Reproducible estimation of retinal vessel width by computerized microdensitometry

An objective method for reliably estimating the width of retinal vessels is presented. A computerized microdensitometer scans film negatives of fundus photographs and reconstructs black and white images of the fundus on a visual display terminal. After this initial scan, a desired region of a retinal vessel is selected with moveable cursors, and a cross-sectional density profile through the vessel is plotted. Vessel width is determined by the half-height width of the profile of the minimum (least transmitting) and average background film densities. Measurement sites can be accurately reproduced on different negatives by landmark mapping. A series of ten fundus photographs were taken of three healthy human eyes, and the width of the superior temporal vein was measured in two places on alle negatives. The coefficient of variation of the six sets ranged from 1.2 and 3.4% with an average of 2.2%.     

Postshock Potential Gradients and Dispersion of Repolarization in Cells Stimulated with Monophasic and Biphasic Waveforms

Effects of Monophasic and Biphasic Stimuli. Introduction: Even though the clinical advantage of biphasic defibrillation waveforms is well documented, the mechanisms that underlie this greater efficacy remain incompletely understood. It is established, though, that the response of relatively refractory cells to the shock is important in determining defibrillation success or failure. We used two computer models of an isolated ventricular cell to test the hypothesis that biphasic stimuli cause a more uniform response than the equivalent monophasic shocks, decreasing the likelihood that fibrillation will be reinduced. Methods and Results: Models of reciprocally polarized and uniformly polarized cells were used. Rapid pacing and elevated [K]_o were simulated, and either 10-nisec rectangular monophasic or 5-msec/5-msec symmetric biphasic stimuli were delivered in the relative refractory period. The effects of stimulus intensity and coupling interval on response duration and postshock transmembrane potential (V_m) were quantified for each waveform. With reciprocal polarization, biphasic stimuli caused a more uniform response than monophasic stimuli, resulting in fewer large gradients of V_m (only for shock strengths ≤ 1.25× threshold vs ≤ 2.125× threshold) and a smaller dispersion of repolarization (1611 msec² vs 1835 msec²). The reverse was observed with uniform polarization: monophasic pulses caused a more uniform response than did biphasic stimuli. Conclusion: These results show that the response of relatively refractory cardiac cells to biphasic stimuli is less dependent on the coupling interval and stimulus strength than the response to monophasic stimuli under conditions of reciprocal polarization. Because this may lead to fewer and smaller spatial gradients in V_m, these data support the hypothesis that biphasic defibrillation waveforms will be less likely to reinduce fibrillation. Further, published experimental results correlate to a greater degree with conditions of reciprocal polarization than of uniform polarization, providing indirect evidence that interactions between depolarized and hyper polarized regions play a role in determining the effects of defibrillation shocks on cardiac tissue.     

保健电脑软件的临床运用评价

通过保健电脑软件对424名儿童体格发育的单项及多项式评价显示:正常组各指标Z分值均在0±2之间,Ⅱ度以上营养不良及肥胖比值有差异。Kaup指数与年龄之间有转折趋势。Funcohi指数对身材高矮评价简便实用。身高标准体重值对营养评价特异性高。体成分营养评价有性别差异。瘦体重(LBM):男>女;体脂(F):女>男。营养不良LBM比例增高,肥胖者F比例明显增高。该软件从不同角度反映儿童近、远期营养状况,有客观与综合的实用价值。     

微机在医院药库管理中的应用

本文介绍自行开发的微机药库管理系统软件的设计目标、设计要点、应用体会。该系统的运行实现了手工难以完成的“药品批号管理”和“药品有效期管理”，并最终可达到甩掉手工帐本的目的。     

A computer-controlled anaesthetic gas mixer

The theory and construction of a prototype computer-controlled gas mixer and flow regulator are described. The device is capable of controlling and mixing flows of oxygen, nitrous oxide and air. The accuracy and repeatability of the device is very high under given conditions, and its performance is quantified. The flow rate and oxygen concentration are selected from a microcomputer and the control program is written in BASIC. Possible improvements to the system are discussed as are uses in both clinical and research work.     

Computer programs to obtain HPLC parameters of β-lactam antibiotics

Listings of BASIC and TI-59 programs are included to obtain the HPLC retention factors for β-lactam antibiotics at given antibiotic pK's, pH, and capacity factor values, which are useful in considering the different chromatographic behaviour of antibiotics as the pH varies     

Pocket computer program for fitting the Hill equation

This paper presents a program written in the BASIC language for the Radio Shack TRS-80 PC-1 or the Sharp PC 1211 pocket computers for fitting the Hill equation to experimental data. The program is based on a procedure involving a combination of an optimization technique and non-linear regression. The program determines precisely all three parameters of the Hill equation and in addition, it performs a simulation of the kinetic experiment using the parameter values previously estimated, calculating the sum of squares of residuals.     

Utility of the Randomization Test and Importance of Nonstatis-tical Inference in Experimental Teratology

The implausibility of random sampling assumption in experimental teratology is pointed out. It is emphasized that nonstatistical inference remains a standard scientific approach, in spite of widespread use of many statistical tests. The randomization test can be introduced to experimental teratologjsts as an alternative to conventional statistical procedures for nonrandom sampling data. A program list for the randomization test written in BASIC for microcompter is given.