Simultaneous assay of platelet adhesion at multiple shear rates within a single microfluidic channel

Cardiovascular diseases are currently the major causes of mortality in the world, especially in developed nations. As a predominant one, thrombosis is the platelet aggregation induced by a high shear rate. Platelet aggregation assay can clarify the occurrence mechanism of thrombosis, as well as be used as an important tool in the clinical diagnosis, personalized treatment, and screening of anticoagulants. Thus, relevant studies attracted considerable attention. As an important step in platelet aggregation, platelet adhesion and its detection also attract intensive concern. Thus, some analytical methods have been developed for platelet adhesion assay, and the impact of shear rate is one of the focuses. Compared with other devices, biosensors can give a more accurate result within a shorter time. Furthermore, some biosensors can achieve real-time analysis. However, only one or several shear rates can be tested at the same time, which may decrease the analytical efficiency. Meanwhile, in most cases, only the average platelet adhesion effect within a reactor is detected, and the impact of the distribution of shear rates is improperly neglected. In this study, a microfluidic device with a single channel is designed and fabricated for platelet adhesion assay. When the platelet-rich plasma flows through the collagen-modified sensing surface of the channel bottom, the interaction between platelets and collagen molecules on the entire surface can be simultaneously monitored by using a surface plasmon resonance imaging (SPRi) system. A gradient of the shear rate (0–546 s^-1) could be formed within the channel by choosing a suitable depth-to-width ratio (1:5), so platelet adhesion at multiple shear rates could be monitored simultaneously. This method enables the measurement of the adhesion process of unlabeled platelets on the entire sensing surface, in vitro, at multiple shear rates. Such a system can obtain more accurate platelet adhesion result at a given shear rate than traditional methods. Furthermore, in an individual operation, platelet adhesion can be repeatedly tested at multiple points with an equal shear rate, so a much higher analytical efficiency can also be achieved.     

基于直觉模糊Petri网的加权直觉模糊推理

利用直觉模糊集合较好地表现不确定信息的能力和Petri网的并行处理能力,构建了直觉模糊Petri网模型。给出了输入权值、变迁阈值等多种约束条件下的直觉模糊推理算法。该算法将直觉模糊推理过程转化为矩阵的运算过程可充分利用直觉模糊Petri网的并行推理能力,有效地避免同一变迁不必要地重复激发从而节省推理时间。实例分析表明所给出的直觉模糊推理算法较已有算法更加合理并且高效。     

Reachability determination in acyclic Petri nets by cell enumeration approach

Reachability is one of the most important behavioral properties of Petri nets. We propose in this paper a novel approach for solving the fundamental equation in the reachability analysis of acyclic Petri nets, which has been known to be NP-complete. More specifically, by adopting a revised version of the cell enumeration method for an arrangement of hyperplanes in discrete geometry, we develop an efficient solution scheme to identify firing count vector solution(s) to the fundamental equation on a bounded integer set, with a complexity bound of O((nu)^n−m), where n is the number of transitions, m is the number of places and u is the upper bound of the number of firings for all individual transitions.     

江苏太湖流域降雨径流年际变化分析

以江苏太湖流域（1956—2012）降雨为基础,分析江苏太湖流域径流及时空变化特征,研究该流域降雨径流的年际年内变化及两者的变化关系。结果表明：降雨径流都呈增长趋势。降雨平均每10年增加29mm,径流平均每10年增加26mm;降雨在年内季节分配上,夏季、冬季呈加大趋势,春季、秋季呈减小趋势;加大的降水年内分配的不均导致径流在年内分配的更加不均匀,径流集中在汛期,汛期径流量约达年径流量的84．8％,加大了某季节内的洪水、干旱风险。     

适用于页岩气藏储量的几种计算方法

页岩气在形式上以游离气和吸附气并存,存储空间上为孔隙和裂缝同存。页岩气藏的产气机制主要为游离气的扩散以及吸附气的解吸。基于此,分析页岩气储量计算的方法,如类比法、静态法、动态法。重点分析动态法,探讨不同方法的适用条件。分析页岩气储量计算中的几个关键因素,简要介绍其确定方法。     

基于DPI和机器学习的网络流量分类方法

网络流量分类是实现网络管理的重要技术之一,但是单一的基于DPI或是机器学习的分类方法分类精确度低.提出了一种基于DPI和机器学习相结合的网络流量分类方法.该方法采用DPI检测已知特征的网络流量,利用机器学习方法辅助分析未知特征以及加密的网络流.实验表明该方法能够提高网络流量分类的精确度.     

An improved security-aware packet scheduling algorithm in real-time wireless networks

Developing security-aware packet scheduling algorithms can efficiently enhance the security while delivering packets through wireless links. Existing scheduling algorithms developed for real-time wireless networks provide security at the cost of other important performance, e.g., schedulability. The performance problem becomes especially apparent when wireless networks are heavily loaded. To address this issue, we propose in this paper an improved security-aware packet scheduling algorithm (or ISAPS in short) in wireless networks. ISAPS first gives high priority to deal with schedulability when the real-time system is heavily loaded. When the system is under light workload, ISAPS strives to improve the security levels while achieving high schedulability for real-time packets. Compared with the existing packet scheduling algorithm SPSS, ISAPS shows excellent scheduling quality under a wide range of workload characteristics.     

一种性能优化的小文件存储访问策略的研究

在分布式文件系统中,小文件的管理一般存在访问性能较差和存储空间浪费较大等缺点.为了解决这些问题,提出了一种性能优化的小文件存储访问(SFSA)策略.SFSA将逻辑上连续的数据尽可能存储在物理磁盘的连续空间,使用Cache充当元数据服务器的角色并通过简化的文件信息节点提高Cache利用率,提高了小文件访问性能;写数据时聚合更新数据及其文件夹域中的相关数据为一次I/O请求写入,减少了文件碎片数量,提高了存储空间利用率;文件传输时利用局部性原理,提前发送批量的高访问率的小文件,降低了建立网络连接开销,提升了文件传输性能.理论分析和实验证明,SFSA的设计思想和方法能有效地优化小文件的存储访问性能.     

RBAC中基于信任的细粒度访问控制研究

针对传统的角色访问控制模型权限控制粒度较大,提出一种基于信任的细粒度访问控制模型,该模型在RBAC基础上引入授权信任约束,采用了一种基于忠诚度的信任度计算方法,有效地遏制恶意行为,实现细粒度访问控制。该模型不仅具有RBAC模型的所有优点,而且比RBAC模型具有更好的通用性、灵活性和可扩展性。     

PIC16F877单片机在智能站用电源系统中的应用

本文简述了智能站用电源系统的工作原理、构成与功能,介绍了PIC16F877单片机在智能站用电源系统中的应用,并分析了其硬件组成和软件功能。