Macro- and microscale variables regulate stent haemodynamics,fibrin deposition and thrombomodulin expression

Drug eluting stents are associated with late stent thrombosis (LST), delayed healing and prolonged exposure of stent struts to blood flow. Using macroscale disturbed and undisturbed fluid flow waveforms, we numerically and experimentally determined the effects of microscale model strut geometries upon the generation of prothrombotic conditions that are mediated by flow perturbations. Rectangular cross-sectional stent strut geometries of varying heights and corresponding streamlined versions were studied in the presence of disturbed and undisturbed bulk fluid flow. Numerical simulations and particle flow visualization experiments demonstrated that the interaction of bulk fluid flow and stent struts regulated the generation, size and dynamics of the peristrut flow recirculation zones. In the absence of endothelial cells, deposition of thrombin-generated fibrin occurred primarily in the recirculation zones. When endothelium was present, peristrut expression of anticoagulant thrombomodulin (TM) was dependent on strut height and geometry. Thinner and streamlined strut geometries reduced peristrut flow recirculation zones decreasing prothrombotic fibrin deposition and increasing endothelial anticoagulant TM expression. The studies define physical and functional consequences of macro- and microscale variables that relate to thrombogenicity associated with the most current stent designs, and particularly to LST.     

多隧洞输水工程进水口整流措施研究

多隧洞输水工程进水口控制段布置不合理往往会引起各隧洞分流不均,从而导致过流能力不足或空气进入有压隧洞的问题。以某水资源配置工程的倒虹吸为例,针对其进口控制段分流不均的现象,通过模型试验进行了分流墩、整流池以及底坎与整流池组合等整流措施的研究。试验成果表明:分流墩结构型式简单,利用其导向功能可较好地解决两洞分流不均问题;整流池通过改变水流的急缓流状态实现水流的横向均化,可达到多隧洞均匀分流的目的,但需要较长的池长,经济性略差;整流池与底坎组合措施横向均化水流的原理和效果与整流池相同,加设底坎可较大程度地缩短池长,其经济性较优。     

Hydrodynamic drag constrains head enlargement for mouthbrooding in cichlids

Presumably as an adaptation for mouthbrooding, many cichlid fish species have evolved a prominent sexual dimorphism in the adult head. Since the head of fishes serves as a bow during locomotion, an evolutionary increase in head volume to brood more eggs can trade-off with the hydrodynamic efficiency of swimming. Here, the differences between males and females in three-dimensional shape and size of the external head surfaces and the effect thereof on drag force during locomotion was analysed for the Nile tilapia (Oreochromis niloticus), a maternal mouthbrooder. To do so, three-dimensional body surface reconstructions from laser scans and computational fluid dynamics simulations were performed. After scaling the scanned specimens to post-cranial body volume, in order to theoretically equalize propulsive power, the external volume of the head of females was 27% larger than that of males (head length + 14%; head width + 9%). These differences resulted in an approximate 15% increase in drag force. Yet, hydrodynamics imposed important constraints on the adaptation for mouthbrooding as a much more drastic drop in swimming efficiency seems avoided by mainly enlarging the head along the swimming direction.     

Environmental impact assessment process substitution: experiences of public participants

This paper explores policy action taken by the federal government in Canada to test the potential for substitution of the federal process to regulatory bodies as a means of encouraging environmental impact assessment (EIA) efficiency. Our purpose is to present the experiences of people who participated in the EIA of the Emera Brunswick Pipeline in order to gauge the impact of such process substitutions on meaningful public participation. Our approach included document reviews and a focus group session with some of the public participants in the Emera Pipeline hearings. We find that the National Energy Board hearing process substituted in the case did not meet many of the key requirements of meaningful participation and left some public participants feeling disrespected and marginalized.     

Great differences in the ways of implementing the new EIA Directive – the offerings of the EIALAW 2018 conference

On the 23 March 2018, the most recent developments of the environmental impact assessment (EIA) law were examined by experts in Helsinki. The main theme of the conference was the comparison of the implementation experiences of various countries concerning the reformed EU EIA Directive. The European EIA debate was reflected against experiences in Canada. This paper examines the key points of the conference presentations and the lessons of the event.     

基于整流化的生产线精益改善方法研究

针对某数字相控阵雷达的核心部件数字阵列模块生产线存在的产能不足、物流路径混乱、生产线不平衡、操作人员疲劳强度高等问题,提出了基于整流化理论的精益改善方案.通过秒表测时、工序内作业拆分、生产线布局调整、瓶颈工序改善、节拍确定和全工序流动等方法实现了在减人缩时的情况下产能提升了50％、日增值工作时间比率从73.9％提高到87.9％.生产线平衡率由原来的55.8％提高到90.3％、在制品数量从76件降低到16件.并应用元单位量份配送方式进行生产线各工位的消耗物料补充,通过带有标签的空盒回收实现对线下准备区作业的看板拉动.     

人才流动与教师队伍建设

针对当前高校教师队伍建设中中青年教师的稳定问题,分析了中青年 状况,探讨人才流动的动机和影响教师职业稳定的社会因素,提出在人才流动中,优化教师队伍的一些措施和看法。     

城市电动汽车快充站网络建设管理探讨

分析当前城市电动汽车充电设施存在的主要问题,介绍基于流程的城市快充站网络建设管理理念和过程,提出城市电动汽车快充站网络建设管理改进方向,为城市电动汽车充电设施建设提供参考。     

提升赢利能力 打造核心竞争力

竞争日趋激烈的时代，打造竞争对手无法跨越的差异化优势已成为各企业关注的焦点和工作重心，而形成这种差异化优势的关键是要提升企业赢利能力，打造企业的核心竞争力。从如何提升企业赢利能力方面阐述和分析强化企业内部管理，把有限的资源用到最需要的地方，精简高效，夯实基础的必要性和方法，从找准核心业务与核心产品，重点突破、做精做强的角度来阐述如何打造企业的核心竞争力。     

Stent strut streamlining and thickness reduction promote endothelialization

Stent thrombosis (ST) carries a high risk of myocardial infarction and death. Lack of endothelial coverage is an important prognostic indicator of ST after stenting. While stent strut thickness is a critical factor in ST, a mechanistic understanding of its effect is limited and the role of haemodynamics is unclear. Endothelialization was tested using a wound-healing assay and five different stent strut models ranging in height between 50 and 150 µm for circular arc (CA) and rectangular (RT) geometries and a control without struts. Under static conditions, all stent strut surfaces were completely endothelialized. Reversing pulsatile disturbed flow caused full endothelialization, except for the stent strut surfaces of the 100 and 150 µm RT geometries, while fully antegrade pulsatile undisturbed flow with a higher mean wall shear stress caused only the control and the 50 µm CA geometries to be fully endothelialized. Modest streamlining and decrease in height of the stent struts improved endothelial coverage of the peri-strut and stent strut surfaces in a haemodynamics dependent manner. This study highlights the impact of the stent strut height (thickness) and geometry (shape) on the local haemodynamics, modulating reendothelialization after stenting, an important factor in reducing the risk of stent thrombosis.