LTE(long term evolution)及其后续演进已成为全球移动通信领域开发的热点。在LTE产业链中,终端射频测试是相对薄弱的环节;信道带宽的增大又对采样速率及硬件处理能力提出很高的要求,成为制约终端射频指标测试的瓶颈。在分析终端射频邻...LTE(long term evolution)及其后续演进已成为全球移动通信领域开发的热点。在LTE产业链中,终端射频测试是相对薄弱的环节;信道带宽的增大又对采样速率及硬件处理能力提出很高的要求,成为制约终端射频指标测试的瓶颈。在分析终端射频邻道泄漏功率比(adjacent channel leakage power ratio,ACLR)测试原理、测试方法及实现技术的基础上,提出一种通过修改测试仪表接收机射频本地振荡器频率来增大观测带宽、降低采样速率的测试方法。该测试方法具有很好的灵活性和可扩展性,大大降低测试成本,因此具有很大的市场应有价值。展开更多
Objective:To examine the effect of anterior cruciate ligament(ACL)reconstruction on spinal-reflex and corticospinal excitability of the quadriceps muscle.Methods:A comprehensive electronic database search was performe...Objective:To examine the effect of anterior cruciate ligament(ACL)reconstruction on spinal-reflex and corticospinal excitability of the quadriceps muscle.Methods:A comprehensive electronic database search was performed to identify studies that objectively measured Hoffmann reflex to muscle response ratio,motor threshold,and motor evoked potentials after ACL reconstruction.Pooled standardized mean differences(SMDs)were computed using a random effects meta-analysis model.Results:A total of 13 studies were eligible for analysis.The Hoffmann reflex to muscle response ratio was significantly higher on both the reconstructed and non-reconstructed legs when compared with the healthy control leg(SMD=0.28,95%confidence interval(95%CI):0.08-0.49,p=0.006 and SMD=0.22,95%CI:0.04-0.40,p=0.016,respectively)but did not differ between legs(SMD=0.10,95%CI:-0.01 to 0.21,p=0.078).The motor threshold was significantly higher on both the reconstructed(SMD=0.76,95%CI:0.40-1.12,p<0.001)and non-reconstructed legs(SMD=0.47,95%CI:0.00-0.95,p=0.049)when compared with the legs of healthy controls.The reconstructed leg also had a higher motor threshold when compared with the non-reconstructed leg(SMD=0.20,95%CI:0.06-0.34,p=0.005).These changes were paralleled by bilateral reductions in quadriceps strength(ACL reconstructed:SMD=-0.78,95%CI:-1.07 to-0.49,p<0.001;non-reconstructed:SMD=-0.32,95%CI:-0.63 to-0.01,p=0.042)and quadriceps voluntary activation(ACL reconstructed:SMD=-0.73,95%CI:-0.97 to-0.50,p<0.001;non-reconstructed:SMD=-0.55,95%CI:-0.82 to-0.27,p<0.001)when compared with healthy controls.Conclusion:There is increased excitability of the spinal-reflex pathways and reduced excitability of the corticospinal pathways following ACL reconstruction.These changes are paralleled by reductions in quadriceps strength and voluntary activation,suggesting that rehabilitation interventions should focus on normalizing the excitability of neural pathways to effectively address quadriceps dysfunction after ACL reconstruction.展开更多
文摘LTE(long term evolution)及其后续演进已成为全球移动通信领域开发的热点。在LTE产业链中,终端射频测试是相对薄弱的环节;信道带宽的增大又对采样速率及硬件处理能力提出很高的要求,成为制约终端射频指标测试的瓶颈。在分析终端射频邻道泄漏功率比(adjacent channel leakage power ratio,ACLR)测试原理、测试方法及实现技术的基础上,提出一种通过修改测试仪表接收机射频本地振荡器频率来增大观测带宽、降低采样速率的测试方法。该测试方法具有很好的灵活性和可扩展性,大大降低测试成本,因此具有很大的市场应有价值。
基金the National Institutes of Health(Grant No.R21-HD092614).
文摘Objective:To examine the effect of anterior cruciate ligament(ACL)reconstruction on spinal-reflex and corticospinal excitability of the quadriceps muscle.Methods:A comprehensive electronic database search was performed to identify studies that objectively measured Hoffmann reflex to muscle response ratio,motor threshold,and motor evoked potentials after ACL reconstruction.Pooled standardized mean differences(SMDs)were computed using a random effects meta-analysis model.Results:A total of 13 studies were eligible for analysis.The Hoffmann reflex to muscle response ratio was significantly higher on both the reconstructed and non-reconstructed legs when compared with the healthy control leg(SMD=0.28,95%confidence interval(95%CI):0.08-0.49,p=0.006 and SMD=0.22,95%CI:0.04-0.40,p=0.016,respectively)but did not differ between legs(SMD=0.10,95%CI:-0.01 to 0.21,p=0.078).The motor threshold was significantly higher on both the reconstructed(SMD=0.76,95%CI:0.40-1.12,p<0.001)and non-reconstructed legs(SMD=0.47,95%CI:0.00-0.95,p=0.049)when compared with the legs of healthy controls.The reconstructed leg also had a higher motor threshold when compared with the non-reconstructed leg(SMD=0.20,95%CI:0.06-0.34,p=0.005).These changes were paralleled by bilateral reductions in quadriceps strength(ACL reconstructed:SMD=-0.78,95%CI:-1.07 to-0.49,p<0.001;non-reconstructed:SMD=-0.32,95%CI:-0.63 to-0.01,p=0.042)and quadriceps voluntary activation(ACL reconstructed:SMD=-0.73,95%CI:-0.97 to-0.50,p<0.001;non-reconstructed:SMD=-0.55,95%CI:-0.82 to-0.27,p<0.001)when compared with healthy controls.Conclusion:There is increased excitability of the spinal-reflex pathways and reduced excitability of the corticospinal pathways following ACL reconstruction.These changes are paralleled by reductions in quadriceps strength and voluntary activation,suggesting that rehabilitation interventions should focus on normalizing the excitability of neural pathways to effectively address quadriceps dysfunction after ACL reconstruction.
