A method for measuring the presampled MTF of digital radiographic systems using an edge test device

The modulation transfer function (MTF) of radiographic systems is frequently evaluated by measuring the system's line spread function (LSF) using narrow slits. The slit method requires precise fabrication and alignment of a slit and high radiation exposure. An alternative method for determining the MTF uses a sharp, attenuating edge device. We have constructed an edge device from a 250-microm-thick lead foil laminated between two thin slabs of acrylic. The device is placed near the detector and aligned with the aid of a laser beam and a holder such that a polished edge is parallel to the x-ray beam. A digital image of the edge is processed to obtain the presampled MTF. The image processing includes automated determination of the edge angle, reprojection, sub-binning, smoothing of the edge spread function (ESF), and spectral estimation. This edge method has been compared to the slit method using measurements on standard and high-resolution imaging plates of a digital storage phosphor (DSP) radiography system. The experimental results for both methods agree with a mean MTF difference of 0.008. The edge method provides a convenient measurement of the presampled MTF for digital radiographic systems with good response at low frequencies.     

High-resolution digital retroillumination imaging of the posterior -004 capsule after cataract surgery

PURPOSE: To develop a system for high-resolution imaging of the posterior lens capsule after intraocular lens surgery for objective assessment of posterior capsule opacification (PCO). SETTING: Department of Cataract and Refractive Surgery, St. Thomas' Hospital, London, United Kingdom. METHODS: A system was developed that uses coaxial illumination and imaging based on Zeiss components with a digital camera directly linked to a computer for online image verification and image analysis. RESULTS: The system produced high-resolution digital images with even background illumination of sufficient quality to demonstrate progressive lens epithelial cell changes that are amenable to computer image analysis. CONCLUSION: This system produced excellent images for objective documentation and quantitative measurement of PCO.     

基于LED光源的热轧带钢表面质量在线检测系统的开发与应用

针对热轧带钢表面缺陷检测需求,采用机器视觉技术自主开发了热轧带钢表面检测系统。该系统采用高速线阵CCD摄像机获取高质量的带钢图像,配以自主研发的超高亮度LED光源,解决了高温带钢成像中远距离均匀照明的问题。系统中采用高效的图像处理和目标识别算法,保证了实时处理图像并准确识别表面缺陷种类。上线8个多月的运行结果证明：系统具有良好的缺陷检出与分类准确率,兼具实时性和可靠性。     

Internal eliminated sequences interrupting the Oxytricha 81 locus: allelic divergence, conservation, conversions, and possible transposon origins

Internal eliminated sequences (IESs) often interrupt ciliate genes in the silent germline nucleus but are exactly excised and eliminated from the developing somatic nucleus from which genes are then expressed. Some long IESs are transposons, supporting the hypothesis that short IESs are ancient transposon relics. In light of that hypothesis and to explore the evolutionary history of a collection of IESs, we have compared various alleles of a particular locus (the 81 locus) of the ciliated protozoa Oxytricha trifallax and O. fallax. Three short IESs that interrupt two genes of the locus are found in alleles from both species, and thus must be relatively ancient, consistent with the hypothesis that short IESs are transposon relics. In contrast, TBE1 transposon interruptions of the locus are allele-specific and probably the results of recent transpositions. These IESs (and the TBE1s) are precisely excised from the DNA of the developing somatic macronucleus. Each IES interrupts a highly conserved sequence. A few nucleotides at the ends of each IES are also conserved, suggesting that they interact critically with IES excision machinery. However, most IES nucleotide positions have evolved at high rates, showing little or no selective constraint for function. Nonetheless, the length of each IES has been maintained (+/- 3 bp). While one IES is approximately 33 bp long, three other IESs have very similar sizes, approximately 70 bp long. Two IESs are surrounded by direct repeats of the sequence TTCTT. No other sequence similarities were found between any of the four IESs. However, the ends of one IES do match the inverted terminal repeat consensus sequence of the "TA" IESs of Paramecium. Three O. trifallax alleles appear to have been recipients in recent conversion events that could have been provoked by double-strand breaks associated with IES ends subsequent to IES transposition. Our findings support the hypothesis that short IESs evolved from ancient transposons that have lost most of their sequences, except those necessary for precise excision during macronuclear development.     

棒材连续切分轧制计算机辅助孔型设计

基于金属塑性变形基本理论,以棒材切分轧制为研究对象,结合生产实践进行了深入的理论研究,在轧制领域开发了棒材切分轧制的计算机辅助孔型设计(computer aid roll-pass design)系统.综合运用了切分轧制的工艺及理论和计算机辅助孔型设计思想,结合Visual Basic 6.0的面向对象技术及数据库功能和AutoCAD成熟的图形处理功能,使开发的CARD系统具有较高的智能化程度和实用性.     

Reduction of scatter in diagnostic radiology by means of a scanning multiple slit assembly

Evidence is presented that an array of long, narrow beam-defining slits scanning a patient coupled with scatter-eliminating slots beneath the patient will substantially reduce scatter in diagnostic radiology. Scatter/primary ratios and the distribution of scatter in the plane of the image detector have been measured as a function of slit width and slot depth for a long, narrow beam-defining geometry. Using these data, calculations for the scatter/primary ratio incident on the image detector are made for a multiple slit assembly and compared with conventional grids. An improvement in contrast is obtained with little or no increase in patient exposure. Design considerations for the construction of such an array and data trends are discussed.     

Effects of lamotrigine and conventional antiepileptic drugs on amygdala- and hippocampal-kindled seizures in rats

A computer aided monitor-data processing system (CAMP-System) was developed in order to get a consistent and comprehensive database which can very precisely reflect intra-operative haemodynamic courses. The goal of the present study was to introduce a new method to scan and to gauge haemodynamic courses and to demonstrate its superiority over the traditional way of data processing based on a handwritten anaesthesia protocol. METHODS: The computerized system was applied to a study which was designed to investigate the influence of ketanserin (K) vs. urapidil (U) on haemodynamic stability during cardiac operations. Twenty male patients scheduled for myocardial revascularization received either 20 mg K or 30 mg U. Heart rate, central venous, arterial and pulmonary artery pressures were measured and on-line recorded every 20 seconds by the computer record system. In the handwritten protocol these variables were registered at eight pre-defined time points. Computerized data processing (including artifact depletion and data condensation) was compared to the results evaluated from the handwritten protocol. RESULTS: While the only significant differences in the handwritten protocol were slightly higher values of pulmonary artery pressures in group K, the computer analysis revealed a number of further differences. Higher maximum and a less stable time course of HR in group K in the pre-bypass phase and lower mean and standard deviation of MAP during cardiopulmonary bypass. CONCLUSION: Computerized data processing including automatic artifact suppression and data condensation was able to reveal differences in the course of haemodynamic variables that cannot be detected in a conventional handwritten protocol.     

长图记录的数字图象识别与拼接

本文提出了一种基于数字图象处理和模式识别技术的方法，用于对无数值显示的长图记录曲线的数据提取、自动识别、区分每日记载，并直接形成月报表输出。     

A method for 3D reconstruction of neuronal processes using semithin serial sections displayed as a cinematographic sequence

In order to study the organization and distribution of dendrites and axons in the cerebral cortex, we have developed a computer-assisted method for 3D reconstruction of neuronal processes based on serial light microscopic images displayed as a continuous sequence. A series of tangential sections (0.65 micron thick) through rat parietal cortex was aligned, digitized into the computer and then used to build a sequence (stack) of images which was stored to a digital real-time video disk. Apical dendrites located in dendritic bundles in laminae III and IV were traced through the sequence. Two tracing modes were tested: (1) cinematographic mode, in which the image stack was displayed continuously and automatically by the computer at various preset speeds (max. speed: 25 images/s) and (2) stepping mode, in which the interval between each image was varied manually according to the choice of the operator. Coordinates were stored in a database and used to build a 3D reconstruction where apical dendrites were displayed as wires or tubes. Tracing in cinematographic mode was about 3 times faster than tracing in stepping mode. We believe that the former mode exploits the built in 'filtering' capacity of the visual system to perform temporal averaging.     

LAP-1 cold preservation solution for isolation of high-quality human pancreatic islets

The purpose of this study was to determine the precision of proprioceptive localization of the hand in humans. We derived spatial probability distributions which describe the precision of localization on the basis of three different sources of information: proprioceptive information about the left hand, proprioceptive information about the right hand, and visual information. In the experiment subjects were seated at a table and had to perform three different position-matching tasks. In each task, the position of a target and the position of an indicator were available in a different combination of two of these three sources of information. From the spatial distributions of indicated positions in these three conditions, we derived spatial probability distributions for proprioceptive localization of the two hands and for visual localization. For proprioception we found that localization in the radial direction with respect to the shoulder is more precise than localization in the azimuthal direction. The distributions for proprioceptive localization also suggest that hand positions closer to the shoulder are localized more precisely than positions further away. These patterns can be understood from the geometry of the arm. In addition, the variability in the indicated positions suggests that the shoulder and elbow angles are known to the central nervous system with a precision of 0.6-1.1 degrees. This is a considerably better precision than the values reported in studies on perception of these angles. This implies that joint angles, or quantities equivalent to them, are represented in the central nervous system more precisely than they are consciously perceived. For visual localization we found that localization in the azimuthal direction with respect to the cyclopean eye is more precise than localization in the radial direction. The precision of the perception of visual direction is of the order of 0.2-0.6 degrees.     

Responses of complex cells in the visual cortex of the cat as a function of the length of moving slits

(1) As a step towards specifying the spatial selectivity characteristics of complex cells with spatially periodic substructures, we have studied single cell responses to narrow slits of variable length moved across the receptive field in the preferred direction. In general, the length-response curves were linear over a considerable and sometimes full range until an optimal slit length was reached. (2) In those cells in which the rate of rise of the slit length-response functions decreased before the optimal length was reached, at least 3 factors contribute to the shape of the curve. First, the receptive field shapes of some complex cells are more ovoid or rounded than rectangular, and the summation of responses from excitatory zones of varying optimal lengths itself results in a nonlinear slit length-response function at long slit lengths. Second, central regions may contribute more to cell response than do more lateral regions along the length dimension. Third, a nonlinearity in the slit length-response curve may occur in the upper range of slit lengths as a saturation effect because discharge rates may reach 600/sec, which appears to be close to a limiting firing rate. (3) Some cells believed to be complex during preliminary receptive field testing showed weak inhibitory regions beyond the region of the optimal slit length. Many of these cells also displayed periodic average response histograms to moving slits. The extent and magnitude of the inhibition were variable from cell to cell. In terms of receptive field properties, these cells and 'regular' complex cells seem part of a continuum.     

An improved electronic pantograph

A device was developed to permit simultaneous observations of a microscopic field, under any light optic conditions, and permanent recording of the relative X-Y coordinates of the center of the field. A modification is described that allows gray scale values to be assigned to the plots. The system can be readily adapted to digital computer data entry.     

Low-cost system for real-time monitoring of luciferase gene expression

In some mammalian cells transfected with luciferase reporter genes, the luciferase/luciferin reaction in a cell monolayer produces a very small light flux. While the low light levels are often measurable with single-photon counting cameras, these devices are expensive and may require long averaging times to acquire an image. We describe an approach for real-time monitoring of light produced by luciferase gene expression in intact, cultured cells using readily available and relatively inexpensive components. The system uses a single-photon counting photomultiplier tube with built-in high voltage supply and photon counting circuitry to rapidly measure average light output from growing cells in a 35 mm culture dish. The fast, accurate and highly sensitive response of the system makes it useful for studying the dynamics of gene expression over time periods ranging from minutes to days.     

The teaching of computer programming and digital image processing in radiography

The increased use of digital processing techniques in Medical Radiations imaging modalities, along with the rapid advance in information technology has resulted in a significant change in the delivery of radiographic teaching programs. This paper details a methodology used to concurrently educate radiographers in both computer programming and image processing. The students learn to program in visual basic applications (VBA), and the programming skills are contextualised by requiring the students to write a digital subtraction angiography (DSA) package. Program code generation and image presentation interface is undertaken by the spreadsheet Microsoft Excel. The user-friendly nature of this common interface enables all students to readily begin program creation. The teaching of programming and image processing skills by this method may be readily generalised to other vocational fields where digital image manipulation is a professional requirement.     

Determining the imaging quality of intraocular lenses

This paper describes research work motivated by an innovative medical application: computer-assisted transbronchial biopsy. This project involves the registration, with no external localization device, of a preoperative three-dimensional (3-D) computed tomography (CT) scan of the thoracic cavity (showing a tumor that requires a needle biopsy), and an intraoperative endoscopic two-dimensional (2-D) image sequence, in order to provide assistance in transbronchial puncture of the tumor. Because of the specific difficulties resulting from the data being processed, a multilevel strategy was introduced. For each analysis level, the relevant information to process and the corresponding algorithms were defined. This multilevel strategy, thus, provides the best possible accuracy. Original image processing methods were elaborated, dealing with segmentation, registration and 3-D reconstruction of the bronchoscopic images. In particular, these methods involve adapted mathematical morphology tools, a "daemon-based" registration algorithm, and a model-based shape-from-shading algorithm. This pilot study presents the application of these algorithms to recorded bronchoscopic video sequences for five patients. The preliminary results presented here demonstrate that it is possible to precisely localize the endoscopic camera within the CT data coordinate system. The computer can thus synthesize in near real-time the CT-derived virtual view that corresponds to the actual endoscopic view.     

喷吹站的计算机控制应用

文章叙述了原高炉喷吹站长期人工操作。继电控制方式能耗大、控制精度低、故障率高、维护困难、系统改动困难。计算机可以实现精确的程序控制。包钢炼铁厂采用了美国HONEYWELL公司的TPS控制系统,由于它具有冗余系统,系统安全稳定,功能方便强大,大大的提高了生产率,降低了成本,减轻了劳动强度。     

Replication of semliki forest virus: polyadenylate in plus-strand RNA and polyuridylate in minus-strand RNA

The 42S RNA from Semliki Forest virus contains a polyadenylate [poly(A)] sequence that is 80 to 90 residues long and is the 3'-terminus of the virion RNA. A poly(A) sequence of the same length was found in the plus strand of the replicative forms (RFs) and replicative intermediates (RIs) isolated 2 h after infection. In addition, both RFs and RIs contained a polyuridylate [poly(U)] sequence. No poly(U) was found in virion RNA, and thus the poly(U) sequence is in minus-strand RNA. The poly(U) from RFs was on the average 60 residues long, whereas that isolated from the RIs was 80 residues long. Poly(U) sequences isolated from RFs and RIs by digestion with RNase T1 contained 5'-phosphorylated pUp and ppUp residues, indicating that the poly(U) sequence was the 5'-terminus of the minus-strand RNA. The poly(U) sequence in RFs or RIs was free to bind to poly(A)-Sepharose only after denaturation of the RNAs, indicating that the poly(U) was hydrogen bonded to the poly(A) at the 3'-terminus of the plus-strand RNA in these molecules. When treated with 0.02 mug of RNase A per ml, both RFs and RIs yielded the same distribution of the three cores, RFI, RFII, and RFIII. The minus-strand RNA of both RFI and RFIII contained a poly(U) sequence. That from RFII did not. It is known that RFI is the double-stranded form of the 42S plus-strand RNA and that RFIII is the experimetnally derived double-stranded form of 26S mRNA. The poly(A) sequences in each are most likely transcribed directly from the poly(U) at the 5'-end of the 42S minus-strand RNA. The 26S mRNA thus represents the nucleotide sequence in that one-third of the 42S plus-strand RNA that includes its 3'-terminus.     

Patterns of neuropsychological impairment in mild dementia: a comparison between Alzheimer''s disease and multi-infarct dementia

Left ventricular wall motion abnormalities secondary to stress-induced myocardial ischemia can be detected with difficulty by mentally comparing echocardiographic images sequentially recorded on videotape. Digital stress-echocardiography, a combination of ultrasound imaging and digital archiving technologies, at least partially can overcome this problem: the technique is based on reviewing images at rest and after stress (exercise or pharmacological) side by side in dual- or quad-screen digital format, in a synchronized cine-loop, as if obtained simultaneously. This technique however is presently not widely used, due to the high cost of most commercially available systems. We have developed a digital stress-echo system, which is easy to use and relatively inexpensive, running on a Macintosh II personal computer with 8-bit graphics. The 2-D echocardiographic images recorded on videotape are digitized offline using a video digitizing board. The image can be displayed and analyzed using the public domain NIH image software developed by Wayne Rasband, without loss in image quality and resolution, particularly if using Super-VHS videotape. We have made a macro procedure for the montage in a quad-screen format of four digital recorded echocardiographic cardiac cycles of six frames that takes only a little more time than commercially available systems. In conclusion, the use of a personal computer and low-cost software may help to make digital stress-echo techniques more widely feasible in the clinical setting and increase the diagnostic power of the ultrasound technique in the evaluation of patients with known or suspected coronary artery disease.     

铁基合金中钛元素可见光谱分析技术

使用看谱镜计算机自动分析系统研究了铁基合金中钛元素看谱分析用可见光谱,模拟了Fe和Ti元素的可见光谱图,制作了数字化彩色图谱.研究了铁基合金中Ti元素的Ti499.95 nm、Ti551.25 nm和Ti489.99 nm等分析谱线组的特征,给出了分析用谱图和半定量分析用强度标志.研究了铁基合金中Ti元素的看谱分析方法.结果可用于铁基合金中Ti元素的定性分析、半定量分析和牌号鉴别.