The effects of a second tunnel on the propagation of ground-borne vibration from an underground railway

Accurate predictions of ground-borne vibration levels in the vicinity of an underground railway are greatly sought in modern urban centers. Yet the complexity involved in simulating the underground environment means that it is necessary to make simplifying assumptions about this environment. One such commonly-made assumption is to model the railway as a single tunnel, despite many underground railway lines consisting of twin-bored tunnels. A unique model for two tunnels embedded in a homogeneous, elastic full space is developed. The vibration response of this two-tunnel system is calculated using the superposition of two displacement fields: one resulting from the forces acting on the invert of a single tunnel, and the other resulting from the interaction between the tunnels. By partitioning of the stresses into symmetric and anti-symmetric mode number components using Fourier decomposition, these two displacement fields can by calculated with minimal computational requirements. The significance of the interactions between twin-tunnels is quantified by calculating the insertion gains that result from the existence of a second tunnel. The insertion-gain results are shown to be localized and highly dependent on frequency, tunnel orientation and tunnel thickness. At some locations, the magnitude of these insertion gains is greater than 20dB. This demonstrates that a high degree of inaccuracy exists in any surface vibration-prediction model that includes only one of the two tunnels. © 2012 Springer.

盘qu属鱼类口吸盘的形态分化及其意义

具大、小吸盘的两个类群是盘qu鱼类在演化进程中分化成的两个自然类群, 它们为适应不同的栖息环境, 吸盘的微观结构和须的长短等进一步分化, 分化途径在两个类群各不相同。图版2参9

涡鞭毛虫(甲藻)着丝粒/动粒蛋白的检索

用ACA血清作荧光观察, 隐沟虫细胞动粒蛋白表明, 隐沟虫的这些蛋白虽结合在核骨架上, 但在间期时并不形成点状的前着丝粒。免疫印迹检查表明隐沟虫和尖尾虫的着丝粒蛋白B彼此一致, 而且与四膜虫和眼虫也高度一致。但用ACA血清作免疫印迹检查时, 尖尾虫的蛋白虽与四膜虫和眼虫的相近, 与隐沟虫的却有极大的差异。以抗动粒蛋白的单抗作此种检查时, 尖尾虫与眼虫的反应带相同, 而隐沟虫则与源真核生物(Archezoa)贾第虫(Giardia lamblia)的相同; 而且隐沟虫和贾第虫都与几种原细菌有两条相同的反应带。

A microfluidic device for high density hydrodynamic cell trapping, growth and super-resolution imaging

Super-Resolution imaging techniques such as Fluorescent Photo-Activation Localisation Microscopy (FPALM) have created a powerful new toolkit for investigating living cells, however a simple platform for growing, trapping, holding and controlling the cells is needed before the approach can become truly widespread. We present a microfluidic device formed in polydimethylsiloxane (PDMS) with a fluidic design which traps cells in a high-density array of wells and holds them very still throughout the life cycle, using hydrodynamic forces only. The device meets or exceeds all the necessary criteria for FPALM imaging of Schizosaccharomyces pombe and is designed to remain flexible, robust and easy to use. © 2011 IEEE.

饲养条件下白豚微量元素的积累

中国科学院水生生物研究所留学归国人员基金资助项目(020102); 中国水产科学研究院首席科学家基金资助项目(1-105011)