Background： This preliminary study examined the effects of an 8-week supervised reactive balance training program on reaction time （RT） and foot speed, static balance and balance confidence in healthy older adults ...Background： This preliminary study examined the effects of an 8-week supervised reactive balance training program on reaction time （RT） and foot speed, static balance and balance confidence in healthy older adults compared to an exercise control group. Methods： Twenty-five older adults were randomly assigned to a reactive balance training group （QuickBoard; n = 12; 71.0 ± 8.6 years） or a stationary cycling group （control; n = 13; 70.2 ± 6.0 years）. Both groups were tested for foot RT foot speed, static balance, and balance confidence at baseline, 4-week, 8-week, and 4-week follow-up. Results： Results indicated significant improvements in QuickBoard foot RT and speed in both groups with greater improvements in the QuickBoard group. However, no group difference was found in static balance performance. Conclusion： Although the improvements in RT and foot speed may be beneficial for fall and trip prevention, the implications of the current findings for trio avoidance and oerformance of daily tasks are unclear.展开更多
We study the property of matter in equilibrium with a static, spherically symmetric black hole in D- dimensional spacetime. It requires that this kind of matter has an equation of state ω≡pr/ρ = -n/（n ＋ 2k）, k,...We study the property of matter in equilibrium with a static, spherically symmetric black hole in D- dimensional spacetime. It requires that this kind of matter has an equation of state ω≡pr/ρ = -n/（n ＋ 2k）, k, n ∈ N （where n 〉 1 corresponds to a mixture of vacuum matter and ＂hair＂ matter）, which seems to be independent of D. However, when we associate this result with specific models, we find that these hairy black holes can live only in some special dimensional spacetime： （i） D = 2 ＋ 2k/n while the black hole is surrounded by cosmic strings, which requires D is even or D ∈ N, depending on the value of n, this is consistent with some important results in superstring theory, it might reveal the relation between cosmic string and superstring in another aspect; （ii） the black hole can be surrounded by linear dilaton field only in 4-dimensional spacetime. In both cases, D = 4 is special. We also present some examples of such hairy black holes in higher dimensions, including a toy model with negative energy density.展开更多
Ebulliometric method based on the error analysis equation is presented for systems with the large phase equilibrium constant. Application is given for the determination and calculation of binary vapor-liquid equilibri...Ebulliometric method based on the error analysis equation is presented for systems with the large phase equilibrium constant. Application is given for the determination and calculation of binary vapor-liquid equilibrium data for the ethanol+n-hexane system. It is also given the comparison results between the ebulliometric method based on the error analysis equation and the quasi-static method.展开更多
文摘Background： This preliminary study examined the effects of an 8-week supervised reactive balance training program on reaction time （RT） and foot speed, static balance and balance confidence in healthy older adults compared to an exercise control group. Methods： Twenty-five older adults were randomly assigned to a reactive balance training group （QuickBoard; n = 12; 71.0 ± 8.6 years） or a stationary cycling group （control; n = 13; 70.2 ± 6.0 years）. Both groups were tested for foot RT foot speed, static balance, and balance confidence at baseline, 4-week, 8-week, and 4-week follow-up. Results： Results indicated significant improvements in QuickBoard foot RT and speed in both groups with greater improvements in the QuickBoard group. However, no group difference was found in static balance performance. Conclusion： Although the improvements in RT and foot speed may be beneficial for fall and trip prevention, the implications of the current findings for trio avoidance and oerformance of daily tasks are unclear.
基金Supported in part by the National Natural Science Foundation of China under Grant Nos. 90503009 and 10775116973 Program under Grant No. 2005CB724508
文摘We study the property of matter in equilibrium with a static, spherically symmetric black hole in D- dimensional spacetime. It requires that this kind of matter has an equation of state ω≡pr/ρ = -n/（n ＋ 2k）, k, n ∈ N （where n 〉 1 corresponds to a mixture of vacuum matter and ＂hair＂ matter）, which seems to be independent of D. However, when we associate this result with specific models, we find that these hairy black holes can live only in some special dimensional spacetime： （i） D = 2 ＋ 2k/n while the black hole is surrounded by cosmic strings, which requires D is even or D ∈ N, depending on the value of n, this is consistent with some important results in superstring theory, it might reveal the relation between cosmic string and superstring in another aspect; （ii） the black hole can be surrounded by linear dilaton field only in 4-dimensional spacetime. In both cases, D = 4 is special. We also present some examples of such hairy black holes in higher dimensions, including a toy model with negative energy density.
基金Supported by the National Natural Science Foundation of China(No. 29976035) and the Natural Science Foundation of Zhejiang Province.
文摘Ebulliometric method based on the error analysis equation is presented for systems with the large phase equilibrium constant. Application is given for the determination and calculation of binary vapor-liquid equilibrium data for the ethanol+n-hexane system. It is also given the comparison results between the ebulliometric method based on the error analysis equation and the quasi-static method.
