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Activation reduction following an eccentric contraction impairs torque steadiness in the isometric steady-state

Journal of Sport and Health Science 2018年第3期7卷 310-317页

作者： Nicole Mazara Adam J.Hess Jackey Chen Geoffrey A.Power Department of Human Health and Nutritional Sciences College of Biological Sciences University of Guelph

Background:The isometric steady-state following active lengthening is associated with greater torque production and lower activation,as measured by electromyographic activity(EMG),in comparison with a purely isometric contraction(ISO)at the same joint *** phenomenon is termed residual force enhancement(RFE).While there has been a great deal of research investigating the basic mechanisms of RFE,little work has been performed to understand the everyday relevance of *** purpose of this study was to investigate whether neuromuscular control strategies differ between ISO and RFE by measuring torque steadiness of the human ankle plantar ***:Following ISO maximal voluntary contractions in 12 males(25±4 years),an active lengthening contraction was performed at 15°/s over a 30°ankle excursion,ending at the same joint angle as ISO(5°dorsiflexion;RFE).Surface EMG of the tibialis anterior and soleus muscles was recorded during all *** steadiness was determined as the standard deviation(SD)and coefficient of variation(CV)of the torque trace in the ISO and RFE condition during activation-matching(20%and 60%integrated EMG)and torque-matching(20%and 60%maximal voluntary contraction)***-tailed,paired t tests were used,within subjects,to determine the presence of RFE/activation reduction(AR)and whether there was a difference in torque steadiness between ISO and RFE ***:During the maximal and submaximal conditions,there was 5%-9%RFE with a 9%-11%AR(p0.05).There were no differences in SD and CV of the torque trace for the 20%and60%activation-matching or the 60%and maximal torque-matching trials in either the RFE or ISO condition(p>0.05).During the 20%torquematching trial,there were～37%higher values for SD and CV in the RFE as compared with the ISO condition(p<0.05).A significant moderate-to-strong negative relationship was identified between

关键词： Eccentric Force steadiness History dependence Residual force enhancement Tremor

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A modified predictive model for estimating gas flow rate in horizontal drain hole

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Petroleum 2019年第1期5卷 35-41页

作者： Fadairo Adesina Oladepo Adebowale Adeyemi Gbadegesin Petroleum Engineering Department Covenant UniversityOtaNigeria

Accurate prediction of the flow rate of horizontal gas well is necessary for economic feasibility,planning and development of gas *** of the early models assumed that the production from the horizontal well is infinitely conductive except few recent *** recent models reported in the literature for estimating flow rate in horizontal well where the pressure losses due to friction along horizontal drain hole was *** improved model that checks the impact of all possible well bore pressure losses on gas production rate of horizontal well is *** neglected impact of well bore pressure losses due to fluid accumulation and kinetic energy in the past models is thought to be a conceivable reason for the inconsistency between computed rates from the models and rates got from production *** new model was validated using the same field contextual investigation utilized by Guo et *** outcome got from the new model yields more satisfactory results.A more realistic results that evident all flow phenomena in gas well include the initial unsteady,pseudo-steady and steady state flow condition hence flow rate at any given production time has been established for flow of gas along horizontal *** outcomes of the study demonstrate that the percentage deviation of the new model at steady state flow condition is less than 5.0%compared with 11.05%acquired from Guo et *** following by 259.7%from Furui's model,and 1118.2%got from Joshi's *** work gives field operators a precise and helpful device for prediction and assessment of production in a gas horizontal well.

关键词： Flow rate Horizontal well Unsteadiness steadiness Well bore pressure losses

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考古学视角与中国古代舞蹈史的几个问题

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舞台艺术（音乐、舞蹈） 2017年第5期 61-65页

作者：茅慧

以考古学领域发现的舞蹈形象资料为核心内容，以这些舞蹈本体的发生、发展、稳定、变化为主干，从形态上观测某一种舞蹈是如何生成并走向稳定，随后又是哪些文化变数的掺入使其“稳定态”发生摇摆、回旋乃至进入“骤变期”的文化解体和... 详细信息

以考古学领域发现的舞蹈形象资料为核心内容，以这些舞蹈本体的发生、发展、稳定、变化为主干，从形态上观测某一种舞蹈是如何生成并走向稳定，随后又是哪些文化变数的掺入使其“稳定态”发生摇摆、回旋乃至进入“骤变期”的文化解体和重组，以这些呈现于舞蹈本体变化历程的此消彼长来给予古代舞蹈史以一种艺术学和文化学意义上的分期；而分期本身涵盖时间和朝代的过程，但朝代的政治性因素已退居于次要位置，建立在考古实证材料基础上的舞蹈文化功能内涵分析、文化功能转变内在动因分析，应成为舞蹈考古学的终极目的。

关键词：舞蹈考古舞蹈史分期稳定态 dance archeology stages of dance history steadiness

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