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91.
H. Tazawa Y. Hashimoto M. Takami Y. Yufu G. C. Whittow 《Medical & biological engineering & computing》1993,31(2):129-134
Using a flexible piezoelectric film, the authors developed a simple system to determine noninvasively the heart rate of chicken
embryos and hatchlings. The film was piezoelectric polyvinylidene fluoride (PVDF), which is sensitive enough to detect cardiogenic
ballistic movements of the egg (ballistocardiogram (BCG)) and precordial movements of the hatchling attributable to cardiac
contractions (apexcardiogram (ACG)). The BCG could be detected, during the second half of incubation, by placing the egg on
the PVDF film on a soft substrate. The detected signal was found to be a measure of movement velocity. The ACG could be measured
when the hatchling's chest wall made contact with the PVDF film installed in a box in which the hatchling was confined. The
heart rate was counted from the lag time of autocorrelation calculated for a certain time segment (e.g. 2s) of the BCG and
ACG recordings. 相似文献
92.
Vvedenskaya OY Avrushchenko MA Bol'shakova TD Khitrov NK Moroz VV 《Bulletin of experimental biology and medicine》2003,135(4):337-339
Acquisition of instrumental defense response with pain reinforcement uncertainty (25% reinforcement) induced the development of acquired helplessness in 50% rats. Acquired helplessness is characterized by the absence of responses to conditioned (light) and unconditioned stimuli (pain), minor response of plasma corticosterone to learning, gas markers of circulatory cerebral hypoxia (DA/V pO2 carotid artery/jugular vein), low sensitivity to severe hypobaric conditions, and high resistance of Purkinje cells in the cerebellum. Piracetam improved learning and prevented the development of acquired helplessness. Local changes in cerebral blood flow and energy deficit in neurons responsible for emotional stress during acquired helplessness impair adaptive capacity, but reduce energy consumption and protect neuronal structures. 相似文献
93.
圆孔外面的观察和测量及其面积的回归方程 总被引:4,自引:0,他引:4
60具成人颅骨颅底外面的圆孔观察和测量结果表明:圆孔多呈圆形,其次是卵圆形,其它形较少见.据圆孔与翼突外侧板根部延长线的位置关系,分圆孔位置为三型.圆孔外面观的各项测值左右间均无统计学差异,但其中管性圆孔管长度个体差异较大.圆孔的面积左右比较对称者占3.33±2.34%,左>右者占65.51±6.30%,右>左者占34.48±6.30%.圆孔面积左右对称性比较,对临床诊断疾病有参考意义.其面积的回归方程可由其长、宽径乘积推算 . 相似文献
94.
J. H. Battocletti R. E. Halbach A. Sances Jun S. J. Larson R. L. Bowman V. Kudravcev 《Medical & biological engineering & computing》1979,17(2):183-191
A new flat crossed-coil nuclear magnetic resonance (n.m.r.) detector can be used to measure flood flow at many regions of
the body, is introduced. It is compared, bothin vitro andin vivo, with the already proven cylindrical crossed-coil n.m.r. detector. Both detectors use a single high-field homogenous magnet.
A single-sideband receiver reduces the effect of transmitter leakage into the receiver coil to allow the use of a high-level
transmitter field. Preliminary application of the flat crossed-coil detector to the detection of cerebral blood flow is presented. 相似文献
95.
Dr. S. Ichioka M. Iwasaka M. Shibata K. Harii A. Kamiya S. Ueno 《Medical & biological engineering & computing》1998,36(1):91-95
There have been few studies of the effect of static magnetic fields on microcirculatory haemodynamics in vivo. The rat skinfold
transparent chamber technique was used, which provides an excellent means of observing and quantifying direct in vivo microvascular
haemodynamic responses to static magnetic fields up to 8 T. An intravital videomicroscope was used to measure the changes
in blood flow before and after exposure to a magnetic field for 20 min in a horizontal type superconducting magnet with a
bore 100 mm in diameter and 700 mm long. After exposure, microcirculatory blood flow showed an initial increase for about
5 min followed by a gradual decrease and a return to the control value. It is hypothesised that these changes represent rebound
hyperaemia following reduced blood flow during exposure. 相似文献
96.
红外多波长无创人体血糖检测阵列模型的研究 总被引:2,自引:0,他引:2
无创血糖监测不仅可以减少患者的痛苦,还能进行连续测量,从而降低并发症的发生,它是一种不需收集血样进行体内血糖浓度测量的新技术。本文根据朗伯-比尔定律(The Lambert—Beer Law)原理,为克服无创血糖检测研究中的难点和缺陷,详细分析了血糖红外光谱的吸收特性,利用阵列技术设计了红外多波长无创血糖检测传感器阵列模型,对关键技术进行了讨论。用ME算法建立了信号检测和标定数学模型,结合了人体各种影响因素,使红外无创血糖检测的精度和稳定性得到了改善。列举了详细的实验实施步骤,同时叙述了系统调试的详细过程,讨论了无创血糖检测中需要注意的问题。 相似文献
97.
O'Goiman's (1979) criticisms of the orienting response (OR) significance hypothesis are not well-founded. The hypothesis is not based solely on electrodermal data—studies reporting significance effects for heart rate and pupillary OR are cited. The hypothesis does not discard novelty but suggests that an interaction between uncertainty and significance triggers OR. Differential reactivity across OR components reflects stimulus- and individual-response factors, and does not require separate “significance registers.” Since the hypothesis specifically maintains that appraisals of stimulus significance affect the OR, not the mere fact of cognitive appraisal per se, no general “cognitive appraisal effect” was ever expected. O'Gorman confuses the difficulty of estimating the subject's spontaneous judgments of significance with the relative ease of manipulating significance in the laboratory. He considers classic OR theory more “objective” only because he fails to look closely enough at the complex judgmental processes involved in stimulus intake, model building, and matching functions. O'Gorman's contentions of different initial- and test-ORs, and of a simple additive relationship between significance and OR, lack supportive data and are challenged by available evidence. Literature is cited suggesting that: a) scanning is continuously biased toward the detection of significant stimuli; b) detection of a sgnificant stimulus feature triggers increased information scanning, increasing the possibility that previously unrecognized uncertainty will be detected, and c) lowers the criterion level of the OR “threshold,” increasing the likelihood of OR if uncertainty is detected. Evidence is cited suggesting that the significance-OR, and perhaps attention in general, is mediated by neocortical-limbic interaction, the limbic' “motivational” evaluator of stimulus input steering and switching neocortical “intellectual” analyzers of stimulus pattern. 相似文献
98.
Studies from the last decade on factors influencing reproductive planning after genetic counselling were reviewed. Increased possibilities of DNA-analysis and prenatal diagnosis might have brought about a shift in the paramountcy of factors influencing reproductive planning after genetic counselling. In contrast to the literature in the seventies, the magnitude of the genetic risk was no longer found to be one of the decisive factors in postcounselling reproductive planning. Instead, the interpretation of the risk as high or low and the desire to have children appeared to be paramount. The impact of new developments in DNA-analysis in prenatal diagnosis and presymptomatic testing will be an important subject for future studies on factors influencing reproductive planning. 相似文献
99.
Background
As assessment with inertial-measurement-units (IMUs) increases in research and in clinics, it is important to be aware of the repeatability of these sensors. The objectives of this experiment were to evaluate the measurement repeatability of IMU joint angles using a repeatable robot controller and an anthropomorphic leg phantom and to determine effects of joint speed and sensor positioning on the angles collected by these sensors. Comparisons to an electro-goniometer and three-dimensional (3D) motion capture cameras were also completed.Methods
Two dual-IMU setups (posterior and lateral) were tested concurrently with an electro-goniometer and 3D motion capture cameras using a repeatable robot controller and a leg phantom. All modalities were attached to the phantom, which was flexed 10 times using a pre-programmed motion pathway during each test. Mean angles were compared across tests. Effects of joint speed, sensor re-positioning, and anatomical placement of the sensors on repeatability were assessed.Results
Re-positioning caused greater deviation to the maximum and minimum angles than differences in speed. Overall, the means?±?standard deviations, and 95% confidence intervals of the maximum angles across all tests for the 3D camera markers, electro-goniometer, posterior IMUs, and lateral IMUs were 119.4?±?0.3° (119.4, 119.5), 112.4?±?0.5° (112.3, 112.5), 116.2?±?2.4° (115.7, 116.7), and 118.3?±?1.1° (118.1, 118.6).Conclusions
Both posterior and lateral IMU setups demonstrated acceptable repeatability in measurement of range of motion that was advantageous to manual goniometer methods. Posterior and lateral IMU setups demonstrated overlapping standard deviations about their means. 相似文献100.
本文研制的袖套式数字血压计,基于示波法原理,通过采用多通道、多气阀以及软件上的改进,改善了目前一般数字血压计的不足,与一般袖套式数字血压计相比,具有重复性好、测量范围大(成人和儿童都可测量)等优点。 相似文献