插线法制作大鼠大脑中动脉闭塞局灶性脑缺血再灌注模型

目的 :比较两种大脑中动脉闭塞 (middle cerebral artery occlusion,MCAO)局灶性脑缺血再灌注模型 ,寻找一种更加理想、稳定和可靠的模型。方法 :选用 Ethicon缝线 (直径 0 .16 mm )和 Takeno钓鱼线 (直径 0 .2 0 mm ) ,按 Koizumi和 L onga插线法制作局灶性脑缺血再灌注模型。缺血 2 h再灌注 4h和 2 2 h神经病学评分计算有效率和死亡率。TTC染色计算梗死面积百分比。结果 :Koizumi模型再灌注 4h有效率和 2 2 h梗死面积百分比较 L onga法为高 ,而再灌注 4h死亡率较低。结论 :大鼠 MCAO局灶性脑缺血再灌注模型采用 Koizumi法优于 L onga法。理想的大鼠插线模型受插线直径、插线头端形态、插入深度和大鼠体重等因素影响。

Wistar大鼠插线法局灶性脑缺血/再灌注模型的实验研究

目的：局灶性脑缺血／再灌注模型是研究缺血性脑血管病的重要模型。本文介绍一种简便易行的插线法Ｗｉｓｔａｒ 大鼠局灶性脑缺血／再灌注模型的制备方法，并通过神经病学评分、ＴＴＣ染色、病理形态学变化的观察，对该模型的可靠性进行评价。方法：用头端处理过的尼龙钓丝，从颈外动脉向颈内动脉插入，可逆性阻断大鼠一侧大脑中动脉（ＭＣＡ）。结果：大鼠ＭＣＡ阻断后１．５ｈ，同时出现Ｈｏｒｎｅｒ＇ｓ征阳性、提尾悬空时梗塞对侧前肢屈曲、内收、自主运动时身体向偏瘫侧划圈的动物，ＴＴＣ染色能清楚地显示梗塞范围，且相对较稳定，光镜下可见脑缺血后的病理改变。阻断后３ｈ及再灌注３、６ｈ时的病理改变加重，神经病学评分同前。结论：该改良法制备的模型简便易行、稳定性好、结果可靠，是用于研究局灶性脑缺血／再灌注的较为理想的实验动物模型。

插线法制作大鼠局灶性脑缺血再灌流模型方法的改进

目的探索插线法制作大鼠局灶性脑缺血再灌流模型方法的改进。方法在前人制作模型方法基础上进行部分改进 ,用提线法阻断血流和在颈外动脉上剪小口进行插线。结果缩短了手术时间 ,简化了模型制作过程 ,提高模型成功率。结论本法复制插线法制作大鼠局灶性脑缺血再灌流模型 ,省时 ,操作简便 。

小鼠插线法局灶性脑缺血/再灌注模型的建立

目的 :建立小鼠局灶性脑缺血 /再灌注模型。方法 :选用尼龙钓丝 (直径 0 .1 2 8mm)经过液体石蜡浸泡后 ,从颈外动脉向颈内动脉插入 ,可逆性阻断小鼠右侧大脑中动脉 ,并通过神经病学评分、TTC染色 ,病理形态学的观察 ,对模型的可靠性进行评价。结果 :小鼠右侧大脑中动脉阻断 3h后 ,出现提尾悬空时头向左歪 ,左前肢内收、肩内旋 ,左前肢肌张力降低 ,不能完全伸直 ,自主活动时向左旋转 ,行走时向左倾斜。TTC染色可清晰地显示出梗塞范围 ,并相对稳定 ,光学显微镜下可见脑缺血后的病理改变。阻断3h再灌 1 8h、2 4 h后病理改变加重 ,神经病学评分同前。结论 :插线法制作小鼠脑缺血 /再灌注模型无需开颅 ,创伤小 ,缺血的部位较恒定、可以准确控制缺血和再灌注时间 ,此模型是研究脑血管疾病的病理生理改变。

大鼠插线法大脑中动脉缺血-再灌流模型的方法学与改进

有关大鼠局灶性脑缺血的动物模型,已经建立有几种,如经颅底直接电凝大脑中动脉(MCA)法、光化学诱导法和插线法等。其中插线法由于可将已抗凝处理的插线拔出而具有可恢复再灌流的优点,因而被越来越多的研究者采用。插线法同时也避免了开颅过程对大鼠的创伤,因此也使结果减少了创伤因素的干扰。此法由Koizumi等于1986年首次发表,以后Nagasawa对本模型的组织学改变与脑血流的(CBF)相关性作了探讨。

颈总与颈外插线构建大脑中动脉栓塞大鼠模型脑微循环灌注的比较

背景:颈总插线法和颈外插线法制备的大脑中动脉栓塞模型是脑缺血临床前研究常使用的模型,但既往关于2种插线方法在模型制备难易度、缺血性脑损伤中微循环灌注量的差异及其相关机制的对比研究较少。目的:比较颈总动脉和颈外动脉插线制备的大脑中动脉栓塞模型在模型制备难易度以及微循环灌注量的差异。方法:SD雄性大鼠随机分为3组,颈总动脉插线组和颈外动脉插线组分别应用颈总动脉和颈外动脉插线法制备大脑中动脉栓塞模型;假手术组大鼠麻醉后除不结扎血管和插入线栓,其他操作与上述2种方法相同。记录各组大鼠插线时间、插线成功率、模型术后死亡率以及造模成功率。插线后采用激光散斑成像技术观察大鼠缺血90 min内和再灌注90 min内缺血半球脑血流灌注量以及缺血半暗带血管直径的变化;LONGA法和改良神经功能缺损评分法分别评价术后2,24,48,72 h大鼠神经功能缺缺损情况;TTC染色法、干湿质量法以及伊文思蓝染色法分别计算术后72 h大鼠脑梗死率、脑组织含水量以及血脑屏障通透性;ELISA法检测大鼠术后72 h血清内皮素1、降钙素基因肽、环磷酸腺苷、前列腺素E2和一氧化氮表达水平。结果与结论:①与颈外动脉插线组相比,颈总动脉插线组手术操作时间明显缩短(P<0.01),模型成功率更高(P<0.05);且颈总动脉插线组再灌注后缺血半球脑血流灌注量和血管直径均显著小于颈外动脉插线组(P<0.05),血清环磷酸腺苷水平也显著降低(P<0.05);②但颈外动脉插线组和颈总动脉插线组在脑梗死率、脑组织含水量、血脑屏障通透性以及血清内皮素1、降钙素基因肽、前列腺素E2和一氧化氮水平方面差异均无显著性意义(P>0.05);③提示相对于颈外动脉插线法,颈总动脉插线法操作简单、模型成功率高,但再灌注后大脑皮质存在明显的微循环血流灌注障碍;微循环血流的灌注不足可能与血清环磷酸腺苷水平的降低有关。

公路放样中曲线定线方法的探讨

介绍了公路放样中直接定线的几种方法 ,并给出了详细的实施步骤 。

改进的线栓法对不同品系小鼠脑缺血模型的构建

目的:建立不同品系小鼠局灶性脑缺血(MCAO)模型的通用方法。方法:健康雄性昆明(KM)小鼠和C57BL/6小鼠各20只,随机分为对照组10只,MCAO组10只,改良线栓法制作小鼠MCAO模型;大脑中动脉血流监测,栓塞24 h后行神经行为学评分,TTC染色测定脑梗死体积百分比,对模型可靠性进行评价。结果:KM和C57BL/6小鼠MCAO模型组脑血流监测显示梗死处血流基值下降比分别为(81.65±4.59)%,(83.68±6.25)%,神经功能评分分别为(2.30±0.82),(2.50±0.80)分,体征明显,TTC染色可清晰地显示出梗死范围且相对稳定,C57BL/6小鼠有1只TTC染色梗死灶不明显,24 h成活率KM和C57BL/6小鼠分别为100%,80%。结论:颈总插线法制作小鼠脑缺血模型无需开颅,创伤极小,缺血的部位较恒定,从模型制备中线栓、温度、麻醉各个关键环节加以优化和改良,使该模型的制备更加完备。

实验性急性脑缺血模型及其研究进展

本文介绍了目前国内外建立鼠实验性急性脑缺血模型的各种方法及其优缺点 ,其中四动脉阻断法、插线法和光化学法是常用的方法 ,予以重点说明 。

NURBS CURVE INTERPOLATOR WITH ADAPTIVE ACCELERATION-DECELERATION CONTROL

The feedrate profile of non-uniform rational B-spline （NURBS） interpolation due to the contour errors is analyzed. A NURBS curve interpolator with adaptive acceleration-deceleration control is presented. In interpo- lation preprocessing, the sensitive zones of feedrate variations are processed with acceleration-deceleration control. By using the proposed algorithm, the machining accuracy is guaranteed and the feedrate is adaptively adjusted to he smoothed. The mechanical shock imposed in the servo system is avoided by the first and the second time derivatives of feedrates. A simulation of NURBS interpolation is given to demonstrate the validity and the effectiveness of the algorithm. The proposed interpolator can also be applied to the trajectory planning of the other parametric curves.

CALCULATION OF NONLINEAR MAGNETIC FIELDS IN CYLINDRICALLY SYMMETRIC SYSTEM

For the calculation of non-linear magnetic fields, a simple program can be as effective as a large commercialized software package. If relaxation methods are used, they must include successive over-relaxation and under-relaxation and much attention must be paid to the relaxation factor and the interpolation. In this paper some skills are proposed on the setting of an interpolation switch and the choosing of saturation point so as to assure satisfied convergence properties. The numerical results by using these methods conform well to the tests.

Precision of meshfree methods and application to forward modeling of two-dimensional electromagnetic sources

Meshfree method offers high accuracy and computational capability and constructs the shape function without relying on predefined elements. We comparatively analyze the global weak form meshfree methods, such as element-free Galerkin method （EFGM）, the point interpolation method （PIM）, and the radial point interpolation method （RPIM）. Taking two dimensional Poisson equation as an example, we discuss the support-domain dimensionless size, the field nodes, and background element settings with respect to their effect on calculation accuracy of the meshfree method. RPIM and EFGM are applied to controlled- source two-dimensional electromagnetic modeling with fixed shape parameters. The accuracy of boundary conditions imposed directly and by a penalty function are discussed in the case of forward modeling of two-dimensional magnetotellurics in a homogeneous medium model. The coupling algorithm of EFG-PIM and EFG-RPIM are generated by integrating the PIM or RPIM and EFGM. The results of the numerical modeling suggest the following. First, the proposed meshfree method and corresponding coupled methods are well-suited for electromagnetic numerical modeling. The accuracy of the algorithm is the highest when the support-domain dimensionless size is 1.0 and the distribution of field nodes is consistent with the nodes of background elements. Second, the accuracy of PIM and RPIM are lower than that of EFGM for the Poisson equation but higher than EFGM for the homogeneous medium MT response. Third, RPIM overcomes the matrix inversion problem of PIM and has a wider selection of support-domain dimensionless sizes as compared to RPIM.

EDGE-DIRECTED INTERPOLATION BASED ON SHIFTED-LINEAR IMAGE MODEL

This paper presents a hybrid image interpolation algorithm to keep details and edges simultaneously. The basic idea is to separate the unknown pixels into two classes and estimate them in different way. One class of unknown pixels is obtained via shifted linear interpolation and the other class through statistical signal processing method. The merit of this hybrid algorithm is that each unknown pixel can be estimated through original pixels simultaneously. Simulation results demonstrate that this hybrid interpolation algorithm improves the quality of the interpolated images over conventional interpolation methods.

Research on the Arc Interpolation for the Nonstandard Section Curve of the Piston

The transverse section of piston skirt is not a standard circle and is with high precision. So the section curve should be interpolated through the high accuracy method of circular arc interpolation before NC machining. In order to smooth the connection of adjacent arcs and shorten the NC machining program, an interpolation method based on Chebyshev theory of function approximation is proposed here. According to the analysis of the interpolation error, the algorithm is simple and with high precision. By this way the fewest interpolating circular arc segments can be got, and the manufacture requirement is satisfied with the circular arc interpolating curves.

Subpixel Target Location Techniques for 3-D Coordinate Measuring System

the close photogrammetric 3-D coordinate measurement is a newmeasuring technology in the fields of the coordinate measurementmachine (CMM) in recent years. In this method, we usually place sometargets on the measured object and take image of targets to determinethe object coordinate. The subpixel location of target image plays animportant role in high accuracy 3-D coordinate measuring procedure.In this paper, some subpixel location methods are reviewed and somefactors which affect location precision are analyzed.

Research on NC interpolation Algorithm based on STM32

This paper analyzes the principle of spline interpolation, pointed out the reasons for the feed rate fluctuations and proposed interpolation algorithm based on the secant iteration method NURBS curve. The algorithm of the speed the planning section uses cubic polynomial acceleration and deceleration control methods to ensure the acceleration of the process of continuous high-speed operation, so that the machine runs smoothly, avoiding the machine have a big impact; while parameter calculation part using the Secant iterative interpolation method to calculate parameter, reducing the speed fluctuation, the machine is further reduced tremor. Simulation results show that the algorithm can obtain a continuous velocity and acceleration curves, and can be controlled in real time interpolation velocity fluctuations in the ideal range, the machine achieve the smooth running ,and meet the high-speed, high quality processing requirements.

GEOMETRIC ERROR CONTROL IN THE PARABOLA-BLENDING LINEAR INTERPOLATOR

This paper considers geometric error control in the parabola-blending linear interpolation method(Zhang,et al.,2011).Classical model of chord error by approximation with contact circle on the parabolas leads to incorrect result.By computing the geometric error directly without accumulating the approximation error and chord error,the authors realize correct geometric error control by establishing inequality constraints on the accelerations of the motion.

Improved Location Algorithm of VIRE Based on RFID

Using linear interpolation method, VIRE algorithm simply treats the signal strength value and distance of the reference tag as a linear relationship, leading to the inaccuracy of signal strength value for virtual reference tags. The threshold in VIRE algorithm is a fixed value that needs repeatedly adjustment through experiments, which results in the complicated algorithm. To solve these problems, an improved algorithm is proposed in this paper, including nonlinear interpolation algorithm, dynamic threshold setting and tag self-correction of fuzzy map, which builds an indoor positioning system based on reference tags. The experimental results show that the improved algorithm can improve the positioning accuracy and improve the stability of positioning results under bad environmental conditions without increasing the number of reference tags.

Uniform analysis of a stabilized hybrid finite element method for Reissner-Mindlin plates

This paper presents a low order stabilized hybrid quadrilateral finite element method for ReissnerMindlin plates based on Hellinger-Reissner variational principle,which includes variables of displacements,shear stresses and bending moments.The approach uses continuous piecewise isoparametric bilinear interpolations for the approximations of the transverse displacement and rotation.The stabilization achieved by adding a stabilization term of least-squares to the original hybrid scheme,allows independent approximations of the stresses and moments.The stress approximation adopts a piecewise independent 4-parameter mode satisfying an accuracy-enhanced condition.The approximation of moments employs a piecewise-independent 5-parameter mode.This method can be viewed as a stabilized version of the hybrid finite element scheme proposed in [Carstensen C,Xie X,Yu G,et al.A priori and a posteriori analysis for a locking-free low order quadrilateral hybrid finite element for Reissner-Mindlin plates.Comput Methods Appl Mech Engrg,2011,200:1161-1175],where the approximations of stresses and moments are required to satisfy an equilibrium criterion.A priori error analysis shows that the method is uniform with respect to the plate thickness t.Numerical experiments confirm the theoretical results.