Acute development of collateral circulation and therapeutic prospects in ischemic stroke

In acute ischemic stroke,collateral circulation plays an important role in maintaining blood flow to the tissue that is at risk of progressing into ischemia,and in increasing the successful recanalization rate without hemorrhagic transformation.We have reported that well-developed collateral circulation is associated with smaller infarct volume and better long-term neurological outcome,and it disappears promptly once the effective recanalization is achieved.Contrary to the belief that collateral vessels develop over time in chronic stenotic condition,there exists a phenomenon that collateral circulation develops immediately in acute stenosis or occlusion of the arteries and it seems to be triggered by fluid shear stress,which occurs between the territories of stenotic/occluded arteries and those fed by surrounding intact arteries.We believe that this acute development of collateral circulation is a target of novel therapeutics in ischemic stroke and refer our recent attempt in enhancing collateral circulation by modulating sphingosine-1-phosphate receptor 1,which is a known shear-stress mechanosensing protein.

Formation mechanism of a rainfall triggered complex landslide in southwest China

This case study is about a landslide that occurred after 4 days of heavy rainfall,in the morning of June 29,2012,in Cengong County,Guizhou Province of China,geographical coordinated 108°20′-109°03′E,27°09′-27°32′N,with an estimated volume of 3.3×106 m3.To fully investigate the landslide process and formation mechanism,detailed geotechnical and geophysical investigations were performed including borehole drilling,sampling,and laboratory tests coupled with monitoring of displacement.Also,a combined seepage-slope stability modeling was performed to study the behavior of the landslide.After the heavy rainfall event,the sliding process started in this area.The landslide development can be divided into different parts.The man-made fill area,spatially distributed in the south side of the landslide area with low elevations,slid first along the interface between the slope debris and the strongly weathered bedrock roughly in the EW direction.Consequently,due to severe lateral shear disturbance,the slope in the main sliding zone slid next towards the SW direction,along the sliding surface developed within the strongly weathered calcareous shale formation located at a depth of 25-35 m.This means it was a rainfall triggered deep-seated landslide.Finally,retrogressive failure of a number of upstream blocks occurred,which moved in more than one direction.The initial failure of the man-made fill area was the‘engine’of the whole instability framework.This artificial material with low permeability,piled up in the accumulation area of surface and sub-surface and destroyed the drainage capacity of the groundwater.The numerical modeling results agreed with the analysis results obtained from the laboratory and field investigations.A conceptual model is given to illustrate the formation mechanism and development process of the landslide.

Multi-frequency lateral shear interferometer system for simultaneous measurement of thickness and three-dimensional shape

This Letter demonstrates a novel lateral shear interferometer system for simultaneous measurement of three-dimensional （3D） shape and thickness of transparent objects. Multi-frequency fringe patterns can be created by tilting mirrors at different inclination angles. With a single camera, the multi-frequency fringes are recorded in one image. The phase-shift of the fringes can be generated synchronously only by moving a plane-parallel plate along an in-plane parallel direction. According to the feature of transparent materials, the thickness and 3D shape can be reconstructed simultaneously based on the relationship between the in-plane displacement and their characteristics. The experiment was conducted on a thin transparent film subjected to a shearing force, which verifies the feasibility of the proposed system.