Effect of gender on trunk and pelvis control during lateral movements with perturbed landing

In lateral reactive movements, core stability may influence knee and hip joint kinematics and kinetics. Insufficient core stabilisation is discussed as a major risk factor for anterior cruciate ligament (ACL) injuries. Due to the higher probability of ACL injuries in women, this study concentrates on how gender influences trunk, pelvis and leg kinematics during lateral reactive jumps (LRJs). Perturbations were investigated in 12 men and 12 women performing LRJs under three different landing conditions: a movable landing platform was programmed to slide, resist or counteract upon landing. Potential group effects on three-dimensional trunk, pelvic, hip and knee kinematics were analysed for initial contact (IC) and the time of peak pelvic medial tilt (PPT). Regardless of landing conditions, the joint excursions in the entire lower limb joints were gender-specific. Women exhibited higher trunk left axial rotation at PPT (women: 4.0 ± 7.5°, men: ?3.1 ± 8.2°; p = 0.011) and higher hip external rotation at both IC and PPT (p < 0.01). But women demonstrated higher knee abduction compared to men. Men demonstrated more medial pelvic tilt at IC and especially PPT (men: –5.8 ± 4.9°, women: 0.3 ± 6.3°; p = 0.015). Strategies for maintaining trunk, pelvis and lower limb alignment during lateral reactive movements were gender-specific; the trunk and hip rotations displayed by the women were associated with the higher knee abduction amplitudes and therefore might reflect a movement strategy which is associated with higher injury risk. However, training interventions are needed to fully understand how gender-specific core stability strategies are related to performance and knee injury.     

模拟中继电路信号电平的自动调节

专网通信中的模拟中继电路的信号电平失调是一种常见的问题．通过分析信号电平调整的原理,提出了2种能够实现信号电平自动调整的改良性方法．一种为模拟式信号电平自动调节,以导频信号为基础,通过调节可控增益放大器白动调节话音信号的电平变化．另一种为数字式信号电平自动调节,先将导频信号进行A/D转换并生成一个基准数值,通过PC机程序改变该基准数值的变化,达到调整语号信号电平的目的．     

单臂路由实现企业网VLAN间通信

为使企业网不同VLAN之间能够互相通信,通过单臂路由实现了该功能,并通过仿真软件YSRouterSim设计了企业网络拓扑结构图,经测试,得出了正确的实验结果.     

汉字起源观念的文化审思

汉字起源的研究误解甚多 ,人们多以为汉字的历史是从甲骨文开始 ,其实 ,甲骨文不是中国最早的文字 ,也不是当时的主流文字 ,更不是当时中华文化的先进代表 ,相反却是那时一种职业性的落后的“变文” ;甲骨———金文———竹简书没有先后的继承关系 ,它们只是书刻文字材料的进化过程 ;汉字的起源不是考古学的问题 ,是心理学的问题 ,是人类文化学的问题。我们不能将文字与书写文字的物质材料等同起来     

Trunk技术在局域网的实现

针对局域冈交换机互联存在瓶颈的问题，结合工程实践，研究分析了交换机端口Trunk的基本原理，提出了使用端口Trunk的方法，提高了网络设备的使用性能。     

基于交换机端口初始化进程的分析

在校园网的维护过程中,交换机的配置十分重要.本文介绍了交换机端口初始化工作原理,针对鞍山师范学院网络拓扑结构的情况,给出了提高交换机接口性能的解决办法,最终达到学院交换机利用率提高、用户上网快捷的目的.     

VLAN 在企业网中的设计

传统的局域网往往是一个平的交换型网络，每台没备都可以看到每个被传播的广播包，这样会导致大量无用的广播信息充斥整个网络，既缺乏安全性，又不能智能地对数据流进行负载均衡。针对这些问题，我们引入虚拟局城网(VLAN)的技术。本文概述了公司内局域网的状况和需求，介绍了Trunk的工作方式及VLAN划分的具体策略，并据此给出了公司局域网内实施VLAN的具体方法。     

浅谈千兆网络改造的设计与实施

根据网络改造的设计目标,采用"主干千兆,支干千兆,百兆交换桌面"的三层设计思路,将网络设计为"核心层 分布层 接入层"的三层网络的网络模型,更大的满足对视频、音频和数据通讯三方面的要求,在网络的安全性、先进性、可扩充性和兼容性方面也达到预期目标.     

The measurement of shoulder alignment in cricket fast bowling

The aim of this study was to compare thoracic spine alignment with two-and three-dimensional calculations of shoulder alignment (defined as a line joining the acromion processes of the right and left scapula) when all measures were projected onto the transverse plane. A six-camera Vicon system was used to reconstruct three markers positioned on the plane of the thorax such that the orthogonal vector to the thoracic spine, projected onto the transverse plane, was used as a virtual shoulder alignment during cricket fast bowling. This same measurement system was used to calculate the three-dimensional line between the acromion processes projected onto the transverse plane. These acromion markers were also used to calculate the two-dimensional transverse plane alignment of the shoulders from images recorded by a video camera positioned above ball release. All cameras operated at 50 Hz. A significant association was recorded between thorax alignment and the three- (0.97) and two-dimensional (0.87) shoulder alignment estimations at back-foot impact. The strength of association remained at front-foot impact, when correlations of 0.89 (three-dimensional) and 0.84 (twodimensional) were recorded. However, at ball release, non-significant associations of 0.58 (three-dimensional) and 0.41 (two-dimensional), representing shoulder alignment differences of approximately 10°, were recorded. The 95% limits of agreement comparisons for shoulder alignment at back-foot impact, front-foot impact and ball release produced mean random errors for the two comparisons of 9.5°, 11.7° and 22.5° respectively. Three- and two-dimensional transverse plane projections of shoulder alignment are reasonable estimates of thorax alignment at back-foot impact and front-foot impact but not at ball release.     

The effect of active sitting on trunk motion

BackgroundProlonged sitting is a risk factor for low-back pain. The primary purpose of this study is to determine if prolonged active sitting will result in increased trunk motion.MethodsFifteen healthy female participants volunteered to sit for 30 min on each of three surfaces including an air-cushion, a stability ball, and a hard surface. Trunk motion was monitored using a Vicon motion capture system, and foot center of pressure was collected with two AMTI force plates.ResultsOur findings indicated that the average speed of the trunk center of mass significantly increased with seating surface compliance. There were significant differences in right and left foot centers of pressure in the antero-posterior direction between the ball and air-cushion conditions and the ball and chair conditions.ConclusionActive sitting results in increased trunk motion and could have a positive effect on low-back health.