12,060 research outputs found

    Exclusive B→PVB \to PV Decays and CP Violation in the General two-Higgs-doublet Model

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    We calculate all the branching ratios and direct CP violations of B→PVB \to PV decays in a most general two-Higgs-doublet model with spontaneous CP violation. As the model has rich CP-violating sources, it is shown that the new physics effects to direct CP violations and branching ratios in some channels can be significant when adopting the generalized factorization approach to evaluate the hadronic matrix elements, which provides good signals for probing new physics beyond the SM in the future B experiments.Comment: 21 page

    Active optical clock based on four-level quantum system

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    Active optical clock, a new conception of atomic clock, has been proposed recently. In this report, we propose a scheme of active optical clock based on four-level quantum system. The final accuracy and stability of two-level quantum system are limited by second-order Doppler shift of thermal atomic beam. To three-level quantum system, they are mainly limited by light shift of pumping laser field. These limitations can be avoided effectively by applying the scheme proposed here. Rubidium atom four-level quantum system, as a typical example, is discussed in this paper. The population inversion between 6S1/26S_{1/2} and 5P3/25P_{3/2} states can be built up at a time scale of 10−610^{-6}s. With the mechanism of active optical clock, in which the cavity mode linewidth is much wider than that of the laser gain profile, it can output a laser with quantum-limited linewidth narrower than 1 Hz in theory. An experimental configuration is designed to realize this active optical clock.Comment: 5 page

    Submilliamp threshold InGaAs-GaAs strained layer quantum-well laser

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    Strained-layer InGaAs-GaAs single-quantum-well buried-heterostructure lasers were fabricated by a hybrid beam epitaxy and liquid-phase epitaxy technique. Very low threshold currents, 2.4 mA for an uncoated laser (L=425 μm) and 0.75 mA for a coated laser (R~0.9, L=198 μm), were obtained. A 3-dB modulation bandwidth of 7.6 GHz was demonstrated at low bias current (14 mA). Procedures for material preparation and device fabrication are introduced

    Designing Personas for Expressive Robots: Personality in the New Breed of Moving, Speaking, and Colorful Social Home Robots

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    Imbuing robots with personality has been shown to be an effective design approach in HRI, promoting user trust and acceptance. We explore personality design in a non-anthropomorphic voice-assisted home robot. Our design approach developed three distinct robot personas: Butler, Buddy, and Sidekick, intended to differ in proactivity and emotional impact. Persona differences were signaled to users by a combination of humanoid (speech, intonation), and indirect cues (colors and movement). We use Big Five personality theory to evaluate perceived differences between personas in an exploratory Wizard of Oz study. Participants were largely able to recognize underlying personality traits expressed through these cue combinations in ways that were consistent with our design goals. The proactive Buddy persona was judged as more Extravert than the more passive Sidekick persona, and the Butler persona was perceived as more Conscientious and less Neurotic than either Buddy or Butler personas. Users also had clear preferences between different personas; they wanted robots that mimicked but accentuated their own personality. Results suggest that future designs might exploit abstract cues to signal personality traits

    Efficient collision-free path planning for autonomous underwater vehicles in dynamic environments with a hybrid optimization algorithm

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    publisher: Elsevier articletitle: Efficient collision-free path planning for autonomous underwater vehicles in dynamic environments with a hybrid optimization algorithm journaltitle: Ocean Engineering articlelink: http://dx.doi.org/10.1016/j.oceaneng.2016.09.040 content_type: article copyright: © 2016 Elsevier Ltd. All rights reserved

    Ionic liquid gate-induced modifications of step edges at SrCoO<sub>2.5</sub> surfaces

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    Intense electric fields developed during gating at the interface between an ionic liquid and an oxide layer have been shown to lead to significant structural and electronic phase transitions in the entire oxide layer. An archetypical example is the reversible transformation between the brownmillerite SrCoO2.5 and the perovskite SrCoO3 engendered by ionic liquid gating. Here we show using in situ atomic force microscopy studies with photothermal excitation detection, that allows for high quality measurements in the viscous environment of the ionic liquid that the edges of atomically smooth terraces at the surface ofSrCoO2.5 films are significantly modified by ionic liquid gating but that the terraces themselves remain smooth. The edges develop ridges that we show, using complementary X-ray photoemission spectroscopy studies, result from the adsorption of hydroxyl groups. Our findings exhibit a way of electrically controlled surface modifications in emergent ionitronic applications

    Social media big data-based research on the influencing factors of insomnia and spatiotemporal evolution

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    Insomnia is a prevalent sleep disorder that causes serious harm to individuals and society. It is closely linked to not only personal factors but also social, economic and other factors. This study explores the influencing factors and spatial differentiation of insomnia from the perspective of social media. This paper chose China’s largest social media platform, Sina Weibo, as its data source. Then, based on the collected relevant data of 288 Chinese cities from 2013 to 2017, it explored the impact of economic, social, and environmental factors and an educated population on insomnia. Additionally, the importance and interaction of each influencing factor were analyzed. According to the results, the gross domestic product (GDP), proportion of households connected to the Internet and number of students in regular institutions of higher education are the major factors that influence insomnia, and their influences show obvious spatial nonstationarity. Rapid GDP growth has increased the probability of insomnia, and the positive correlation between the proportion of households connected to the internet and insomnia has strengthened annually. Although the impact of insomnia on college students decreased in some regions, the overall impact was still increasing annually, and spatial nonstationarity was obvious. Properly controlling GDP growth and unnecessary time spent online and guiding people to develop healthy Internet surfing habits and lifestyles will help improve their sleep quality. Our research results will help relevant professionals better understand the distribution of regional insomnia and provide a reference for related departments to formulate regional insomnia prevention and treatment policies
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