566 research outputs found

    Generating Giant and Tunable Nonlinearity in a Macroscopic Mechanical Resonator from Chemical Bonding Force

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    Nonlinearity in macroscopic mechanical system plays a crucial role in a wide variety of applications, including signal transduction and processing, synchronization, and building logical devices. However, it is difficult to generate nonlinearity due to the fact that macroscopic mechanical systems follow the Hooke's law and response linearly to external force, unless strong drive is used. Here we propose and experimentally realize a record-high nonlinear response in macroscopic mechanical system by exploring the anharmonicity in deforming a single chemical bond. We then demonstrate the tunability of nonlinear response by precisely controlling the chemical bonding interaction, and realize a cubic elastic constant of \mathversion{bold}2×1018 N/m32 \times 10^{18}~{\rm N}/{\rm m^3}, many orders of magnitude larger in strength than reported previously. This enables us to observe vibrational bistate transitions of the resonator driven by the weak Brownian thermal noise at 6~K. This method can be flexibly applied to a variety of mechanical systems to improve nonlinear responses, and can be used, with further improvements, to explore macroscopic quantum mechanics

    A seismological phenomenon preceding the 2017 Ms7.0 Jiuzhaigou earthquake

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    On 8 August 2017, a Ms7.0 earthquake occurred in Jiuzhaigou in the Sichuan Province of China. In this study, we obtained the vertical continuous data recorded at 12 nearby broadband seismometers from April to December 2017, in order to characterize the temporal and spatial variations in the vertical ground motion prior to the onset of the earthquake. Using the self-mutual information method, we determined that from July to August 2017, the self-mutual information value of the vertical ground motion increased at several stations. The spatiotemporal evolution also shows that the region of highest value migrates from south to north toward the earthquake epicenter. Among them, the change of SPA (the station closest to the epicenter) is the most prominent. We believe that this phenomenon is related to the formation of the Jiuzhaigou earthquake. Our work, in combination with other published works, indicates that the Jiuzhaigou earthquake was caused by the continued eastward movement and obstruction of the Qinghai Tibet Plateau by the Sichuan Basin, and the movement of Longmenshan fault is also one of the causes of the earthquake

    A seismological phenomenon preceding the 2017 Ms7.0 Jiuzhaigou earthquake

    Get PDF
    On 8 August 2017, a Ms7.0 earthquake occurred in Jiuzhaigou in the Sichuan Province of China. In this study, we obtained the vertical continuous data recorded at 12 nearby broadband seismometers from April to December 2017, in order to characterize the temporal and spatial variations in the vertical ground motion prior to the onset of the earthquake. Using the self-mutual information method, we determined that from July to August 2017, the self-mutual information value of the vertical ground motion increased at several stations. The spatiotemporal evolution also shows that the region of highest value migrates from south to north toward the earthquake epicenter. Among them, the change of SPA (the station closest to the epicenter) is the most prominent. We believe that this phenomenon is related to the formation of the Jiuzhaigou earthquake. Our work, in combination with other published works, indicates that the Jiuzhaigou earthquake was caused by the continued eastward movement and obstruction of the Qinghai Tibet Plateau by the Sichuan Basin, and the movement of Longmenshan fault is also one of the causes of the earthquake

    Real-time Automatic M-mode Echocardiography Measurement with Panel Attention from Local-to-Global Pixels

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    Motion mode (M-mode) recording is an essential part of echocardiography to measure cardiac dimension and function. However, the current diagnosis cannot build an automatic scheme, as there are three fundamental obstructs: Firstly, there is no open dataset available to build the automation for ensuring constant results and bridging M-mode echocardiography with real-time instance segmentation (RIS); Secondly, the examination is involving the time-consuming manual labelling upon M-mode echocardiograms; Thirdly, as objects in echocardiograms occupy a significant portion of pixels, the limited receptive field in existing backbones (e.g., ResNet) composed from multiple convolution layers are inefficient to cover the period of a valve movement. Existing non-local attentions (NL) compromise being unable real-time with a high computation overhead or losing information from a simplified version of the non-local block. Therefore, we proposed RAMEM, a real-time automatic M-mode echocardiography measurement scheme, contributes three aspects to answer the problems: 1) provide MEIS, a dataset of M-mode echocardiograms for instance segmentation, to enable consistent results and support the development of an automatic scheme; 2) propose panel attention, local-to-global efficient attention by pixel-unshuffling, embedding with updated UPANets V2 in a RIS scheme toward big object detection with global receptive field; 3) develop and implement AMEM, an efficient algorithm of automatic M-mode echocardiography measurement enabling fast and accurate automatic labelling among diagnosis. The experimental results show that RAMEM surpasses existing RIS backbones (with non-local attention) in PASCAL 2012 SBD and human performances in real-time MEIS tested. The code of MEIS and dataset are available at https://github.com/hanktseng131415go/RAME

    Impact of emphysema heterogeneity on pulmonary function

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    Results: The majority (128/160) of the subjects with COPD had a heterogeneity greater than zero. After adjusting for age, gender, smoking history, and extent of emphysema, heterogeneity in depicted disease in upper lobe dominant cases was positively associated with pulmonary function measures, such as FEV1 Predicted (p<.001) and FEV1/FVC (p<.001), as well as disease severity (p<0.05). We found a negative association between HI% , RV/TLC (p<0.001), and DLco% (albeit not a statistically significant one, p = 0.06) in this group of patients
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