目的:糖尿病前期(prediabetes,PD)与认知缺陷及神经退行性疾病的风险增加有关。然而,PD相关脑疾病的机制尚不明确。PD患者的脑灰质和脑白质会发生不同程度的损害,这些神经结构的改变可能会影响大尺度脑网络的组织。灰质协变网络在推断...目的:糖尿病前期(prediabetes,PD)与认知缺陷及神经退行性疾病的风险增加有关。然而,PD相关脑疾病的机制尚不明确。PD患者的脑灰质和脑白质会发生不同程度的损害,这些神经结构的改变可能会影响大尺度脑网络的组织。灰质协变网络在推断大规模脑结构网络中具有重要价值。但PD是否影响灰质结构网络的拓扑特性尚不清楚。本研究旨在通过图论分析方法探讨PD患者中脑灰质结构协变网络拓扑特征的变化。方法:本研究纳入48名受试者,包括23名PD患者(PD组)和年龄、性别匹配的25名正常对照(Ctr组)。采用3.0 T磁共振机器采集所有患者的头部高分辨三维T1结构像图像;采用简易智力状态检查量表(Mini-mental State Examination,MMSE)评估患者的认知状态;使用自动解剖标记(anatomical automatic labeling,AAL)模板计算116个脑区的灰质体积,通过区域间结构相关矩阵的阈值处理和图论分析构建灰质结构协方差网络;采用曲线下面积(area under the curve,AUC)联合非参数检验对小世界参数、标准化聚类系数、标准化路径长度、全局效率、特征路径长度及网络稳健性等参数的组间差异进行分析。结果:两组灰质结构网络均遵循小世界属性,表现为小世界指数大于1,标准化聚类系数远高于1及标准化路径长度接近1。与Ctr组比较,PD组灰质结构网络的小世界指数、标准化路径长度及标准化聚类系数均增加,其中标准化聚类系数在0.12~0.16的网络稀疏度范围内高于Ctr组,但AUC分析显示两组各参数差异均无统计学意义(均P>0.05)。对于网络整合指标,PD组灰质结构网络表现为特征路径长度增加及全局效率降低,其中特征路径长度在0.12~0.16范围内较Ctr组增加,但AUC分析发现二者的组间差异均无统计学意义(均P>0.05)。对于网络分离指标,PD组灰质结构网络表现为局部效率和平均聚类系数显著增高,AUC分析显示PD组的局部效率(P=0.001)和平均聚类系数(P=0.004)显著高于Ctr组。网络稳健性分析结果显示:PD组灰质结构网络较Ctr组更加容易受到随机损害(P=0.001)。结论:PD患者的灰质结构网络较正常对照表现出平均聚类系数及局部效率增加及更容易受到随机损害的特性,提示PD患者的灰质结构协变网络拓扑组织特性发生了改变,表现为网络分离属性增加及网络稳健性降低,这可能为PD患者相关脑损害提供了新证据。展开更多
Smart distribution grid needs data communication systems as a support to complete their important functions. The smart distribution grid of the data and information are increasingly adopting internet protocol and Ethe...Smart distribution grid needs data communication systems as a support to complete their important functions. The smart distribution grid of the data and information are increasingly adopting internet protocol and Ethernet technology. The IP addresses are more and more important for the smart distribution grid equipment. The current IPv4 protocol occupies a dominant position; therefore, the challenges of the evolution to IPv6 and network security are faced by data communication systems of the smart distribution grid. The importance of data communications network and its main bearer of business were described. The data communications network from IPv4 to IPv6 evolution of the five processes and four stages of the transition were analyzed. The smart distribution grid data communications network security and types of their offensive and defensive were discussed. And the data communications network security architecture was established. It covers three dimensions, the security level, the communications network security engineering and the communications network security management. The security architecture safeguards the evolution to IPv6 for the smart distribution grid data communication systems.展开更多
文摘目的探讨阿尔茨海默病(Alzheimer's disease,AD)患者大脑灰质体积、灰质皮层厚度及基于皮层厚度的结构协变网络(structural covariance network,SCN)的拓扑属性改变。材料与方法本研究共筛选了250例来自ADNI数据库的被试,包括AD组100人,健康对照(healthy controls,HCs)组150人。首先,利用基于体素的形态学分析方法(voxel-based morphometry,VBM)和基于表面的形态学分析方法(surface-based morphometry,SBM)分别计算每组被试的灰质体积和皮层厚度并比较其组间差异。其次,将有组间差异的脑区定义为感兴趣区(region of interest,ROI),提取每一个ROI的灰质体积和皮层厚度值,与认知量表进行偏相关分析。最后,构建基于皮层厚度的SCN并利用图论分析方法分析该网络的全局属性及局部属性的变化特征。结果第一,相较于HCs组,AD组的灰质体积和皮层厚度显著下降[体素和顶点水平总体误差(family-wise error,FWE)校正后P<0.001]。AD组灰质体积下降的脑区主要包括双侧海马、双侧眶额皮层、左侧岛叶、右侧枕下回、左侧楔前叶、左侧中央前回、左侧中央扣带回。AD组皮层厚度变薄的脑区主要包括双侧颞叶、双侧额叶、双侧顶叶、双侧扣带回、双侧梭状回、双侧岛回、双侧楔前叶等。第二,偏相关分析表明,AD组简易精神状态检查量表(Mini-Mental State Examination,MMSE)得分分别与右侧海马体积[rs=0.35,错误发现率(false discovery rate,FDR)校正后P<0.001]、左侧海马体积(r_(s)=0.38,FDR校正后P<0.001)、右侧梭状回皮层厚度(r_(s)=0.38,FDR校正后P<0.001)呈正相关;临床痴呆评定量表(Clinical Dementia Rating Sum of Boxes,CDR-SB)评分与左侧梭状回皮层厚度(r_(s)=-0.39,FDR校正后P<0.001)呈负相关。第三,脑网络分析表明,AD组SCN的全局效率(P<0.001)、局部效率(P=0.03)及小世界属性(P<0.001)高于HCs组,最短路径低于HCs组(P<0.001)。结论联合VBM、SBM的形态学分析及SCN的图论分析有助于全面理解AD患者脑网络的重组及其意义,进而为AD患者神经影像学改变提供新的见解和证据。
文摘目的:糖尿病前期(prediabetes,PD)与认知缺陷及神经退行性疾病的风险增加有关。然而,PD相关脑疾病的机制尚不明确。PD患者的脑灰质和脑白质会发生不同程度的损害,这些神经结构的改变可能会影响大尺度脑网络的组织。灰质协变网络在推断大规模脑结构网络中具有重要价值。但PD是否影响灰质结构网络的拓扑特性尚不清楚。本研究旨在通过图论分析方法探讨PD患者中脑灰质结构协变网络拓扑特征的变化。方法:本研究纳入48名受试者,包括23名PD患者(PD组)和年龄、性别匹配的25名正常对照(Ctr组)。采用3.0 T磁共振机器采集所有患者的头部高分辨三维T1结构像图像;采用简易智力状态检查量表(Mini-mental State Examination,MMSE)评估患者的认知状态;使用自动解剖标记(anatomical automatic labeling,AAL)模板计算116个脑区的灰质体积,通过区域间结构相关矩阵的阈值处理和图论分析构建灰质结构协方差网络;采用曲线下面积(area under the curve,AUC)联合非参数检验对小世界参数、标准化聚类系数、标准化路径长度、全局效率、特征路径长度及网络稳健性等参数的组间差异进行分析。结果:两组灰质结构网络均遵循小世界属性,表现为小世界指数大于1,标准化聚类系数远高于1及标准化路径长度接近1。与Ctr组比较,PD组灰质结构网络的小世界指数、标准化路径长度及标准化聚类系数均增加,其中标准化聚类系数在0.12~0.16的网络稀疏度范围内高于Ctr组,但AUC分析显示两组各参数差异均无统计学意义(均P>0.05)。对于网络整合指标,PD组灰质结构网络表现为特征路径长度增加及全局效率降低,其中特征路径长度在0.12~0.16范围内较Ctr组增加,但AUC分析发现二者的组间差异均无统计学意义(均P>0.05)。对于网络分离指标,PD组灰质结构网络表现为局部效率和平均聚类系数显著增高,AUC分析显示PD组的局部效率(P=0.001)和平均聚类系数(P=0.004)显著高于Ctr组。网络稳健性分析结果显示:PD组灰质结构网络较Ctr组更加容易受到随机损害(P=0.001)。结论:PD患者的灰质结构网络较正常对照表现出平均聚类系数及局部效率增加及更容易受到随机损害的特性,提示PD患者的灰质结构协变网络拓扑组织特性发生了改变,表现为网络分离属性增加及网络稳健性降低,这可能为PD患者相关脑损害提供了新证据。
文摘Smart distribution grid needs data communication systems as a support to complete their important functions. The smart distribution grid of the data and information are increasingly adopting internet protocol and Ethernet technology. The IP addresses are more and more important for the smart distribution grid equipment. The current IPv4 protocol occupies a dominant position; therefore, the challenges of the evolution to IPv6 and network security are faced by data communication systems of the smart distribution grid. The importance of data communications network and its main bearer of business were described. The data communications network from IPv4 to IPv6 evolution of the five processes and four stages of the transition were analyzed. The smart distribution grid data communications network security and types of their offensive and defensive were discussed. And the data communications network security architecture was established. It covers three dimensions, the security level, the communications network security engineering and the communications network security management. The security architecture safeguards the evolution to IPv6 for the smart distribution grid data communication systems.
