基于可导性方差分解的居民收入省际差距分析

本文提出了一个基于收入构成差异和收入差距动因的分解框架,旨在量化相关决定因素对居民人均收入省际差距的贡献度.从指标内在关联性维度将居民人均收入指标进行多指标分解,由此导出因变量指标与各自变量之和(或之乘积)之间存在恒等关系的表达式,并引入可导性方差分解法构造了地区间居民收入绝对差距和相对差距的结构与动因分解模型.研究结果表明,驱动2005-2012年中国居民人均收入省际间差距形成和缩小的首要动力是人均设备性资本,其次是非设备性资本与设备性资本比例;人力资本与总人口比例在差距形成和绝对差距缩小中具有显著的推动作用,但在相对差距缩小中表现出明显的抑制效应;非设备性资本产出率在差距形成中具有较大的推动作用,但在差距缩小中表现出巨大的抑制效应;劳动力与人力资本比例在差距形成和绝对差距缩小中具有显著的抑制作用,但在相对差距缩小中表现出巨大的推动作用;产出分配率在差距形成中发挥了较小的抑制作用,但在差距缩小中表现出巨大的遏制作用.

城市人口预测及其城市规划意义--以北京为例

以北京为例,通过将人口增长动因分解的方式,根据人口增长组分预测2020年人口规模。人口增长动因分解法将北京人口机械增长分为就业驱动、发展机会驱动、公共服务驱动、社会关系驱动等不同动因组分。根据对常住人口的预测(增长动因分解法),再考虑到未统计人口,北京2020年人口规模在3000万～3250万(包括常住人口和未统计人口)。最后, 本文指出,常住人口预测对北京这样的世界性城市的规划管理的意义有限,并对控制北京人口增长的措施和效果持有异议,提醒关注人口控制带来的空间蔓延发展及其严重后果,指出市场经济下城市人口增长的不可控性。

Molecular Characterization of Four ADF Genes Differentially Expressed in Cotton

Actin depolymerizing factor （ADF）, highly conserved in all eukaryotic cells, is a low molecular mass of actin-binding protein, which plays a key role in modulating the polymerizing and depolymerizing of the actin filaments. Four cDNAs （designated GhADF2, GhADF3, GhADF4, and GhADF5, respectively） encoding ADF proteins were isolated from cotton （Gossypium hirsutum） fiber cDNA library. GhADF2 cDNA is 705 bp in length and deduces a protein with 139 amino acids. GhADF3 cDNA is 819 bp in length and encodes a protein of 139 amino acids. GhADF4 cDNA is 804 bp in length and deduces a protein with 143 amino acids. GhADF5 cDNA is 644 bp in length and encodes a protein of 141 amino acids. The molecular evolutionary relationship of these genes was analyzed by means of bioinformatics. GhADF2 is closely related to GhADF3 （99% identity） and PetADF2 （89% identity）. GhADF4 is closely related to AtADF6 （78% identity）, and GhADF5 is closely related to AtADF5 （83% identity）. These results demonstrated that the plant ADF genes are highly conserved in structure. RT-PCR analysis showed that GhADF2 is predominantly expressed in fiber, whereas, GhADF5 is mainly expressed in cotyledons. On the other hand, it seems that GhADF3 and GhADF4 have no tissue specificity. Expression levels of different ADF genes may vary considerably in the same cell type, suggesting that they might be involved in regulating tissue development of cotton and the each ADF isoform may diverge to form the functional difference from the other ADFs during evolution.

An approach for complex activity recognition by key frames

A new method for complex activity recognition in videos by key frames was presented. The progressive bisection strategy(PBS) was employed to divide the complex activity into a series of simple activities and the key frames representing the simple activities were extracted by the self-splitting competitive learning(SSCL) algorithm. A new similarity criterion of complex activities was defined. Besides the regular visual factor, the order factor and the interference factor measuring the timing matching relationship of the simple activities and the discontinuous matching relationship of the simple activities respectively were considered. On these bases, the complex human activity recognition could be achieved by calculating their similarities. The recognition error was reduced compared with other methods when ignoring the recognition of simple activities. The proposed method was tested and evaluated on the self-built broadcast gymnastic database and the dancing database. The experimental results prove the superior efficiency.

中美两国数字经济效率测算、动因及演进

本文基于2013-2020年中美两国数字经济企业投入产出数据,综合运用BCC-DEA与超效率SBM模型、Dagum基尼系数、Epanechnikov核函数和绝对β收敛模型对中美两国数字经济产业效率进行分解测算,研究结果表明:(1)样本期内中国数字经济产业总效率高于美国,但其增长率低于美国同期水平。(2)中美两国数字经济产业总效率的改进主要来源于规模效率的提高,纯技术效率影响有限。(3)从核密度分析来看,中国数字经济产业效率双峰特征明显,有两极化趋势;同期美国数字经济产业效率核密度右移趋势显著,无双峰特征。(4)中美两国数字经济产业效率均存在绝对收敛现象。基于以上结论,本文提出促进我国数字经济产业发展的相关建议。