962 research outputs found

    WATER ENTRY HYDROELASTICITY ANALYSIS OF LATTICE SANDWICH PANEL WITH IMPERFECTION: SIMULATION AND ENGINEERING MODEL

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    In the present work, the three dimensional (3D) hydroelasticity characteristics of imperfect lattice sandwich panel (ILSP) subjected to water entry via analytical prediction and numerical simulations are proposed. Firstly, numerical investigations are performed on water entry characteristics based on Arbitrary Eulerian-Lagrange (ALE) coupling method for modeling fluid-structure interaction (FSI) at an impact velocity of 5.0m/s. The results show the impact pressure on total FSI surface of ILSP is generally lower than that of the perfect lattice sandwich panel. Then a novel semi-analytical method to calculate the elastic constants of ILSP is introduced. Based on this approach, an engineering computational model is developed to predict the deformation of ILSP, in which the total deformation is separated into two parts; local field deformation and global field deformation. Good agreement between the numerical and analytical results is achieved. And the effects of geometric parameters such as the thickness of face sheet, height of ILSP and relative density of core are discussed

    A Short Review of U. S. Naval Ship Concept Design Technology Development Features

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    In present study, a history analysis and review of last 30 years for U.S. naval ship concept design development trend is proposed. Based on the development of naval ship concept design model history, the three features of development process are further summarized. The first is that model-based system engineering (MBSE) becomes the basic of naval ship concept design, while the second one is that the multi-discipline crossing and combination becomes a general innovation model. And the third one is that systematization oriented naval system integration is the developing goal. Some detailed examples are presented to illustrate these three characteristics. Finally, the technology difficulties in naval ship concept design are also presented

    Realization of Polarization Control in High-Order Harmonic Generation

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    The nature of high-order harmonic generation process limits the harmonics emission to linear polarization. In this paper, we review the recent progress to generate elliptically or circularly polarized high-harmonic EUV pulses. We further demonstrate how complete control of polarization state of isolated high-harmonic pulse can be realized today by noncollinear focusing of two driving pulses with identical ellipticity but counter-rotating helicity. This paper opens a path towards the study of the fastest dynamics--down to attosecond time scales--in circular dichroism of magnetic materials, chiral molecules, and electronic spin motion.Taiwan Ministry of Science and Technology; Academia Sinica; Junta de Castilla y León; Ministerio de Economía y Competitividad; Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation; Ministerio de Ciencia, Innovación y Universidades for a Ramón y Cajal; European Social Fund; Ministerio de Educación, Cultura y Deporte

    Functional building blocks for scalable multipartite entanglement in optical lattices

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    Featuring excellent coherence and operated parallelly, ultracold atoms in optical lattices form a competitive candidate for quantum computation. For this, a massive number of parallel entangled atom pairs have been realized in superlattices. However, the more formidable challenge is to scale-up and detect multipartite entanglement due to the lack of manipulations over local atomic spins in retro-reflected bichromatic superlattices. Here we developed a new architecture based on a cross-angle spin-dependent superlattice for implementing layers of quantum gates over moderately-separated atoms incorporated with a quantum gas microscope for single-atom manipulation. We created and verified functional building blocks for scalable multipartite entanglement by connecting Bell pairs to one-dimensional 10-atom chains and two-dimensional plaquettes of 2×42\times4 atoms. This offers a new platform towards scalable quantum computation and simulation

    Therapeutic Effect of Large Channel Endoscopic Decompression in Lumbar Spinal Stenosis

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    Background: Percutaneous endoscopic decompression (PED) is a minimally invasive surgical technique that is now used for not only disc herniation but also lumbar spinal stenosis (LSS). However, few studies have reported endoscopic surgery for LSS. Therefore, we conducted this study to evaluate the outcomes and safety of large channel endoscopic decompression.Methods: Forty-one patients diagnosed with LSS who underwent PED surgery were included in the study. The estimated blood loss, operative time, length of hospital stay, hospital costs, reoperations, complications, visual analogue scale (VAS) score, Oswestry Disability Index (ODI) score, Japanese Orthopaedic Association (JOA) score and SF-36 physical-component summary scores were assessed. Preoperative and postoperative continuous data were compared through paired-samples t-tests. The significance level for all analyses was defined as p < 0.05.Results: A total of 41 consecutive patients underwent PED, including 21 (51.2%) males and 20 (48.8%) females. The VAS and ODI scores decreased from preoperatively to postoperatively, but the JOA and SF-36 physical component summary scores significantly increased. The VAS (lumbar) score decreased from 5.05 ± 2.33 to 0.45 ± 0.71 (P = 0.000); the VAS (leg) score decreased from 5.51 ± 2.82 to 0.53 ± 0.72 (P = 0.000); the ODI score decreased from 52.80 ± 20.41 to 4.84 ± 3.98 (P = 0.000), and the JOA score increased from 11.73 ± 4.99 to 25.32 ± 2.12 (P = 0.000). Only 1 patient experienced an intraoperative complication (2.4%; dural tear), and 1 patient required reoperation (2.4%).Conclusions: Surgical treatment for LSS is to sufficiently decompress and minimize the trauma and complications caused by surgery. This study did not reveal any obvious shortcomings of PED and suggested PED is a safe and effective treatment for LSS

    Ground calibration of Gamma-Ray Detectors of GECAM-C

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    As a new member of GECAM mission, GECAM-C (also named High Energy Burst Searcher, HEBS) was launched onboard the SATech-01 satellite on July 27th, 2022, which is capable to monitor gamma-ray transients from \sim 6 keV to 6 MeV. As the main detector, there are 12 gamma-ray detectors (GRDs) equipped for GECAM-C. In order to verify the GECAM-C GRD detector performance and to validate the Monte Carlo simulations of detector response, comprehensive on-ground calibration experiments have been performed using X-ray beam and radioactive sources, including Energy-Channel relation, energy resolution, detection efficiency, SiPM voltage-gain relation and the non-uniformity of positional response. In this paper, the detailed calibration campaigns and data analysis results for GECAM-C GRDs are presented, demonstrating the excellent performance of GECAM-C GRD detectors.Comment: third versio

    Polarization control of isolated high-harmonic pulses

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    High-harmonic generation driven by femtosecond lasers makes it possible to capture the fastest dynamics in molecules and materials. However, thus far, the shortest isolated attosecond pulses have only been produced with linear polarization, which limits the range of physics that can be explored. Here, we demonstrate robust polarization control of isolated extreme-ultraviolet pulses by exploiting non-collinear high-harmonic generation driven by two counter-rotating few-cycle laser beams. The circularly polarized supercontinuum is produced at a central photon energy of 33 eV with a transform limit of 190 as and a predicted linear chirp of 330 as. By adjusting the ellipticity of the two counter-rotating driving pulses simultaneously, we control the polarization state of isolated extreme-ultraviolet pulses—from circular through elliptical to linear polarization—without sacrificing conversion efficiency. Access to the purely circularly polarized supercontinuum, combined with full helicity and ellipticity control, paves the way towards attosecond metrology of circular dichroism.The experimental work was carried out at National Tsing Hua University, Institute of Photonics Technologies, supported by the Ministry of Science and Technology, Taiwan (grants 105-2112-M-007-030-MY3, 105-2112-M-001-030 and 104-2112-M-007-012-MY3). The concept of isolated circularly polarized attosecond pulses was developed by C.H.-G., D.D.H., M.M.M., C.G.D., H.C.K., A.B. and A.J.-B.. C.H.-G. acknowledges support from the Marie Curie International Outgoing Fellowship within the EU Seventh Framework Programme for Research and Technological Development (2007–2013), under Research Executive Agency grant agreement no. 328334. C.H.-G. and L.P. acknowledge support from Junta de Castilla y León (SA046U16) and the Ministerio de Economía y Competitividad (FIS2013-44174-P, FIS2016-75652-P). C.H.-G. acknowledges support from a 2017 Leonardo Grant for Researchers and Cultural Creators (BBVA Foundation). M.M.M. and H.C.K. acknowledge support from the Department of Energy Basic Energy Sciences (award no. DE-FG02-99ER14982) for the concepts and experimental set-up. For part of the theory, A.B., A.J.-B., C.G.D., M.M.M. and H.C.K. acknowledge support from a Multidisciplinary University Research Initiatives grant from the Air Force Office of Scientific Research (award no. FA9550-16-1-0121). A.J.-B. also acknowledges support from the US National Science Foundation (grant no. PHY-1734006). This work utilized the Janus supercomputer, which is supported by the US National Science Foundation (grant no. CNS-0821794) and the University of Colorado, Boulder. This research made use of the high-performance computing resources of the Castilla y León Supercomputing Center (SCAYLE, www.scayle.es), financed by the European Regional Development Fund (ERDF). J.L.E. acknowledges support from the National Science Foundation Graduate Research Fellowship (DGE-1144083). L.R. acknowledges support from the Ministerio de Educación, Cultura y Deporte (FPU16/02591)

    Angiogenesis in Differentiated Placental Multipotent Mesenchymal Stromal Cells Is Dependent on Integrin α5β1

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    Human placental multipotent mesenchymal stromal cells (hPMSCs) can be isolated from term placenta, but their angiogenic ability and the regulatory pathways involved are not known. hPMSCs were shown to express integrins αv, α4, α5, β1, β3, and β5 and could be induced to differentiate into cells expressing endothelial markers. Increases in cell surface integrins α5 and β1, but not α4, αvβ3, or αvβ5, accompanied endothelial differentiation. Vascular endothelial growth factor-A augmented the effect of fibronectin in enhancing adhesion and migration of differentiated hPMSC through integrin α5β1, but not αvβ3 or αvβ5. Formation of capillary-like structures in vitro from differentiated cells was inhibited by pre-treatment with function-blocking antibodies to integrins α5 and β1. When hPMSCs were seeded onto chick chorioallantoic membranes (CAM), human von Willebrand factor-positive cells were observed to engraft in the chick endothelium. CAMs transplanted with differentiated hPMSCs had a greater number of vessels containing human cells and more incorporated cells per vessel compared to CAMs transplanted with undifferentiated hPMSCs, and overall angiogenesis was enhanced more by the differentiated cells. Function-blocking antibodies to integrins α5 and β1 inhibited angiogenesis in the CAM assay. These results suggest that differentiated hPMSCs may contribute to blood vessel formation, and this activity depends on integrin α5β1
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