第9届大运会健美操女子三人操项目难度动作出现位序分析

通过文献资料、录像分析、数理统计等方法,对第9届大学生运动会健美操女子三人操前8名成套动作的难度动作出现位序进行分析。

花球啦啦操手位动作技术特征探讨

啦啦操作为我国新兴的体育项目,虽然没有悠久的历史积淀,但近几年来其发展速度之快。迄今为止,我国啦啦操已发展成为一项具有较高技术水平和较深文化内涵的体育竞技项目。花球啦啦操是啦啦操运动最受欢迎,传播力度最广的项目,其核心动作则是手位动作。提高手位动作的标准性是啦啦操独特性与唯一性最重要的体现,也是确保啦啦操在众多体育项目中得以稳固、持续发展的前提。故该文简要阐述了花球啦啦操手位动作的现实意义,分析了其中蕴含的技术特征,以便为改进我国花球啦啦操的训练方法、提高技术水平提供指导依据。

啦啦操基本手位动作技术的应用研究

啦啦操英文为cheerleading,起源于美国,指在音乐的伴奏下,通过集体参与完成复杂的基本手位、和一些过渡链接的舞蹈动作,充分展示队员的运动技巧与能力,体现运动员青春活力的团队精神的一项体育运动。啦啦操自2002年传入我国至今已经有近15年的历史,在相关协会的大力推广下,啦啦操如今已经被广大的群众所接受和喜爱。对啦啦操基本手位的研究不仅可以提高了啦啦操技术水平,而且可以规范啦啦操基本技术动作,同时也让喜爱啦啦操的人更好的学习和认识。因此,对啦啦操基本手位的研究是非常重要的。

啦啦操基本手位动作技术特征研究

啦啦操是一种团体体育运动项目,自其引入我国后,在较短时间内得到了迅速的发展。我国啦啦操项目及相关技术水平也在多年的摸索、学习、模仿以及创新过程中得到了完善与发展,并完成了与国际接轨的目标。但是,我国啦啦操项目的技术动作仍较西方发达国家存在着诸多的不足。啦啦操基本手位动作既是该项目的基础与核心动作,也是其独特性的具体展现,因此,就啦啦操基本手们动作技术的特征进行系统研究,以期为提高我国啦啦操体育运动项的水平及未来发展提供更多的参考。

大学体育啦啦操手位动作训练要领

在刚刚结束的第34界世界大学生啦啦操锦标赛上,中国广西师范大学拉啦啦队获得舞蹈啦啦操双人街舞项目冠军,这是我国大学生在该项目的国际高校顶级赛事中首次摘得世界冠军桂冠,引起了我国高校大学生的关注。同时,大学生对啦啦操运动的热爱程度也再次提高。啦啦操普及性很强,是一项综合了体操、舞蹈、音乐、健身、娱乐为一体的体育项目,深受大家喜爱。笔者通过一段时间对相关文献的搜集和整理。结合学生啦啦操训练课呈现出的突出特点和普遍规律,对啦啦操的基本手位动作技术要领及规格进行分析和总结,希望能够对提高学生啦啦操训练水平起到一定的帮助作用。

曲轴磨床液压卡盘松开不到位问题分析及改进

通过对液压卡盘液压参数及液压缸作用点进行的联合改进,解决了液压缸不能使卡爪完全打开的问题。

复合趋向补语的趋向意义

一般语法著作将现代汉语的趋向动词分为以下三组: 第一组 上 下 进 出 过 回 开 起 第二组 来 去

Mechanisms of Cyclovirobuxine D on APD Prolongation in Rat Ventricular Myocytes

Aim To study the effects of cyclovirobuxine D on inward rectifier K^- current(I_(k1) ) > transient outward K^+ current (I_(to)), L-type Ca^(2+) current (I_(Ca-L)), and actionpotential duration (APD) in isolated rat ventricular myocytes. Methods The whole cell patch-clamptechniques were used to study the changes of I_(k1), I_(to), I_(Ca-L) and APD in rat ventricularmyocytes. Results Cyclovirobuxine D (1-10 μmol·L^(-1)) significantly prolonged APD_(50) andAPD_(90) in isolated rat ventricular myocytes. Resting potential (RP) was decreased by 10μmol·L^(-1) of cyclovirobuxine D. Cyclovirobuxine D significantly decreased both inward andoutward components of I_(k1) . At - 100 mV, 1 and 10 μmol·L^(-1) of cyclovirobuxine D decreasedI_(k1), density from (-8.0+- 1.1) pA/pF to ( - 4.1 +- 0.7) pA/pF and ( - 3.4 +- 0.8) pA/pF,respectively, whereas at - 30 mV, I-(k1) density was decreased from (1.10 +-0.24) pA/pF to (0.61+-0.18) pA/pF and (0.36+- 0.11) pA/pF, respectively. 1_(to) was markedly inhibited bycyclovirobuxine D from the test potential of 0 mV to + 60 mV. At + 40 mV, 1 and 10μmol·L^(-1) ofcyclovirobuxine D decreased I_(to) density from (8.9+- 2.0) pA/pF to (5.5 +- 1.2) pA/pF and (4.9+-0.9) pA/pF, respectively. Cyclovirobuxine D inhibited I_(Ca-L) in a concentration-dependentmanner. At 10 mV, 1 and 10μmol·L^(-1) of cyclovirobuxine D decreased I_(Ca-L) density from ( - 9.9+- 1.8) pA/pF to ( - 6.4 +- 1.4) pA/pF and (-4.2+-0.6) pA/pF, respectively. ConclusionCyclovirobuxine D significantly prolonged APD and inhibited I_(k1), I_(to), and I_(Ca-L) in ratventricular myocytes. The inhibitory effects of cyclovirobuxine D on _(k1) and I_(to) are majormolecular mechanisms of APD prolongation in rat.

Dartfish运动分析软件在啦啦操教学中的应用研究

目的:探讨Dartfish运动分析软件在啦啦操教学中的应用效果。方法:本研究采用文献资料法、问卷调查法、实验法等方法,于2021年9月至12月期间对某高校体育课啦啦操课程班中随机抽取2个班共42名学生进行教学实验研究。实验组运用Dartfish运动分析软件作为教学辅助手段,对照组采用传统教学方式。结果:实验组学生完成啦啦操36个手位动作总时间[(22.08±1.97)秒]小于对照组学生[(24.91±1.64)秒],且存在显著性差异(P<0.01)。实验组学生在K、侧K、W、上X、下X、上A、下A这7个手位完成的角度比对照组学生更标准,且均存在显著性差异(P<0.05)。实验组学生的手位动作得分、套路动作得分以及手位动作技术掌握程度、学习兴趣等评分均高于对照组,且均存在显著性差异(P<0.05)。结论:Dartfish运动分析软件作为教学辅助手段,可以有效提高学生啦啦操手位动作完成的标准度,对手位技术的掌握程度、学习兴趣等方面有一定的促进作用。

颈动脉内-中膜厚度与血压变异性的关系

目的探讨颈动脉内-中膜厚度(IMT)与血压变异性(BPV)的关系,评价通过观察颈动脉IMT来推测血压变异大小的作用。方法共125例,经颈动脉超声检查测量颈总动脉IMT、动态血压监测并计算有关参数、卧位-立位动作前后血压测量,根据IMT≤1.0mm与>1.0mm分两组对比分析。结果在测动态血压的病例中,两组年龄、24小时平均收缩压与24小时平均舒张压、脉压指数(脉压占收缩压比率)相仿,24小时收缩压变异性和白昼收缩压变异性IMT>1.0mm组大于IMT≤1.0mm组(P值分别为<0.01和<0.05),而夜间收缩压变异性及所有舒张压变异性两组间无显著差异。在测卧位-立位动作前后血压的病例中,IMT>1.0mm组收缩压增高率大于IMT≤1.0mm组(P<0.05)。结论颈动脉IMT大者收缩压变异增大,活动可能是血压变异增大的促发因素。

Effects of IQ_23 on the Repolarization and Both Components of the Delayed Rectifier Potassium Current in Guinea Pig Ventricular Myocytcs

Using patch clamp whole cell recording techiques, we examined the effects ofIQ_23, a benzyl-isoquinoline derivative with antiarrhythmic activities, on the action potential (AP) andpotassium currents in single guinea pig ventricular myocytes. The results showed that IQ_23 at 10, 30and 100 μmol ·L_-1 slowed the repolarization in AP dose-dependently. The APD_90 were prolonged by15%, 28% and 31% respectively. This effect did not depend on the extracellular Ca^2+. In voltageclamp mode, IQ_23 effectively blocked both the components of the delayed rectifier potassium current(I_k), i.e., I_ks and I_kr. At concentrations of 30 and 100 μmol· L^-1, IQ_23 suppressed I_ks by 21% and 26%and suppressed I_kr by 67% and 86% respectively. But even at 100 μmol·L^-1, IQ_23 had little effect onthe inward rectifier potassium current (I_k1). It is concluded: 1. IQ_23 can dose-dependently prolongAPD in the ventriculas myocytes of guinea pig, the effect does not depend on the extracellular Ca^2+; 2.IQ_23 blocks both I_ks and Ikr in the ventricular myocytes without obvious specificities between them.

Effects of 2-[p-(Dimethylamino)Styrl] PyridineMethiodide on Slow Response Action Potentialand Slow lnward Current of Guinea PigPapillary Muscles

The effects of 2-[p-(Dimethylamino)styryl] pyridine methiodide(DSPM)on slow response action potential(SRAP)and slow inward current(Isi) of guinea pig papillary muscles were studied by intracellular microelectrodes and voltage clamp techniques.The APA and V_(max) of SRAP induced by high K￣+were decreased after 50 min of perfusion with DSPM solu- tion. Isi was suppressed from a peak value of8.8± 1.6μA to 5.7± 1.8μA, The results indicated that DSPM has a selective blocking effect on calcium channel.

Electrical wave transmission in healthy black pine seedlings

Non-injurious local stimuli, such as a cold shock, and injurious stimuli, such as local burning, punctures or chemicals, were applied to study electrical wave transmission in black pine (Pinus thunbergii) seedlings. The results showed that non-injurious stimuli evoked the action potential (AP) transmission and injurious stimulation induced both AP transmission and the more complex variation (VP) transmission in the seedlings. The causes of these phenomena were discussed. Key words Black pine - Pinus thunbergii - Action potential (AP) - Variation potential (VP) - Electrical wave transmission CLC number S791.256 Document code A Foundation item: This paper was supported by the National Nature Science Foundation of China (grant No. 39670613).Biography: GUO Jian (1971-), male, lecturer in Haikou Bureau of Forestry. Hainan, P. R. China.Responsible editor: Song Funan

Effects of IQ23 on the Repolarization and Both Components of the Delayed Rectifier Potassium Current in Guinea Pig Ventricular Myocytcs

Using patch clamp whole cell recording techiques, we examined the effects ofIQ23, a benzyl-isoquinoline derivative with antiarrhythmic activities, on the action potential （AP） andpotassium currents in single guinea pig ventricular myocytes. The results showed that IQ23 at 10, 30and 100 μmol ·L-1 slowed the repolarization in AP dose-dependently. The APD90 were prolonged by15%, 28% and 31% respectively. This effect did not depend on the extracellular Ca2+. In voltageclamp mode, IQ23 effectively blocked both the components of the delayed rectifier potassium current（Ik）, i.e., Iks and Ikr. At concentrations of 30 and 100 μmol· L-1, IQ23 suppressed Iks by 21% and 26%and suppressed Ikr by 67% and 86% respectively. But even at 100 μmol·L-1, IQ23 had little effect onthe inward rectifier potassium current （Ik1）. It is concluded: 1. IQ23 can dose-dependently prolongAPD in the ventriculas myocytes of guinea pig, the effect does not depend on the extracellular Ca2+; 2.IQ23 blocks both Iks and Ikr in the ventricular myocytes without obvious specificities between them.

基于智能手机的行人荷载测试研究

现代智能手机测试技术的飞速发展及其高普及性,为突破行人荷载测试的技术瓶颈提供了可能。研究首先利用小型振动台,通过对比不同型号的智能手机对正弦波、扫频波及地震动信号的测量精度,筛选出适合行人荷载测试的手机软硬件系统。随后利用三维动作捕捉技术,研究测试者进行步行、跳跃和屈伸运动时,手机的携带方式、位置以及自身转动等对加速度测试精度的影响,采用该携带方式和坐标转换算法,手机所获得人体运动加速度与试验对照值非常接近,主频特征则完全一致。进而,将手机记录的加速度与人体运动的动力学模型相结合,可获得对应的人致荷载时程,与测力板的记录结果对比表明,采用单刚体模型即可获得精度良好的跳跃和屈伸荷载时程,而步行荷载的精度一般。

Characterization of a Chinese KCNQ1 mutation （R259H） that shortens repolarization and causes short QT syndrome 2

Objectives To evaluate the association between a KCNQ 1 mutation, R259H, and short QT syndrome （SQTS） and to explore the elec- trophysiological mechanisms underlying their association. Methods We performed genetic screening of SQTS genes in 25 probands and their family members （63 patients）. We used direct sequencing to screen the exons and intron-exon boundaries of candidate genes that en- code ion channels which contribute to the repolarization of the ventricular action potential, including KCNQI, KCNH2, KCNE1, KCNE2, KCNJ2, CACNAlc, CACNB2b and CACNA2D1. In one of the 25 SQTS probands screened, we discovered a KCNQ1 mutation, R259H. We cloned R259H and transiently expressed it in HEK-293 cells; then, currents were recorded using whole cell patch clamp techniques. Results R259H-KCNQ 1 showed significantly increased current density, which was approximately 3-fold larger than that of wild type （WT） after a depolarizing pulse at 1 s. The steady state voltage dependence of the activation and inactivation did not show significant differences between the WT and R259H mutation （P 〉 0.05）, whereas the time constant of deactivation was markedly prolonged in the mutant compared with the WT in terms of the test potentials, which indicated that the deactivation of R259H was markedly slower than that of the WT. These results suggested that the R259H mutation can effectively increase the slowly activated delayed rectifier potassium current （Irs） in phase 3 of the cardiac action potential, which may be an infrequent cause of QT interval shortening. Conclusions R259H is a gain-of-function muta- tion of the KCNQ1 channel that is responsible for SQTS2. This is the first time that the R259H mutation was detected in Chinese people.

Cell and gene therapy for arrhythmias： Repair of cardiac conduction damage

Action potentials generated in the sinoatrial node （SAN） dominate the rhythm and rate of a healthy human heart. Subsequently, these action potentials propagate to the whole heart via its conduction system. Abnormalities of impulse generation and/or propagation in a heart can cause arrhythmias. For example, SAN dysfunction or conduction block of the atrioventricular node can lead to serious bradycardia which is currently treated with an implanted electronic pacemaker. On the other hand, conduction damage may cause reentrant tachyarrhythmias which are primarily treated pharmacologically or by medical device-based therapies, including defibrillation and tissue ablation. However, drug therapies sometimes may not be effective or are associated with serious side effects. Device-based therapies for cardiac arrhythmias, even with well developed technology, still face inadequacies, limitations, hardware complications, and other challenges. Therefore, scientists are actively seeking other alternatives for antiarrhythmic therapy. In particular, cells and genes used for repairing cardiac conduction damage/defect have been investigated in various studies both in vitro and in vivo. Despite the complexities of the excitation and conduction systems of the heart, cell and gene-based strategies provide novel alternatives for treatment or cure of cardiac arrhythmias. This review summarizes some highlights of recent research progress in this field.

Variability in local action potential durations, dispersion of repolarization and wavelength restitution in aged wild-type and Scn5a^＋/- mouse hearts modeling human Brugada syndrome

Brugada syndrome is a primary arrhythmia syndrome characterized by loss-of-function mutations in the SCN5A gene, which encodes for the cardiac Na^＋ channel. In affected individuals, the risk of developing malignant ventricular arrhythmias and sudden cardiac death are increased.

Age-related increase of early afterdepolarization in calsequestrin-2 knock-in mouse cardiomycyte

Objective To characterize early afterdepolarizations （EADs） caused triggered activity （TA） among calsequestrin-2 （CASQ2） knock-in （CASQ2 KI） mice and its relationship with aging. Methods Electrophysiological properties of ventricular myocytes from 3- month （mo, young）, 9-mo （adult-l） and 12-too （adult-2） in wild-type （WT） and CASQ2 KI mice were investigated with patch-clamp technique. Results The incidences of EADs and TA in CASQ2 KI cardiomyocytes increased with increasing age. In contrast, WT mice cardiomyocytes showed no significant change in matched-age groups. Compared with that in 3-mo CASQ2 KI mice, the 50% repolarization of action potential （APD50） showed prolongation in both 9-mo and 12-mo ones （9.2±0.9 ms of 9-mo and 10.3 ± 1.2 ms of 12- mo vs. 5.6± 0.3 ms of 3-mo）, while the 90 % repolarization of action potential （APD90） was similar among 3 age groups. Compared with 3-mo mice, the 9-mo and 12-mo CASQ2 KI mice showed markedly reduced transient outward potassium current （Ito） densities but increased L-type calcium current （ICa-L） densities. Conlcusion This study suggested that events of EADs and TA in CASQ2 KI mice increased with increasing age, It might be associated partly with the augment of cellular calcium concentration and the prolongation of APD50 induced by decrease of Ito and increase of ICa-L in adult CASQ2 KI mice

More severe toxicity of gold nanoparticles with rougher surface in mouse hippocampal neurons

Gold nanoparticles(GNPs)have been extensively used in nanomedicine and neuroscience owing to their biological inertness,peculiar opto-electronic and physico-chemical features.However,the effect of GNPs shape on the neurophysiological properties of single neuron is still unclear.To tackle this issue,different shape GNPs(nanosphere,nanotriakisoctahedron and nanoflower)were synthesized to investigate the effect of GNPs on the voltage-dependent sodium channel and the action potential(AP)of hippocampal CA1 neurons in mice.The results indicated that GNPs inhibited the amplitudes of voltage-gated sodium current(I_(Na))and led to a hyperpolarizing shift in the voltage-dependence curve of both activation and inactivation of I_(Na).GNPs also increased neuronal excitability and altered some properties of AP.Moreover,most alterations in AP properties were observed in nanoflower GNPs treated CA1 neurons,suggesting that the neurotoxicity of gold nanoparticles is surface roughness-dependent.These results may provide a valuable direction in the clinical application of GNPs.