This paper focuses on the symmetry analysis for brain MRI images in 2D slices. It can be used to detect 2D pathological
brain automatically. The main challenges in this work are the extraction of the geometry symmetry axis (GSA) from both
normal and pathological neuroimages and the quantification of the symmetry for the gray level distribution (GLS) of the
brain with the GSA. We present a fast approach to extract the GSA based on a group of assistant parallel lines and to
make veracity estimation for the GSA using the resultant moment of gravitational force (RMGF), followed by
quantification for the two hemispheres partitioned by the GSA based on the correlation to the GLS. Finally, the
quantification results are considered as a feature to distinguish the normal and abnormal brain slices. In the experiment
result, the mean running time of each symmetry quantization measure for 181×217 2D 8bits MRI images was 0.91
seconds, the area of the corresponding ROC curve to distinguish the normal and abnormal brain of this approach is
0.9628, which shows that to detect the pathological brain in MRI based on this symmetry analysis is fast and effective.
During the STM-based surface modification process, the phenomena of tip-sample interaction in the case of sample bias voltage were studied in the paper. It's found that the high local current density in the tip-to-sample spacing can raise the temperature in a very small volume near the surface of sample. The local high temperature environment resulted to local melting of SiO2 glass substrate with Cr film coating. During the modification process, the Si tip oscillated with large amplitude and inserted into the glass substrate due to attractive capillary force of molten liquid. The surface can be modified and a Cr-rich hillock formed in the scanning process. A jump-to-contact mechanism can be applied to explain the surface modification process. In some special conditions, the Si tip can be bonded with glass substrate in the area on micrometer scale. The bonding strength is high. The micro-bonding technique can be applied for assembly and repair of complicated MEMS.
We report studies on photobleaching process of polymer waveguides by means of a high pressure mercury lamp. After considering the film shrinkage and the surface index in the bleaching front, an inversed treatment based on the improved WKB method was employed to determine the index profiles of the bleached polymer film using experimentally measured mode indices. Index profiles presented in this paper are consistent with the photobleaching kinetics.
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