906 research outputs found

    Heating of Flare Loops With Observationally Constrained Heating Functions

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    We analyze high cadence high resolution observations of a C3.2 flare obtained by AIA/SDO on August 1, 2010. The flare is a long duration event with soft X-ray and EUV radiation lasting for over four hours. Analysis suggests that magnetic reconnection and formation of new loops continue for more than two hours. Furthermore, the UV 1600\AA\ observations show that each of the individual pixels at the feet of flare loops is brightened instantaneously with a timescale of a few minutes, and decays over a much longer timescale of more than 30 minutes. We use these spatially resolved UV light curves during the rise phase to construct empirical heating functions for individual flare loops, and model heating of coronal plasmas in these loops. The total coronal radiation of these flare loops are compared with soft X-ray and EUV radiation fluxes measured by GOES and AIA. This study presents a method to observationally infer heating functions in numerous flare loops that are formed and heated sequentially by reconnection throughout the flare, and provides a very useful constraint to coronal heating models.Comment: This paper is revise

    Effect of Vibration Training on Anaerobic Power and Quardroceps Surface EMG in Long Jumpers

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    Objective: To explore the anaerobic power and surface EMG (sEMG) of quardrocep muscle in lower extremities after single vibration training intervention. Methods: 8 excellent male long jumpers voluntarily participated in this study. Four intervention modes were devised, including high frequency high amplitude (HFHA,30Hz,6mm), low frequency low amplitude(LFLA,15Hz,3mm), high frequency low amplitude (HFLA,30Hz,3mm), and non-vibration (CON). All subjects received a knee extensor maximal voluntary contraction (MVC) test before the vibration. After the test, a 5×1 min. vibration would be carried out and the subjects were asked to pedal. Results: Peak power and average power output of the four vibration treatment methods did not reach obvious level. There was no obvious difference in root-mean-square(RMS) EMG of the dominant leg among the four treatments. The RMS EMG of the non-dominant leg of HFLA method during peak power output was much higher than that of HFHA and CON . The quotient between root-mean-square and peak power of the four groups did not reach significant level. Conclusion: Single vibration could not improve the anaerobic performance of long jumpers and HFLA might decrease the work efficiency of the non-dominant leg muscle of excellent long jumpers participating anaerobic test

    Rethinking Generalized Beta Family of Distributions

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    We approach the Generalized Beta (GB) family of distributions using a mean-reverting stochastic differential equation (SDE) for a power of the variable, whose steady-state (stationary) probability density function (PDF) is a modified GB (mGB) distribution. The SDE approach allows for a lucid explanation of Generalized Beta Prime (GB2) and Generalized Beta (GB1) limits of GB distribution and, further down, of Generalized Inverse Gamma (GIGa) and Generalized Gamma (GGa) limits, as well as describe the transition between the latter two. We provide an alternative form to the "traditional" GB PDF to underscore that a great deal of usefulness of GB distribution lies in its allowing a long-range power-law behavior to be ultimately terminated at a finite value. We derive the cumulative distribution function (CDF) of the "traditional" GB, which belongs to the family generated by the regularized beta function and is crucial for analysis of the tails of the distribution. We analyze fifty years of historical data on realized market volatility, specifically for S\&P500, as a case study of the use of GB/mGB distributions and show that its behavior is consistent with that of negative Dragon Kings.Comment: 21 pages, 11 figyes, 2 table
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