脑胶质瘤是颅内最常见的恶性肿瘤,复发率高,预后较差。较低级别脑胶质瘤是指2021世界卫生组织中枢神经系统肿瘤分类(World Health Organization Central Nervous System,WHO CNS)分级为2级和3级的肿瘤,较低级别脑胶质瘤的分子分型对其...脑胶质瘤是颅内最常见的恶性肿瘤,复发率高,预后较差。较低级别脑胶质瘤是指2021世界卫生组织中枢神经系统肿瘤分类(World Health Organization Central Nervous System,WHO CNS)分级为2级和3级的肿瘤,较低级别脑胶质瘤的分子分型对其治疗与预后有着重要的指导意义,因此分子分型诊断对脑胶质瘤的临床管理至关重要。分子分型诊断的金标准是病理检测,获取病理组织基因测序,但其有一定的有创性和滞后性。近年来,随着功能磁共振成像(functional MRI,fMRI)的发展,越来越多的研究明确了fMRI预测较低级别胶质瘤分子分型的价值,本文就近年来多种fMRI技术,包括扩散成像、灌注成像、酰胺质子转移成像等,对预测较低级别胶质瘤多种分子分型的研究进展作一综述,并就各种fMRI技术对不同分子分型的预测价值分别进行分析,旨在为预测较低级别胶质瘤分子分型提供影像学指标,从而达到临床精准诊治的目的。展开更多
目的探讨平均表观传播扩散MRI(mean apparent propagator-MRI,MAP-MRI)与动态对比增强MRI(dynamic contrast enhanced-MRI,DCE-MRI)在鉴别胶质母细胞瘤(glioblastoma,GBM)与脑转移瘤(brain metastases,BMs)中的临床应用价值。材料与方...目的探讨平均表观传播扩散MRI(mean apparent propagator-MRI,MAP-MRI)与动态对比增强MRI(dynamic contrast enhanced-MRI,DCE-MRI)在鉴别胶质母细胞瘤(glioblastoma,GBM)与脑转移瘤(brain metastases,BMs)中的临床应用价值。材料与方法对经手术病理确诊的GBM[异柠檬酸脱氢酶野生型(isocitrate dehydrogenase-wildtype,IDH-wt)]患者27例及经手术病理确诊或临床随访证实的BMs患者24例行常规MRI序列及扩散频谱成像(diffusion spectrum imaging,DSI)与DCE-MRI检查,DSI经解析得到MAP-MRI的各参数图,DCE-MRI经西门子工作站处理后得到多个参数图。在各参数图上分别测量两组患者肿瘤实质区、瘤周水肿区及对侧正常脑组织区的参数值。为了最小化个体差异,将各参数值除以对侧正常脑组织的值,得到各参数的相对值。采用卡方检验对两组患者的性别进行组间比较;采用两独立样本t检验及Mann-Whitney U检验对两组患者的年龄、MAP-MRI及DCE-MRI各参数值及其相对值进行组间比较,P<0.05为差异有统计学意义,并绘制受试者工作特征(receiver operating characteristic,ROC)曲线,采用DeLong检验以评估各参数值鉴别诊断的效能。结果GBM(IDH-wt)组与BMs组患者的年龄、性别差异均无统计学意义(P=0.327和P=0.247)。GBM(IDH-wt)组患者肿瘤实质区的非高斯轴向(non-Gaussianity axial,NGAx)、非高斯垂直(non-Gaussianity vertical,NGRad)、返回轴概率(return to the axis probability,RTAP)、返回平面概率(return to the plane probability,RTPP)均高于BMs组,均方位移(mean square displacement,MSD)低于BMs组,且差异有统计学意义(P<0.05)。GBM(IDH-wt)组患者瘤周水肿区的相对转运常数(relative volume transfer constant,rK^(trans))高于BMs,而相对渗出速率常数(relative the rate constant,rK_(ep))低于BMs组,且差异有统计学意义(P<0.05)。肿瘤实质区RTPP与NGAx是鉴别GBM(IDH-wt)与BMs时曲线下面积(area under the curve,AUC)较高的单一参数,AUC分别为0.985、0.937,敏感度分别为0.963、0.926,特异度分别为0.917、0.833。结论MAP-MRI与DCE-MRI在鉴别GBM(IDH-wt)与BMs时表现出了较好的诊断价值,且肿瘤实质区的RTPP与NGAx可作为较好的影像学标记。展开更多
Here we report the theory formulation and the experiment realization of sum-frequency generation vibrational spectroscopy （SFG-VS） in the cross-propagation （XP） geometry or configuration. In the XP-SFG-VS, the vis...Here we report the theory formulation and the experiment realization of sum-frequency generation vibrational spectroscopy （SFG-VS） in the cross-propagation （XP） geometry or configuration. In the XP-SFG-VS, the visible and the infrared （IR） beams in the SFG experiment are delivered to the same location on the surface from visible and IR incident planes perpendicular to each other, avoiding the requirement to have windows or optics to be transparent to both the visible and IR frequencies. Therefore, the XP geometry is applicable to study surfaces in the enclosed vacuum or high pressure chambers with far infrared （FIR） frequencies that can directly access the metal oxide and other lower frequency surface modes, with much broader selection of visible and IR transparent window materials. The potential applications include surface science, material science, fundamental catalytic sciences, as well as low temperature molecular sciences, etc.展开更多
This paper discusses the validity of (adaptive) Lagrange generalized plain finite element method (FEM) and plate element method for accurate analysis of acoustic waves in multi-layered piezoelectric structures with ti...This paper discusses the validity of (adaptive) Lagrange generalized plain finite element method (FEM) and plate element method for accurate analysis of acoustic waves in multi-layered piezoelectric structures with tiny interfaces between metal electrodes and surface mounted piezoelectric substrates. We have come to conclusion that the quantitative relationships between the acoustic and electric fields in a piezoelectric structure can be accurately determined through the proposed finite element methods. The higher-order Lagrange FEM proposed for dynamic piezoelectric computation is proved to be very accurate (prescribed relative error 0.02% - 0.04% ) and a great improvement in convergence accuracy over the higher order Mindlin plate element method for piezoelectric structural analysis due to the assumptions and corrections in the plate theories.The converged lagrange finite element methods are compared with the plate element methods and the computedresults are in good agreement with available exact and experimental data. The adaptive Lagrange finite elementmethods and a new FEA computer program developed for macro- and micro-scale analyses are reviewed, and recently extended with great potential to high-precision nano-scale analysis in this paper and the similarities between piezoelectric and seismic wave propagations in layered structures and plates are stressed.展开更多
An autapse is an unusual synapse that occurs between the axon and the soma of the same neuron. Mathematically, it can be described as a self-delayed feedback loop that is defined by a specific time-delay and the so-ca...An autapse is an unusual synapse that occurs between the axon and the soma of the same neuron. Mathematically, it can be described as a self-delayed feedback loop that is defined by a specific time-delay and the so-called autaptic coupling strength. Recently, the role and function of autapses within the nervous system has been studied extensively. Here, we extend the scope of theoretical research by investigating the effects of an autapse on the transmission of a weak localized pacemaker activity in a scale-free neuronal network. Our results reveal that by mediating the spiking activity of the pacemaker neuron, an autapse increases the propagation of its rhythm across the whole network, if only the autaptic time delay and the autaptic coupling strength are properly adjusted. We show that the autapse-induced enhancement of the transmission of pacemaker activity occurs only when the autaptic time delay is close to an integer multiple of the intrinsic oscillation time of the neurons that form the network. In particular, we demonstrate the emergence of multiple resonances involving the weak signal, the intrinsic oscillations, and the time scale that is dictated by the autapse. Interestingly, we also show that the enhancement of the pacemaker rhythm across the network is the strongest if the degree of the pacemaker neuron is lowest. This is because the dissipation of the localized rhythm is contained to the few directly linked neurons, and only afterwards, through the secondary neurons, it propagates further. If the pacemaker neuron has a high degree, then its rhythm is simply too weak to excite all the neighboring neurons, and propagation therefore fails.展开更多
文摘目的 探讨应用平均表观传播子MRI(mean apparent propagator-magnetic resonance imaging, MAP-MRI)及动态对比增强MRI(dynamic contrast enhanced magnetic resonance imaging, DCE-MRI)预测3、4级胶质瘤患者O6-甲基鸟嘌呤-DNA-甲基转移酶(O6-methylguanine-DNA methyhransferase, MGMT)启动子甲基化状态的可行性。材料与方法 前瞻性纳入本院自2018年6月至2022年1月经病理证实的14例MGMT启动子甲基化和17例MGMT启动子非甲基化胶质瘤患者,进行了术前常规MRI、DCE-MRI及MAP-MRI扫描。通过手动勾画肿瘤实质区域为感兴趣区(region of interest, ROI)并提取ROI定量参数特征,测量DCE-MRI参数及MAP-MRI参数。参数与MGMT甲基化间的相关性采用Pearson相关分析。所有参数均采用两独立样本t检验,比较DCE-MRI和MAP-MRI对预测3、4级胶质瘤MGMT启动子甲基化状态的诊断效能。进一步建立单因素和多因素logistic回归模型,分析构建受试者工作特征(receiver operating characteristic, ROC)曲线,以DeLong检验比较DCE-MRI参数、MAP-MRI参数与多参数联合模型预测MGMT甲基化的诊断效果。结果 DCE-MRI参数容积转运常数(volume transfer constant,Ktrans)、血管外细胞外容积分数(fractional volume of the extravascular-extracellular space, Ve)以及MAP-MRI参数非高斯(non-Gaussianity, NG)、非高斯轴向(non-Gaussianity axial, NGAx)、Q空间逆方差(Q-space inverse variance,QIV)、返回原点概率(return to the origin probability, RTOP)、返回轴线概率(return to the axis probability,RTAP)与MGMT启动子甲基化间呈中等相关性,对预测3、4级胶质瘤MGMT启动子甲基化与非甲基化组间差异具有统计学意义(P<0.05);ROC曲线下面积(area under the curve, AUC)分别为0.803、0.815、0.807、0.803、0.765、0.790、0.739。多因素logistic分析显示Ve是预测MGMT启动子甲基化的最佳预测因子,其准确性最高,AUC为0.815(95%CI:0.659~0.971),比值比(odds ratio, OR)为0.891(95%CI:0.815~0.975)。DeLong检验结果表明DCE-MRI和MAP-MRI多参数联合后预测胶质瘤MGMT启动子甲基化状态的诊断效能最高,AUC为0.992。结论 DCE-MRI和MAP-MRI对于预测高级别胶质瘤MGMT启动子甲基化状态具有一定的应用价值,同时应用两者联合诊断将有助于进一步提高诊断的效能。
文摘脑胶质瘤是颅内最常见的恶性肿瘤,复发率高,预后较差。较低级别脑胶质瘤是指2021世界卫生组织中枢神经系统肿瘤分类(World Health Organization Central Nervous System,WHO CNS)分级为2级和3级的肿瘤,较低级别脑胶质瘤的分子分型对其治疗与预后有着重要的指导意义,因此分子分型诊断对脑胶质瘤的临床管理至关重要。分子分型诊断的金标准是病理检测,获取病理组织基因测序,但其有一定的有创性和滞后性。近年来,随着功能磁共振成像(functional MRI,fMRI)的发展,越来越多的研究明确了fMRI预测较低级别胶质瘤分子分型的价值,本文就近年来多种fMRI技术,包括扩散成像、灌注成像、酰胺质子转移成像等,对预测较低级别胶质瘤多种分子分型的研究进展作一综述,并就各种fMRI技术对不同分子分型的预测价值分别进行分析,旨在为预测较低级别胶质瘤分子分型提供影像学指标,从而达到临床精准诊治的目的。
文摘目的探讨平均表观传播扩散MRI(mean apparent propagator-MRI,MAP-MRI)与动态对比增强MRI(dynamic contrast enhanced-MRI,DCE-MRI)在鉴别胶质母细胞瘤(glioblastoma,GBM)与脑转移瘤(brain metastases,BMs)中的临床应用价值。材料与方法对经手术病理确诊的GBM[异柠檬酸脱氢酶野生型(isocitrate dehydrogenase-wildtype,IDH-wt)]患者27例及经手术病理确诊或临床随访证实的BMs患者24例行常规MRI序列及扩散频谱成像(diffusion spectrum imaging,DSI)与DCE-MRI检查,DSI经解析得到MAP-MRI的各参数图,DCE-MRI经西门子工作站处理后得到多个参数图。在各参数图上分别测量两组患者肿瘤实质区、瘤周水肿区及对侧正常脑组织区的参数值。为了最小化个体差异,将各参数值除以对侧正常脑组织的值,得到各参数的相对值。采用卡方检验对两组患者的性别进行组间比较;采用两独立样本t检验及Mann-Whitney U检验对两组患者的年龄、MAP-MRI及DCE-MRI各参数值及其相对值进行组间比较,P<0.05为差异有统计学意义,并绘制受试者工作特征(receiver operating characteristic,ROC)曲线,采用DeLong检验以评估各参数值鉴别诊断的效能。结果GBM(IDH-wt)组与BMs组患者的年龄、性别差异均无统计学意义(P=0.327和P=0.247)。GBM(IDH-wt)组患者肿瘤实质区的非高斯轴向(non-Gaussianity axial,NGAx)、非高斯垂直(non-Gaussianity vertical,NGRad)、返回轴概率(return to the axis probability,RTAP)、返回平面概率(return to the plane probability,RTPP)均高于BMs组,均方位移(mean square displacement,MSD)低于BMs组,且差异有统计学意义(P<0.05)。GBM(IDH-wt)组患者瘤周水肿区的相对转运常数(relative volume transfer constant,rK^(trans))高于BMs,而相对渗出速率常数(relative the rate constant,rK_(ep))低于BMs组,且差异有统计学意义(P<0.05)。肿瘤实质区RTPP与NGAx是鉴别GBM(IDH-wt)与BMs时曲线下面积(area under the curve,AUC)较高的单一参数,AUC分别为0.985、0.937,敏感度分别为0.963、0.926,特异度分别为0.917、0.833。结论MAP-MRI与DCE-MRI在鉴别GBM(IDH-wt)与BMs时表现出了较好的诊断价值,且肿瘤实质区的RTPP与NGAx可作为较好的影像学标记。
文摘Here we report the theory formulation and the experiment realization of sum-frequency generation vibrational spectroscopy （SFG-VS） in the cross-propagation （XP） geometry or configuration. In the XP-SFG-VS, the visible and the infrared （IR） beams in the SFG experiment are delivered to the same location on the surface from visible and IR incident planes perpendicular to each other, avoiding the requirement to have windows or optics to be transparent to both the visible and IR frequencies. Therefore, the XP geometry is applicable to study surfaces in the enclosed vacuum or high pressure chambers with far infrared （FIR） frequencies that can directly access the metal oxide and other lower frequency surface modes, with much broader selection of visible and IR transparent window materials. The potential applications include surface science, material science, fundamental catalytic sciences, as well as low temperature molecular sciences, etc.
文摘This paper discusses the validity of (adaptive) Lagrange generalized plain finite element method (FEM) and plate element method for accurate analysis of acoustic waves in multi-layered piezoelectric structures with tiny interfaces between metal electrodes and surface mounted piezoelectric substrates. We have come to conclusion that the quantitative relationships between the acoustic and electric fields in a piezoelectric structure can be accurately determined through the proposed finite element methods. The higher-order Lagrange FEM proposed for dynamic piezoelectric computation is proved to be very accurate (prescribed relative error 0.02% - 0.04% ) and a great improvement in convergence accuracy over the higher order Mindlin plate element method for piezoelectric structural analysis due to the assumptions and corrections in the plate theories.The converged lagrange finite element methods are compared with the plate element methods and the computedresults are in good agreement with available exact and experimental data. The adaptive Lagrange finite elementmethods and a new FEA computer program developed for macro- and micro-scale analyses are reviewed, and recently extended with great potential to high-precision nano-scale analysis in this paper and the similarities between piezoelectric and seismic wave propagations in layered structures and plates are stressed.
文摘An autapse is an unusual synapse that occurs between the axon and the soma of the same neuron. Mathematically, it can be described as a self-delayed feedback loop that is defined by a specific time-delay and the so-called autaptic coupling strength. Recently, the role and function of autapses within the nervous system has been studied extensively. Here, we extend the scope of theoretical research by investigating the effects of an autapse on the transmission of a weak localized pacemaker activity in a scale-free neuronal network. Our results reveal that by mediating the spiking activity of the pacemaker neuron, an autapse increases the propagation of its rhythm across the whole network, if only the autaptic time delay and the autaptic coupling strength are properly adjusted. We show that the autapse-induced enhancement of the transmission of pacemaker activity occurs only when the autaptic time delay is close to an integer multiple of the intrinsic oscillation time of the neurons that form the network. In particular, we demonstrate the emergence of multiple resonances involving the weak signal, the intrinsic oscillations, and the time scale that is dictated by the autapse. Interestingly, we also show that the enhancement of the pacemaker rhythm across the network is the strongest if the degree of the pacemaker neuron is lowest. This is because the dissipation of the localized rhythm is contained to the few directly linked neurons, and only afterwards, through the secondary neurons, it propagates further. If the pacemaker neuron has a high degree, then its rhythm is simply too weak to excite all the neighboring neurons, and propagation therefore fails.
