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71.
乳房体积生物立体测量系统的研制 总被引:7,自引:1,他引:6
目的 利用立体视觉方法建立乳房体积测量系统 ,并探讨其准确性和精确程度。方法 通过采用两台CCD摄相机从两个不同视角观察乳房模型 ,运用激光投射仪和光栅获得计算机能识别的平行采样点 ,依靠计算机图像处理技术和生物立体测量技术 ,求取乳房模型表面采样点的三维坐标 ,设计乳房体积测量运算模式 ,在Windows下编制程序 ,建立乳房体积测量和分析系统 ,应用所建的测量系统和水体积置换术分别对 12例乳房模型进行体积测量 ,并将两种测量方法及其结果进行比较和统计分析 ,观察其精确性和准确性。结果 本系统测量乳房体积实现了数据的快速处理 ,测试空间范围为12 0mm× 14 0mm× 80mm ,特点是快速、非接触性和非侵入性。与水体积置换方法比较 ,P =0 .4 73>0 .0 5 ,差值的 95 %可信区间为 - 14 .0 2~ 7.0 8ml。结论 本系统可应用于乳房体积测量 ,简捷而且精确 ,为临床工作提供了一种有效手段 ,并为软组织形态分析的开展提供了一种新的理论基础。 相似文献
72.
A method has been derived for calculating the mean absorption time of an oral drug and its interconversion metabolite which is generated from the drug systemically and presystemically. The method evolves from the convolution integral and requires plasma AUC and AUMC values after separate intravenous administration of the drug and its interconversion metabolite and oral administration of the drug. It can also be used to calculate the mean input time of a drug undergoing reversible metabolism and administered by any other extravascular route. Results of a simulation study using both errorless and errant data indicate that, when the absorption rate constant of a drug or its interconversion metabolite is not much larger than the apparent elimination rate constant, the proposed method performs satisfactorily. However, when the absorption rate constant of a drug or its interconversion metabolite is much larger than the apparent elimination rate constant, the proposed method appears to be inaccurate. 相似文献
73.
Little is known about whether patients with photosensitive disorders exhibit a different ultraviolet erythema time course from subjects with a normal response to sunlight. We have described the application of an instrument for ambulatory monitoring of the development of ultraviolet erythema by a reflectance method in a group of patients with chronic actinic dermatitis (CAD) and in a group of normal subjects. Investigations of the time course have been reported previously but the techniques used relied upon manual measurement. Consequently sampling frequencies have been considerably lower than the one-minute sample rate used here. We have not demonstrated any difference in the rate at which erythema develops and peaks between patients with CAD and subjects with a normal response to sunlight. 相似文献
74.
75.
把分段线性函数和斜波脉冲函数进行统一处理,定义成新的函数,使得新的函数既保持了原先两种函数的基本特性,又获得微分和积分递推算法。应用中具有方便,快速计算的优点。 相似文献
76.
T.G. van Kooten J.M. Schakenraad H.C. van der Mei A. Dekker C.J. Kirkpatrick H.J. Busscher 《Medical engineering & physics》1994,16(6):506-512
In this study, human umbilical vein and human saphenous vein endothelial cells were seeded on glass and exposed to fluid shear in a parallel-plate flow chamber. Cell retention, morphology and migration were studied as a function of shear stress and of adhesion time prior to exposure to shear. Three-hour and 24-h adhesion times gave rise to comparable cell retention values after 2 h of flow for both cell types. Cell retention decreased from 85 to 20% as shear stress increased from 88 to 264 dynes cm−2 (8.8 to 26 Pa). Mean spreading areas decreased after the onset of flow, but subsequently stabilized to plateau values, which were smaller at higher shear stresses. Shape factors increased faster to higher values as cells were exposed to higher shear stresses, without any obvious preference in orientation of the cells with respect to the direction of flow. Migration was unidirectional with flow and linear with time. Migration was faster for cells which had adhered for 24 h than for cells which had adhered for 3 h and was accompanied by the presence of fibrillar structures left behind on the surface upstream of migrating cells. It is concluded that after 3 h adhesion to glass, cells have adhered with an adhesion strength that does not substantially increase during the next 21 h. However, during this time changes in cell-substratum interactions seem to occur judging by the differences in, e.g., migration rates. 相似文献
77.
用机械分离法从豚鼠前庭感觉上皮中分离出不同种类的前庭感觉毛细胞(VHC)。VHC主要可分为Ⅰ型和Ⅱ型细胞。两种细胞形态虽有所差异,但一般均有四形或瓶形胞体,胞核位于细胞基部,胞颈和纤毛变化较大。细胞的活性可通过1%中性红染色鉴定,发现在室温下,1h内大约90%以上的分离VHC可维持其正常形态和活性。并参照对外毛细胞形态的研究提出活性VHC的鉴别标准。此项工作为进一步研究VHC的感觉机制和某些疾病的发生机理打下了基础。 相似文献
78.
79.
目的探讨首次自杀未遂者和重复自杀未遂者的区别.方法检查126名因自杀未遂而入院的患者,分为首次自杀未遂组和重复自杀未遂组,获得有关的临床资料并进行自杀意图及自杀企图冲动性和致死性的测定,将有关项目作对比分析.结果有51(40.5%)名重复自杀未遂者,与首次自杀未遂者比较,重复自杀未遂者已婚居多、文化程度较低、缺乏固定的经济收入、有较多的既往精神科治疗史、常饮酒、企图自杀前与他人交流少,自杀意图较低,冲动性较高(P均<0.05).结论对伴有某些危险因素的自杀未遂者应积极进行医学干预,以期减少自杀行为的再次发生. 相似文献
80.
Bennet Givens 《Psychopharmacology》1997,129(2):135-140
Acute exposure to ethanol produces deficits in sustained attention in humans, but these attentional deficits have not been
modeled in animals. In this study, an operant task was used to investigate the effects of low and moderate doses of ethanol
on sustained attention in rats. Performance on a two-choice reaction time task over a 1-h session was assessed immediately
following administration of ethanol (0.0, 0.5, 0.75, 1.0 and 1.5 g/kg IP). Each rat was required to respond to a light stimulus
of variable duration (20, 100, and 500 ms) occurring at one of two locations. Under control and saline conditions, increases
in stimulus length systematically increased choice accuracy and decreased reaction time. Ethanol produced a dose-dependent
decrease in choice accuracy that interacted with time, with an initial impairment that was stimulus length-dependent followed
by a general vigilance decrement. The data demonstrate that ethanol impaired the ability of rats to direct and sustain attention
to brief, infrequent stimuli, and provide a model for further investigations into the underlying neurobiological mechanisms
for ethanol-induced attentional deficits.
Received: 19 March 1996 / Final version: 30 August 1996 相似文献