Influence of head model in biomagnetic source localization

Summary We evaluated the influence of the head model on biomagnetic source localization by utilizing a computer simulation. We localized the source of a magnetic field that was calculated using a realistic head model, and then evaluated the localization errors. It was seen that the sphere model adequately localized the dipole in cases near the sensor, but not in cases where the dipole was deeply situated.     

Automatic boundary identification of a region in gamma camera image

A new automatic method for the identification of the boundary of an image obtained with a gamma camera is proposed. The advantages of this method are a short calculation time and its applicability to images with a low signal-to-noise ratio. The limitations of the method are discussed.     

实验性隐睾术后大白鼠生精上皮的反应性变化——一,光镜下形态学观察

本文报道人工隐睾术后雄性成年大白鼠生精上皮的组织学变化。术后1—10天,曲细精管界膜呈波纹状收缩、增厚和断裂。支持细胞发生空泡样变。各级生精细胞的增生、分化失调、排列紊乱、游离和逐渐退化,出现双核和多核细胞。术后15—30天,上皮中只剩支持细胞和精原细胞,其它生精细胞逐渐消失。术后40—70天,形态学变化处于相对稳定状态。本文提出了实验性隐睾术后,引起生精上皮的原发性和继发性变化,生精上皮各种细胞对腹温的敏感性和耐受性的差异,初步讨论了多核细胞形成机理及生物学意义。     

Supervised Segmentation of Polycystic Kidneys: a New Application for Stereology Data

Stereology is a volume estimation method, typically applied to diagnostic imaging examinations in population studies where planimetry is too time-consuming (Chapman et al. Kidney Int 64:1035–1045, 2003), to obtain quantitative measurements (Nyengaard J Am Soc Nephrol 10:1100–1123, 1999, Michel and Cruz-Orive J Microsc 150:117–136, 1988) of certain structures or organs. However, true segmentation is required in order to perform advanced analysis of the tissues. This paper describes a novel method for segmentation of region(s) of interest using stereology data as prior information. The result is an efficient segmentation method for structures that cannot be easily segmented using other methods.     

磁敏感加权成像(SWI)在高级别脑胶质瘤手术中的应用价值

目的探讨磁敏感加权成像在高级别脑胶质瘤手术中的指导价值。方法回顾性分析35例高级别胶质瘤病例的MRI资料,比较SWI与常规包括T1WI、T2WI、T2-FLAIR序列相比在显示肿瘤血运、边界方面的优势,探讨SWI在高级别胶质瘤手术中的指导作用。结果 SWI较其他序列在显示胶质瘤边界、病理静脉、出血灶方面显示清楚,对手术计划的制定、术后放疗有指导作用。结论 SWI在显示胶质瘤边界、病理静脉、出血灶情况方面具有优势,对胶质瘤手术制定具有指导意义。     

基于形态学滤波的寄生虫卵图像混合分割算法

寄生虫卵的自动识别是当今寄生虫医学图像处理的一个重要课题,目前已有算法一般都要求寄生虫标本杂质含量较少。提出一种基于形态学滤波的混合分割算法,首先采用B颜色信号提取有用信息,接着利用改进的形态学操作进行滤波,除去大量杂质及虫卵边缘粘合物,最后结合凸包运算并定义两个图像特征参数,即边界光滑度和区域填充度,做进一步选择。实验结果表明,该算法明显优于当前的一些虫卵分割算法,能充分利用虫卵的有用信息,有效剔除杂质,大大降低虚假目标。虫卵边界保留完整清晰,为寄生虫卵的自动识别打下了良好基础。     

Estimation of the Shear Stress on the Surface of an Aortic Valve Leaflet

The limited durability of xenograft heart valves and the limited supply of allografts have sparked interest in tissue engineered replacement valves. A bioreactor for tissue engineered valves must operate at conditions that optimize the biosynthetic abilities of seeded cells while promoting their adherence to the leaflet matrix. An important parameter is shear stress, which is known to influence cellular behavior and may thus be crucial in bioreactor optimization. Therefore, an accurate estimate of the shear stress on the leaflet surface would not only improve our understanding of the mechanical environment of aortic valve leaflets, but it would also aid in bioreactor design. To estimate the shear stress on the leaflet surface, two-component laser-Doppler velocimetry measurements have been conducted inside a transparent polyurethane valve with a trileaflet structure similar to the native aortic valve. Steady flow rates of 7.5, 15.0, and 22.5 L/min were examined to cover the complete range possible during the cardiac cycle. The laminar shear stresses were calculated by linear regression of four axial velocity measurements near the surface of the leaflet. The maximum shear stress recorded was 79 dyne/cm², in agreement with boundary layer theory and previous experimental and computational studies. This study has provided a range of shear stresses to be explored in bioreactor design and has defined a maximum shear stress at which cells must remain adherent upon a tissue engineered construct. © 1999 Biomedical Engineering Society. PAC99: 8719Rr, 8768+z, 8719Hh, 4262Be, 4727Nz, 0630Gv     

信息技术压力对医护人员离职倾向的影响机制研究

目的：探索信息技术压力对医护人员离职倾向的影响,工作干涉家庭的中介作用以及边界管理偏好的调节作用。方法：采用信息技术压力量表、工作干涉家庭量表、边界管理偏好量表和离职倾向量表对北京市6家三级甲等综合医院的817名医护人员进行问卷调查。结果：信息技术压力会导致医护人员离职倾向的增加;工作干涉家庭在信息技术压力和离职倾向间发挥了部分中介作用;边界管理偏好不仅调节了信息技术压力对工作干涉家庭的影响,还调节了工作干涉家庭在信息技术压力与离职倾向间的中介作用。结论：当前医护人员的离职倾向较高,信息技术压力会通过工作干涉家庭进一步提高其离职倾向,边界管理偏好能缓解信息技术压力对工作干涉家庭的影响。各医疗机构及管理者应重视信息技术使用对医护人员的负面效应,积极疏解信息技术带来的压力,帮助医护人员做好边界管理。