Purpose: To assess the growth hormone(GH) response to the Wingate anaerobic test(WAn T) among children with short stature and suspected GH deficiency. We hypothesized that the GH response to the WAn T would be similar...Purpose: To assess the growth hormone(GH) response to the Wingate anaerobic test(WAn T) among children with short stature and suspected GH deficiency. We hypothesized that the GH response to the WAn T would be similar to the GH response to a commonly used pharmacologic provocation test.Methods: Ten children(6 males and 4 females, age range 9.0–14.9 years) participated in the study. Each participant performed 2 tests: a standard all-out WAn T, cycling for 30 s against constant resistance, and a standardized pharmacologic test(clonidine or glucagon). Blood samples for GH were collected before and 10, 30, 45, and 60 min after the beginning of exercise. In addition, we collected pre-and post-exercise blood lactate levels.Results: There was a significant increase in GH levels after the WAn T, yet in 9 of 10 participants, this increase was below the threshold for GH sufficiency. Peak GH after the WAn T was significantly lower compared to the pharmacologic GH provocation tests(with 9 of 10 demonstrating GH-sufficient response).Conclusion: The traditional WAn T cannot be used as a GH provocation test. Further research is needed to develop anaerobic exercise protocols sufficient to promote GH secretion.展开更多
The subcritical crack growth and fracture toughness in peridotite, lherzolite and amphibolite were investigated with double torsion test. The results show that water-rock interaction has a significant influence on sub...The subcritical crack growth and fracture toughness in peridotite, lherzolite and amphibolite were investigated with double torsion test. The results show that water-rock interaction has a significant influence on subcritical crack growth. With water-rock interaction, the crack velocity increases, while the stress intensity factor declines, which illustrates that water-rock interaction can decrease the strength of rocks and accelerate the subcritical crack growth. Based on Charlse theory and Hilling & Charlse theory, the test data were analyzed by regression and the correlation coefficients were all higher than 0.7, which shows the correlation is significant. This illustrates that both theories can explain the results of tests very well. Therefore, it is believed that the subcritical crack growth attributes to the breaking of chemical bond, which is caused by the combined effect of the tensile stress and the chemical reaction between the material at crack tip and the corrosive agent. Meanwhile, water-rock interaction has a vital effect on fracture toughness. The fracture toughness of samples under atmospheric environment is higher than that of samples immersed in water. And water-rock interaction has larger influence on fracture toughness in amphibolite than that in peridotite and lherzolite.展开更多
A Bayesian sequential testing method is proposed to evaluate system reliability index with reliability growth during development.The method develops a reliability growth model of repairable systems for failure censore...A Bayesian sequential testing method is proposed to evaluate system reliability index with reliability growth during development.The method develops a reliability growth model of repairable systems for failure censored test,and figures out the approach to determine the prior distribution of the system failure rate by applying the reliability growth model to incorporate the multistage test data collected from system development.Furthermore,the procedure for the Bayesian sequential testing is derived for the failure rate of the exponential life system,which enables the decision to terminate or continue development test.Finally,a numerical example is given to illustrate the efficiency of the proposed model and procedure.展开更多
We study the relationship between energy consumption and economic growth in the case of USA by using an asymmetric ARDL bounds test approach to achieve the actual model. The quarterly data set covers the period of 197...We study the relationship between energy consumption and economic growth in the case of USA by using an asymmetric ARDL bounds test approach to achieve the actual model. The quarterly data set covers the period of 1973:1- 2013:4. The findings indicate that the effect of energy consumption is asymmetric in the long term but not in the short term. In the long run, the effect of negative component of energy consumption on economic growth is small and statistically insignificant. The coefficient of the positive component of energy consumption is found about 0.9 and statistically significant at 1% level. We conclude that energy saving policies such as technological progress and organizational rearrangements may have the dimmer effect for the impact of a negative component of energy consumption and the booster effect for impact of the positive component of energy consumption. Thus, energy saving policy should be tightly followed by the goal of high economic growth.展开更多
The foundations of the ＂Africa rising＂ narrative may have increasingly been tested in recent months. Security concerns, the Ebola crisis in West Africa and conflict in Libya have been some of the stumbling blocks th...The foundations of the ＂Africa rising＂ narrative may have increasingly been tested in recent months. Security concerns, the Ebola crisis in West Africa and conflict in Libya have been some of the stumbling blocks the continent has had to face. These have continuously challenged its ability to respond to events that could derail the past years＇ economic growth. The impact of lower oil prices particularly could be a major shock to the region, especially for oilexporting countries.展开更多
Background: The relationship between growth hormone (GH) and cytokines remains unclear. Several studies have suggested that GH increases tumor necrosis factor (TNF)-α production in both children and adults. However, ...Background: The relationship between growth hormone (GH) and cytokines remains unclear. Several studies have suggested that GH increases tumor necrosis factor (TNF)-α production in both children and adults. However, a number of studies have demonstrated a negative correlation between GH and TNF α. The aim of this study is to explore the relationship between endogenous GH secretion and certain pro and anti-inflammatory cytokines in short children undergoing GH stimulation testing for evaluation for GH deficiency. Methods: Plasma growth hormone, TNF α, CRP, IL-6, IL1-β, IL-4 and IL-10 levels are obtained at baseline and every 30 minutes for 150 minutes following two provocative agents (clonidine, and either arginine or glucagon). Results: Among the 23 children, 7 are found to be GH deficient. No significant differences in baseline TNF α levels are found between GH deficient and GH sufficient children. No correlation is identified between TNF α levels and GH levels during stimulation testing. Furthermore, no relationship is found between GH and pro-inflammatory cytokines or GH and anti-inflammatory cytokines. Conclusion: Our results do not demonstrate an acute relationship between endogenous GH secretion and the cytokines examined.展开更多
装备测试性工程技术起源于20世纪80年代,是先进测试技术与系统工程紧密结合的产物。该技术经过40余年的发展逐渐成熟,在测试性需求分析与分配、测试性建模与方案优化设计、机内测试(Built⁃In Test,BIT)与自动测试系统(Automatic Test Sy...装备测试性工程技术起源于20世纪80年代,是先进测试技术与系统工程紧密结合的产物。该技术经过40余年的发展逐渐成熟,在测试性需求分析与分配、测试性建模与方案优化设计、机内测试(Built⁃In Test,BIT)与自动测试系统(Automatic Test System,ATS)设计、测试性试验与评估等方面形成了较完善的理论体系,并在各型装备中得到了普遍应用,取得了较大的军事和社会效益。今后测试性基础研究和应用探索究竟该如何开展,未来发展方向是怎样的,是亟需深入探讨的问题。在对测试性工程技术的产生背景与需求、概念与内涵、发展历程、关键技术现状与新进展进行剖析的基础上,指出了目前测试性工程技术研究存在的问题和今后研究突破的方向。展开更多
基金supported in part by grants from The Meir Medical Center Research Authority and Ferring Israel
文摘Purpose: To assess the growth hormone(GH) response to the Wingate anaerobic test(WAn T) among children with short stature and suspected GH deficiency. We hypothesized that the GH response to the WAn T would be similar to the GH response to a commonly used pharmacologic provocation test.Methods: Ten children(6 males and 4 females, age range 9.0–14.9 years) participated in the study. Each participant performed 2 tests: a standard all-out WAn T, cycling for 30 s against constant resistance, and a standardized pharmacologic test(clonidine or glucagon). Blood samples for GH were collected before and 10, 30, 45, and 60 min after the beginning of exercise. In addition, we collected pre-and post-exercise blood lactate levels.Results: There was a significant increase in GH levels after the WAn T, yet in 9 of 10 participants, this increase was below the threshold for GH sufficiency. Peak GH after the WAn T was significantly lower compared to the pharmacologic GH provocation tests(with 9 of 10 demonstrating GH-sufficient response).Conclusion: The traditional WAn T cannot be used as a GH provocation test. Further research is needed to develop anaerobic exercise protocols sufficient to promote GH secretion.
基金Project(51374246,51474249)supported by the National Natural Science Foundation of ChinaProject(2013FJ6002)supported by the Science-Technology Project of Science-Technology Department of Hunan Province,China
文摘The subcritical crack growth and fracture toughness in peridotite, lherzolite and amphibolite were investigated with double torsion test. The results show that water-rock interaction has a significant influence on subcritical crack growth. With water-rock interaction, the crack velocity increases, while the stress intensity factor declines, which illustrates that water-rock interaction can decrease the strength of rocks and accelerate the subcritical crack growth. Based on Charlse theory and Hilling & Charlse theory, the test data were analyzed by regression and the correlation coefficients were all higher than 0.7, which shows the correlation is significant. This illustrates that both theories can explain the results of tests very well. Therefore, it is believed that the subcritical crack growth attributes to the breaking of chemical bond, which is caused by the combined effect of the tensile stress and the chemical reaction between the material at crack tip and the corrosive agent. Meanwhile, water-rock interaction has a vital effect on fracture toughness. The fracture toughness of samples under atmospheric environment is higher than that of samples immersed in water. And water-rock interaction has larger influence on fracture toughness in amphibolite than that in peridotite and lherzolite.
基金supported by the National Natural Science Foundation of China (70571083)the Research Fund for the Doctoral Program of Higher Education of China (20094307110013)
文摘A Bayesian sequential testing method is proposed to evaluate system reliability index with reliability growth during development.The method develops a reliability growth model of repairable systems for failure censored test,and figures out the approach to determine the prior distribution of the system failure rate by applying the reliability growth model to incorporate the multistage test data collected from system development.Furthermore,the procedure for the Bayesian sequential testing is derived for the failure rate of the exponential life system,which enables the decision to terminate or continue development test.Finally,a numerical example is given to illustrate the efficiency of the proposed model and procedure.
文摘We study the relationship between energy consumption and economic growth in the case of USA by using an asymmetric ARDL bounds test approach to achieve the actual model. The quarterly data set covers the period of 1973:1- 2013:4. The findings indicate that the effect of energy consumption is asymmetric in the long term but not in the short term. In the long run, the effect of negative component of energy consumption on economic growth is small and statistically insignificant. The coefficient of the positive component of energy consumption is found about 0.9 and statistically significant at 1% level. We conclude that energy saving policies such as technological progress and organizational rearrangements may have the dimmer effect for the impact of a negative component of energy consumption and the booster effect for impact of the positive component of energy consumption. Thus, energy saving policy should be tightly followed by the goal of high economic growth.
文摘The foundations of the ＂Africa rising＂ narrative may have increasingly been tested in recent months. Security concerns, the Ebola crisis in West Africa and conflict in Libya have been some of the stumbling blocks the continent has had to face. These have continuously challenged its ability to respond to events that could derail the past years＇ economic growth. The impact of lower oil prices particularly could be a major shock to the region, especially for oilexporting countries.
文摘Background: The relationship between growth hormone (GH) and cytokines remains unclear. Several studies have suggested that GH increases tumor necrosis factor (TNF)-α production in both children and adults. However, a number of studies have demonstrated a negative correlation between GH and TNF α. The aim of this study is to explore the relationship between endogenous GH secretion and certain pro and anti-inflammatory cytokines in short children undergoing GH stimulation testing for evaluation for GH deficiency. Methods: Plasma growth hormone, TNF α, CRP, IL-6, IL1-β, IL-4 and IL-10 levels are obtained at baseline and every 30 minutes for 150 minutes following two provocative agents (clonidine, and either arginine or glucagon). Results: Among the 23 children, 7 are found to be GH deficient. No significant differences in baseline TNF α levels are found between GH deficient and GH sufficient children. No correlation is identified between TNF α levels and GH levels during stimulation testing. Furthermore, no relationship is found between GH and pro-inflammatory cytokines or GH and anti-inflammatory cytokines. Conclusion: Our results do not demonstrate an acute relationship between endogenous GH secretion and the cytokines examined.
文摘装备测试性工程技术起源于20世纪80年代,是先进测试技术与系统工程紧密结合的产物。该技术经过40余年的发展逐渐成熟,在测试性需求分析与分配、测试性建模与方案优化设计、机内测试(Built⁃In Test,BIT)与自动测试系统(Automatic Test System,ATS)设计、测试性试验与评估等方面形成了较完善的理论体系,并在各型装备中得到了普遍应用,取得了较大的军事和社会效益。今后测试性基础研究和应用探索究竟该如何开展,未来发展方向是怎样的,是亟需深入探讨的问题。在对测试性工程技术的产生背景与需求、概念与内涵、发展历程、关键技术现状与新进展进行剖析的基础上,指出了目前测试性工程技术研究存在的问题和今后研究突破的方向。
