基于快速节律性运动的皮层脑电分析

节律运动是人们生活中一种基本的运动形式,与单次运动相区别,快速节律运动在脑电中有特殊的表现形式.本文以两位植入皮层电极的癫痫病人作为受试,在1Hz与2Hz听觉节拍器提示下进行手指节律运动,同时记录皮层脑电数据.对脑电数据的能量和相关性进行离线分析,结果显示节律运动中运动感觉皮层脑电的能量在特定频段上呈下降趋势,相干性呈上升趋势,且运动相关能量与相干性在不同的运动速度下具有明显的统计性差异.对不同功能区之间相干性的分析表明辅助运动区可能是与运动速度有关的皮层功能区.     

Force-, power-, and elasticity-velocity relationships in walking,running, and jumping

Summary Ground reaction forces and mechanical power were investigated when the subjects walked normally, while they were racing or running at four speeds, and when they performed the running long jump take-off. In addition, the apparent spring constants of the support leg in eccentric and concentric phases were investigated at the four running speeds, during the running long jump take-off, and in the triple jump. Six club level track and field athletes, four national level long jumpers, and six national level triple jumpers took part in the study. Cinematographic technique and a mathematical model of hopping (Alexander and Vernon 1975) were employed in the analysis. Force and power values were found to vary in the following order (from highest to lowest): long jump take-off, maximal running speed, submaximal running (80, 60, and 40% of maximum speed), racing gait, and normal gait. The data disclosed that the measured parameters had the highest values in the long jump take-off performed by the long jump athletes. Their peak values were: resultant ground reaction force 3270±74 N and mechanical power 160.1±10.5 J×kg^–1×s^–1. For the track and field athletes the values were 2010±80 N and 126.0±12.6 J ×kg^–1×s^–1. The apparent spring constant values of the support leg in the national level jumper group were in eccentric phase 30.54±8.38 N×mm^–1 ×kg^–1 and in concentric phase 0.129±0.012 N×mm^–1×kg^–1. In the track and field athletes the values were 13.97±1.01 N×mm^–1×kg^–1 and 0.093±0.003 N×mm^–1×kg^–1, respectively. In general, the increase in force and mechanical power output was related to the value of the apparent spring constant of the support leg in the eccentric phase. The spring constant in the eccentric phase increased with the velocity of motion in running, the long jump take-off and the triple jump. This suggests that it may be possible to use this parameter as a measure of mechanical performance, as it may reflect the combined elasticity of muscles, tendons, and bones.     

Effects of evening bright light exposure on melatonin, body temperature and sleep

SUMMARY  Five male subjects were exposed to a single 2-h period of bright (2500 lux) or dim (<100 lux) light prior to sleep on two consecutive nights. The two conditions were repeated the following week in opposite order. Bright light significantly suppressed salivary melatonin and raised rectal temperature 0.3°C (which remained elevated during the first 1.5 h of sleep), without affecting tympanic temperature. Bright light also increased REM latency, NREM period length, EEG spectral power in low frequency, 0.75-8 Hz and sigma, 12–14 Hz (sleep spindle) bandwidths during the first hour of sleep, and power of all frequency bands (0.5–32 Hz) within the first NREMP. Potentiation of EEG slow wave activity (0.5-4.0 Hz) by bright light persisted through the end of the second NREMP. The enhanced low-frequency power and delayed REM sleep after bright light exposure could represent a circadian phase-shift and/or the effect of an elevated rectal temperature, possibly mediated by the suppression of melatonin.     

Hyperthermia and maximal oxygen uptake in men and women

To compare the effect of hyperthermia on maximal oxygen uptake (O_2max) in men and women, O_2max was measured in 11 male and 11 female runners under seven conditions involving various ambient temperatures (T_a at 50% RH) and preheating designed to manipulate the esophageal (T_es) and mean skin temperatures at O_2max. The conditions were: 25°C, no preheating (control); 25, 35, 40, and 45°C, with exercise-induced preheating by a 20-min walk at ~33% of control O_2max; 45°C, no preheating; and 45°C, with passive preheating during which T_es and were increased to the same degree as at the end of the 20-min walk at 45°C. Compared to O_2max (l·min^–1) in the control condition (4.52±0.46 in men, 3.01±0.45 in women), O_2max in men and women was reduced with exercise-induced or passive preheating and increased T_a, ~4% at 35°C, ~9% at 40°C and ~18% at 45°C. Percentage reductions (7–36%) in physical performance (treadmill test time to exhaustion) were strongly related to reductions in O_2max (r=0.82–0.84). The effects of hyperthermia on O_2max and physical performance in men and women were almost identical. We conclude that men and women do not differ in their thermal responses to maximal exercise, or in the relationship of hyperthermia to reductions in O_2max and physical performance at high temperature. Data are reported as mean (SD) unless otherwise stated.     

Changes in the surface electromyogram during increasing isometric shoulder forward flexions

Summary When using electromyographic techniques in the evaluation of muscular load it is necessary to determine the mathematical relationship between the torque and the amplitude of the electromyographic signal. Isometric gradually increasing contractions up to 100% MVC can then be used. Often more than linear increases for the amplitude (RMS) — force regression have been reported. The present study was designed to test whether changes in power spectral density function take place during a gradually increasing isometric contraction (duration 10 s). Twenty-two clinically healthy females performed an increasing isometric shoulder forward flexion for 10 s using an isokinetic dynamometer. Electromyographic activity was measured in trapezius, deltoid, infraspinatus and biceps brachii using surface electrodes. Mean torque values were determined together with mean power frequency (MPF) and root mean square values (RMS) from the EMG signals for each 256 ms period. The RMS-torque regressions showed higher regression coefficients during the 6th to 9th sec than during the first 5 s. No significant correlation existed between MPF for the four muscles and the torque. A gradual decrease in MPF was generally found from the 6th s. It is concluded that this decrease in power spectral density function might have contributed to the significantly higher regression coefficient for the RMS torque regression at the high output part of the gradually increasing isometric contraction.     

Effects of a second bout of maximal eccentric exercise on muscle damage and electromyographic activity

This study examined whether a second bout of maximal eccentric exercise performed 3 days after the first exercise bout would produce further changes in muscle damage and electromyographic activity (EMG). Male students (n=26) were randomly assigned to experimental 70 (EX70; n=9), experimental 30 (EX30; n=8), and control (CON; n=9) groups. The initial exercise was 30 maximal voluntary isokinetic eccentric contractions (MAX1) on non-dominant elbow flexors at 60° s⁻¹ (1.05 rad s^-1). The EX70 and EX30 groups performed a second bout of 70 and 30 eccentric contractions (MAX2), respectively, 3 days after MAX1. Upper arm circumference , range of motion , strength, integrated EMG (IEMG), and mean power frequency (MPF) were measured before, immediately after, and once a day for 9 days after MAX1. Plasma creatine kinase (CK) activity and muscle soreness were assessed before and for 9 days after MAX1. Total work, work per contraction, IEMG, and MPF were also recorded during MAX1 and MAX2. All indicators of muscle damage changed following MAX1 for each group (P<0.05), but no indicators of additional damage (P>0.05) were apparent after MAX2 for either the EX70 or EX30 groups. IEMG (P=0.03) and MPF (P=0.04) were lower for MAX2 compared with MAX1 for both the EX30 and EX70 groups. It is concluded that performing a second bout of eccentric exercise with damaged muscles 3 days after the initial bout does not produce further damage or retard recovery, even when the second bout of exercise is more strenuous. EMG findings were consistent with reduced activation of fast-twitch motor units during the second eccentric bout. These results may be interpreted as evidence of a neural protective mechanism. Electronic Publication     

做强、做大、做活,培育一流科技期刊

【目的】 总结《材料科学技术(英文版)》在发展过程中“做强、做大、做活”的实践经验,探索培育一流科技期刊的可行道路。【方法】 采用文献研究、对比分析、定性分析、列举实证等方法,分析讨论如何通过“做强、做大、做活”培育一流科技期刊。【结果】 历经十余年努力,《材料科学技术(英文版)》的影响因子从0.175提升到10.319,年发文量从180篇增加到1000篇左右,进入JCR学科排名Top 2,成为国际材料领域的主流期刊。【结论】 培育世界一流科技期刊是我国科技创新事业的当务之急,也是重中之重。“做强、做大、做活”是培育一流期刊的可行且有效的途径。     

Nutritional Controlled Preparation and Administration of Different Tomato Purées Indicate Increase of β-Carotene and Lycopene Isoforms,and of Antioxidant Potential in Human Blood Bioavailability: A Pilot Study

The isoforms of lycopene, carotenoids, and their derivatives including precursors of vitamin A are compounds relevant for preventing chronic degenerative diseases such as cardiovascular diseases and cancer. Tomatoes are a major source of these compounds. However, cooking and successive metabolic processes determine the bioavailability of tomatoes in human nutrition. To evaluate the effect of acute/chronic cooking procedures on the bioavailability of lycopene and carotene isoforms in human plasma, we measured the blood levels of these compounds and of the serum antioxidant potential in volunteers after a meal containing two different types of tomato sauce (rustic or strained). Using a randomized cross-over administration design, healthy volunteers were studied, and the above indicated compounds were determined by HPLC. The results indicate an increased bioavailability of the estimated compounds and of the serum antioxidant potential with both types of tomato purée and the subsequently derived sauces (the increase was greater with strained purée). This study sheds light on the content of nutrient precursors of vitamin A and other antioxidant compounds derived from tomatoes cooked with different strategies. Lastly, our study indicates that strained purée should be preferred over rustic purée.     

头部电导纳图的导纳微分环及功率谱分析

通过多例头部电纳图的导纳微分环面积和功率谱分析,发现陡直型和转折型波形,其功率谱中的某些指标有显著性差异（P＜0．05）,导纳微分环中的Ⅰ,Ⅱ,Ⅳ相面积也有显著性差异（P＜0．05）。