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The development of fatigue during exercise and the subsequent onset of exhaustion occur earlier in the heat than in cooler environments. The underlying mechanisms responsible for the premature development of fatigue in the heat have yet to be clearly identified. However, the proposed mechanisms include metabolic, cardiovascular and central nervous system perturbations, together with an elevated core temperature. Fluid ingestion is one of three strategies that have been shown to be successful in enhancing the performance of endurance exercise in the heat, with the other interventions being precooling and acclimatization. However, like the development of fatigue in the heat, the mechanisms by which fluid ingestion allows for improved exercise performance remain unclear. We propose that fluid ingestion enhances exercise performance in the heat by increasing the heat storage capacity of the body. We suggest that the thermoregulatory, metabolic and cardiovascular alterations that occur as a result of this increased heat storage capacity contribute to performance enhancement when fluid is ingested during exercise heat stress. 相似文献
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The thermoregulatory responses of upper-body trained athletes were examined at rest, during prolonged arm crank exercise and recovery in cool (21.5 ± 0.9°C, 43.9 ± 10.1% relative humidity; mean ± s) and warm (31.5 &± 0.6°C, 48.9 - 8.4% relative humidity) conditions. Aural temperature increased from rest by 0.7 ± 0.7°C (P ? 0.05) during exercise in cool conditions and by 1.6 ± 0.7°C during exercise in warm conditions (P ? 0.05). During exercise in cool conditions, calf skin temperature decreased (1.5 ± 1.3°C), whereas an increase was observed during exercise in warm conditions (3.0 ± 1.7°C). Lower-body skin temperatures tended to increase by greater amounts than upper-body skin temperatures during exercise in warm conditions. No differences were observed in blood lactate, heart rate or respiratory exchange ratio responses between conditions. Perceived exertion at 45 min of exercise was greater than that reported at 5 min of exercise during the cool trial (P ? 0.05), whereas during exercise in the warm trial the rating of perceived exertion increased from initial values by 30 min (P ? 0.05). Heat storage, body mass losses and fluid consumption were greater during exercise in warm conditions (7.06 ± 2.25 J·g-1 ·°C-1, 1.3 ± 0.5 kg and 1038 ± 356 ml, respectively) than in cool conditions (1.35 ± 0.23 J·g-1·°C-1, 0.8 ± 0.2 kg and 530 ± 284 ml, respectively; P ? 0.05). The results of this study indicate that the increasing thermal strain with constant thermal stress in warm conditions is due to heat storage within the lower body. These results may aid in understanding thermoregulatory control mechanisms of populations with a thermoregulatory dysfunction, such as those with spinal cord injuries. 相似文献
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朱海涛 《现代图书情报技术》2012,(1):68-72
以北京第二外国语学院图书馆VMware虚拟化系统的构建与应用作为实例,阐明虚拟网络vNetwork的三种网络服务组成和光纤存储通道的多路径与故障切换是虚拟化系统构建的两个重要方面,分析归纳虚拟化系统在高校图书馆实际应用中的一些经验与体会,提出在安全防护、合理使用、应急措施、备份机制等方面的一些合理建议。 相似文献
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虚拟化技术和模拟器在高校、培训机构的实验室,尤其是网络与信息安全实验室中表现出很多独到的优势。软硬件结合的虚拟化技术能够提供真实性很好的虚拟实验环境,但是需要投入相对较多的人力和物力,而纯软件的模拟器构建的实验环境的真实性表现虽然不是那么优秀,支持的设备也相对较少,但是,极低的投入,甚至无需投入就能让学生拥有自己的实验室,对于高校学生来说已经能够满足绝大多数的实验要求,并且更加易于普及和推广。虚拟化技术虚拟器结合使用的实验教学模式虽然具有很多独到的优势,是未来实验教学的重要途径和方式,目前还取代不了传统的实验教学模式,还有待进一步的成熟和完善。 相似文献
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介绍了基于ASP.Net平台B/S架构的应用系统网络安全的设计,分析了B/S三层网络架构的安全机制,给出了通过身份验证、权限控制、数据加密、存储过程访问数据库等手段实现系统的安全性的技术要点。 相似文献
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虚拟存储技术在流媒体管理系统中的应用 总被引：1，自引：0，他引：1
虚拟存储是存储技术发展的重要方向之一。目前虚拟存储技术取得了很大进展,很多产品化的解决方案已经出现。就虚拟存储技术在流媒体管理系统中不同应用来分析两种典型虚拟存储结构各自的优势与缺陷。 相似文献
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主要介绍了在Windows Server 2008中的虚拟机技术Hyper-V的功能和核心特性。通过对比目前较为主流的多项虚拟化技术与Hyper-V技术在原理和方法方面的多项不同,论述了Hyper-V技术的优势和对企业的重要意义。 相似文献
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本文论述了双机热备实验在SAN网络基础课程中的重要性,阐述了利用Pluswell Cluster模拟双机热备实验的优势,并给出了实际的实验环境和步骤. 相似文献