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1.
An efficient BASIC program was established on Apple-Ⅱmicrocomputer with the CHESTAC-35F pulmonary function testing system tocalculate the time-constant histogram from the spirogram.By a set of analogousstudies,we confirmed that the recovered time-constant histogram was within onecompartment of the assumed one and that the root of mean square values of theresiduals between the experimental and model volume-time curves was 0.02.Infour healthy adult subjects,the mean value of time-constant histograms(TCx)hadthe variation coefficient 6.6%.The results show that our method is reliable andreproducible,and it can be used for clinical investigation. 相似文献
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Septal unit activity and hippocampal EEG during the sleep-wakefulness cycle of the rat 总被引:1,自引:0,他引:1
The functional relationship between septal unit activity and hippocampal EEG was studied during the sleep-wakefulness cycle in chronically implanted unrestrained rats. Results were statistically analyzed in order to obtain the time interval and auto and crosscorrelation histograms. During REM sleep and restless wakefulness the hippocampal EEG showed a theta rhythm of 4–8 cps and the septal unit activity was characterized by the presence of rhythmic bursts with a frequency in every single instance similar to that of the hippocampus. The septal units showed a bimodal time interval histogram. Their autocorrelation histogram exhibited a sinusoidal pattern of decreasing amplitude. The crosscorrelation histogram of septal units and the hippocampal EEG also showed a sinusoidal pattern suggestive of the functional relationship between both neural structures. During slow wave sleep and quiet wakefulness there was a disappearance of the hippocampal theta rhythm and rhythmic septal unit bursts. The second mode was missing in the time interval histogram and the auto and crosscorrelation histograms showed an irregular pattern. It is concluded that medial septal nucleus and hippocampal temporal patterns of activity are similar during REM sleep and restless wakefulness. 相似文献
4.
医学图像增强的目的是通过图像增强的方法得到优化的医学图像,以帮助医生从图像中获得更多细节信息,进一步做出更加客观的诊断及制定更全面的治疗方案,在一定程度上可提高临床诊断的准确性。本文首先归纳总结当前应用较为广泛的医学图像增强处理技术,包括传统的图像增强方法、改进的图像增强方法、融合的图像增强方法以及深度学习方法,然后对这些方法的原理、优缺点加以分析和总结。最后指出无论是传统方法还是现代图像增强方法,都应在最大限度保留其优势的情况下进行融合,取长补短,注重简单化和时效性,使提高图像的视觉质量同时更具有实用性。 相似文献
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H. Ozaki MD H. Sato M. Hori T. Matsuyama K. Imai H. Yokoyama A. Kitabatake M. Inoue T. Kamadal 《European journal of clinical pharmacology》1992,43(5):455-461
Summary Xamoterol acts as a
1-adrenoceptor agonist at low sympathetic activity and as an antagonist at high activity. Although its long-term efficacy has been proven in patients with mild to moderate heart failure, it remains unclear which effect, agonism or antagonism, accounts for its long-term activity.To clarify the effect of xamoterol on cardiac sympathetic activity in daily life, 24-h R-R interval histograms were obtained during administration of xamoterol 100 mg b. d. for 1 week to 10 patients with mild to moderate heart failure. Eight normal subjects were also studied as controls. To examine the relation between the effect of xamoterol and sympathetic activity, plasma noradrenaline (NA) levels were measured under 5 graded conditions simulating daily living.Xamoterol administration significantly decreased the standard deviation of the R-R interval, both in patients with heart failure and in normal subjects. The mean R-R interval, however, was increased in patients with heart failure, relative to normal subjects.In both groups, the R-R interval histograms had two peaks, i. e. a short daytime peak and a long night-time peak. Xamoterol decreased the median of the night-time peak without changing the daytime peak in normal subjects. In contrast, it increased the median of the daytime peak without producing a significant change in the nighttime peak in patients with heart failure. Levels of plasma NA were significantly higher in patients than in normal subjects under all conditions.Thus, in normal subjects xamoterol predominantly increased the slower heart rate at night with only a minor effect on the higher heart rate in the daytime, whereas it predominantly attenuated the daytime tachycardia induced by sympathetic stimulation in patients with heart failure.It is concluded that xamoterol tends overall to act as a-adrenoceptor antagonist during the day, especially in the daytime in patients with mild to moderate heart failure. Its antagonist rather than its agonist effect may account for the long-term efficacy of xamoterol in patients with mild to moderate heart failure. 相似文献
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一种基于内容的医学图像检索方法的实现 总被引:4,自引:0,他引:4
介绍颜色相关图及其改进算法在医学图像检索中的应用,并与标准灰度直方图的检索效果做了比较. 相似文献
8.
提出一种从航空影像中自动提取主要道路的方法。以对称边缘方向直方图作为主要道路特征矢量,先采用一种顾及数据空间分布特性的模糊C均值聚类算法分割提取主要道路种子段,然后利用Snakes算法跟踪提取完整主要道路网络。实验结果表明,所提方法能有效地从航空影像中自动提取主要道路网。 相似文献
9.
《International journal of audiology》2013,52(3):137-149
In measurements near auditory threshold, the influence of nonstationary artifacts (movement, swallowing, muscle activity, etc.) leads to response-like averaged results which should be further evaluated before determining the objective threshold. It is pointed out that, especially in recording VIII-nerve compound action potentials, as well as cortical potentials near threshold, the difference-amplitude histogram is a helpful procedure for identifying real neural responses.Diazepam-induced reducation of amplitude of the averaged result observed in a few adults with relative weak response amplitudes leads to the conclusion that this was caused by a further increase of latency variability. It is also mentioned that a complex interplay exists between the influence of diazepam upon amplitude and latency variability of the single response, which sometimes may result in a peculiar response of the average (e.g., increase of both may result in no change of the average). 相似文献
10.
张加辉 《浙江中西医结合杂志》2021,31(11)
肝局灶性结节性增生(focal nodular hyperplasia, FNH)是一种较少见的良性富血供肿瘤样病变,是肝细胞对局部血管异常产生的一种反应性增生,而非真正意义上的肿瘤[1]。肝脏血管平滑肌脂肪瘤是肝脏内少见的肿瘤,由增生的厚壁血管、平滑肌及成熟的脂肪组织构成,且3种成分构成比例、分布各不相同,且具有潜在的恶性转化和自发破裂的危险,应该积极手术治疗[2]。肝脏血管平滑肌脂肪瘤可分为4 种类型:脂瘤型(脂肪含量≥ 70%)、肌样型(脂肪含量≤ 10%,上皮样型及梭形细胞型)、血管型(以多发粗大、扭曲的畸形血管为主)及混合型(3 种组成成分比例相近)[3]。肌样型及血管型是含微量成熟脂肪的少脂型血管平滑肌脂肪瘤(Low-fat hepatic angiomyolipoma,LF-HAML),与肝癌、肝腺瘤及FNH等肝脏富血供病变鉴别困难,术前FNH和LF-HAML在临床和影像表现存在较多的重叠[4],目前国内外对此研究较少,因此准确诊断并鉴别对确定治疗方案和改善患者预后至关重要, 纹理分析是影像组学研究的基础,在肿瘤病灶提取、定性、疗效评估及预后预测方面具有较高的价值[5-6]。笔者旨在探讨基于直方图的MRI-DWI纹理特征方法鉴别两种病变的价值。 相似文献