目的评价与卧床休息相比,早期下床活动对急性深静脉血栓患者继发肺栓塞率的有效性。方法运用计算机检索Cochrane、JBI、Medline、EMbase、CINAHL、Web of Knowledge、CBM、万方和CNKI数据库,查找关于对比早期下床活动和卧床休息处理急...目的评价与卧床休息相比,早期下床活动对急性深静脉血栓患者继发肺栓塞率的有效性。方法运用计算机检索Cochrane、JBI、Medline、EMbase、CINAHL、Web of Knowledge、CBM、万方和CNKI数据库,查找关于对比早期下床活动和卧床休息处理急性深静脉血栓患者继发肺栓塞问题的相关研究文献。检索时间均从建库至2015年1月1日。由2位评价员按纳入与排除标准独立筛选文献、提取资料并评价质量后,采用RevMan 5.3软件进行Meta分析。结果共纳入9项研究,共847例患者。Meta分析结果显示:与卧床休息相比,早期下床活动对急性深静脉血栓患者继发肺栓塞率[RR=0.42,95%CI(0.16,1.09),P=0.08]差异无统计学意义。结论现有证据表明:早期下床活动不会增加深静脉血栓患者继发肺栓塞率。鉴于纳入研究数量有限,上述结论尚需开展更多研究予以验证。展开更多
This paper provides an analytic performance evaluation of dual-hop cognitive amplify-and-forward (AF) relaying networks over independent nonidentically distributed (i.n.i.d.) fading channels. Two different transmit po...This paper provides an analytic performance evaluation of dual-hop cognitive amplify-and-forward (AF) relaying networks over independent nonidentically distributed (i.n.i.d.) fading channels. Two different transmit power constraint strategies at the secondary network are proposed to investigate the performance of the secondary network. In the case of combined power constraint,the maximum tolerable interference power on the primary network and the maximum transmit power at the secondary network are considered. Closed-form lower bound and its asymptotic expression for the outage probability (OP) are achieved. Utilizing the above results,average symbol error probability (ABEP) at high signal-to-noise ratios (SNRs) are also derived. In order to further study the performance of dual-hop cognitive AF relaying networks,the Closed-form lower bounds and asymptotic expressions for OP with single power constraint of the tolerable interference on the primary network is also obtained. Both analytical and simulation are employed to validate the accuracy of the theoretical analysis. The results show that the secondary network obtains a better performance when higher power constraint is employed.展开更多
The impact of outdated Channel State Information(CSI) on the performance of relay selections,including the partial relay selection and the best relay selection,is studied,with respect to Amplify-and-Forward(AF) mode c...The impact of outdated Channel State Information(CSI) on the performance of relay selections,including the partial relay selection and the best relay selection,is studied,with respect to Amplify-and-Forward(AF) mode cooperative systems.The proposed method is analysed by deriving the asymptotic closedform expressions for some figures of merit such as the outage probability and the Symbol Error Probability(SEP).Moreover,the validity of the proposed theoretical analysis is proven via simulations.Numerical results prove that the performance of the proposed scheme is impacted considerably by various parameters such as the number of candidate relays and the end-to-end Signal-to-Noise Ratio(SNR).In the presence of cooperative networks with outdated CSI feedback,a performance improvement of more than 3 dB in terms of either outage probability or SEP can be observed by utilizing the Source-to-Destination(S D) link rather than the method of simply increasing the number of relays.展开更多
文摘目的评价与卧床休息相比,早期下床活动对急性深静脉血栓患者继发肺栓塞率的有效性。方法运用计算机检索Cochrane、JBI、Medline、EMbase、CINAHL、Web of Knowledge、CBM、万方和CNKI数据库,查找关于对比早期下床活动和卧床休息处理急性深静脉血栓患者继发肺栓塞问题的相关研究文献。检索时间均从建库至2015年1月1日。由2位评价员按纳入与排除标准独立筛选文献、提取资料并评价质量后,采用RevMan 5.3软件进行Meta分析。结果共纳入9项研究,共847例患者。Meta分析结果显示:与卧床休息相比,早期下床活动对急性深静脉血栓患者继发肺栓塞率[RR=0.42,95%CI(0.16,1.09),P=0.08]差异无统计学意义。结论现有证据表明:早期下床活动不会增加深静脉血栓患者继发肺栓塞率。鉴于纳入研究数量有限,上述结论尚需开展更多研究予以验证。
基金National Natural Science Foundation of China(No.61461024)
文摘This paper provides an analytic performance evaluation of dual-hop cognitive amplify-and-forward (AF) relaying networks over independent nonidentically distributed (i.n.i.d.) fading channels. Two different transmit power constraint strategies at the secondary network are proposed to investigate the performance of the secondary network. In the case of combined power constraint,the maximum tolerable interference power on the primary network and the maximum transmit power at the secondary network are considered. Closed-form lower bound and its asymptotic expression for the outage probability (OP) are achieved. Utilizing the above results,average symbol error probability (ABEP) at high signal-to-noise ratios (SNRs) are also derived. In order to further study the performance of dual-hop cognitive AF relaying networks,the Closed-form lower bounds and asymptotic expressions for OP with single power constraint of the tolerable interference on the primary network is also obtained. Both analytical and simulation are employed to validate the accuracy of the theoretical analysis. The results show that the secondary network obtains a better performance when higher power constraint is employed.
基金supported by the National Key Basic Research Program of China (973 Program) under Grant No. 2012CB315905the National Natural Science Foundation of China under Grants No. 61172050,No. 60903211+3 种基金the Foundation of Beijing Engineering and Technology Centre for Convergence Networks and Ubiquitous Servicesthe National Key Projects under Grants No. 2012ZX03001029-005,No. 2012ZX03001032-003Beijing Science and Technology Program under Grant No. Z1111-00054011078Program for New Century Excellent Talents in University under GrantNo. NCET-12-0774
文摘The impact of outdated Channel State Information(CSI) on the performance of relay selections,including the partial relay selection and the best relay selection,is studied,with respect to Amplify-and-Forward(AF) mode cooperative systems.The proposed method is analysed by deriving the asymptotic closedform expressions for some figures of merit such as the outage probability and the Symbol Error Probability(SEP).Moreover,the validity of the proposed theoretical analysis is proven via simulations.Numerical results prove that the performance of the proposed scheme is impacted considerably by various parameters such as the number of candidate relays and the end-to-end Signal-to-Noise Ratio(SNR).In the presence of cooperative networks with outdated CSI feedback,a performance improvement of more than 3 dB in terms of either outage probability or SEP can be observed by utilizing the Source-to-Destination(S D) link rather than the method of simply increasing the number of relays.
