DESIGN OF EXACT REGENERATING HIERARCHICAL CODE FOR DISTRIBUTED STORAGE SYSTEM

Erasure code is widely used as the redundancy scheme in distributed storage system. When a storage node fails, the repair process often requires to transfer a large amount of data. Regenerating code and hierarchical code are two classes of codes proposed to reduce the repair bandwidth cost. Regenerating codes reduce the amount of data transferred by each helping node, while hierarchical codes reduce the number of nodes participating in the repair process. In this paper, we propose a "sub-code nesting framework" to combine them together. The resulting regenerating hierarchical code has low repair degree as hierarchical code and lower repair cost than hierarchical code. Our code can achieve exact regeneration of the failed node, and has the additional property of low updating complexity.

A CLASS OF DETERMINISTIC CONSTRUCTION OF BINARY COMPRESSED SENSING MATRICES

Compressed Sensing (CS) is an emerging technology in the field of signal processing, which can recover a sparse signal by taking very few samples and solving a linear programming problem. In this paper, we study the application of Low-Density Parity-Check (LDPC) Codes in CS. Firstly, we find a sufficient condition for a binary matrix to satisfy the Restricted Isometric Property (RIP). Then, by employing the LDPC codes based on Berlekamp-Justesen (B-J) codes, we construct two classes of binary structured matrices and show that these matrices satisfy RIP. Thus, the proposed matrices could be used as sensing matrices for CS. Finally, simulation results show that the performance of the proposed matrices can be comparable with the widely used random sensing matrices.

皮肤晚期糖基化终末产物与正常糖调节人群颈动脉粥样硬化的相关性

目的探讨皮肤晚期糖基化终末产物(AGEs)与正常糖调节人群颈动脉粥样硬化(AS)的相关性。方法本研究为横断面研究。采用2019年1—6月中国科学技术大学附属第一医院健康管理中心健康体检者资料, 选取40~79岁正常糖调节体检者902例, 根据颈动脉超声结果分为对照组530例, IMT增厚组150例, 斑块组222例。分别收集体检者性别、年龄、收缩压、舒张压、体质指数(BMI)、三酰甘油(TG)、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、空腹血糖(FPG)、糖化血红蛋白(HbA1c)、AGEs等信息。采用ANOVA单因素方差分析进行多组间比较。以Logistic回归分析筛选颈动脉粥样硬化斑块发生的独立影响因素, 采用Spearman相关分析检验AGEs与变量的相关性。以受试者工作特征(ROC)曲线评价AGEs预测正常糖调节人群发生颈动脉粥样硬化斑块的效能。结果对照组、IMT增厚组、斑块组三组间性别、年龄、SBP、DBP、TC、LDL-C、FPG、HbA1c、AGEs差异均有统计学意义(均P<0.05);斑块组年龄、SBP、AGEs均高于IMT增厚组[55(50, 60)比53(49, 56)岁;132(122, 141)比126(115, 142)mmHg(1 mmHg=0.133 kPa);74(67, 81)比72(67, 78)AU](均P<0.001);IMT增厚组年龄、LDL-C、HbA1c、AGEs均高于对照组[53(49, 56)比48(45, 52)岁;(2.8±0.7)比(2.7±0.7)mmol/L;5.4%(5.2%, 5.6%)比5.4%(5.1%, 5.6%);72(67, 78)比70(66, 76)AU](均P<0.05)。年龄(OR=1.179, 95%CI:1.107~1.255)、SBP(OR=1.045, 95%CI:1.013~1.077)、LDL-C(OR=2.028, 95%CI:1.036~3.969)、AGEs(OR=1.049, 95%CI:1.000~1.100)是正常糖调节人群发生颈动脉粥样硬化斑块的独立影响因素(均P<0.05)。AGEs与年龄、HbA1c、颈动脉粥样硬化斑块均呈正相关(r=0.407、0.092、0.172)(均P<0.01)。皮肤AGEs预测正常糖调节人群颈动脉粥样硬化斑块的ROC曲线下面积为0.650(95%CI:0.601~0.698), 最佳截断值是70.5, 灵敏度为65.8%, 特异度为56.9%。结论正常糖调节人群皮肤AGEs水平与AS的发生密切相关。