Determination of the International Sensitivity Index of a new near-patient testing device to monitor oral anticoagulant therapy--overview of the assessment of conformity to the calibration model

A key issue for the reliable use of new devices for the laboratory control of oral anticoagulant therapy with the INR is their conformity to the calibration model. In the past, their adequacy has mostly been assessed empirically without reference to the calibration model and the use of International Reference Preparations (IRP) for thromboplastin. In this study we reviewed the requirements to be fulfilled and applied them to the calibration of a new near-patient testing device (TAS, Cardiovascular Diagnostics) which uses thromboplastin-containing test cards for determination of the INR. On each of 10 working days citrated whole blood and plasma samples were obtained from 2 healthy subjects and 6 patients on oral anticoagulants. PT testing on whole blood and plasma was done with the TAS and parallel testing for plasma by the manual technique with the IRP CRM 149S. Conformity to the calibration model was judged satisfactory if the following requirements were met: (i) there was a linear relationship between paired log-PTs (TAS vs CRM 149S); (ii) the regression line drawn through patients data points, passed through those of normals; (iii) the precision of the calibration expressed as the CV of the slope was <3%. A good linear relationship was observed for calibration plots for plasma and whole blood (r = 0.98). Regression lines drawn through patients data points, passed through those of normals. The CVs of the slope were in both cases 2.2% and the ISIs were 0.965 and 1.000 for whole blood and plasma. In conclusion, our study shows that near-patient testing devices can be considered reliable tools to measure INR in patients on oral anticoagulants and provides guidelines for their evaluation.     

基于线型激光的钢板表面缺陷三维检测技术

提出将线型激光束垂直投射到钢板表面,通过面阵CCD摄像机采集激光线在钢板表面的图像来计算表面缺陷深度的三维检测方法.利用中点法对激光图像进行细化,并根据稳定点判别依据提取激光线形.采用分区标定方法对摄像机进行标定,由空间还原思想恢复激光线形的空间坐标.根据扫描投影的方法选择理想表面方向作为缺陷深度计算的基准,实现对缺陷深度信息的定量计算.通过对缺陷样品验证的结果表明,采用该方法得到的计算值与实际值非常接近.     

Procedure to Calibrate and Verify Numerical Models of Estuarine Hydrodynamics

In most hydrodynamic models, friction and turbulent diffusion∕dispersion coefficients are the important calibration parameters affecting the calculation of surface elevation, velocity and salinity distribution. This paper presents a rational approach to calibrate and verify a hydrodynamic model of partially stratified estuaries. The calibration procedures and verification requirements are demonstrated with the application of a vertical (laterally averaged) two-dimensional model to a branched estuarine river system. The friction coefficient is calibrated and verified with model simulation of barotropic flow, and the turbulent diffusion and dispersion coefficients are calibrated through comparison of salinity distributions. The overall model verification is suggested to be achieved with comparisons of Eulerian residual circulation and salinity distribution. In the case of the Tanshui River system, the available prototype current records are too short to calculate slowly varying residual currents. The snapshots of the model-computed and field-measured residual currents are provided to qualitatively agree with theoretical analysis. The overall performance of the model is verified with an additional set of salinity data.     

Line stimulation parallel to myofibers enhances regional uniformity of transmembrane voltage changes in rabbit hearts

The sign of transmembrane voltage (Vm) change (delta Vm) in the heart during unipolar point stimulation is nonuniform, which introduces dispersion of states of Vm-dependent ion channels that depends on fiber orientation. We hypothesized that line stimulation parallel to cardiac fibers increases regional uniformity of the delta Vm sign. To test this, we evaluated electrode current distribution and delta Vm produced by unipolar line stimulation in isolated rabbit hearts. The Vm-sensitive fluorescent dye, di-4-ANEPPS, and a laser scanner provided delta Vm measurements at 63 spots in an 8 x 8-mm epicardial region. Line stimulation was tested at specific angles with respect to the fiber direction. Current peaks occurred at electrode ends. For electrodes parallel to fibers (0 degree), epicardium in regions beyond the ends exhibited a nonuniform delta Vm sign, whereas epicardium between the ends exhibited a uniform delta Vm sign that was essentially negative (hyperpolarized) during anodal pulses and positive (depolarized) during cathodal pulses. The delta Vm sign between the ends became less uniform when the stimulation angle was increased relative to the long axis of the fibers. At 90 degrees, the delta Vm sign between the ends was nonuniform and was frequently opposite, near versus away from the electrode. Spatial distributions of delta Vm during line stimulation were qualitatively predictable from anisotropic effects of point stimulation provided that combined effects of points along the electrode and points with higher current near ends were considered. For biphasic line stimulation, delta Vm during the second phase was weakly correlated with the temporal sum of effects of phases given individually, indicating limited ability of summation to predict delta Vm. Thus, uniformity of the delta Vm sign during stimulation is enhanced in the region between the ends of a line electrode parallel to fibers. This may lessen arrhythmogenic dispersion of Vm-dependent ion channel states in the region.     

Commutability of control materials in glycohemoglobin determinations

The intermethod variabilities of control materials and patient blood samples for the measurement of glycohemoglobin were compared. Sets of 50 blood samples and 15 control materials were analyzed by HPLC and affinity and immunochemical methods. For each pair of methods, the distances of the materials from the regression line of patient blood results (expressed as normalized residuals) were calculated. Only two of 15 controls had normalized residuals exceeding 3 standard deviations from the regression line. Total hemoglobin (Hb) content, Hb derivatives, and cellulose acetate electrophoresis demonstrated that only a minority of controls could be considered similar to patients' blood samples. We selected Menarini's and our home-prepared controls to simulate calibration of the different techniques by these materials. Intermethod calibration succeeded mostly in harmonizing results obtained by HPLC methods. On the contrary, calibration of the immunochemical techniques (Boehringer and Roche) did not improve intermethod agreement to a clinically useful level.     

Prothrombin time standardization by correction of the Pivka inhibitor

The standardization of prothrombin time (PT) assays needs two steps: (1) calibration of PT assays towards a reference assay or reference thromboplastin, (2) correction of PT assays according to the calibration. The present recommended calibration by clotting times is favored for the linearity between assays; the clotting times of abnormal plasma are partly prolonged due to the protein induced by vitamin K absence (Pivka) inhibitor. Calibration by coagulation activities also demonstrated linearity between PT assays; the regression line for abnormal plasma deviated from the line of identity due to differences in sensitivity of assays for the Pivka inhibitor. The corrected PT assays demonstrated similar results using calibration by clotting time or coagulation activities, but the correction was simpler for coagulation activities. Patient plasma was the preferable material in calibration by clotting times as well as by coagulation activities. The corrections between the reference assay and other PT assays were equal to the differences in sensitivities for the Pivka inhibitor. The corrected PT assays did not differ from the reference assay by statistical analysis; any of the six PT assays tested might be used as reference assay.     

Preflex Beams: A Method of Calculation of Creep and Shrinkage Effects

This paper presents a method of calculation of creep and shrinkage effects for composite beams. It is particularly applicable to Preflex and Flexstress beams, which are composed of a steel I-girder with the bottom flange encased by concrete. The concrete is prestressed by predeflection of the steel beam and the subsequent release after hardening of the concrete flange or by means of prestressing cables. The presented approach using concrete age-adjusted modular ratios allows the calculation of time-dependent stresses in the concrete flange due to creep and shrinkage, with sufficient accuracy for practical applications and without carrying out cumbersome numerical computations. The results can be extended directly to the analysis of ordinary steel–concrete composite beams. The main goal of the present paper is the calibration of the parameters which must be introduced to simplify the equations describing the system. This calibration is discussed and its sensitivity to some calculation inputs is presented. The conclusions are very encouraging and the simplified approach seems to agree very well with the results of the numerical approach.     

Calibration of On-Demand Irrigation Network Models

In this study, a new procedure for calibrating on-demand irrigation network models was developed. This procedure used a new objective function called maximum data with a reasonable error (MDRE) for calibrating the network. It was compared with the two more commonly used objective functions in calibration procedures that are the simple least squares (SLS) and the maximum likelihood estimator for the heteroscedastic error case (HMLE). In order to carry out the calibration, a quasi-Newton optimization method was used having as variable the Hazen-Williams head losses coefficient (C). This procedure was applied to an on-demand irrigation network located in Tarazona de La Mancha (Albacete, Spain) where flow and pressure at hydrant level was measured. The calibration procedure using the MDRE objective function was applied considering all the pressure control points simultaneously and the obtained results were compared with the results of considering the pressure control points independently. Therefore, the effect of the location of the pressure control point was studied. Results showed that, when the proposed objective function was used, the root mean squared error (RMSE) comparing the measured and simulated data after calibration was lower than when the SLS or HMLE objective functions were used. The location of the pressure control points throughout the irrigation network could affect the results; therefore, it was more accurate to use all the control points simultaneously than independently in the calibration process.     

S400G中硫含量检测的不确定度评定

测量不确定度是反映被测量值的分散性、与测量结果相联系的参数,是对测量结果质量的定量表征。结合宝钢特钢检测中心炼钢炉前分析作业区的生产实际,依照国标GB/T 20123—2006,运用高频燃烧红外吸收法对S400G中硫含量进行分析,对样品的测量重复性分量、校正时测量变动性分量进行了A类不确定度评定,对标准物质硫含量分量、称量引起的分量、仪器显示分辨率的分量分别进行了B类不确定度评定,明确了评定过程所需参数的数据采集和计算方法。结果表明,采用高频燃烧红外吸收法的检测可信度较高,同时也为其他钢种的高硫含量测量评定提供了参考依据。     

直线外设站放样直线上任意点方法的应用探讨

在工程测量的直线标定中，当直线不通视情况下在直线两端设站放样直线上的任意点非常困难，本文根据笔者的亲身实践，探讨了在直线外设站，利用已知坐标、方位角、距离等要素，快速计算放样数据，放样直线上的任意点的几种方法。     

高温蒸气管道直埋技术的应用

以临沂市高温蒸汽管道直埋工程为例,介绍了应用２高温蒸气管道直埋技术时,应准确同带状图,施工及验收标准要切合实际、严格要求钢管质量。     

Evaluation of multiwavelength chromatograms for the quantification of mixtures of pesticides by high-performance liquid chromatography-diode array detection with multivariate calibration

Three multivariate calibration methods, partial least squares (PLS-1 and PLS-2) and principal component regression, were applied to the simultaneous determination of the five pesticides iprodione, procymidone, chlorothalonil, folpet and triazophos by high-performance liquid chromatography with diode array detection. Such detection gives multiwavelength chromatograms from a single analysis of one sample. In this paper, calibration models at two different wavelengths were developed to resolve mixtures of five pesticides with overlapping chromatographic peaks. The first model, carried out at 220 nm as detector compromise wavelength, yielded satisfactory sensitivity for accurate estimation of the concentration of iprodione, procymidone, chlorothalonil and folpet and the second model, at 200 nm, was used for accurate estimation of triazophos. Both calibration models were evaluated using the chromatograms and first-derivative (1D) chromatograms by predicting the concentrations of independent test set samples. Finally, the proposed 1D calibration models were successfully applied to the determination of these pesticides in groundwater and soil samples. In all cases, the PLS-1 calibration method showed superior quantitative prediction ability than the PLS-2 or principal component regression methods.     

回归分析在环境监测中的应用

文章主要阐述了一元线性回归方程的建立,影响校准曲线回归的因素以及如何应用回归方程进行相关分析.严格控制影响校准曲线回归的因素,决定着校准曲线的质量和样品测定结果的准确度.     

大型连续带钢生产线活套结构形式及特点

在大型连续带钢生产线中,活套作为机组的关键设备,其主要作用是储存钢带,以保证机组以正常的工艺速度连续生产。介绍了活套的多种结构形式;重点针对立式活套中链条传动和钢丝绳传动的优缺点进行了深入分析和比较,指出了链条传动式活套在实际生产过程中造成钢带跑偏的原因;分析了活套传动部分的选型计算方法并用实例加以验证。     

Characterization of Heterogeneous Soils Using Surface Waves: Homogenization and Numerical Modeling

Seismic surface waves are well-adapted to study the elastic parameters, and hence the mechanical properties, of soils. The aim herein is to evaluate whether Rayleigh waves in heterogeneous soils may be used to estimate average elastic parameters and to determine how these parameters are influenced by heterogeneities. The heterogeneous medium, underlain by a homogeneous half-space, is considered as a homogeneous matrix with one or several types of randomly distributed inclusions (with a normal distribution) in the matrix. Seismic waves generated by surface loads and propagating in this medium were calculated using the finite element method (FEM) and then compared with single- and multiple-scattering homogenization methods. For the FEM calculation, special care was taken to reduce numerical dispersion through the use of elements smaller than 1/20 of the dominant wavelength. The group and phase velocity dispersion curves were measured and inverted in order to obtain the effective shear wave velocity of the heterogeneous medium. The results show a clear dependence of the wave velocity with respect to the nature, concentration, and size of the inclusions. The dependence with respect to the nature and concentration of inclusions coincides with that obtained from a multiple-scattering homogenization method up to an inclusion concentration of approximately 50%.     

Geometrical calibration of X-ray imaging chains for three-dimensional reconstruction

Reconstructing a three-dimensional (3D) object from a set of its two-dimensional (2D) X-ray projections requires that the source position and image plane orientation in 3D space be obtained with high accuracy. We present a method for estimating the geometrical parameters of an X-ray imaging chain, based on the minimization of the reprojection mean quadratic error measured on reference points of a calibration phantom. This error is explicitly calculated with respect to the geometrical parameters of the conic projection, and a conjugate gradient technique is used for its minimization. By comparison to the classical unconstrained method, better results were obtained in simulation with our method, specially when only a few reference points are available. This method may be adapted to different X-ray systems and may also be extended to the estimation of the geometrical parameters of the imaging chain trajectory in the case of dynamic acquisitions.     

溶液制样-偏振能量色散X射线荧光光谱法分析石煤钒矿中五氧化二钒

以硝酸、次氯酸溶解样品,溶液制样法,采用偏振能量色散X射线荧光光谱法(EDXRF)对石煤钒中五氧化二钒含量进行了定量分析。采用盐酸溶解高纯五氧化二钒配制校准溶液并绘制校准曲线,线性相关系数为0.999 7,方法检出限为1.99 mg/L。试样中其他元素Si、Ca、Fe、Al、Mg对钒的测定无显著影响;XRF能谱图考察发现：Si、Ca、Fe、Al、Mg的Kα线与V的Kα线均无重叠,并且这些元素的Kβ线及次级线对V的Kα线也无重叠。精密度试验表明,10次测量结果的相对标准偏差为1.5%。方法用于石煤钒矿中钒元素的分析,与滴定法测定结果一致性较好。     

The development of a new method of cephalometric and study cast mensuration with a computer controlled, video image capture system. Part II: Study cast mensuration

A computerized system for mensuration of dental casts, developed at the Royal Berkshire Hospital in Reading was tested against a conventional manual method and a computer controlled reflex microscope. Systematic errors, calibration, and handling aspects are discussed. Results showed that the computerized system provided data which while statistically different, were clinically comparable with the same measurements carried out using conventional manual or digitizing techniques. The results indicated that future research is required with respect to object illumination for all indirect techniques.     

Edge geometry of pipe blanks produced by JCOE flexure

For the shaping of welded straight-seam large-diameter pipe in the TESA 1420 production line, methods are proposed for calculating the geometric parameters of the edge of the blank and the profile of the deforming tool. The edge geometry obtained on an edge-bending press is compared when using surface tools of involute and single-radius type. For tools of single-radius type, edge geometry consistent with the required shaping quality may be produced. For the edge-bending presses, a method of calculating the edge geometry in loading and unloading is outlined. The height of the bent edge, the residual radii of curvature, and the coordinates of the loading and unloading points at the external and internal edge contour of the pipe blank are determined. The coordinates of the edge formed by a tool with an involute profile are also calculated. The involute tool profile is universal on passing from one type of tool to another within a standardized group. The calculation permit conversion from an involute edge profile to a multiradial profile, followed by determination of the fixed coordinates of the points of the blank after springback. On the basis of those coordinates, the output edge geometry is estimated. Within the 1220–1420 mm standardized group, the longitudinal edge deformation for the 1220 × 10 mm type is calculated. Standardization is found to be much simpler with a single- radius tool profile. For edge-bending presses, a method of calculating the edge parameters of the pipe blank when using a tool with an involute contact profile is developed and tested in industrial conditions. Single- radius calibration of the profile of the edge-bending tool is proposed, such that fixed time coordinates are ensured. These are analogous to the coordinates with an involute punch profile. The blank’s weighted mean radius of curvature maximizes the agreement of the coordinates of the blank profile at fixed points in both approaches. (The maximum discrepancy is no more than 6–7%.)     

X射线荧光光谱法测定铝锂合金中多元素含量

选择铝锂合金系列标样建立校准曲线,通过基本参数法校正基体效应和光谱干扰,结果表明,校正后多数元素校准曲线的标准偏差(SD)和品质因子(K)变得更小,曲线的离散度降低,线性关系得到较大改善,由此建立了波长色散X射线荧光光谱法测定铝锂合金中Mg、Si、Ti、Cr、Zr、Fe、Cu、Zn、Mn等9种元素含量的新方法。各元素的检出限均低于4.5 μg/g。对E986铝锂合金标准样品进行精密度考察,各元素测定结果的相对标准偏差均低于0.9%;对铝锂合金实际样品进行分析,测定值与湿法及火花源原子发射光谱法的测定值吻合较好,能够满足铝锂合金中各元素的检测要求。