针对Spines覆盖网络的逐跳传输特性,提出了一种具有较强网络动态适应性的可用带宽测量算法(band-width estimation linear regression,BELR).该算法是一元线性回归算法,采用传输消息大小和带宽限制的链路延时之间的线性关系来测量链路...针对Spines覆盖网络的逐跳传输特性,提出了一种具有较强网络动态适应性的可用带宽测量算法(band-width estimation linear regression,BELR).该算法是一元线性回归算法,采用传输消息大小和带宽限制的链路延时之间的线性关系来测量链路的可用带宽,使用可靠链路传输探测包,利用链路的单向延迟计算逐跳之间虚拟链路的带宽,所需带宽测量时间可减少一半.通过仿真分析了算法的性能,仿真结果表明,运用BELR算法可以在较短时间内得到比较准确的带宽估计,可适用于具有较大动态变化特性的覆盖网络可用带宽测量.展开更多
Objective Biomechanical properties of the anterior cervical pedicle screw artificial vertebral system and conventional anterior screw plate system were analyzed in lower cervical spine by finite element.Methods CT ima...Objective Biomechanical properties of the anterior cervical pedicle screw artificial vertebral system and conventional anterior screw plate system were analyzed in lower cervical spine by finite element.Methods CT images were obtained from a 38-year-old female volunteer.Following models were established and analyzed by Mimics14.0,Geomagic Studio 2013,ANSYS 14.0 software:the intact cervical model(C3-C7),corpectomy of C5 model,the model of conventional anterior screw plate system fixation(AP),and the model of anterior transpedicular screw artificial vertebral body sys-展开更多
Introduction-The cervical spine is subjected to injury frequently,especially among pilots who are usually on the condition of high acceleration.Injuries of the cervical spine will be potential risk of damage to the sp...Introduction-The cervical spine is subjected to injury frequently,especially among pilots who are usually on the condition of high acceleration.Injuries of the cervical spine will be potential risk of damage to the spinal cord,which could be result in life threatening展开更多
目的 采用磁共振魔镜成像(mDixon-Quant)技术测量中老年女性的腰椎R2^(*)值及质子密度脂肪分数(proton density fat fraction,PDFF)以评估骨髓铁沉积、脂肪含量并探讨其与骨密度(bone mineral density,BMD)之间的相关性及对骨质疏松(ost...目的 采用磁共振魔镜成像(mDixon-Quant)技术测量中老年女性的腰椎R2^(*)值及质子密度脂肪分数(proton density fat fraction,PDFF)以评估骨髓铁沉积、脂肪含量并探讨其与骨密度(bone mineral density,BMD)之间的相关性及对骨质疏松(osteoporosis,OP)的诊断价值。材料与方法 采用mDixon-Quant序列对105例中老年女性进行腰椎MRI扫描,测量腰1~5椎体R2^(*)值及PDFF,并行腰椎定量计算机体层成像(quantitative computed tomography,QCT)扫描后处理得到腰1~5各椎体BMD,记录一般临床资料。分析腰1~5椎体骨髓R2^(*)值、PDFF及BMD的变化趋势。采用偏相关分析探讨腰椎R2^(*)、PDFF及BMD之间的相关性。采用受试者工作特征(receiver operating characteristic,ROC)曲线分析腰椎R2^(*)、PDFF诊断OP的效能,并采用DeLong检验比较其诊断效能。结果 腰1~5椎体自上向下R2^(*)值及BMD逐渐减低(P_(trend)<0.05),腰椎PDFF逐渐增高(P_(trend)<0.05)。校正年龄后,腰椎R2^(*)与PDFF呈负相关(r=-0.227,P=0.020),腰椎R2^(*)与BMD呈正相关(r=0.332,P<0.001)。腰椎R2^(*)、PDFF诊断OP的ROC曲线下面积(area under the curve,AUC)分别是0.792、0.702,差异无统计学意义(P=0.07)。R2^(*)及PDFF联合诊断OP的AUC值为0.804[95%置信区间(confidence interval,CI):0.702~0.865],敏感度为81.8%,特异度为73.5%,诊断效能优于PDFF单独诊断OP(P=0.01)。结论 中老年女性腰椎R2^(*)、PDFF存在生理性梯度,R2^(*)与BMD及PDFF均相关。腰椎R2^(*)诊断OP的效能与PDFF相当,而R2^(*)联合PDFF诊断OP效能最佳。展开更多
文摘针对Spines覆盖网络的逐跳传输特性,提出了一种具有较强网络动态适应性的可用带宽测量算法(band-width estimation linear regression,BELR).该算法是一元线性回归算法,采用传输消息大小和带宽限制的链路延时之间的线性关系来测量链路的可用带宽,使用可靠链路传输探测包,利用链路的单向延迟计算逐跳之间虚拟链路的带宽,所需带宽测量时间可减少一半.通过仿真分析了算法的性能,仿真结果表明,运用BELR算法可以在较短时间内得到比较准确的带宽估计,可适用于具有较大动态变化特性的覆盖网络可用带宽测量.
基金supported by Natural Science Foundation of China(31170903)
文摘Objective Biomechanical properties of the anterior cervical pedicle screw artificial vertebral system and conventional anterior screw plate system were analyzed in lower cervical spine by finite element.Methods CT images were obtained from a 38-year-old female volunteer.Following models were established and analyzed by Mimics14.0,Geomagic Studio 2013,ANSYS 14.0 software:the intact cervical model(C3-C7),corpectomy of C5 model,the model of conventional anterior screw plate system fixation(AP),and the model of anterior transpedicular screw artificial vertebral body sys-
文摘Introduction-The cervical spine is subjected to injury frequently,especially among pilots who are usually on the condition of high acceleration.Injuries of the cervical spine will be potential risk of damage to the spinal cord,which could be result in life threatening
文摘目的 采用磁共振魔镜成像(mDixon-Quant)技术测量中老年女性的腰椎R2^(*)值及质子密度脂肪分数(proton density fat fraction,PDFF)以评估骨髓铁沉积、脂肪含量并探讨其与骨密度(bone mineral density,BMD)之间的相关性及对骨质疏松(osteoporosis,OP)的诊断价值。材料与方法 采用mDixon-Quant序列对105例中老年女性进行腰椎MRI扫描,测量腰1~5椎体R2^(*)值及PDFF,并行腰椎定量计算机体层成像(quantitative computed tomography,QCT)扫描后处理得到腰1~5各椎体BMD,记录一般临床资料。分析腰1~5椎体骨髓R2^(*)值、PDFF及BMD的变化趋势。采用偏相关分析探讨腰椎R2^(*)、PDFF及BMD之间的相关性。采用受试者工作特征(receiver operating characteristic,ROC)曲线分析腰椎R2^(*)、PDFF诊断OP的效能,并采用DeLong检验比较其诊断效能。结果 腰1~5椎体自上向下R2^(*)值及BMD逐渐减低(P_(trend)<0.05),腰椎PDFF逐渐增高(P_(trend)<0.05)。校正年龄后,腰椎R2^(*)与PDFF呈负相关(r=-0.227,P=0.020),腰椎R2^(*)与BMD呈正相关(r=0.332,P<0.001)。腰椎R2^(*)、PDFF诊断OP的ROC曲线下面积(area under the curve,AUC)分别是0.792、0.702,差异无统计学意义(P=0.07)。R2^(*)及PDFF联合诊断OP的AUC值为0.804[95%置信区间(confidence interval,CI):0.702~0.865],敏感度为81.8%,特异度为73.5%,诊断效能优于PDFF单独诊断OP(P=0.01)。结论 中老年女性腰椎R2^(*)、PDFF存在生理性梯度,R2^(*)与BMD及PDFF均相关。腰椎R2^(*)诊断OP的效能与PDFF相当,而R2^(*)联合PDFF诊断OP效能最佳。
