问：测量人体动脉血压时，是在柯氏音突然变调时，或是在柯氏音消失时选取舒张庄份值？

问：测量人体动脉血压时，是在柯氏音突然变调时，或是在柯氏音消失时选取舒张庄份值？答：自１９０５年柯罗特科夫创立听诊法间接测量人体动脉血压技术以来，其舒张压的读取是在柯氏音突然变调时或是在柯氏音消失时，一直争论不休。一般来说，柯氏音可夕了高调的敲击音和...     

无创式振动法血压仪测量原理及其影响测量精度的因素

自Cushing首次在外科手术中监测血压后,血压已成为危重病人和手术病人监护中的一个重要指标。据报道世界上大约有30万台血压监护仪在手术室和CCU病房中发挥作用,其中绝大多数是振动法(Oscillometrjc Method)血压监护仪,另一部分为柯氏音法或超声法血压监护仪。振动法与柯氏音法一样也需要气袖阻断动脉血流,但放气过程     

鱼类耳石微结构的计算机自动识别

本文介绍了鱼类耳石微结构图像识别系统的工作原理和应用实例 ,该系统实现了对鱼类的耳石日轮的自动识别计数和测量日轮宽度 ,并将分析结果自动保存为Excel可识别格式的数据文件。用草鱼微耳石对该系统进行测试的结果表明 ,在随机抽取的 30个样本中 ,有 2 8个样本日轮自动识别的正确率为 1 0 0 % ,其余 2个样本经过手工修改后也能达到对日轮的完全识别。此外 ,采用 768× 5 82像素的BMP格式数字图像测量日轮宽度 ,计算机的分辨率比显微镜提高了约 1 3倍。该系统还可应用于鱼类的鳞片、胸鳍棘和脊椎骨等年龄鉴定材料的微结构分析     

柯氏鼠兔的食性分析

柯氏鼠兔(Ochotona koslowi)是兔形目(Lagomorpha)鼠兔属中最古老的遗留种,也是稀有的濒危物种,自1894年命名以来,国内外对该物种的生存现状、生物学特征知之甚少.2007年10~11月,在藏北地区捕获到13只柯氏鼠兔,通过显微组织分析法对其胃及结肠内容物和收集的60份粪样进行了食性分析.结果表明,柯氏鼠兔胃、结肠内容物和粪便中镜检到可识别植物碎片属6科15种,其中豆科植物碎片占可识别植物碎片的39.44%,藜科植物碎片占36.00%,莎草科植物碎片占16.42%,禾本科、十字花科和菊科植物碎片分别占3.75%、2.67%和1.25%.食性分析表明,柯氏鼠兔偏爱豆科植物.     

基于通量塔净生态系统碳交换数据的植被物候遥感识别方法评价

选择北美洲72座通量塔观测的净生态系统碳交换（NEE）数据来计算植被物候,并以此作为参考数据,从可行性和准确性两方面对阈值法、移动平均法和函数拟合法三大类常用的植被物候遥感识别方法进行了综合评价.结果表明： 基于局部中值的阈值法对植被物候识别的可行性和准确性均最优;其次为Logistic函数拟合法中的一阶导数方法;移动平均法对植被物候识别的可行性和准确性与移动窗口的大小有关,对于16 d合成的归一化差值植被指数（NDVI）时间序列数据来说,移动窗口大小为15时能获得较优的结果;而全局阈值法对植被物候识别的可行性和准确性均最差;Logistic函数拟合法中的曲率变化率方法在识别植被物候时虽然与基于NEE数据得到的植被物候在数值上存在较大偏差,但二者之间具有较高的相关性,说明基于曲率变化率方法识别出的植被物候能较真实地反映植被物候在时空上的变化趋势.     

基于通量塔净生态系统碳交换数据的植被物候遥感识别方法评价

选择北美洲72座通量塔观测的净生态系统碳交换（NEE）数据来计算植被物候,并以此作为参考数据,从可行性和准确性两方面对阈值法、移动平均法和函数拟合法三大类常用的植被物候遥感识别方法进行了综合评价.结果表明： 基于局部中值的阈值法对植被物候识别的可行性和准确性均最优;其次为Logistic函数拟合法中的一阶导数方法;移动平均法对植被物候识别的可行性和准确性与移动窗口的大小有关,对于16 d合成的归一化差值植被指数（NDVI）时间序列数据来说,移动窗口大小为15时能获得较优的结果;而全局阈值法对植被物候识别的可行性和准确性均最差;Logistic函数拟合法中的曲率变化率方法在识别植被物候时虽然与基于NEE数据得到的植被物候在数值上存在较大偏差,但二者之间具有较高的相关性,说明基于曲率变化率方法识别出的植被物候能较真实地反映植被物候在时空上的变化趋势.     

梨小食心虫自动监测识别计数系统研制

针对果园梨小食心虫监测中存在的人工计数调查费力且欠准确的问题,本研究设计了一种基于性诱的害虫自动监测装置,通过构建配套的图像处理系统实现了害虫自动识别计数。应用诱芯与粘虫板相结合进行害虫诱捕;机器视觉定时采集粘虫板图像;基于Visual C#与Matlab混合编程,构建害虫自动识别计数系统。并在桃园应用研制的性诱害虫自动监测系统对梨小食心虫监测结果进行比较。结果显示:自动监测装置的平均诱捕率为89. 58%;梨小食心虫平均识别准确率为94. 11%。表明该自动监测系统的害虫诱捕率和识别准确率均高,提高了害虫监测识别的效率,在害虫监测中具有广阔的应用前景。     

比重法定量局部脑组织含水量方法的改良

目的：在保证比重法测量脑组织含水量准确性的基础上,改良其测量方法。方法：观察使用密度计建立的液体比重柱的稳定性和梯度均匀性;比较低温脑组织采集法与冷冻法对比重法测定脑组织含水量的影响。结果：采用密度计制备的液体比重柱的稳定性和梯度均匀性提高;低温脑组织直接采集法减少比重法测量脑组织含水量的系统误差。结论：采用密度计和低温直接标本采集法不仅提高比重法测定脑组织含水量的准确性,且简化实验步骤。     

利用Rayleigh模型和B—snake自动提取冠脉内超声图像管腔轮廓

提出了一种自动提取冠状动脉内超声图像管腔轮廓的方法。首先根据冠状动脉内B型超声图像灰度呈Rayleigh分布的特点计算得到轮廓的初始曲线,然后通过B-snake方法检测管壁的最优轮廓。结果表明:与传统GVFsnake方法相比,采用该方法得到的轮廓在平滑性和准确性方面有提高。     

水的饱和辛醇溶液水分标准物质的研制

生物燃料的国家标准规定了产品的技术指标和相应的检测方法。水的饱和辛醇溶液的水分标准物质,用于生物燃料水分测量时仪器的校准和方法的验证,能够保障测量结果的准确可靠和等效一致。该标准物质采用卡尔·费休库仑法、卡尔·费休容量法和定量核磁共振等三种不同原理的方法定值。通过方法研究和改进,实现了库仑法和容量法的一致;通过引入新的核磁共振方法,提高了结果的准确性。最终标准物质的水分量值为4.76％,扩展不确定度为0.09％。     

Auscultatory Blood Pressure Measurement—Effect of Pressure on the Head of the Stethoscope

Excessive pressure on the stethoscope head in auscultatory blood pressure measurement does not affect systolic blood pressure value but it does erroneously lower diastolic readings and frequently causes the sounds to persist to zero. Consequently, the lightest possible pressure should be placed on the stethoscope head.     

Comparative accuracy of two new electronic devices for the noninvasive determination of blood pressure

Recent developments in behavioral approaches to cardiovascular disease have called for physiological monitoring devices that reduce experimenter bias, are easy to operate, can be used ambulatorily, and/or provide ongoing, automated monitoring of pertinent cardiovascular functions--i.e., blood pressure and heart rate. Neither the invasive monitoring (via catheterization) nor the standard auscultatory method of blood pressure determination, however, has these characteristics. In the present study, two new methods/devices--(1) a low-weight, low-cost, battery-operated sphygmomanometer (SM), and (2) a more expensive automated electronic SM with electrical pump-are compared with each other and with the more common auscultatory method and a standard mercury SM. Both new devices were also compared with a standard pulse count. Data were derived from 10 readings of 10 healthy subjects each across the three possible comparisons, thus totaling N = 30. Correlation coefficients and average differences were computed and indicated high intercorrelations (between r = .89 and r = .99) between each pairing of the new electronic devices and the mercury SM. Intercorrelations of blood pressure determination with the two new electronic devices, however, were only moderate. Potential reasons for the variability are discussed, and guidelines for the optimal use of the new, easy-to-operate electronic devices are presented.     

Comparative accuracy of two new electronic devices for the noninvasive determination of blood pressure

Recent developments in behavioral approaches to cardiovascular disease have called for physiological monitoring devices that reduce experimenter bias, are easy to operate, can be used ambulatorily, and/or provide ongoing, automated monitoring of pertinent cardiovascular functions—i.e., blood pressure and heart rate. Neither the invasive monitoring (via catheterization) nor the standard auscultatory method of blood pressure determination, however, has these characteristics. In the present study, two new methods/devices — (1) a low-weight, low-cost, battery-operated sphygmomanometer (SM), and (2) a more expensive automated electronic SM with electrical pump — are compared with each other and with the more common auscultatory method and a standard mercury SM. Both new devices were also compared with a standard pulse count. Data were derived from 10 readings of 10 healthy subjects each across the three possible comparisons, thus totalingN=30. Correlation coefficients and average differences were computed and indicated high intercorrelations (betweenr=.89 andr=.99) between each pairing of the new electronic devices and the mercury SM. Intercorrelations of blood pressure determination with the two new electronic devices, however, were only moderate. Potential reasons for the variability are discussed, and guidelines for the optimal use of the new, easy-to-operate electronic devices are presented.     

Numerical simulation of noninvasive blood pressure measurement

In this paper, a simulation model based on the partially pressurized collapsible tube model for reproducing noninvasive blood pressure measurement is presented. The model consists of a collapsible tube, which models the pressurized part of the artery, rigid pipes connected to the collapsible tube, which model proximal and distal region far from the pressurized part, and the Windkessel model, which represents the capacitance and the resistance of the distal part of the circulation. The blood flow is simplified to a one-dimensional system. Collapse and expansion of the tube is represented by the change in the cross-sectional area of the tube considering the force balance acting on the tube membrane in the direction normal to the tube axis. They are solved using the Runge-Kutta method. This simple model can easily reproduce the oscillation of inner fluid and corresponding tube collapse typical for the Korotkoff sounds generated by the cuff pressure. The numerical result is compared with the experiment and shows good agreement.     

Noninvasive, automatic 24-h ambulatory blood pressure monitoring in normotensive subjects

The reliability of noninvasive, automatic blood pressure monitoring is not yet clearly established. A 24-h ambulatory blood pressure profile was obtained in 9 healthy, normotensive subjects with an automatic, noninvasive device. The blood pressure profile showed the typical circadian pattern with lower systolic and diastolic values during sleep, although pulse pressure was fairly constant (about 40 mm Hg). The systolic blood pressure rose steeply in the early morning hours--before waking up. The results were compared with simultaneous hourly readings using the auscultatory method. There were no statistically significant differences between the automatic and auscultatory readings, 13 of the 18 mean values at different time points being within 2 mm Hg of each other. All the auscultatory means fell within the 95% confidence limits of those measured hourly by the automatic method. Although the automatic method seemed to be reliable compared with the auscultatory method, its sensitivity to motion artifacts is a disadvantage in a truly ambulatory setting.     

Blood pressure tracking systems and their application to biofeedback

Two automatic electronic systems for tracking diastolic or systolic blood pressure (BP) and their use in biofeedback experiments are described. Both systems are based on the use of an arm cuff and the recording of Korotkoff sounds with a microphone. An electronic control system receives input from the microphone and provides output to several solenoid valves that control compressed airflow to the cuff. For one of the tracking systems we devised, the cuff is alternately inflated for 45 sec and deflated for 45 sec. During inflation, small increments and decrements in cuff pressure, based on the occurrence of Korotkoff sounds, are used to track BP. The other tracking system is slower but provides more continuous measurements: The cuff is alternately inflated to approximately the BP level for 5 sec and then deflated for 5 sec. During each inflation, the number of Korotkoff sounds is recorded by the system and according to this number, the amount of inflation on the next trial is automatically adjusted so that the cuff pressure follows BP. Both systems have been used successfully in biofeedback applications.The authors thank Mark Goldman for helpful discussions of the techniques, and Maureen Delphia and Dianne Auty for their assistance in the preparation of this paper. This work was partially supported by a grant-in-aid from the Michigan Heart Association.     

New methodology for measuring blood pressure in awake baboons with use of behavioral training techniques

Adult male baboons were behaviorally conditioned to extend an arm outside of the living cage and to accept repeated cuff inflations for manual auscultatory blood pressure measurements. Frequency distributions of systolic and diastolic blood pressure for both normotensive and renovascular hypertensive baboons generally were normally distributed. The procedure accurately tracked rapid changes in blood pressure after oral administration of antihypertensive drugs. Advantages over direct arterial cannulation for blood pressure measurement during extended, chronic experiments are discussed.     

Accuracy of auscultatory blood pressure measurement with a long cuff.

Intra-arterial blood pressure was compared with simultaneous auscultatory measurements in 37 subjects with a wide range of blood pressures and arm circumferences; six cuffs of various lengths and widths were used. Nineteen subjects had an arm circumference of 34 cm or more (mean 40 cm) and the other 18 were considered to be non-obese and had a mean arm circumference of 30 cm. With each larger cuff, in terms of bladder surface area, auscultatory blood pressure decreased a few mm relative to intra-arterial pressure both for systolic and for diastolic measurements. Apart from diastolic pressure measured with the two 12 cm wide cuffs (12 X 23 cm, 12 X 30 cm) in the obese group all other auscultatory measurements differed less than 5% from intra-arterial pressure, albeit with considerable variability among the subjects. The differences in error among measurements with the four largest cuffs in the obese group (13 X 30 cm, 14 X 30 cm, 14 X 38 cm, and a conical cuff) were clinically irrelevant, and there was even less to choose among all six cuffs in the non-obese subjects. These results suggest that auscultatory blood pressure may be measured with acceptable accuracy with a single long bladdered cuff both in subjects with large arms and in subjects with normal sized arms.     

Observer error in blood pressure measurement.

This paper describes an experiment undertaken to determine observer error in measuring blood pressure by the auscultatory method. A microcomputer was used to display a simulated mercury manometer and play back tape-recorded Korotkoff sounds synchronized with the fall of the mercury column. Each observer''s readings were entered into the computer, which displayed a histogram of all readings taken up to that point and thus showed the variation among observers. The procedure, which could easily be adapted for use in teaching, was used to test 311 observers drawn from physicians, nurses, medical students, nursing students and others at nine health care institutions in Ottawa. The results showed a strong bias for even-digit readings and standard deviations of roughly 5 to 6 mm Hg. The standard deviation for the systolic readings was somewhat smaller for the physicians as a group than for the nurses (3.5 v. 5.9 mm Hg). However, the standard deviations for the diastolic readings were roughly equal for these two groups (approximately 5.5 mm Hg).     

Automated methods for accurate determination of the critical velocity of packed bed chromatography

Knowing the critical velocity (ucrit) of a chromatography column is an important part of process development as it allows the optimization of chromatographic flow conditions. The conventional flow step method for determining ucrit is prone to error as it depends heavily on human judgment. In this study, two automated methods for determining ucrit have been developed: the automatic flow step (AFS) method and the automatic pressure step (APS) method. In the AFS method, the column pressure drop is monitored upon application of automated incremental increases in flow velocity, whereas in the APS method the flow velocity is monitored upon application of automated incremental increases in pressure drop. The APS method emerged as the one with the higher levels of accuracy, efficiency and ease of application having the greater potential to assist defining the best operational parameters of a chromatography column.