bladder cancer cell growth and migration in a concentration-related manner. Western blot analysis demonstrated that nitroxoline downregulated the expressions of epithelial mesenchymal transition (EMT)-related proteins. Furthermore, treatment with nitroxoline in the C3H/He mice bladder cancer subcutaneous model resulted in significant inhibition of tumor growth. Moreover, the percentage of myeloid-derived suppressor cells (MDSC) in peripheral blood cells significantly decreased after treatment of nitroxoline. Taken together, our results suggested that nitroxoline may be used as a potential drug for bladder cancer
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