模拟4800m低氧环境训练的适应效果研究

目的:对20名平原受试者进行为期3周递增性低氧训练,测试其低氧训练前后模拟海拔4 800m(PO2为10.4%～10.8%)时血清抗利尿激素(AVP)和醛固酮(ALD)的变化,并结合AMS评分、心率和血压,探讨递增性低氧训练对模拟高海拔低氧环境的适应效果。方法:阶段1:受试者于模拟海拔4 800m低氧环境中急性暴露6 h,以60rpm、80 W的定量负荷仰卧蹬车20 min,LLS量表评价AMS,测试低氧暴露过程中的HR和BP,低氧结束时的血清AVP和ALD;阶段2:进行3周递增性低氧训练后,再重复阶段1的测试。结果:低训后模拟海拔4 800m低氧环境下,AMS评分大于等于3分的人数由9人降到2人;运动时的心率明显低于低训前;急性低氧暴露6h,血清AVP和ALD均较常氧值显著下降;低训3周后再次低氧暴露,血清AVP和ALD与常氧值相比较,均无显著差异。结论:递增性低氧训练有助于增强机体对低氧的习服。     

广东省山洪灾害分布特征及关键影响因素分析

基于已发山洪灾害数据,首先探讨山洪灾害的空间分异规律;其次基于山洪灾害形成的地形、物源、水动力条件,选择相对高差、坡度、水系密度、地层岩性、多年平均24 h降雨和距水系距离6大主因子,定量分析山洪灾害与各因子之间的数量和概率相关关系.基于ArcGIS将广东省划分为179801个网格,按网格分别统计每个因子中山洪灾害的数...     

桥梁高墩施工爬摸技术

近年来,随着我国交通事业的蓬勃发展,公路、铁路和城市道路不断出现越来越高的桥墩。高墩施工方法的研究成为桥梁建筑工作者十分关注的问题。本文针对桥梁高墩施工的关键技术——爬模施工做了初步分析。     

Influence of wheel size on muscle activity and tri-axial accelerations during cross-country mountain biking

ABSTRACT

This study aimed to investigate the influence of different mountain bike wheel diameters on muscle activity and whether larger diameter wheels attenuate muscle vibrations during cross-country riding. Nine male competitive mountain bikers (age 34.7 ± 10.7 years; stature 177.7 ± 5.6 cm; body mass 73.2 ± 8.6 kg) participated in the study. Riders performed one lap at race pace on 26, 27.5 and 29 inch wheeled mountain bikes. sEMG and acceleration (RMS) were recorded for the full lap and during ascent and descent phases at the gastrocnemius, vastus lateralis, biceps brachii and triceps brachii. No significant main effects were found by wheel size for each of the four muscle groups for sEMG or acceleration during the full lap and for ascent and descent (P > .05). When data were analysed between muscle groups, significant differences were found between biceps brachii and triceps brachii (P < .05) for all wheel sizes and all phases of the lap with the exception of for the 26 inch wheel during the descent. Findings suggest wheel diameter has no influence on muscle activity and vibration during mountain biking. However, more activity was observed in the biceps brachii during 26 inch wheel descending. This is possibly due to an increased need to manoeuvre the front wheel over obstacles.     

Differences in forearm strength,endurance, and hemodynamic kinetics between male boulderers and lead rock climbers

This study examined differences in the oxygenation kinetics and strength and endurance characteristics of boulderers and lead sport climbers. Using near infrared spectroscopy, 13-boulderers, 10-lead climbers, and 10-controls completed assessments of oxidative capacity index and muscle oxygen consumption (m?O₂) in the flexor digitorum profundus (FDP), and extensor digitorum communis (EDC). Additionally, forearm strength (maximal volitional contraction MVC), endurance (force–time integral FTI at 40% MVC), and forearm volume (FAV and ΔFAV) was assessed. MVC was significantly greater in boulderers compared to lead climbers (mean difference?=?9.6, 95% CI 5.2–14?kg). FDP and EDC oxidative capacity indexes were significantly greater (p?=?.041 and .013, respectively) in lead climbers and boulderers compared to controls (mean difference?=??1.166, 95% CI (?3.264 to 0.931?s) and mean difference?=??1.120, 95% CI (?3.316 to 1.075?s), respectively) with no differences between climbing disciplines. Climbers had a significantly greater FTI compared to controls (mean difference?=?2205, 95% CI=?1114–3296 and mean difference?=?1716, 95% CI?=?553–2880, respectively) but not between disciplines. There were no significant group differences in ΔFAV or m?O₂. The greater MVC in boulderers may be due to neural adaptation and not hypertrophy. A greater oxidative capacity index in both climbing groups suggests that irrespective of climbing discipline, trainers, coaches, and practitioners should consider forearm specific aerobic training to aid performance.     

高山滑雪运动中技能学习过程的心理学研究

高山滑雪运动是随着我国经济的高速发展,人民生活水平的不断提高,为了满足人民日益增长的物质与文化需求逐步发展起来的。其运动适合各个年龄阶段的人群,具有广泛的普及特点。对于滑雪运动者来讲,高山滑雪有其独特的运动特点与技术形成过程,在掌握高山滑雪运动的过程中,心理因素对滑雪者的技能形成过程具有重要的影响作用。研究旨在探讨影响高山滑雪运动中技能学习过程中的心理学问题,以便为更好、更快地促进高山滑雪运动的普及和开展提供一定的理论建议和帮助。     

庐山自然保护区森林生态系统服务价值评估

森林生态系统具有多种重要的生态功能,分析与评价森林生态系统服务功能的价值已成为当前生态学与生态经济学研究的前沿课题。根据森林生态系统服务价值的计算方法,估算了庐山自然保护区森林生态系统7项服务价值总量为26.1086×108元/年。庐山森林生态系统服务功能的直接经济价值和间接经济价值分别为16.1605×108元/年和9.9481×108元/年,直接经济价值是间接经济价值的1.62倍。在森林生态系统各项服务功能价值的贡献之中,其大小顺序依次为:森林游憩>固CO2释O2>土壤保持>净化空气>涵养水源>林果产品>保护生物多样性。森林游憩价值以16.0838×108元/年稳居第1位,占总价值的61.60%;其次为固CO2释O2的价值,占总价值的32.91%,两项合计占到95.51%。庐山森林生态系统服务在价值构成上异于全国一般规律的原因,主要在于庐山自然保护区高度发达的旅游产业和小规模的林业生产活动等。森林生态系统价值评估有助于人们对于森林生态系统价值的认识,有利于区域可持续发展战略的实施和推进。     

贫困山区生态渔业扶贫模式的实践与思考——从湖北恩施到贵州六盘水

科学技术的发展和应用始终以国家需要和人民诉求为导向,科技扶贫是脱贫攻坚工作的重要方式之一。根据部分贫困地区人均可用耕地少、水域面积广的地理资源特点,中国科学院水生生物研究所在湖北省恩施市龙凤镇和贵州省六盘水市水城县的扶贫实践中总结出一套"中科院技术+当地政府+当地龙头企业+贫困户/贫困集体"的生态渔业扶贫模式。即联合当地政府和龙头企业,在合理构建鱼类群落结构的基础上,科学利用山区水资源,可在保障水质的同时给周边渔农民带来经济收入。生态渔业扶贫模式的示范与推广不仅保护了生态环境,还有效促进了贫困山区水产养殖业的科学发展,使得当地群众增强了生态文明意识,掌握了一定的科学养殖技术,加速了贫困户增收脱贫,体现了扶贫模式的"造血"功能,保障了贫困户脱贫不返贫。     

汶川地震重灾区生态退化及其恢复重建对策

2008年5月12日在四川汶川境内发生的里氏8.0级大地震是我国大陆历史上发生的破坏性最严重的地震灾害干扰事件。不仅造成重大经济损失,也使区域生态功能衰退显著。本文在分析地震灾区基本特点的基础上,揭示了重灾区目前比较突出的生态退化问题与恢复重建任务,提出了灾后生态恢复重建对策。     

中国山地科学发展构想

我国山地面积约占陆地面积的70%,是世界第一山地大国。我国人口与经济快速增长,山区土地利用、矿产资源、森林资源等开发强度的增加与山区脆弱的生态环境难以承受的尖锐矛盾日益凸显,严重影响国家未来经济和生态环境安全。当前,国外重大研究计划(IGBP,IHDP,GTOS)非常关注山地重大科学问题的探索,山地研究已成国际热点和科学前沿。加强山地科学研究,着力发展山地科学体系,为新山区建设提供强有力的科技支撑,确保山区发展又好又快,同时对提高我国在国际地球系统科学领域的影响力和引领作用具有重大的战略意义。