THE STABLE RECONSTRUCTION OF STRONGLY-DECAYING BLOCK SPARSE SIGNALS

In this paper,we reconstruct strongly-decaying block sparse signals by the block generalized orthogonal matching pursuit(BgOMP)algorithm in the l2-bounded noise case.Under some restraints on the minimum magnitude of the nonzero elements of the strongly-decaying block sparse signal,if the sensing matrix satisfies the the block restricted isometry property(block-RIP),then arbitrary strongly-decaying block sparse signals can be accurately and steadily reconstructed by the BgOMP algorithm in iterations.Furthermore,we conjecture that this condition is sharp.

Simulated annealing spectral clustering algorithm for image segmentation

The similarity measure is crucial to the performance of spectral clustering. The Gaussian kernel function based on the Euclidean distance is usual y adopted as the similarity measure. However, the Euclidean distance measure cannot ful y reveal the complex distribution data, and the result of spectral clustering is very sensitive to the scaling parameter. To solve these problems, a new manifold distance measure and a novel simulated anneal-ing spectral clustering （SASC） algorithm based on the manifold distance measure are proposed. The simulated annealing based on genetic algorithm （SAGA）, characterized by its rapid convergence to the global optimum, is used to cluster the sample points in the spectral mapping space. The proposed algorithm can not only reflect local and global consistency better, but also reduce the sensitivity of spectral clustering to the kernel parameter, which improves the algorithm’s clustering performance. To efficiently apply the algorithm to image segmentation, the Nystrom method is used to reduce the computation complexity. Experimental results show that compared with traditional clustering algorithms and those popular spectral clustering algorithms, the proposed algorithm can achieve better clustering performances on several synthetic datasets, texture images and real images.

Intravitreal brimonidine inhibits formdeprivation myopia in guinea pigs

Background:The use of ocular hypotensive drugs has been reported to attenuate myopia progression.This study explores whether brimonidine can slow myopia progression in the guinea pig form-deprivation(FD)model.Methods:Three-week-old pigmented male guinea pigs(Cavia porcellus)underwent monocular FD and were treated with 3 different methods of brimonidine administration(eye drops,subconjunctival or intravitreal injections).Four different concentrations of brimonidine were tested for intravitreal injection(2μg/μL,4μg/μL,20μg/μL,40μg/μL).All treatments continued for a period of 21 days.Tonometry,retinoscopy,and A-scan ultrasonography were used to monitor intraocular pressure(IOP),refractive error and axial length(AL),respectively.On day 21,guinea pigs were sacrificed for RNA sequencing(RNA-seq)to screen for associated transcriptomic changes.Results:The myopia model was successfully established in FD animals(control eye vs.FD eye,respectively:refraction at day 20,0.97±0.18 D vs.−0.13±0.38 D,F=6.921,P=0.02;AL difference between day 0 and day 21,0.29±0.04mm vs.0.45±0.03 mm,F=11.655,P=0.004).Among the 3 different brimonidine administration methods,intravitreal injection was the most effective in slowing myopia progression,and 4μg/μL was the most effective among the four different concentrations of brimonidine intravitreal injection tested.The AL and the refraction of the brimonidine intravitreal injection group was significantly shorter or more hyperopic than those of other 2 groups.Fourμg/μL produced the smallest difference in AL and spherical equivalent difference values.FD treatment significantly increased the IOP.IOP was significantly lower at 1 day after intravitreal injections which was the lowest in FD eye of intravitreal injection of brimonidine.At day 21,gene expression analyses using RNA-seq showed upregulation of Col1a1 and Mmp2 expression levels by intravitreal brimonidine.Conclusions:Among the 3 different administration methods,intravitreal injection of brimonidine was the most effective in slowing myopia progression in the FD guinea pig model.Intravitreal brimonidine at 4μg/μL significantly reduced the development of FD myopia in guinea pigs.Expression levels of the Col1a1 and Mmp2 genes were significantly increased in the retinal tissues of the FD-Inj-Br group.

Intravitreal brimonidine inhibits formdeprivation myopia in guinea pigs

Background:The use of ocular hypotensive drugs has been reported to attenuate myopia progression.This study explores whether brimonidine can slow myopia progression in the guinea pig form-deprivation(FD)model.Methods:Three-week-old pigmented male guinea pigs(Cavia porcellus)underwent monocular FD and were treated with 3 different methods of brimonidine administration(eye drops,subconjunctival or intravitreal injections).Four different concentrations of brimonidine were tested for intravitreal injection(2μg/μL,4μg/μL,20μg/μL,40μg/μL).All treatments continued for a period of 21 days.Tonometry,retinoscopy,and A-scan ultrasonography were used to monitor intraocular pressure(IOP),refractive error and axial length(AL),respectively.On day 21,guinea pigs were sacrificed for RNA sequencing(RNA-seq)to screen for associated transcriptomic changes.Results:The myopia model was successfully established in FD animals(control eye vs.FD eye,respectively:refraction at day 20,0.97±0.18 D vs.−0.13±0.38 D,F=6.921,P=0.02;AL difference between day 0 and day 21,0.29±0.04mm vs.0.45±0.03 mm,F=11.655,P=0.004).Among the 3 different brimonidine administration methods,intravitreal injection was the most effective in slowing myopia progression,and 4μg/μL was the most effective among the four different concentrations of brimonidine intravitreal injection tested.The AL and the refraction of the brimonidine intravitreal injection group was significantly shorter or more hyperopic than those of other 2 groups.Fourμg/μL produced the smallest difference in AL and spherical equivalent difference values.FD treatment significantly increased the IOP.IOP was significantly lower at 1 day after intravitreal injections which was the lowest in FD eye of intravitreal injection of brimonidine.At day 21,gene expression analyses using RNA-seq showed upregulation of Col1a1 and Mmp2 expression levels by intravitreal brimonidine.Conclusions:Among the 3 different administration methods,intravitreal injection of brimonidine was the most effective in slowing myopia progression in the FD guinea pig model.Intravitreal brimonidine at 4μg/μL significantly reduced the development of FD myopia in guinea pigs.Expression levels of the Col1a1 and Mmp2 genes were significantly increased in the retinal tissues of the FD-Inj-Br group.

基于辐射防护用参考人系列标准的中国参考人数学模型研究

目的:构建符合中国成年男性人体特征的辐射防护用中国参考人数学模型(CRH-MIRD)。方法:基于我国辐射防护用参考人系列标准(GBZ/T 200)数据,辅以《中国参考人解剖生理和代谢数据》和亚洲参考人数据,以欧美参考人数学模型(MIRD)为蓝本进行缩放修正,构建CRH-MIRD模型。利用蒙特卡罗方法计算不同射线能量、各种标准照射方式下CRH-MIRD模型主要组织器官的吸收剂量转换系数和全身有效剂量转换系数,与国际权威机构报告数据以及MIRD模型和体素模型计算数据进行对比、分析和验证。结果:利用2种模型计算所得的剂量转换系数基本反映中国参考人和欧美参考人的解剖数据差异,体素模型因其构建模式及参考人体特征数据不同,计算结果较上述2种模型有较大的差别。结论:基于中国参考人数据库,采用国际通用的辐射防护用人体数学模型构建方法建立的CRH-MIRD模型计算结果合理可信。