保定市区域差异特点分析及区域发展战略探讨

运用统计学定量分析方法,综合分析了保定市及所属各县市经济区域差异的分布现状和变化状况,并对保定市经济区域协调发展战略的理论进行了探讨。     

Parameter identification of internal wave and mesoscale eddy

1. Introduction The ocean is an acoustic wave-guide limited above by the sea surface and below by the seafloor. In the acoustic viewpoints, the sea is extremely variable. The sea current, internal wave, mesoscale eddy, etc. all disturb the sound propagation. The mesoscale eddy is frequently seen in places close to the strong peak front current. The peak front eddies are often of ring type. The ring becomes a large bend when getting out of the main current. The diameter of the ring may reach …     

练习变异性在运动技能学习中的研究进展

练习变异性与一般动作程序的参数变化有关,是通过改变运动参数及不同的背景干扰效应对练习效果产生影响,相对比于以往的固定练习法,变换练习法能够使参与者在练习运动技能过程中因环境、速度、距离、力量等参数的不同,从而体验到不同的运动特征,有效地促进运动技能的学习。现就近10年的研究成果进行综述,希望为今后的研究带来裨益。     

离心运动伴不同程度的血流限制对外周疲劳及心脏自主神经功能的效应研究

目的:探讨急性离心运动伴4种不同程度的血流限制对年轻女性外周疲劳及心脏自主神经功能的影响,综合评价各方案的安全性,为长期血流限制运动干预提供参考。方法:将40名女大学生随机分为4组,分别进行小强度抗阻(30%1RM)伴0%(CON组)、40%(BFR₄₀组)、60%(BFR₆₀组)和80%(BFR80组)动脉闭塞压(AOP)的血流限制运动。各小组进行4组伸膝离心运动,第1组重复30次,后3组重复15次,组间休息30 s。检测运动前、运动后即刻、15 min、30 min、1 h以及24 h的骨骼肌收缩性能(最大径向位移、收缩速度)、最大等长力量和心脏自主神经功能。结果:1)与CON组相比,BFR₄₀组的副交感神经活性受到轻微抑制(P<0.05),可在运动后30 min内恢复(P>0.05);2)BFR₆₀组的最大等长力量在运动后显著下降(P<0.01),副交感神经活性进一步抑制(P<0.01),交感神经支配增强(P<0.05),运动后30 min内恢复交感—副交感神经的平衡性(P>0.05);3)BFR80组运动后诱发显著的外周疲劳(P<0.01),使副交感恢复显著延迟,交感活性大幅增强(P<0.05),需更长时间恢复交感—副交感神经的平衡性(24 h内);4)相关性分析显示,副交感神经活性分别与最大径向位移(r=0.65)、收缩速度(r=0.62)和最大等长力量(r=0.55)呈正相关(P<0.05),交感神经活性与上述3个指标呈负相关(P<0.05)。结论:血流限制运动中,40%AOP会抑制迷走神经活性;60%AOP可明显影响交感神经活性和交感—副交感调控的平衡性;80%AOP可诱发显著的外周疲劳,且与心脏自主神经调控密切相关。综上所述,不建议心血管风险高的患者使用80%AOP训练。     

Segment coordination and variability among prospectively injured and uninjured runners

ABSTRACT

Coordinative variability (CAV) and underlying coordinative patterns are potential running-related overuse injury (RROI) mechanisms, but prospective analyses are needed. This study compared lower limb CAV and coordinative patterns between prospectively injured and uninjured runners. Knee, shank, and ankle kinematics were collected for 39 recreational runners at the beginning of a 6-month follow-up period. Subjects were classified as injured (n=21) or controls (n=18) based on RROI incidence during follow-up. CAV was quantified using modified vector coding. Time spent in each coordinative pattern category was quantified using binning frequency analysis. Coordinative patterns were classified as mechanically unsound if underlying joint/segment motions opposed anatomically allowable running motion. Wilcoxon Rank-Sum tests compared CAV and binning frequencies between groups within different stance portions for knee-shank, shank-ankle, and knee-ankle couplings (α≤0.05). During initial-stance, the injured group displayed significantly greater knee-ankle CAV (effect size (ES)=1.1), knee-shank CAV (ES=0.97), and greater frequency of mechanically unsound knee-shank (ES=0.72) and shank-ankle (ES=0.63) motion. During mid-stance, the injured group displayed lower frequency of mechanically sound knee-ankle motion (ES=0.31). In late-stance, the injured group displayed greater shank-ankle CAV (ES=0.11). Mechanically unsound coordinative patterns along with greater knee-ankle and shank-ankle CAV potentially lead to RROI.     

迟子建《越过云层的晴朗》中语言的变异性分析

艺术语言也叫变异语言,是对常规语言规律的超脱和违背,其变异性也通常以一定的语言形式表现出来,分析《越过云层的晴朗》中语言的变异性,以展现小说中变异语言的独特功能与魅力。     

Influence of Emotion on the Control of Low-Level Force Production

The accuracy and variability of a sustained low-level force contraction (2% of maximum voluntary contraction) was measured while participants viewed unpleasant, pleasant, and neutral images during a feedback occluded force control task. Exposure to pleasant and unpleasant images led to a relative increase in force production but did not alter the variability of force production compared to conditions in which participants viewed neutral images. Findings are discussed with respect to prior work, emphasizing arousal specific changes that emerge at low target force levels.     

Variation and homogeneity in affective responses to physical activity of varying intensities: An alternative perspective on dose – response based on evolutionary considerations

A model for systematic changes in patterns of inter-individual variation in affective responses to physical activity of varying intensities is presented, as a conceptual alternative to the search for a global dose?–?response curve. It is theorized that trends towards universality will emerge in response to activities that are either generally adaptive, such as moderate walking, or generally maladaptive, such as strenuous running that requires anaerobic metabolism and precludes the maintenance of a physiological steady state. At the former intensity the dominant response will be pleasure, whereas at the latter intensity the dominant response will be displeasure. In contrast, affective responses will be highly variable, involving pleasure or displeasure, when the intensity of physical activity approximates the transition from aerobic to anaerobic metabolism, since activity performed at this intensity entails a trade-off between benefits and risks. Preliminary evidence in support of this model is presented, based on a reanalysis of data from a series of studies.     

Effect of a Marathon Run on Serum Lipoproteins,Creatine Kinase,and Lactate Dehydrogenase in Recreational Runners

Abstract

The objective of this study was to determine the effect of a marathon run on serum lipid and lipoprotein concentrations and serum muscle enzyme activities and follow their recovery after the run. These blood concentrations were measured before, immediately after, and serially after a marathon run in 15 male recreational runners. The triglyceride level was significantly elevated postrace, then fell 30% below baseline 1 day after the run, and returned to baseline after 1 week. Total cholesterol responded less dramatically but with a similar pattern. High-density lipoprotein cholesterol remained significantly elevated and low-density lipoprotein cholesterol was transiently reduced for 3 days after the run. The total cholesterol/high-density cholesterol ratio was significantly lowered for 3 days. Serum lactate dehydrogenase activity significantly doubled postrace and then declined but remained elevated for 2 weeks. Serum creatine kinase activity peaked 24 hr after the run, with a 15-fold rise, and returned to baseline after 1 week. The rise of these enzymes reflects mechanically damaged muscle cells leaking contents into the interstitial fluid. It is concluded that a prolonged strenuous exercise bout in recreational runners, such as a marathon, produces beneficial changes in lipid blood profiles that are significant for only 3 days. However, muscle damage is also evident for 1 week or more from the dramatic and longlasting effect on enzyme levels. Laboratory values for these runners were outside normal ranges for some days after the race.     

Haptic perception accuracy depending on self-produced movement

Abstract

This study measured whether self-produced movement influences haptic perception ability (experiment 1) as well as the factors associated with levels of influence (experiment 2) in racket sports. For experiment 1, the haptic perception accuracy levels of five male table tennis experts and five male novices were examined under two different conditions (no movement vs. movement). For experiment 2, the haptic afferent subsystems of five male table tennis experts and five male novices were investigated in only the self-produced movement-coupled condition. Inferential statistics (ANOVA, t-test) and custom-made devices (shock & vibration sensor, Qualisys Track Manager) of the data were used to determine the haptic perception accuracy (experiment 1, experiment 2) and its association with expertise. The results of this research show that expert-level players acquire higher accuracy with less variability (racket vibration and angle) than novice-level players, especially in their self-produced movement coupled performances. The important finding from this result is that, in terms of accuracy, the skill-associated differences were enlarged during self-produced movement. To explain the origin of this difference between experts and novices, the functional variability of haptic afferent subsystems can serve as a reference. These two factors (self-produced accuracy and the variability of haptic features) as investigated in this study would be useful criteria for educators in racket sports and suggest a broader hypothesis for further research into the effects of the haptic accuracy related to variability.