Purpose. The purpose of the study was to examine the repeatability of electromyography (EMG) normalization in office workers with neck and shoulder symptoms. Methods. Fifteen female office workers with neck/shoulder symptoms were recruited to participate in two separate days of testing. Maximum voluntary isometric contraction (MVIC) was used for the normalization of EMG data on the following muscles: cervical erector spinae, upper trapezius, lower trapezius and anterior deltoid. Repeatability was calculated using the intra-class correlation (ICC), relative standard error of measurement (%SEM) and relative coefficient of variation (%CV). Results. Peak root mean square (rms) and median frequency (MF) showed good to high repeatability in the UT, AD and CES (ICC?=?0.87–0.95, %SEM=?2.65–9.48, %CV=?0.2–5.9). The repeatability of peak rms was good (ICC?=?0.87, %SEM?=?12.56, %CV?=?3.3) and the MF of the LT was fair (ICC?=?0.76, %SEM?=?5.71, %CV?=?2.9). Conclusion. Peak rms and MF from the MVIC normalization method can be measured with sufficient repeatability in symptomatic office workers. 相似文献
为了验证我国本土鱼种稀有鮈鲫(Gobiocypris rarus)在鱼类胚胎急性毒性试验的适用性,评价其在鱼类替代试验中的应用潜力,选取3,4-二氯苯胺和五水硫酸铜,按照《OECD化学品测试准则No.236鱼类胚胎急性毒性试验》,分别开展6次稀有鮈鲫胚胎急性毒性试验,通过评价试验结果的重复性,验证稀有鮈鲫是否适用于鱼类胚胎急性毒性试验.结果表明:3,4-二氯苯胺和五水硫酸铜对稀有鮈鲫胚胎的96 h LC50(96 h半数致死浓度)平均值(x)分别为12.8和1.76 mg/L,标准差(s)分别为1.70和0.197 mg/L;变异系数(CV)分别为13.3%和11.2%,均小于30%;两种化学品6次试验的96 h LC50均在各自x±2s范围内.研究显示,稀有鮈鲫胚胎的形态特征、发育过程及孵化时间等生物学特征均与斑马鱼类似,3,4-二氯苯胺和五水硫酸铜这两种化学品的胚胎急性毒性试验结果具有良好的重复性,其敏感性也与成鱼类似.因此,稀有鮈鲫作为一种我国本土的标准试验鱼种,具有鱼类胚胎急性毒性试验的应用潜力. 相似文献
Objective: The goal of this study was to characterize the rollover crash and to evaluate the repeatability of the Dynamic Rollover Test System (DRoTS) in terms of initial roof-to-ground contact conditions, vehicle kinematics, road reaction forces, and vehicle deformation.
Methods: Four rollover crash tests were performed on 2 pairs of replicate vehicles (2 sedan tests and 2 compact multipurpose van [MPV] tests), instrumented with a custom inertial measurement unit to measure vehicle and global kinematics and string potentiometers to measure pillar deformation time histories. The road was instrumented with load cells to measure reaction loads and an optical encoder to measure road velocity. Laser scans of pre- and posttest vehicles were taken to provide detailed deformation maps.
Results: Initial conditions were found to be repeatable, with the largest difference seen in drop height of 20 mm; roll rate, roll angle, pitch angle, road velocity, drop velocity, mass, and moment of inertia were all 7% different or less. Vehicle kinematics (roll rate, road speed, roll and pitch angle, global Z′ acceleration, and global Z′ velocity) were similar throughout the impact; however, differences were seen in the sedan tests because of a vehicle fixation problem and differences were seen in the MPV tests due to an increase in reaction forces during leading side impact likely caused by disparities in roll angle (3° difference) and mass properties (2.2% in moment of inertia [MOI], 53.5 mm difference in center of gravity [CG] location).
Conclusions: Despite those issues, kinetic and deformation measures showed a high degree of repeatability, which is necessary for assessing injury risk in rollover because roof strength positively correlates with injury risk (Brumbelow 2009). Improvements of the test equipment and matching mass properties will ensure highly repeatable initial conditions, vehicle kinematics, kinetics, and deformations. 相似文献
The ion chromatography combined solid phase extraction (SPE) method was developed for the analysis of low concentration haloacetic acids(HAAs),a calss of disinfection by-products formed as a result of chlorination of hospital wastewater. The monitored HAAs included monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, dibromoacetic acid and trichloroacetic acid. The method employed a sodium hydroxide eluent at a flow rate of 0.8 ml/min, electrolytically generated gradients, and suppressed conductivity detection. To analyze the HAAs in real hospital wastewater samples, C18 pretreatment cartridge was utilized to reduce samples' turbidity. Preconcentration with SPE and matrix elimination with treatment cartridges were investigated and were found to be able to obtain acceptable detection limits. Linearity, repeatability and detection limits of the above method were evaluated. The detection limits of monobromoacetic acid and dibromoacetic acid were 2.61 μg/L and 1.30 μg/L respectively, and the other three are ranging from 0.48 to 0.82 μg/L under 25-fold preconcentration. When the above optimization procedure was applied to three hospital wastewater samples with different treatment processes in Tianjin, it was found that the dichloroacetic acid is the major compound, and the growth ratios of the HAAs after disinfection by sodium hypochlorite were 91.28%, 63.61% and 79.50%, respectively. 相似文献