Combined effects of exposure to hypoxia and cool on walking economy and muscle oxygenation profiles at tibialis anterior

We investigated combined effects of ambient temperature (23°C or 13°C) and fraction of inspired oxygen (21%O₂ or 13%O₂) on energy cost of walking (C_w: J·kg^?1·km^?1) and economical speed (ES). Eighteen healthy young adults (11 males, seven females) walked at seven speeds from 0.67 to 1.67 m s^?1 (four min per stage). Environmental conditions were set; thermoneutral (N: 23°C) with normoxia (N: 21%O₂) = NN; 23°C (N) with hypoxia (H: 13%O₂) = NH; cool (C: 13°C) with 21%O₂ (N) = CN, and 13°C (C) with 13%O₂ (H) = CH. Muscle deoxygenation (HHb) and tissue O₂ saturation (StO₂) were measured at tibialis anterior. We found a significantly slower ES in NH (1.289 ± 0.091 m s^?1) and CH (1.275 ± 0.099 m s^?1) than in NN (1.334 ± 0.112 m s^?1) and CN (1.332 ± 0.104 m s^?1). Changes in HHb and StO₂ were related to the ES. These results suggested that the combined effects (exposure to hypoxia and cool) is nearly equal to exposure to hypoxia and cool individually. Specifically, acute moderate hypoxia slowed the ES by approx. 4%, but acute cool environment did not affect the ES. Further, HHb and StO₂ may partly account for an individual ES.     

Did London 2012 deliver a sports participation legacy?

Despite the increasing academic interest in the analysis of the Olympic legacy, there is a relative knowledge gap as far as sports participation legacy is concerned. The authors bridge this gap by analysing the short-term sports participation legacy of the London 2012 Olympic and Paralympic Games on the adult population in England. By using data from the Active People Survey and considering different sports participation variables and the effect of the economic climate, results demonstrate a positive association with participation from hosting the Games. Participation rates were adjusted to take into account seasonality and changes in the gross domestic product (GDP), accounting in this way for the effect of the recent economic recession. The biggest effect was observed in relation to frequent participation (at least three times per week for at least 30 min) in the year immediately after the Games. In 2014, the sports participation rates fell relative to 2013 but remained higher than pre-Olympic levels. The sport participation legacy of the Olympic Games appeared to have significant differences between socio-demographic groups.     

Transmission of vibration from a vibrating plate to the head of standing people

Little is known about the transmission of vibration to the head when using whole-body vibration (WBV) training machines. This paper investigates the effect of frequency and posture on the transmission of vibration from a vibrating plate to the head of standing people. Nine male participants were exposed to vertical vibration at nine frequencies in the range of 17–46 Hz and vibration acceleration in the range of 7.85–18.64 m/s² (peak). The participants adopted four standing postures described as standing with locked knee (LK), bent knee (BK), one leg (OL), and one foot to the front and the other to the back (FB). The transmissibility to the head differed among postures (t-test, p < 0.05) and was greatest with the FB posture and smallest with the BK posture. The transmissibility to the head decreased with increasing the frequency (t-test, p < 0.05) but the extent of the decrease depended on the adopted posture. This frequency-posture interaction effect on the transmissibility should be considered when designing a training program. The data will be useful for developing standards/protocols that govern the use of WBV machines as well as for building human body models that can predict potential risks arising from using WBV machines.     

北京冬奥会推动京津冀冰雪旅游发展效应及协同推进策略研究

摘要：以冬奥会进入“北京周期”后为契机,采用文献资料和实地调查等研究方法,对北京冬奥会推动京津冀冰雪旅游发展效应及协同推进策略进行了研究。研究认为：北京冬奥会推动京津冀冰雪旅游发展的效应明显,主要表现在北京市冰雪场馆建设数量明显增加、连续举办的国际冰雪赛事和国内冰雪赛事促进冰雪旅游发展的影响力明显提升、冰雪旅游融合效应显著;天津市冰雪旅游协同发展目标明确深耕细作释放新活力效果显著、冰雪旅游民生工程建设落实有声、“冰雪旅游+文化”深度融合带来红利;河北省在滑雪场和滑冰场数量逐年提升、以张家口为核心的冰雪旅游发展区位优势明显、生态冰雪旅游发展成效显著。据此提出构建京津冀冰雪体育产业链,促进京津冀冰雪旅游产业经济生态圈建设的可持续发展;以全域旅游发展理念为引领,构建多元化的京津冀冰雪旅游公共服务体系;构建完善的京津冀生态冰雪旅游资源开发与环境保障体系的北京冬奥会推动京津冀冰雪旅游发展效应的协同推进策略。     

降水对蔬菜价格的冲击效应——以广州为例

降水对蔬菜价格波动有重要影响,分析降水的蔬菜价格冲击效应对菜价预测及市场供需调整具有重要意义.本文首先构建了一个包含降水因素的蔬菜供需动态模型,揭示逐日降水对菜价的影响机制,并阐明了降水对不同蔬菜冲击效应存在异质性的原因;然后基于广州市2004-2018年逐日的菜心、生菜和豆角3种蔬菜零售价格数据及降水数据,采用VAR...     

数据库营销对县域经济发展的促进效应研究——以河北省为例

数据库营销这一贯彻现代营销管理理念的新型工具可加快市场资源的合理配置．理顺市场运行机制,促进县域经济的发展。当前河北省县域经济发展中存在着营销管理观念落后、市场拓展力较弱、产品市场影响力低、资源利用率低等问题。在这种情况下,应利用数据库营销的优势．健全“三农”信息服务体系;拓展县域市场渠道,提高市场运行效率;加大信息传播力度,优化乡镇中小企业发展环境。     

景观动态及其驱动因素和效应分析——以江西省泰和县灌溪乡千烟洲为例

本文运用土地利用的ＤＬＵ（ＤｉｆｅｒｅｎｔｉａｔｅｄＬａｎｄＵｓｅ）战略理论和景观动态分析模型，分析了江西省泰和县灌溪乡千烟洲的土地利用时间动态，并对其产生的效应和它们的驱动因素进行了概括和总结。     

大学本科力学类课程的公式辅助记忆方法研究

力学课程作为工科专业的重要基础课程,有大量公式需要学生记忆和掌握,从而给学习带来了一定困难。文章作者从力学课程的特点出发,结合多年的教学实践经验,针对多门力学课程,总结出了多种辅助记忆公式的方法,并取得了良好的授课效果。     

财税政策组合对企业技术创新的影响

以沪深A股高新技术上市公司2011~2019年相关数据为研究对象,实证检验财税政策组合对企业技术创新和可持续发展的影响效果和机理。研究发现:财税政策组合与企业技术创新之间呈倒U 型曲线关系,且随着创新水平的提高,财税政策组合对技术创新的影响弹性不断降低。同时,财税政策组合会通过“技术创新”这一中介桥梁对企业可持续发展产生倒U 型的影响作用,且与低技术创新相比,由于高技术创新更能提高企业竞争力,它发挥的中介作用更加显著。     

远场类谐和地震作用下双柱墩梁桥失效分析

根据远场类谐和地震动、普通地震动反应谱与规范反应谱之间的包络关系,选取输入结构的地震动加速度峰值?建立双柱墩式抗震梁桥,分析同峰值加速度的远场类谐和地震动和普通地震动作用下双柱墩式梁桥主梁、墩柱的地震响应等,揭示远场类谐和地震动作用下双柱墩式梁桥的动力响应与失效机理?采用SR模型模拟双柱墩抗震梁桥墩底的SSI效应,分析远场类谐和地震动作用下梁桥地震响应变化规律。结果表明,远场类谐和地震动对桥梁的地震响应为普通地震动作用的1.5倍以上,其设防烈度至少应提高一度才能保证桥梁的安全?墩-系梁连接点处弯矩随桩土刚度减小而增大,有可能会引起桥墩弯曲破坏。