924 research outputs found

    The Calder\'{o}n problem for nonlocal parabolic operators

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    We investigate inverse problems in the determination of leading coefficients for nonlocal parabolic operators, by knowing the corresponding Cauchy data in the exterior space-time domain. The key contribution is that we reduce nonlocal parabolic inverse problems to the corresponding local inverse problems with the lateral boundary Cauchy data. In addition, we derive a new equation and offer a novel proof of the unique continuation property for this new equation. We also build both uniqueness and non-uniqueness results for both nonlocal isotropic and anisotropic parabolic Calder\'on problems, respectively.Comment: 34 pages. All comments are welcom

    KINEMATICS ANALYSIS OF THE UPPER EXTREMITY DURING THE TWOHANDED BACKHAND DRIVE VOLLEY FOR FEMALE TENNIS PLAYERS

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    The purpose of this study was to discuss the motion characteristics of the arms in the two-handed backhand drive volley. Five elite female tennis players participated in this study, their two-handed backhand drive volley strokes were analysed, and all participants are right handed. Motion Analysis System with 10 Eagle Digital inferred high speed cameras at 200Hz were used for this study. The results show a similar elbow and wrist speed strategy in x-axis between two-handed ground stroke and drive volley, our study also found that the rear arm dominates the stroke and mainly provide the topspin that is required for the skill of the drive volley. In order to create better stroke efficiency, the right elbow reached peak velocity first, followed by the right wrist before racket impact with the ball

    Alcohol Use, Abuse, and Dependency in Shanghai

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    The use of alcohol for social and ceremonial occasions was recorded in Chinese history as early as 1760 B.C. during the Yin Dynasty (Ci-Hai Encyclopedia, 1979:936). The cultural tradition of ancient China placed alcoholic beverages at the center of social occasions, which presumably was the origin of the adage: Without wine, there is no li (or etiquette). Thus, the use of alcoholic beverages has always been accompanied by the concept of propriety and the discharging of one\u27s role obligations m social functions, rather than that of personal indulgence

    Mass-accretion, spectral, and photometric properties of T Tauri stars in Taurus based on TESS and LAMOST

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    We present the analysis of 16 classical T Taur stars using LAMOST and TESS data, investigating spectral properties, photometric variations, and mass-accretion rates. All 16 stars exhibit emissions in Hα\alpha lines, from which the average mass-accretion rate of 1.76×109 Myr11.76\times10^{-9}~M_{\odot}yr^{-1} is derived. Two of the stars, DL Tau and Haro 6-13, show mass-accretion bursts simultaneously in TESS, ASAS-SN, and/or ZTF survey. Based on these observations, we find that the mass-accretion rates of DL Tau and Haro 6-13 reach their maximums of 2.5×108 Myr12.5 \times 10^{-8}~M_{\odot}yr^{-1} and 2×1010 Myr12 \times 10^{-10}~M_{\odot}yr^{-1} during the TESS observation, respectively. We detect thirteen flares among these stars. The flare frequency distribution shows that the CTTSs' flare activity is not only dominated by strong flares with high energy but much more active than those of solar-type and young low-mass stars. By comparing the variability classes reported in the literature, we find that the transition timescale between different classes of variability in CTTSs, such as from Stochastic (S) to Bursting (B) or from quasi-periodic symmetric (QPS) to quasi-periodic dipping (QPD), may range from 1.6 to 4 years. We observe no significant correlation between inclination and mass-accretion rates derived from the emission indicators. This suggests that inner disk properties may be more important than that of outer disk. Finally, we find a relatively significant positive correlation between the asymmetric metric "M" and the cold disk inclination compared to the literature. A weak negative correlation between the periodicity metric "Q" value and inclination has been also found.Comment: 39 pages, 22 figures, 8 table

    THE EFFECTS Of VOLLEYBALL ATTACKING ON SCORE POINTS: A CASE STUDY OF 2014 TVL IN TAIWAN

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    Volleyball is a sport in which team tactical and players' attacking skills determine to score points. Therefore, an effective team tactical is achieved by main spikers' and middle blockers' skills. To name but a few, delayed spike, open spike and back-row spike are main spikers' skills, yet quick spike, and individual time difference attack are associated with middle blockers'. Under this aspect, a case study of male teams of Taiwan Top Volleyball League (TVL) was yield out, which aimed at exploring the effects of team tactical and players attacking skills on score points. The results indicated that the attacking point ratio of main spikers and middle blockers in the champion team was higher than others. This was because the middle blockers gave cover to main spikers as attacking. By doing so, it promoted point ratio to main spikers. Furthermore, it found that to strengthen main spikers and middle blockers' skills would increase team's attacking point ratio
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