Visualization of the interaction between blood vessels and podocytes in the mouse embryonic glomerulus using a barium-infusion method for scanning electron microscopy

The present study revealed three dimensionally the formation of epithelial cells and vascular capillaries in glomeruli of the kidney of the mouse embryo. Barium sulphate was infused through the umbilical vessel of 16.5-17.5-day embryos and the backscattered electron (BSE) image and the secondary electron (SE) image of the identical area of glomeruli were obtained by scanning electron microscopy (SEM). The BSE images directly showed the vascular structure of the glomerulus, while the SE images showed a developmental process of podocytes from epithelial cells. Podocytes were more closely located to the vascular capillary than other epithelial cells. These findings were compared with those obtained in the resin cast model of glomeruli. Thus, the metal infusion-SEM method described here can trace the process of formation of urine filtration barrier in the mouse embryonic glomerulus.     

Three-dimensional studies of cytoskeletal organizations in cultured thyroid cells by quick-freezing and deep-etching method

Isolated porcine thyroid cells were cultured on collagen gels (control group, TSH-stimulated group, and double-layered culture). They were split or cut to remove cytoplasmic soluble proteins for replica preparations. Some specimens were immunostained with anti-actin antibody or decorated with S1 myosin fragments to identify actin filaments. The basal cell membranes of thyroid cells of monolayer culture were in contact with collagen gels and the apical cell membranes faced the culture medium. Networks of actin filaments were attached to the cytoplasmic sides of the apical cell membranes, while intermediate filaments were localized along the basal ones. The thyroid-stimulating hormone (TSH) treatment induced the formation of microvilli only on the apical cell membranes and the accumulation of actin filaments under the apical cell membranes, indicating the apical-basal polarity of the cells. In double-layered culture, the primitive follicular lumens with microvilli appeared between two adjacent cells. The interaction of cell membranes with collagen gels is a determinant factor in the orientation of apical-basal polarity. Moreover, the TSH treatment and cell-cell contact further intensify the polarization through reorganizing the cytoskeletons.     

Blur identification by the method of generalized cross-validation

The point spread function (PSF) of a blurred image is often unknown a priori; the blur must first be identified from the degraded image data before restoring the image. Generalized cross-validation (GCV) is introduced to address the blur identification problem. The GCV criterion identifies model parameters for the blur, the image, and the regularization parameter, providing all the information necessary to restore the image. Experiments are presented which show that GVC is capable of yielding good identification results. A comparison of the GCV criterion with maximum-likelihood (ML) estimation shows the GCV often outperforms ML in identifying the blur and image model parameters.     

Visualization of vasculature with convolution surfaces: method, validation and evaluation

We present a method for visualizing vasculature based on clinical computed tomography or magnetic resonance data. The vessel skeleton as well as the diameter information per voxel serve as input. Our method adheres to these data, while producing smooth transitions at branchings and closed, rounded ends by means of convolution surfaces. We examine the filter design with respect to irritating bulges, unwanted blending and the correct visualization of the vessel diameter. The method has been applied to a large variety of anatomic trees. We discuss the validation of the method by means of a comparison to other visualization methods. Surface distance measures are carried out to perform a quantitative validation. Furthermore, we present the evaluation of the method which has been accomplished on the basis of a survey by 11 radiologists and surgeons.     

Analysis of microstrip discontinuities by FDTD method combined with SOC technique

In this paper, the application of the finite-difference time-domain (FDTD) algorithm combined with the short-open calibration SOC technique to three-dimensional microstrip discontinuity is presented. This SOC technique is directly accommodated in the FDTD algorithm. It is used to remove the unwanted parasitic errors brought by the approximation of the impressed voltage sources and the feed lines. The FDTD is formulated in such a way that the port voltages and currents are explicitly represented through relevant network matrices. This new method is also used to analyze finite periodic structures. The scattering parameters of the whole periodic structure can be approximately obtained through analyzing only one cell of it. The results for microstrip discontinuities and finite periodic structures are compared with the conventional FDTD method.     

Three-dimensional structure of intracellular membranous organelles in embryonic chick skeletal muscle cells in vitro revealed with scanning electron microscope

Using the freeze-polishing and osmium-maceration procedures, the ultrastructure of intracellular membranous organelles in embryonic chick skeletal muscle cells in vitro was investigated three-dimensionally with the scanning electron microscope (SEM). T-system tubules followed a tortuous course and possessed many warts. Some of these tubules could be traced to the sarcolemma. The sarcoplasmic reticulum (SR) had elaborate structures of a hexagonal pattern. By comparing the SEM images with those of ultrathin sections of myotubes impregnated with ferritin particles, the distinction between the T-system and SR was confirmed. Late in the culture, these two intracellular membranous systems were arranged periodically at right angles to the longitudinal axis of the myotubes. Round-shaped mitochondria were often arranged in chains connected with slender rods. Long rod-shaped mitochondria exhibited occasional branchings.     

采用透视变换提高车辆识别准确率的方法研究

道路交通中运动目标多,给基于视频的车辆准确计数带来了挑战。本文采用动态高斯背景建模和背景相减法检测运动目标,然后对图像进行透视变换,这样对一定视场范围内的远近不同的行人、自行车和摩托车等非监控目标,可用同一面积阈值将其与车辆区分开来,该算法简单,计算效率高。实验结果证明该方法能够有效地对非监控目标进行屏蔽,减少对机动车辆错误识别率。     

Calculation of transfer functions of three-dimensional indentedobjects by the physical optics approximation combined with the method ofstationary space

Transient scattering by variously shaped objects is obtained from the transfer functions and the spectrum of the incident pulse by using the Fourier synthesis technique. In order to evaluate the transfer functions of indented three-dimensional smooth objects, an effective method based on the physical optics approximation combined with the method of stationary phase is presented. It is shown that for indented three-dimensional objects, there exist several stationary phase points, including the complex ones. It is confirmed from the numerical results that an accurate solution can be obtained by taking into account the complex stationary points. Also, for a complete solution, the creeping wave term should be included     

光流法在运动目标识别领域的理论与应用

在介绍运动检测以及光流的基本概念的基础上引出基于光流方程的两种常用的图像分析方法—梯度法、块匹配法;通过对光流法在红外图像序列的运动目标检测、活动轮廓模型以及医学图像处理方面的应用来阐述这两种光流法的优缺点进行分析从而得出光流法在运动图像识别领域具有较大的优势,最后对光流法在未来其他领域的应用提出展望.     

Co-localization of HSV-1 DNA and ICP35 protein by in situ hybridization and immunocytochemistry

In an effort to obtain a better signal-to-noise ratio and ultrastructural preservation, we sought to improve electron microscopic in situ hybridization technique. In our method, protease treatment was omitted and visualization of the digoxigenin (DIG)-labelled deoxyribonucleic acid (DNA)-probe was enhanced using a three-step procedure. These improvements allowed us to localize viral DNA with good signal-to-noise ratio. DNA specific to herpes simplex virus 1 (HSV-1) was localized by this method to HSV-1 infected cultured cells; DNA was not observed in the empty-cored HSV-1. Using this method and the immunogold cytochemical method, we co-localized viral DNA and capsid protein ICP35 on Lowicryl-embedded sections of HSV-1 infected cells. Interestingly, labelling for both DNA and ICP was observed on some HSV-1 particles in cell nucleus. This finding is consistent with the notion that ICP35 is necessary for assembly of viral DNA. Combination of in situ hybridization and immunocytochemical techniques is a powerful tool for examination of the functional relationship between viral DNA and proteins and help us to study protein function in viral multiplication.     

A parametric method of identification of single-trial event-relatedpotentials in the brain

A parametric method of identification of event-related (or evoked) potentials on a single-trial basis through an ARX (autoregressive with exogenous input) algorithm is discussed. The basic estimation of the information contained in the single trial is taken from an average carried out on a sufficient number of trials, while the noise sources, EEG and EOG, are characterized as exogenous inputs in the model. The simulations as well as the experimental results confirm the capability of the model of drastically improving the S/N (signal-to-noise) ratio in each single trial and satisfactorily identifying the contributions of signal and noise to the overall recording. A particularly efficient reduction of ocular artifacts is also achieved     

Assessment of autonomic regulation of heart rate variability by the method of complex demodulation

Complex demodulation was used to examine the effect of both divisions of the autonomic nervous system (sympathetic and parasympathetic) on heart rate. Data were analyzed from dogs during classical conditioning procedures which caused different changes in the autonomic regulation of heart rate. Two significant peaks in the heart rate variability spectrum were examined by this technique. The amplitude of the peak at the respiration frequency showed parasympathetic changes, while the amplitude of the low frequency peak (0-0.124 Hz) showed both sympathetic and parasympathetic effects. Complex demodulation results at these frequencies clearly showed the activities of both branches of the autonomic nervous system in regulating heart rate. During the CS+ period, when trained dogs were presented with a tone predicting a subsequent shock, the observed tachycardia was due to decreased parasympathetic activity and a transient increase in sympathetic activity. During the CS- period where a different tone predicts no shock, parasympathetic and sympathetic activities were unchanged from the baseline condition. The use of complex demodulation enables us to examine autonomic contributions to heart rate regulation in conditioning and a variety of other physiological and environmental conditions where autonomic input can be expected to change rapidly.     

基于改进的AG-CNN的视网膜OCT图像的黄斑病变识别方法

本文针对目前应用全局图像训练卷积神经网络可能会受到若干无关噪声区域的影响,易导致视网膜OCT图像黄斑病变识别或诊断错误等问题,提出了一种改进的注意力引导四分支卷积神经网络的视网膜OCT图像黄斑病变识别方法.采用改进注意力引导卷积神经网络框架,通过集成全局分支、局部分支和层分割分支构成融合分支,利用注意力热图对重要区域进...     

一种融合天地基多源数据的电离层反演方法

数据融合是观测数据稀疏条件下电离层精确反演的重要技术途径.文中提出了一种融合天地基多源数据的电离层反演方法.选择地基GNSS、低轨卫星(Low Earth Orbiting,LEO)掩星、卫星信标及垂测仪等手段为观测系统,国际参考电离层(International Reference Ionosphere,IRI)为背景模型,利用改进的克里格插值及乘法代数重构方法实现多源数据的有效融合.以中国区域为例,观测系统模拟试验的结果表明:文中提出的方法能将各类观测资料有效地融合到背景模式中,反演得到的总电子含量及电子密度误差相比经验模型均有显著降低;在地基GNSS观测的基础上,融入地基垂测与天基掩星可有效提升电子密度的反演精度.相关研究结果可为中国现有电离层观测系统的优化提供科学依据.     

Analysis and Visualization of Scientific Communities with Information Extracted from the Web

The aim of the present work is to represent graphically the structures of a specific area of knowledge, from data extracted from the Web. The recent development of Internet network has facilitated the access to new resources, which has contributed to create new disciplines that try to exploit these resources. The main problems for their use are their location and processing. Through this work we will combine techniques of extraction, analysis and visualization of data, in order to define an architecture to solve the problems of processing resources. We will specifically explore two of the most important structures that define a scientific community, the subjects that generate a greater interest and its social network. As an example of the application of the architecture and the techniques used, we will present a study on the community of the JISBD using data extracted from the Web.     

Modelling of periodic structures using the finite difference time domain method combined with the Floquet theorem

The Floquet theorem is combined with the finite-difference time-domain (FDTD) method to obtain sufficiently accurate results for the scattering parameters of a metal strip grating. This accuracy can be achieved by using a suitable absorbing boundary condition. The algorithm described allows any periodically repeated complex irregular shape to be studied.<>     

复杂结构精密焊件中缺陷空间定位及可视化

探讨了复杂结构激光焊件X射线检测图像中定位特征点的选择,建立了缺陷深度与偏移量计算的数学模型,确定了缺陷在精密焊缝中的空间分布特征.提出了缺陷空间位置数据的自动提取算法,实现了复杂结构激光焊件中缺陷空间位置数据的快速提取,并对提取结果进行了实验验证.结果表明所提出的提取算法是可行的.建立了复杂激光焊件的三维模型,自动导入已提取的缺陷空间位置数据,实现了复杂结构激光焊件中批量缺陷的空间位置可视化.     

利用快速共聚焦显微镜观察花粉管中线粒体的分布及其动态变化

线粒体是真核细胞中高度动态变化的一种细胞器。但目前有关植物细胞,尤其是花粉管中线粒体的分布及其动态变化的信息还比较少。本文应用Zeiss 5 live快速共聚焦显微镜结合线粒体荧光探针Mitotracker Green对百合花粉管中线粒体的分布及其动态变化进行了观察和测定。结果显示,正常培养的百合花粉管中线粒体呈倒喷泉式移动,即花粉管基部的线粒体移动到亚顶端后即发生回流,因此花粉管顶端锥形区域内很少观察到线粒体的存在。对单个线粒体进行跟踪分析结果表明花粉管中的线粒体分为快速运动和锚定状态两种。快速移动的线粒体在花粉管两侧质膜下及花粉管中央沿着与花粉管长轴平行的方向运动,在花粉管亚顶端则沿着一定曲线移动;锚定在细胞质中的线粒体则随着胞质环流而被动移动。低浓度的微丝骨架抑制剂Jas处理时间依赖性地引起花粉管亚顶端的线粒体逐渐前移,并最终充满整个花粉管顶端,同时花粉管中快速移动线粒体的比例逐渐减少。上述结果表明,花粉管中的线粒体主要沿着微丝骨架进行快速移动,而花粉管亚顶端精细微丝组成的领区(Collar)在花粉管线粒体的分布和动态变化中起重要作用。     

A new heart rate variability analysis method by means of quantifying the variation of nonlinear dynamic patterns

A new heart rate variability (HRV) analysis method, quantifying the variation of nonlinear dynamic pattern (VNDP) in heart rate series, is proposed and validated against the age stratified Fantasia database. The method is based on three processes: (1) a recurrence quantification analysis (RQA) to quantify the dynamic patterns, (2) the use of mutual information (MI) and the entropy (EN) to characterize the VNDP, and 3) linear discriminant analysis to exploit the associations within MI and EN measures. Practically, the VNDP method overcomes the nonstationarity problem and exploits the nonstationary properties in HRV analyses. Physiologically, the VNDP reflects the properties of the fundamental short-term HRV dynamic system and the external associations of the system within the autonomous nervous system (ANS). The characteristic probability density peaks portrayed by VNDP plots indicate the quantum-like heart dynamics, which may provide valuable insights into the control of the ANS. The discrimination results of the reduced pattern dynamic range due to aging, from a new perspective, display the reduction in HRV. The significantly improved discriminatory power, compared to conventional RQA analyses, shows that the VNDP analysis can practically quantify the nonstationary nonlinear dynamics for ANS assessments.     

基于HOG特征与SVM的胶体气泡识别方法研究

本文提出了一种基于HOG特征与支持向量机的分类方法,来代替目前人工检测光纤连接器中的胶体是否存在气泡.该方法先对视频中的胶体部分进行逐帧取样,根据样本制作正、负样本训练集以及测试集,接着选择适当的参数提取了训练集和测试集中胶体气泡HOG特征,并通过支持向量机来进行训练和测试统计的HOG特征,来识别胶体是否存在气泡.最后以人工识别为标准,并与本方法的分类结果进行验证.其实验结果表明该方法能够有效地将有、无气泡的样本进行分类,并在时间和人力上取得明显的优势.