This paper presents a symmetric cooperation strategy for cooperative relay networks with multiple users. The multi-user symmetric cooperation model and the relay selection algorithm are proposed. Then, the time slot a...This paper presents a symmetric cooperation strategy for cooperative relay networks with multiple users. The multi-user symmetric cooperation model and the relay selection algorithm are proposed. Then, the time slot allocation problem is cast into a bargaining problem, and the optimal time slot allocation solution is obtained by Nash bargaining solution （NBS）. Moreover, we also consider the implementations of the cooperation strategy, i.e., the grouping and admission control algorithm. Simulation results show that users can obtain larger rates under the symmetric cooperation strategy than the non-cooperative case.展开更多
Background： Angiopoietin-2 （Ang-2） plays a crucial role in hypoxia-induced angiogenesis and is expressed only in sites of vascular remodeling. Ang-2 expression can be regulated by hypoxia inducible factors and othe...Background： Angiopoietin-2 （Ang-2） plays a crucial role in hypoxia-induced angiogenesis and is expressed only in sites of vascular remodeling. Ang-2 expression can be regulated by hypoxia inducible factors and other regulators with exposure to hypoxia. The objective of this study was to investigate the influence of percutaneous coronary intervention （PCI） on serum Ang-2 concentrations, and analyze the correlation between serum Ang-2 and the severity of coronary artery stenosis in patients with coronary heart disease （CHD）. Methods： Sixty-four patients with CHD were selected as the study group, each undergone PC1. Thirty-two healthy subjects were selected as the control group. Pre-PCI and post-PCl serum Ang-2 were measured by enzyme-linked immunosorbent assay. The severity of coronary artery stenosis was evaluated using angiographic Gensini scores, and the coronary collateral vessels were scored according to Rentrop＇s classification. Results： Concentrations of pre-PCI serum Ang-2 in the study group were significantly higher than those in the control group （4625.06 ~ 1838.06 vs. 1945.74 ：k 1588.17 pg/ml, P 〈 0.01 ）; however, concentrations of post-PCl serum Ang-2 were significantly lower than those of pre-PCI （3042.63 ＋ 1845.33 pg/ml vs. 4625.06 .k 1838.06 pg/ml, P 〈 0.01）. Concentrations of pre-PCl serum Ang-2 were significantly correlated with Gensini scores （r= 0.488, P〈 0.01）; however, the decrease in serum Ang-2 after PC1 was not correlated with Gensini scores, coronary collateral vessel grading, or left ventricular ejection fraction. Conclusions： Serum Ang-2 concentrations significantly increased in patients with CHD, and PCI treatment significantly decreased these concentrations. Serum Ang-2 concentrations, but not the decrease in serum Ang-2 concentrations, were significantly correlated with the severity of coronary artery stenosis. These results suggested that Ang-2 may be a biomarker of myocardial ischemia and vessel remodeling.展开更多
基金supported by National Basic Research Program of China (973 Program) (No. 2010CB731800)Key Project of National Natural Science Foundation of China (No. 60934003)Scientific and Technological Supporting Project of Hebei Province(No. 072435155D)
文摘This paper presents a symmetric cooperation strategy for cooperative relay networks with multiple users. The multi-user symmetric cooperation model and the relay selection algorithm are proposed. Then, the time slot allocation problem is cast into a bargaining problem, and the optimal time slot allocation solution is obtained by Nash bargaining solution （NBS）. Moreover, we also consider the implementations of the cooperation strategy, i.e., the grouping and admission control algorithm. Simulation results show that users can obtain larger rates under the symmetric cooperation strategy than the non-cooperative case.
基金This study was supported by the grants from National Natural Science Foundation of China，Guangxi Natural Science Foundation，High Level Innovation Team and Outstanding Scholar Program in Guangxi Colleges
文摘Background： Angiopoietin-2 （Ang-2） plays a crucial role in hypoxia-induced angiogenesis and is expressed only in sites of vascular remodeling. Ang-2 expression can be regulated by hypoxia inducible factors and other regulators with exposure to hypoxia. The objective of this study was to investigate the influence of percutaneous coronary intervention （PCI） on serum Ang-2 concentrations, and analyze the correlation between serum Ang-2 and the severity of coronary artery stenosis in patients with coronary heart disease （CHD）. Methods： Sixty-four patients with CHD were selected as the study group, each undergone PC1. Thirty-two healthy subjects were selected as the control group. Pre-PCI and post-PCl serum Ang-2 were measured by enzyme-linked immunosorbent assay. The severity of coronary artery stenosis was evaluated using angiographic Gensini scores, and the coronary collateral vessels were scored according to Rentrop＇s classification. Results： Concentrations of pre-PCI serum Ang-2 in the study group were significantly higher than those in the control group （4625.06 ~ 1838.06 vs. 1945.74 ：k 1588.17 pg/ml, P 〈 0.01 ）; however, concentrations of post-PCl serum Ang-2 were significantly lower than those of pre-PCI （3042.63 ＋ 1845.33 pg/ml vs. 4625.06 .k 1838.06 pg/ml, P 〈 0.01）. Concentrations of pre-PCl serum Ang-2 were significantly correlated with Gensini scores （r= 0.488, P〈 0.01）; however, the decrease in serum Ang-2 after PC1 was not correlated with Gensini scores, coronary collateral vessel grading, or left ventricular ejection fraction. Conclusions： Serum Ang-2 concentrations significantly increased in patients with CHD, and PCI treatment significantly decreased these concentrations. Serum Ang-2 concentrations, but not the decrease in serum Ang-2 concentrations, were significantly correlated with the severity of coronary artery stenosis. These results suggested that Ang-2 may be a biomarker of myocardial ischemia and vessel remodeling.
